# IEA Annex 26: Advanced Supermarket Refrigeration/Heat Recovery Systems

Final Report Volume 1 – Executive Summary

Canada
Denmark

Sweden United Kingdom United States (Operating Agent)

Compiled by

Van D. Baxter Oak Ridge National Laboratory Oak Ridge, TN, USA

April, 2003ii List of Contributors

This volume of the IEA Annex 26 final report contains a detailed summary of the Annex activities including principal conclusions from each participant. The following persons provided the information for this report.

Canada - Daniel Giguère
Natural Resources Canada CANMET Energy Technology Centre –Varennes (CETC) 1615 Lionel-Boulet Blvd., Box 4800 Varennes, Québec J3X 1S6
Canada 1-450-652-5015 phone
1-450-652-5177 fax daniel.giguere@nrcan.gc.ca

Vasile Minea Hydro Québec, Institut de recherché Laboratoire des technologi es de l'énergie (LTE) 600, avenue de la Montagne Shawinigan, Québec G9N 7N5
Canada 1-819-539-1400, ext 1507 phone
1-819-539-1409 fax minea.vasile@lte.ireq.ca

Denmark - Hans Jørgen Høgaard Knudsen Department of Mechanical Engineering Technical University of Denmark Nils Koppels Allé DTU – Building 402 DK-2800 Kgs. Lyngby, Denmark 45-45-254121 phone
45-45-935215 fax hk@mek.dtu.dk

Sweden - Per Lundqvist & Jaime Arias The Royal Institute of Technology Department of Energy Technology Div. of Applied Thermodynamics and Refrigeration S-100-44 Stockholm, Sweden 46-8-790-7452 phone (Lundqvist) 46-8-790-8642 phone (Arias)
46-8-20-3007 faxiii perlundq@egi.kth.se jaime@thermo.kth.se

UK - Alison Crompton
Faber Maunsell Marlborough House Upper Marlborough Road St Albans, Hertfordshire AL1 3UT United Kingdom 44-20-8784-5586 phone
44-20-8784-5562 fax alison.crompton@fabermaunsell.com

John Palmer
Faber Maunsell
Beaufort House
94/96 Newhall Street Birmingham B3 1PB United Kingdom 44-121-262-6750 phone
44-121-262-1999 fax john.palmer@fabermaunsell.com

US - Van D. Baxter
Steven K. Fischer Oak Ridge National Laboratory Box 2008, Bldg 3147, MS-6070 Oak Ridge, TN 37831-6070
USA 1-865-574-2104 phone (Baxter) 1-865-574-2017 phone (Fischer)
1-865-574-9329 or 9338 fax vdb@ornl.gov fis@ornl.gov

David H. Walker Foster-Miller, Inc.
350 Second Avenue Waltham, MA 02451 1-781-684-4237 phone
1-781-890-3489 fax dwalker@foster-miller.comiv Table of Contents

List of Contributors .......................................................................................................... .............. ii

Table of Contents.............................................................................................................. ............. iv

List of Figures................................................................................................................ ................ vi

List of Tables ................................................................................................................. ................ vi

Introduction to IEA Annex 26 ......................................................................................................1

Background

............................................................................................................................... .....2

General summary of system technology approaches to reduce supermarket TEWI ..............5 Secondary loop type systems ...................................................................................................6 Estimates of cost premium ..................................................................................................9 Estimates of TEWI reduction ............................................................................................10 Distributed compressor refrigeration system ......................................................................10 Estimates of cost premium ................................................................................................12 Estimates of TEWI reduction ............................................................................................12 Low charge multiplex systems ..............................................................................................12 Estimates of cost premium ................................................................................................14 Estimates of TEWI reduction ............................................................................................14 Advanced self-contained systems

.......................................................................................................... 14 Estimates of cost premium ................................................................................................15 Estimates of TEWI reduction ............................................................................................15 HVAC integration approaches .............................................................................................15

Country report summaries ..........................................................................................................18 Canada - CANMET Energy Technology Ce ntre –Varennes (CETC–Varennes) of
Natural Resources Canada ..............................................................................................18 Canada - Hydro-Quebec Research Institut, Laboratoire des technologies de l’énergie (LTE )

............................................................................................................................... ..20 Total Heat Recovery (”System1-phase1”) ........................................................................21 Total Heat Recovery (”System2–phase1”) ........................................................................21 High Speed Defrost ............................................................................................................23 Liquid Pumping and Injection ...........................................................................................23 Geothermal Cooling ...........................................................................................................24 Further Developments .......................................................................................................24

Denmark

............................................................................................................................... ..25
Sweden

............................................................................................................................... .....27 United Kingdom .....................................................................................................................33 Secondary Systems .............................................................................................................33 Defrost

............................................................................................................................... .34v CHP/CCHP ........................................................................................................................35
Case and Store Environment Interaction ...........................................................................36
UK Overall Conclusions ....................................................................................................37
United States ...........................................................................................................................37 System analysis summary ...................................................................................................38 Payback estimates ..............................................................................................................40 Field test summary .............................................................................................................41

Supermarket energy use screening level model ........................................................................42

Overall Summary .........................................................................................................................42
Canada

............................................................................................................................... .....43

Denmark

............................................................................................................................... ..43
Sweden

............................................................................................................................... .....44 United Kingdom .....................................................................................................................44
United States ...........................................................................................................................45 Summary comments ..............................................................................................................45

References

............................................................................................................................... ......46

Acknowledgements ......................................................................................................................47

Appendix A - Case Study Summaries ........................................................................................48
Canada - LTE .........................................................................................................................48

Denmark

............................................................................................................................... ..62
United States ...........................................................................................................................66vi List of Figures

Fig. 1. Layout of a typical modern supermarket .........................................................................3 Fig. 2. Total equivalent warming impact (TEW I) for low temperature supermarket refrigeration in North America . .............................................................................................4 Fig. 3. Multiplex refrigeration system ..........................................................................................5 Fig. 4. Elements of the secondary loop refrigeration system ......................................................7 Fig. 5. Propane/carbon dioxide cascade refrigeration system ....................................................8 Fig. 6. Distributed compressor refrigeration system schematic . .............................................11 Fig. 7. Low-charge multiplex system compressor rack concept 1 . ..........................................13 Fig. 8. Low-charge multiplex system compressor rack concept 2 . ..........................................13 Fig. 9. Roof top heat pump unit . .................................................................................................17 Fig. 10. Plate heat exchangers (HX) for heat pump evaporators and refrigeration desuperheaters and subcooler ...............................................................................................17 Fig. 11. Results from CyberMart ................................................................................................29 Fig. 12. Indoor temperature, outdoor temperature and indoor relative humidity in
Hedemora and Sala ................................................................................................................30 Fig. 13. Temperatures, relative humidity and compressor power in Sala. .............................31 Fig. 14. Temperatures in a deep freeze cabinet and indoor and outdoor temperatures during four days in July in Hedemora .................................................................................32 Fig. 15. Refrigeration energy usage in The United Kingdom by end use . ..............................33 Fig. 16. Example of freezer case type tested by UK team in environmental chamber to determine impact of store temperature, relative humidity and ventilation mode (conventional or displacement) on performance .................................................................36 Fig. A1. Comparison of energy use of Fakta Beder store (with cascade refrigeration system) to that of eight other Fakta stores (with conventional R404A DX refrigeration systems); July 2000 through February 2002 . .......................................................................................65

List of Tables

Table 1. Predicted Energy Consumption for Low-Charge Refrigeration Systems ................39
Table 2. Total Equivalent Warming Impact (TEWI) for Supermarket Refrigeration ..........401 Annex 26 Final Report Advanced Supermarket Refrigeration/Heat Recovery Systems Executive Summary

Introduction to IEA Annex 26

With increased concern about the imp act of refrigerant leakage on global warming, a number of new supermarket refrig eration system configurations requiring significantly less refrigerant charge are being considered. In order to help promote the development of advanced systems and expa nd the knowledge base for energy-efficient supermarket technology, the International En ergy Agency (IEA) established IEA Annex 26 (Advanced Supermarket Refrigeration/Heat Recovery Systems) under the IEA Implementing Agreement on Heat Pumping Technologies . Annex 26 focuses on demonstrating and documenting the energy saving and environmental benefits of advanced systems design for food refrig eration and space heating and cooling for supermarkets. Advanced in this context m eans systems that use less energy, require less refrigerant and produce lower refrigerant emi ssions. Stated another way, the goal is to identify supermarket refrigeration and HV AC technology options that reduce the total equivalent warming impact (TEWI) of superm arkets by reducing both system energy use (increasing efficiency) and reduci ng total refrigerant charge. The Annex has five participating countri es: Canada, Denmark, Sweden, the United Kingdom, and the United States. The work ing program of the Annex has involved analytical and experimental investigation of several candidate system design approaches to determine their potential to reduce re frigerant usage and energy consumption. Advanced refrigeration system types investigated include the following:

distributed compressor systems – small para llel compressor racks are located in close proximity to the food display cases they serve thus significantly shortening the connecting refrigerant line lengths; secondary loop systems – one or more centr al chillers are used to refrigerate a secondary coolant (e.g. br ine, ice slurry, or CO 2 ) that is pumped to the food display cases on the sales floor; self-contained display cases – each food di splay case has its own refrigeration unit; low-charge direct expansion – similar to conventional multi plex refrigeration systems but with improved controls to limit charge.

Means to integrate store HVAC system s for space heating/cooling with the refrigeration system have been investigated as well. One approach is to use heat pumps to recover refrigeration waste heat and raise it to a sufficient level to provide for store heating needs. Another invol ves use of combined heating and power (CHP) or combined cooling, heating, and power (CCHP) systems to integrate the refrigeration, HVAC, and power services in stores . Other methods including direct recovery of refrigeration reject heat for space and water heati ng have also been examined.2 A workshop on advanced supermarket refrigeration was held October 2-4, 2000 in Stockholm. Reports were made by Annex part icipants and other invited experts on the status of refrigeration resear ch and development activities in the US and Europe. The workshop proceedings (in cd-rom format) are av ailable from the IEA Heat Pump Centre (Lundqvist, ed, 2000). This report provides an account of the resu lts of the work programs of the Annex participants. This volume gives an executive summary of the results. Full details are given in the individual c ountry reports in volume 2.

Background

Supermarkets are one of the most energy- intensive types of commercial buildings. Significant energy is used to maintain chil led and frozen food in both product display cases and storage refrigerators. The refrigeration systems also produce a large amount of rejected heat that can be r ecovered and used by heat pumps or other equipment to provide space and water heating for store requirements. There is a wide range in size of supermarkets among the Annex 26 countries. In Europe stores range in size from about
500 m 2 to 3000 m 2 or somewhat larger. Stores are ty pically larger in Canada and the US ranging from a minimum of about 1000 m 2 to 10000 m 2 . Plant capacities range from 30-
60 kW for small markets to over 400 kW for th e largest stores. Similarly, annual energy use ranges from about 100,000 kWh/y for the smaller stores to 1.5 million kWh/y or more for the largest. Refrigeration is the largest component of supermarket energy use, accounting for
half or more of the store total. Perishab le products must be kept refrigerated during display and for storage. Compressors and condensers account for 60-70% of refrigeration energy consumption. The remai nder is consumed by the display and storage cooler fans, display case lighting, evaporator defrosting, and for anti-sweat heaters used to prevent condensate from forming on doors and outside surfaces of display cases. Figure 1 shows a representative layout fo r a supermarket showing refrigerated display cases and storage areas located generally around the st ore perimeter. The most commonly used refrigeration system for supermarkets today is the multiplex direct expansion (DX) system. All display cases a nd cold store rooms use direct expansion airrefrigerant coils that are connected to the sy stem compressors in a remote machine room
located in the back or on the roof of the store. This requ ires thousands of meters of pipe with case connections that have historically been designed for ease a nd rapidity of service rather than low leakage. This practice is changing for new supermarkets with more emphasis on reducing leakage. Heat rejecti on is usually done with air-cooled condensers
because these are the least cost to install and maintain. Evaporative condensers can be used as well and will reduce condensing temperature and system energy consumption. However, they carry the burden of increased maintenance effort and cost. In either case, system controls are usually set to allow the condensing temperature to float with the outdoor dry bulb (or wet bulb) temperature, usually to a minimum level of around 21 ° C (about the lowest condensing temperature fo r reciprocating compressors which are the most common type used in supermarkets).3 The amount of refrigerant needed to charge multiplex DX systems is very large - typically 4-5 kg/kW of refriger ation capacity. The large amount of piping and pipe joints required can also result in large refrigerant lo sses – historically 30% or more of the total charge annually. New systems can achieve annual refrigerant leakage rates of around 15% or somewhat lower (Sand, et al, 1997). The large refrigerant charge and high loss rate for multiplex direct expansion refrigera tion systems results in high values of TEWI (total equivalent warming im pact) with direct refrigerant loss impact accounting for about half of the total as shown in Figure 2.

Figure 1 – Layout of a typi cal modern supermarket

Figure 3 shows the major elements of a multiplex refrigeration system. Multiple compressors operating at the same saturated suction temperature ar e mounted on a skid, or rack, and are piped with common suction and discharge refrigeration lines. Using multiple compressors in parallel provides a means of capacity control, since the compressors can be selected and cycled as needed to meet the refrigeration load.4 Figure 2 – Total equivalent warming impact (TEWI) for low temperature supermarket refrigeration in North America5 Figure 3 – Multiplex refrigeration system

General summary of system technology approaches to reduce supermarket TEWI

Part of the UK’s contribution to the A nnex was a detailed review of existing technologies and new technologies for supermar kets (see UK country report, Volume 2).
The bottom line from this state of the art revi ew of advanced supermarket refrigeration is
that there are a number of areas in which si gnificant energy savings may be realized and environmental impact reduced. From the ove rall design of the en ergy supply, from CHP and CCHP, through to the intera ction of the store environment and the cabinets, savings
can be made. These factors offer a wide ra nge of opportunities to bring about reductions in the energy use and TEWI of supermarket refrigeration systems. The advanced supermarket refrigeration systems described in this section are designed primarily to reduce the amount of re frigerant needed for operation and thereby the amount of annual refrigerant loss. This is generally accomplished by use of secondary refrigerants in a secondary l oop type system, reduction of refrigerant connecting line length between compressors and display cases, improved refrigerant management and flow controls, or a combina tion of these approaches. Advantages and disadvantages of these systems with respect to energy efficiency and possible cost implications are briefly discussed in this sectio n also. These issues ar e dealt with in more6 comprehensive fashion in the individual country reports. Four generic system types have been investigated as part of the Annex 26 work effort. They are secondary loop, distributed, low-charge multiplex, and a dvanced self-contained systems.

Secondary loop type systems Secondary loop refrigeration systems can take many forms, but they generally employ one or more chillers to refrigerate a secondary fluid that is then pumped to the display cases and storage rooms. Figure 4 shows the elements of one secondary loop approach. In this case the chillers, simila r in configuration to multiplex compressor racks, provide chilled secondary refriger ant for the cases. The discharge of the compressors is to a common manifold and the discharge gas is piped to a remote condenser, normally located on the roof above the machine ro om. The use of evaporative condensing can produce the lowest average condensing temperature with lower fan energy than seen with air-cooled conde nsers, thus minimizing overall energy consumption especially in warmer climate ar eas. Primary refrigerant charge requirement
can be reduced to about 10-15% of that needed for conventiona l direct expansion system. A variation on the system shown in Figure 4 is to use a secondary fluid on the heat rejection (condenser) side of the chiller as well as on the refrigerati on (evaporator) side. This approach can reduce primary refrigerant requirements to less than 5% of direct expansion but would introduce an additional secondary heat exchanger thermodynamic energy penalty to the system and increase energy usage. Secondary loop systems have features that tend to improve the efficiency of the primary system. These include close coup ling of the compressors to the chiller evaporators, and the ability to subcool the primary refrigerant with the secondary fluid (brine) and use the warmed brine to defrost the case heat exchangers.7 Figure 4 - Elements of the secondary loop refrigeration system

For large stores secondary loop systems generally use at least two separate secondary fluid loops and chillers – one each for the low temperature (frozen food) cases and storage rooms and medium temperature (c hilled food) cases a nd rooms. Using only two fluid loops for refrigeration, however mean s that all display cases and storage coolers must operate with these two temperatures. The use of multiple secondary fluid loops with temperatures more closely matching the case air temperature requirements can improve energy efficiency because it raises the effective average evaporator temperature of the system. The US country report include s an analysis of such a system using four different fluid loops. It must be stated however, that each loop will require a separate
chiller and controls and that will increase the system cost. Another approach to sec ondary systems is the cascade-type system. Figure 5 schematically illustrates one example of a ca scade system. The high temperature loop (using propane as the refrigerant in this illustration) removes heat from the low temperature loop (using CO 2 ) condenser and also chills a brine (propylene glycol), which
is circulated to the chilled f ood cases. The CO 2 refrigerates the frozen food cases through direct expansion evaporators. Other combinat ions of refrigerants are possible for this
system concept.8 Figure 5 - Propane/carbon dioxide cascad e refrigeration system (from Danish country report)

The following is a listing of several candi date fluids for use in secondary loop systems that have been investigated in pr ior studies (Melinder, 2000; Kazachki, et al, 1997; Hrnjak, 1996; Hrnjak, 2000; Horton, 2002; Sherwood, 1999). Under Annex 26 some detailed property measurements and comparisons were conducted by the UK team (see country report in Volume 2).

Ethylene glycol/water Propylene glycol/water
Potassium Formate/water
Pekasol 50
Freezium Hycool Trichloroethylene
Inhibited alkali ethanate solution Tyfoxit Hydrofluoroether
HFE-L-13938
HFE-7100 Cyclohexene
D-Limonene Polydimethilsiloxane (Silicon Oil) Syltherm
Dowtherm Synthetic Isoparaffinic Petroleum Hydrocarbons
Therminol9 No single one of these fluids can be considered ideal fo r all secondary refrigerant applications. Those most widely used in supermarket systems appear to be propylene glycol/water solutions for medium temperature loops a nd potassium formate/water solutions for low temperature loops. However, some analytical studi es indicate thermal and pressure droop advantages for HFE-7100 over potassium formate solutions for low temperature applications -- below about - 20 °C (Sherwood, 1999; Ho rton, 2002). Liquid
CO 2 is also seeing increasing use as a seco ndary fluid for both temperature levels particularly in Europe. Means must be consider ed to deal with internal tube pressures in
CO 2 systems in the event of power outages or other failures. Estimates of cost premium . A number of studies have been conducted to estimate cost premiums with the added cost estimat es ranging from none to about 40%. A study by Sherwood (1999) compared installed costs for a secondary loop and a multiplex direct expansion system for a low-temperature system typical of North American supermarkets
– about 80 kW total coo ling capacity. The secondary system used NH 3 in the primary loop and HFE-7100 as the brine while the DX us ed R-404A. Installation cost (material and labor) for the DX system was the actual figure taken from the refrigeration schedule for the store. Costs for the secondary loop system were estimated based on interviews with supermarket industry professionals. Th is study considered the total cost of the system (including cases, piping, refrigerant, br ine, and labor in addition to the compressor rack or primary chiller) with the exception of the condenser subsystem. It was determined that installed costs for both appr oaches were equal – i. e., 0% cost premium for the secondary approach. Vana (2000) noted in discussions at the Annex 26 workshop that installation cost premiums for secondary loop approaches (usi ng R404A or R507 as primary refrigerant and propylene glycol or potassium formate br ines for secondary loops) were about 15% for typical US markets. He also noted that maintenance costs for the secondary system should be less. Horton (2002) conducted an operating (energy and maintenance) cost comparison between secondary loop (NH 3 primary/HFE-7100 secondary) and multiplex DX (R22 medium temperature/R404A low temp erature) systems and concluded that maintenance costs were 25% lower and operating costs 15% lower for the secondary approach. All of the operating savings were attributed to the high efficiency of the NH 3 primary system – high enough to overcome the secondary pumping power and heat transfer penalties in this analysis. A cost and payback analysis is include d in the US country report for secondary loop (R507 primary/ propylene glycol and potassium formate secondary brines) and multiplex DX (R22/R404A) systems serving a s upermarket with a 330 kW refrigeration load. The DX system was assumed to have standard air-cooled condensers while the secondary system was assumed to have evaporative condensers (to minimize energy use). The secondary system had an estimated in stallation cost premium of $147,000 US that was based on interviews with engineering de partments of two supermarket companies. Payback in this case ranged from 8 to 17 years depending on climate conditions. More details are given in the US report (in Volume 2). The Danish country report (Volume 2) co mpares installation costs and operating efficiencies for a cascade system based on that shown in Fi gure 5 and R404A DX systems. A test system installed in a sma ll store (30 kW load) was estimated to cost10 about 20% more than a traditional DX syst em and to have about the same energy efficiency. With more experience for installe rs the premium is estimated to drop to under 15%. For larger systems (90 kW) the prem ium is estimated to be 10% or less. Estimates of TEWI reduction. TEWI reduction estimates from the investigations carried out under Annex 26 range from <10% to about 60% compared to the multiplex DX/air-cooled condensing baseline. The wide ra nge in TEWI estimates is attributable to assumptions made about the overall system design (compressor type, heat rejection approach, selection of secondary fluid, etc. ) and operation. Secondary loop systems must be designed and operated carefully with an ey e to minimizing the inherent secondary heat exchange and pumping power penalties in orde r to achieve the greatest TEWI benefit.

Distributed compressor refrigeration system Figure 6 shows a diagram of the distributed compressor refrigeration system. The big difference between this system and conventional multiplex systems is that several small compressor racks are located in cabinet s that are distributed throughout the store and close-coupled to the display case lineups or storage rooms they serve. With this approach the long lengths of piping needed to connect the cases with large remote compressor racks in a machine room are eliminated. The cabinets may be placed either at the end of a case lineup on the sales floor or behind the cases around the perimeter of the

store. With this arrangement, the saturated suction temperature (SST) employed for each compressor cabinet can closely match th e evaporator temperature of the display
cases and walk-in coolers to wh ich it is connected. This is not always possible with conventional multiplex systems, since a single rack will often provide refrigeration to display cases with three or four different ev aporator temperatures. Each compressor rack of a multiplex system must operate at a SST value that will satisfy the temperature requirements of all display ca ses connected to it. The be tter temperature matching seen with distributed refrigeration can benefit th e energy consumption of the overall system. The refrigerant charge requirement for the distributed system is much less than for multiplex systems. The reduction in charge is due to the shortening of the suction and liquid lines to the display cases . If a secondary fluid loop is used for heat rejection (as shown in Figure 6) then the refrigerant heat rejection piping to a remote condenser and it’s associated charge is eliminated as well. With a secondary loop fo r heat rejection, the refrigerant charge required for a distribut ed system would be about 30-35% of that required for multiplex systems. If separate rooftop condensers are used for each cabinet, the total charge requirement will be about 50-60% that of multiplex systems. A secondary heat rejection loop will result in higher condensing te mperatures and energy consumption than if direct r oof top condensers are used.11 Figure 6 - Distributed compressor refrigeration system schematic

Each compressor cabinet in a distributed system is similar to a multiplex rack only smaller. All necessary electrical and piping connections are provided within the cabinet, such that the only field connections are the refrigerant liqui d and suction lines, fluid inlet and outlet piping for heat rejecti on, and electric servic e wiring. Multiple compressors of several sizes are employed, which are piped in parallel so that multiplex operation can be used to match the refrigera tion capacity to the load. Usually, three to five compressors are installed in each cabinet . The cabinets are equipped with discharge and suction manifolds for parallel piping of the compressors. The suction manifold can be divided so that multiple suction temperatur es can be provided from a single cabinet. Current distributed refrigeration system s generally employ scroll compressors, because of the very low noise and vibratio n levels encountered with this type of compressor. These characteristics are necessary if the compressor cabinets are located in12 or near the sales area. Current refrigeration scroll compressors are typically less efficient at evaporating and condensing temperatures of interest for supermarket refrigeration than the reciprocating types used in most conventional systems. However, they do have
several features that can offset this effici ency disadvantage in system applications and potentially yield system efficiency improveme nts. For instance, scroll compressors have no valves, and, therefore, can be operated at significantly lower condensing temperatures than can reciprocating compressors. The lo west condensing temperat ure possible is at a suction-to-discharge pressure ratio of two (2 ), which means for supermarket systems that the lowest condensing temperature possi ble is on the order of 10 – 15 °C. The close coupling of the display cases to the distributed refrigeration cabinets has other ramifications to energy consumption. The shorter suction lines mean that the pressure drop between the case evaporator and the compressor suction manifold should be less than that seen with conventional multiplex systems, which means that the compressors’ SST will be closer to the displa y case evaporator temperature. Typically, the SST of conventional multiplex racks will be 1-2.5 °C less than the case evaporator temperature. SST values for the distribute d system will be about 0.5-1 °C less than the case evaporator temperature. The shorter suc tion lines also mean that less heat gain to the return gas should be experienced. The cooler return gas has a higher density and results in higher compressor mass flow rates, which means that less compressor on time is needed to satisfy the refrigeration load. The return gas temperat ure rise expected for distributed refrigeration systems is normally on the order of 3 to 9 °C, depending on the distance between the compressor cabinet and the display cases and the evaporator temperature of the display cases. A greater re turn gas temperature rise is seen in low temperature systems than is seen in medium temperature. In comparison, the return gas temperature rise typically seen with multiple x systems falls between 20 and 35 °C, due to the longer length of suction lines employe d. The liquid temperature can also be adversely affected by line length if subcoolin g is employed. Heat gain to a subcooled liquid line will result in a rise in liquid refr igerant temperature before reaching the display

cases. Estimates of cost premium . The US country report includes cost and payback estimates for this system. Installed cost for a distributed (using a secondary fluid loop and evaporative cooling tower for condenser heat rejection) was estimated at $60,000 (about 15%) over a baseline multiplex DX system (R22/R404A with air-cooled condensers) for a supermarket with a 330 kW refrigeration load. Payback ranged fro about 3 to 7 years depending on location. Estimates of TEWI reduction. Potential TEWI reductions from this work range from a high of about 60% (analytical estimate for well designed system) to 40% (from a field test). As in the secondary loop case, careful attention to design and operation is essential to achieving maximum benefits.

Low charge multiplex systems. Several approaches have been taken by refrigeration system manufacturers to reduce the refrigerant charge required by traditional multiplex system compressor racks. These approaches reduce the overall system refrigerant charge but retain the long connecting lines between compressors and disp lay cases. Figures 7 and 8 illustrate two such low charge multiplex rack options.13 Figure 7 – Low-charge multiplex sy stem compressor rack concept 1

Figure 8 – Low-charge multiplex sy stem compressor rack concept 214 The first system (Figure 7) limits refri gerant charge by minimizing the refrigerant inventory in the receiver during normal operatio n (the receiver’s prim ary function in this design is to provide refrigerant storage during system servicing). Total charge required for this system is expected to be about 2/3 that of a conventional multiplex system. This charge control approach also can yield so me energy savings because it can allow the system compressors to operate at lower conde nsing temperatures than would normally be
the case. The control valve a nd ambient temperature sensor are intended to maintain a constant temperature difference between the condenser outlet liquid and the ambient. Liquid refrigerant flow through the valve is vaporized by heat exchange with the discharge manifold. Any refrigerant not vapori zed is stored in the receiver. Saturated discharge temperatures can be as low as a bout 5 °C for low temperature racks and about 15 °C for medium temperature racks. Norma lly reciprocating compressors are limited to minimum condensing temperatures of about 21 °C and scroll compressors to a minimum
of about 15 °C. The second charge control approach (Figure 8) tries to reduce charge to the minimum needed for correct operation of the system evaporators. A mixture of vapor and liquid refrigerant is sent to each displa y case lineup and storage room. Operation of the evaporators is done using a combination of relay and balancing valves to control refrigerant flow and evaporation. Refriger ant mixture flow to each case lineup is controlled at the compressor rack. Total refr igerant charge required by this approach is expected to be as little as 30% of that needed by conventional multiplex systems and the energy efficiency is claimed to equal that of conventional systems. Heat reclaim can be done with a heat exchanger and fluid loop as shown in Figure 8. Estimates of cost premium . System economic analysis in the US country report (Volume 2) assumed the installed cost for this system type to be the same as for baseline multiplex DX systems (if both use the same type condenser). Estimates of TEWI reduction. TEWI could be reduced by from 20% to over 40% by these systems (compared to the baseline) if the charge reductio n and energy saving targets can be achieved in real systems.

Advanced self-contained systems. A self-contained refrigeration system consis ts of display cases or storage coolers each having their own condensing units. Self -contained systems are presently used in supermarkets for a limited number of cases, wh ere the cases are in a location inaccessible to the central refrigeration piping. An example is a refrigerated beverage case placed at the cash registers for spot sales. Self-cont ained units are also employed as add-on cases or for temporary display of special sales ite ms. Present self-contained display cases use small reciprocating compressors and air-cooled c ondensers. Heat is re jected directly into the sales area. Only a limited number of self-contained units of this type can be employed before noise and heat rejection leve ls interfere with store operation. Problems of this type caused store designers in the past to go to the remote machine room approach now used in most supermarkets. The self-contained system approach could be attractive for reduction of refrigerant charge. It is estimated that the total charge for a supermarket could be15 reduced to about 5-10% that of conventiona l multiplex systems if self-contained systems
were used for all re frigeration needs. An advanced self-contained system c ould be formulated using water-cooled condensers and a fluid loop for heat rejection to eliminate concerns of heat rejection in the store sales area. The compressor noise issue will still be a factor, but can be addressed by the use of scroll compressors. Until recently, scroll compressors were available only in a vertical configuration, which was not suit able for placement in display cases. Now, horizontal scroll compressors have been introduced, which could be employed for this purpose. These horizont al scrolls are capable of continuous unloading for capacity control and maintenance of a suction pressure set point. Estimates of cost premium . No referencable cost studies have been found for this system approach. The system can be assumed to be an extreme case of the distributed compressor approach, however, and therefore the cost premium over multiplex DX could
be assumed to be similar as well. Estimates of TEWI reduction. No definite estimate has been made for this system type. However, as above it could potentiall y achieve the same TEWI reductions as the distributed system if effici ent enough small compressors a nd other system components can be found or developed to keep the system en ergy use on a par with or better than that of the baseline DX system.

HVAC integration approaches The large amount of heat rejected by th e refrigeration system in a typical supermarket offers an attractive resource fo r use in store space heating. Integration approaches examined during the course of th is Annex have included straightforward heat reclaim, use of heat pumps integrated with the refrigeration system, and use of CHP or CCHP systems. During a meeting of the Annex in Canada a supermarket with a heat reclaim system was visited. The stor e had two R22 multiplex refrig eration compressor racks (one each for medium temperature and low temperatur e loads) with two condensers in series. In winter, primary condensing is done in a pl ate heat exchanger with water on the other side. The water from the medium temperature ra ck heat exchanger is piped to coils in the
HVAC air ducts and used for stor e heating. Heat from the low temperature rack is used for store water heating and for reheat for th e store dehumidification system in summer. An auxiliary boiler is include d in the HVAC system to cover times when heat from the refrigeration condenser cannot meet the store h eating load. According to the installer, the propane boiler was not needed during the first winter (01/02) of operation. The refrigeration system saturated discharge temper ature is allowed to float to a minimum of
about 27 °C under most condit ions. In periods of high space heat demand, the refrigeration system condensing temperature is raised as necessary (to a maximum of 35 °C with some negative impact on refrigerati on compressor energy use) to meet the store heating demand. In summer the refrigeration system uses a conventional rooftop aircooled condenser for heat rejection. Also accord ing to the installer this system has about 3% higher cost than a conventional refr igeration/HVAC system (Bastrash, 2002). The use of heat pumps represents an excel lent way to utilize refrigeration reject heat for space heating. Two different heat pump integration approaches have been examined by individual Annex participants. One involves direct integration of the heat16 pump evaporator(s) and refrigeration system condenser(s) and the s econd utilizes watersource heat pumps (WSHP) wh ere water-cooled condensers and water/glycol loops are used for refrigeration system heat rejection. The heat pumps can be installed in the glycol/water loop and use the rejected heat to provide space he ating. Either method enables reclamation of a very large portion of the reject heat without requiring elevation of the condensing temperature of the re frigeration system as can happen with conventional heat reclaim approaches. Refrig eration system energy savings achieved by low head pressure operation ca n be realized along with the energy bene fits seen through
heat reclaim. An example of the first type was also s een during the Annex meeting in Canada. The refrigeration system is a traditional R22 multiplex system w ith two racks (low temperature and medium temperature) and bot h used a common set of two condensers in series. Figures 9 and 10 illustrate this heat pump integration approach. In winter, the discharge gas from the refrigeration comp ressors goes first through three plate heat exchangers which serve to desuperheat a nd precondense the gas. Final condensing is accomplished in a conventional rooftop air-cooled condeser. The other side of the three heat exchangers serve as th e evaporators for three roof top heat pumps which supply space heating to the store. A fourth rooftop heat pump is si milarly integrated with the liquid line exiting the air-cooled condenser via a fourth plate heat exchanger. This heat pump subcools the liquid refrigerant leaving th e refrigeration system condenser and uses the recovered heat for store sp ace heating. In summer, the re frigeration system uses the
air-cooled condenser ex clusively and the heat pumps use their own condensers to reject heat from space cooling loads. The refrigera tion system also includes a liquid refrigerant pump to boost the pressure of the refrigerant before it is sent to the cases. The pump is included because with the heat pump integrati on the refrigeration system head pressure is
allowed to float to about 15 °C minimum satu rated discharge temperature. According to the installer the system cost for that store is about 8% more than what a conventional refrigeration and HVAC system would have co st (Kantchev, 2002). Some details of this system are included in Canada’s country repo rt where it is identified as the LMP system.17 Figure 9 – Roof top heat pump unit

Figure 10 – Plate heat exchangers (H X) for heat pump evaporators and refrigeration desuperheaters and subcooler18 The use of WSHPs in conjunction with water-loop heat rejection for the refrigeration system was examined by the US (see US country repor t, Volume 2). An analysis was performed for a supermarket HVAC system where conventional rooftop airconditioner/gas heating units and water-source heat pumps were examin ed and compared.
The combination of a water-cooled distribut ed compressor refrigeration system with water-source heat pumps was predicted to save about 10-20% in overall operating (refrigeration plus HVAC energy) costs depend ing on local climate a nd utility rates when compared to the baseline air-cooled multiple x DX refrigeration system with conventional rooftop HVAC units. The a dded installation cost for the WSHP approach was estimated to be about $25,000 US (about 30%) over th e conventional rooftop unit system. CHP/CCHP system concepts were studi ed in detail by the UK team. They concluded that CCHP has an improved load match compared to CHP, when used with absorption chilling for building cooling. In tegral cascade vapor compression systems within each display case integr ated with the absorption system provide food refrigeration. Primary energy savings are around 15%, and th ere is a TEWI reduction of more than 50% compared with conventional supermarket systems. The impact that store ambient conditions can have on refrigeration system and case energy use was illustrate d by part of the UK team effo rt. Environmental chamber tests of low and medium temperature case sy stems show that an increase in ambient temperature from 19 to 22 ° C increases system energy use by 20%. Increasing RH from
35 to 50% at an ambient of 22 ° C increased the medium temper ature case energy use by
15% but had no effect on the freezer case.

Country report summaries

Following are summarized key results from the work programs carried out by each country under Annex 26. Full details of these projects can be found in the individual country reports.

Canada - CANMET Energy Technology Centre –Varennes (CETC–Varennes) of
Natural Resources Canada
The CETC–Varennes contribu tion to the Annex included a supermarket showcase with a fully integrated HVAC/Refrigeration system using secondary fluid on condenser and evaporator sides, the organization of an advisory committee, one workshop for the Canadian refrigeration industry and two research projects directly related to supermarket refrigeration. There are approximately 31,000 retail food stores in Ca nada 7,150 of which are considered large supermarkets – with a floor cover area of over 1,000 m 2 . Supermarkets are among the most energy intensive buildings in the commercial sector with a total energy consumption of more than 800 kWh-equivalent/m 2 /year (and increasing with time). Refrigeration represents about 50% of the electrical ener gy consumption of a supermarket, costing on average $150,000 C ND per year for a typical large size supermarket (2000 m 2 ). The typical refrigeration syst em contains approximately 750 kg of synthetic refrigerant e quivalent to 2,000 tonnes of CO 2 in terms of greenhouse gas19 effect. Refrigerant losses are on average, 25% per year of the total charge. The refrigeration sector is currently facing seve ral major challenges such as: the legislated replacement of synthetic refrigerants that have negative environmental impacts; the increasing cost of refrigerants ; the poor efficiency of equi pment that are not adapted to Canadian climatic conditions; new regulati ons for refrigerated product storage and transportation; and a lack of innovation and adequate expertise in Canada to address these
issues. CTEC signed an agreement with a major Canadian supermarket chain to develop a supermarket technology showcase in a Mont real area in the end of 2003. The project’s objective is to develop innovative integr ated HVAC&R technologies and practices suitable for Canadian climatic conditions, using compact and hermetic refrigeration systems using secondary fluid for the evaporat or and condenser sides, and to demonstrate them in partnership with a major chain of s upermarkets in Canada. These demonstrations will provide the opportunity to get a better understanding of their technical requirements such as design, installation, commissioni ng, and performance as well as their nontechnical barriers (knowledge transfer to energy consultants and technical operators, costs, procurements, etc.). The selected m easures should result in reductions in operating and maintenance costs, refrigerant leakage a nd, indirectly, food spoilage. Secondary fluid systems will contain less refrigerant and fewer potential refrigerant leak locations, resulting in a substantial reduc tion in the emission of gree nhouse gases. This project is part of a strategy to transfer technology and disseminate know-how. CTEC organized meetings of an I ndustry Advisory Panel consisting of supermarket and refrigeration sector representatives. The objective of these committees is to provide advice for case studies, laboratory experiments or demonstration projects in accordance with the Canadian supermarket sector needs. The committee’s invited membership includes companies representing retailers, compressor rack manufacturers, display case manufacturers, supermarket refri geration control manuf acturers, consulting engineers and government agencies. The Indus try Advisory Panel participants understand and are pleased with the Annex 26 strate gy to increase the energy efficiency/heat recovery of supermarket refrigeration syst ems, while reducing the overall refrigerant charge and potential leaks. More than 85 people attended the firs t Canadian Workshop on Refrigeration Systems on March 11, 2003 in Montreal. Th e event was sponsored by CETC-Varennes and the Office of Energy Efficiency (OEE), in collaboration with Agence de l’efficacité énergétique (AEE), Hydro-Québec, Manito ba Hydro and BC Hydro. With a possible reduction of 1.4 Mt equivalent CO 2 /year by 2010, refrigeration in supermarkets has a great potential of energy efficiency a nd greenhouse gas emission reductions. The refrigeration industry (equipment manufactur ers, food retailers, design engineers, mechanical contractors, utilities) sees th is as an opportunity. The event allowed the identification of proven and emerging refriger ation technologies and the validation of the supermarkets’ interests. In addition, six di scussion groups shared ideas on how to lift barriers for adoption of the energy efficient refrigeration technologies. The information collected will provide CETC-Varennes and OEE with new ways to facilitate the adoption of the technologies developed A laboratory test bench wa s developed to test novel methods of providing refrigeration for the food marketi ng industry. In the first series of tests, CETC is expected20 to develop the knowledge to operate refrigera tion systems at minimal head pressure and maintaining controllability of refrigeration sy stem using an electronic expansion valve. Results from this work will validate or further improved the accuracy of refrigeration equipment models and will help to transfer th e know-how to refrigeration experts. Some technical papers will be published soon. During the year 2000, CTEC started a new stra tegic project schedul ed to last four years. The main objective is to constr uct and perform experiments on a liquid CO 2 secondary fluid loop test bench. The seconda ry objectives are development of basic know-how (technical documentation, simula tion models, experimental data) and demonstration of the technologies feasibilit y to potential partners. CTEC got a CFD program (Computational Fluid Dynamic) to model complex problems related to refrigeration technologies. A major partner from the carbon dioxide industry has joined the research team to realise this project.

Canada - Hydro-Quebec Research Instit ut, Laboratoire des technologies de l’énergie (LTE ) The contribution of LTE covered the following areas:

- Development of two improved methods for to tal heat recovery in cold climates.

- Development of a high-speed defrost technique.

- Effective use of liquid pumping and injection.

- Further research on systems having lo w refrigerant charges and reduced supplementary costs and energy consumption.

In Canada, supermarkets are one of the mo st energy-intensive types of commercial buildings, and the major source of elect ric energy use and demand comes from refrigeration systems (around 50 %), of wh ich compressors and condensers account for 60-70 %. Also, the majority of conventional supermarkets ta ke partial advantage of the large amount of heat rejected, by using this heat for space or wate r heating. Generally, a
conventional heat reclaim coil located in th e central air handler allows recovery of approximately 35 % to 45 % of to tal heat rejection. However, th is amount of heat is not sufficient to completely eliminate the use of fossil fuel combustion (natural gas, propane) during the coldest periods of the year. Moreov er, at the present time, an issue facing the industry is the phase-out of ozone depleting refrigerants and the redu ction of refrigerant charge and leakage, because a typical supermarket may experience refrigerant leakage of 10 % to 30 % per year. The main objective of the LTE project was to experimentally document the benefits of two improved heat recove ry systems developed in Canada, and to compare their performances with those of existing multiplex systems. Specific aims were to measure the energy usage for both low and medium-tempe rature zones and for total store, as the main system operating parameters and overall energy performances. An ultimate goal was the further development of options to reduce total equivalent warming impact (TEWI) of supermarkets by reduc ing the total refrigeration charge and leakage risks. LTE Laboratory worked with three retailers a nd two Canadian manufacturers on development and field testing of two co mmercial prototypes. The “ System1-phase 1 ” (known as RSD ) comprises a method to maximize the heat re covery capability for space and water21 heating, and a new, high-speed defrost concept. The “ System2-phase 1 ” (known as LMP ) proposes a new heat recovery and air-c onditioning/dehumidifying method involving intermediate heat exchangers and multifunctio nal refrigerant-to-air heat pumps. These systems represented the first phase of their respective development processes. They have already been further improved, pa rticularly in order to reduce total refrigerant charge and leak hazards. Three new supermarkets were extensively instrumented in order to compare a number of operating parameters, high-effici ency features such as heat recovery, defrosting, sub-cooling and liquid pumping, and to quantify energy performances (compressors and store energy consumption and demand, etc.). Two of the stores monitored, having approximately the same size and energy usage, (basically, electric refrigeration and natural gas cooking) we re equipped with above-mentioned improved refrigeration systems, and a third one was used as a new baseline supermarket. In these stores, food is stored prior to transfer to th e store in walk-in storage areas, and a variety of display cases are located at the periphe ry. A continuous monitoring of these systems was performed over a 12-month period (2000 – 2001). Total Heat Recovery (”System1-phase1”). This heat recovery method consists of bi-directional valves to supply discharge supe rheated vapour to condensers (in winter), or to a groundwater cooling device (in summer), depending on the outdoor temperature, or to heat reclaim coils for air or domestic hot water heating, when required. A parallel installed modulating valve equi pped with an outside temp erature sensor adjusts the discharge pressure depending on the outside temperat ure, and automatically re-directs a predetermined quantity of superheated vapour to the heat reclaim coils by means of a simple, economical and efficient method. If th e system controller requires heating during the winter cold months, the modulating valve w ill direct some or all of the refrigerant to the heat recovery coils in order to cove r up to 100 % of the space heating demand. The
last heat reclaim coil and remote condensers ar e separately connected to a main receiver where the liquids flow at approximately the sa me pressure, independently of one another. Prior to being fed to the evaporators, the liqui d is further sub-cooled by an internal heat exchanger equipped with special thermostatic expansion valves. Total Heat Recovery (”System2–phase1”). In conventional supermarket refrigeration systems, the condensing pressure and temperat ure are subject to ambient air temperature. During the cold periods of the year, even if there is a possibility of reducing condensing pressure, a high level is artificially maintain ed in order to provide sufficient pressure differential for proper operation of the expansion valves, a nd for heat reclaim. The

” System2-phase1 ” heat recovery concept provides an original method to maximize the extraction of the condensing heat by using heat pumps. Refrigeration system superheated vapour is first directed to four intermediate plate heat exchangers that also serve as evaporators for heat rec overy heat pumps where a minimum suction pressure, corresponding at about 10 °C re frigeration condensing temperat ure, is maintained. When store space heating is required, the plate heat exchangers and their respective refrigerantto-refrigerant heat pumps are activated. Sensible (superheat) and, if n ecessary, latent heat are removed from the hot discharge gas of the refrigeration system, which is then fed to
the remote air condensers. The heat extracti on from the superheated vapour is effected without excessively increasing the discharge pressure, thus allowing a reduction of the refrigeration compressor energy consumption as compared to conventional heat reclaim methods. In air conditioning mode, the plate heat exchangers aren ’t used, and heat22 removed from the store is rejected outdoor s through each heat pump’s own condenser. The heat recovery system is completely independent of the refrigeration system, and it is possible to extract total condensing heat without affecting its normal operating conditions. Each heat pump includes a heat exchanger for space heating, and the same coil is used for air re-heating in dehumidi fication mode. The heat pump’s condenser and air conditioning coil are not ope rational in heating m ode, and special inlet pressure valves maintain a minimum suction pressure. Refr igeration system liquid returns from the remote condensers to a liquid delivery unit (including a refrigerant pump) where static pressure is increased before supplying the display cases, and a small quantity can be injected into the common discharge line dur ing the summer. Low condensing pressures during the cold periods of the year are comp ensated for by the pre ssure increase provided by the liquid delivery system. Inside the heat pump dedicated to sub-cooling/heat reclaim
, the evaporator removes heat from the condensed liquid of the main re frigeration system before it is sent to the display cases and storage coolers/freezers. When this heat pump operates in heat recovery mode, its own intermediate plate heat exchange r plays the role of an evaporator, and the discharge line goes to an air-heating coil for store space heating. It should be noted that this heat pump-heat reclaim concept is easily adaptable to any existing refrigeration system using a liquid delivery system.
Results

- With lower compressor energy consum ption, the 12-month field monitoring proved that fossil fuel consumption for space heating in supermarkets has been completely eliminated in both cases.

- “ System1–phase1 ” raised the head pressures/ condensing temperatures during the heating demand periods as high as th ey were in the baseline system with conventional heat reclaim devices, and also modified refrigerant flow and
controls to eliminate current limitation of heat reclaim capability and giving priority to the heat reclaim mode . A modulating valve operating on the ambient temperature optimizes this process by varying head pressures as a function of the actual heating demand a nd the outdoor temperature variation.

- The “ System2-phase 1 ” was capable of reducing discharge pressures to an almost constant level (about 29 % lowe r than the other system), without compromising its own heat reclaim me thod. The discharge pressures were lowered to about 125 psig during the winter, but the thermodynamic level of the heat reclaim was increased by us ing heat pumps as a cascade stage. Savings in compressor energy consump tion were however obtained, mainly by using four refrigerant-to-air heat pumps having average coefficients of performance of around 3.0.

- The total annual specific energy consumption (kWh/y/m 2 ) of the refrigeration

compressors represented 32.5 % (“ System1–phase1 ”) and 34 % (“ System2– phase1 ”, including the four heat pumps), of to each store’s total electrical energy usage, compared to the current average in Canada, of 39 %. These performances were obtained even if the “ System1 – phase1 ” was slightly penalized by the use of less efficient screw compressors, excessive fouling and lack of proper maintenance of groundwater heat exchangers. “ System2– phase1 ” was also penalized by the heat pump’s supplementary energy23 consumption, even when compensated for by lower head pressu re operation in winter. Simultaneously, the total annual specific electrical energy consumption (vs. sales area) of improved supermarkets was reduced by 6 %, and the corresponding energy costs, including power demand cost, by 12.9 % and 17.9 % respectively, compared to th e baseline monitored supermarket. High Speed Defrost. “System 1-phase1” system includes a high speed defrost concept capable of performing defrost cycles in a short period of time. In fact, the major disadvantages of conventional defrosting met hods are their fairly lengthy cycles, because of a low-pressure differential across the ev aporators, adverse effects on foodstuffs and compressors (energy cost in creases, overheating, reduced technical life). As in conventional systems, when a refrigeration zo ne goes into a defrost cycle; superheated vapour is fed to the outlet of the evaporator co il. The return line of the defrost circuit is provided with a second valve wh ich is open during the defros t cycle. This valve connects the return line to a special auxiliary receive r, which has a sufficient volume to take the full refrigerant charge and protect the compre ssors during and after each defrost cycle. The auxiliary receiver is connected to the low suction pressure header by means of a solenoid valve. By using an auxiliary receiv er, a pressure differential can be created across the evaporator coils within a range of about 200 to 700 kPa, thus achieving quick defrost. In order to keep the main receiver supplied with suffi cient quantities of liquid, it is necessary to periodically flush the auxiliary receiver du ring the refrigeration cycle. When the refrigerant temperature is below a predetermined value, normally –1 °C, the refrigerant liquid is directed to the main receiver. A pressure differential of about 200 kPa is created in order to have sufficient pressure to flush out most of the liquid accumulated in the auxiliary receiver. If the liquid is abov e –1 °C, it is sent to the remote condensers
and then back into the main receiver. The auxi liary receiver is also provided with a level detector. When the liquid level reaches a pr edetermined value, the flushing circuit will operate during the next refrigeration cycle. A second level detector feeds an alarm that produces both a visual a nd an acoustic signal.
Results

- The new high-speed defrost method proposed by “ System1-phase1 ” reduced defrost cycle time by about 85 % compared with a conventional hot gas
defrost method. Immediate beneficial eff ects were a better quality and about 50 % less perishable f ood losses. The actual ma ximum deformation of a representative case evaporat or during a fast defrost cycle represents about 56 % of the elastic limit of existing materi als, but the long-term effects are not known, nor are they known for ex isting conventional systems.

- Because of the high speed defrost, it wa s estimated that is possible to reduce the number of the refrigeration lines a nd consequently, the total refrigerant quantity by up to 15 %. Liquid Pumping and Injection. A simple, reliable liqu id delivery technology developed in Canada can improve refrigera tion efficiency, reduce compression ratios and work, and allow refrigerati on systems to better operate with floating condensing pressures, depending on outdoor temperatur es. This technology ge nerally produces energy savings of up to 35 %, but creates difficulties in the area of heat recovery, especially when total condensing heat reclaim is required, because the air to be heated is warmer than the refrigerant to be cooled. Accordingly, when heat reclaim is required, the24 condensing pressure has to be ar tificially raised in order to achieve proper heat transfer, thus losing the benefits of the liquid delivery system. However, by combining liquid pumping with the new ”System2 – phase1” h eat recovery method, it was expected that head pressures would not be artificially raised when h eating is required. Refrigerant pumping pressurizes the liquid refrigerant e nough to compensate for any pressure losses
between the receiver and the expansion valve, and thus e liminates the formation of vapour. The liquid pump is a seal ed unit, with no moving seal s to wear out or leak. The

” System2 – phase 1 ” new heat recovery concept allows the use of the same equipment (heat pumps) for air conditioning and sub-cooling purposes, and also improves the efficiency of the liquid pumping technology. It is well known that the compressor’s energy consumption and efficiency are a f unction of the ratio between the condensing and evaporating pressures. By lowering the co ndensing temperature to 16 °C or even 10 °C, the compressor energy consumption and power diminish, and its refrigeration capacity increases. Moreover, because the pressure of the pump is usually higher than the compressor discharge, the injection of a sma ll percentage of the liquid (6 – 10 %) back into the discharge line was possible. Thus , for ambient temperatures above 24 °C, the temperature of the discharge vapour was reduc ed, and the efficiency of the condenser increased. The liquid injection means lowe r velocity through the condenser, lower pressure drop, reduction of the discharge temperature, an in crease in the area of the condenser used for condensing, and increased system capacity.
Result

- Liquid pumping technology used by “ System2 - phase1 ” helped this new heat recovery technique by incr easing the liquid pressure by about 180 kPa during the cold periods when the head pressure decreased to 860 kPa. Geothermal Cooling. During the hottest periods of the year, condensing heat
from the ” System1–phase1 ” refrigeration system was rejected to the ground instead to the ambient air in order to reduce energy consumption and thus optimize the overall efficiency of the system. This concept a llowed the reduction of the compressor’s head pressures and condensing temperatures, because the cooling fluid will be groundwater at an average temperature of about 8°C (46.4°F) instead the ambient air at more than 30°C (86°F). This objective was achieved by usin g supply and discharg e groundwater wells. Two refrigerant-to-water heat exchangers for both low and medium temperature racks were employed. The main disadvantage of this energy efficiency method is the risk of clogging of the groundwater heat exchangers, which in volves additional costs for periodical maintenance. However, the ener gy savings may generally justify the initial investment and supplementary maintenance. Further Developments. The major weakness of the proposed systems lies in the large of refrigerant required, a nd the associated environmental disadvantages (1,400 to 2,300 kg for total sales area of 3,000 to 5,600 m 2 ). Even if the “ System1 – phase1 ” has demonstrated that the developed high spee d defrost method enables a reduction in refrigerant charge of up to 15 %, it isn’t considered sufficient . Therefore, the main objective of future systems improvement is to reduce total refrigerant quantity and leakage risks, and also to replace the HCFC-22 by alternative fluids, in order to develop new environmentally low-TEWI systems. (i) The “ System1 – phase2 ” improved system, availabl e since 2001, was developed by retaining both prior innovations (integral heat recovery and high speed defrost). It aims to25 replace the actual HCFC-22 fluid with a good replacement having no, or lower environmental impact (e.g., R-404a). The cent ral refrigeration system was divided into several smaller, ultra-compact units that can be installed on the roof (distributed compressor approach). The previous conventional cent ral refrigeration room was thus completely eliminated, and the space created could be used for commercial activitie s. This arrangement reduces total refrigeration piping length and number of fittings, thermal insulation and electric piping by 60%, and total refrigerant char ge by 30 – 40%, because of the proximity of display cases and of heat reclaim coils, reduced diameters and length. Thus, the additional costs are lowered by 40 % compared to the pr evious system. These cabinets are insulated and equipped with their own heating and cooling devices ( 21°C in winter and 32°C in summer). Additional ventilati on or make-up air and evacua tion devices aren’t needed.

“ System1 – phase3 ” improved system aims also to re tain the main previously analysed innovations, and also to reduce the refrigerant charge by 60 % or more compared with the
first method. This concept retains the same small cabine ts, but each high temperature side (condensers and heat reclaim) uses closed loops with circulation pumps and anti-freeze secondary fluid, storage tanks and controls. These condensing circuits can transfer heat directly to each heated space , or can use water-to-air heat pumps. Reduction of additional
costs is estimated at 50 % compared to the first improved system. (ii)“ System2 – phase2 ” aims to maintain heat r ecovery by heat pumps, but to improve the liquid delivery system (horizonta l receiver installed out doors with improved level control), accelerate the defrost cycles by increasing the refrigerant flow rate, and reduce the additional cost by about 10 % compared to the previous concept. On the other hand, “ System2 -phase3 ” aims to develop a simplified heat recovery method without heat pumps, a zoned defrost concept, and to redu ce the refrigerant charge by up to 30 % and the additional cost by 80 % compared to the first improved system. Summary information on the phase 1 test systems is included in Appendix A. Full details on the tested and improved syst ems may be found in the Canada country
report.

Denmark There is a great deal of concern in Denmark about the use of HFCs due to concerns about their impact on the enviro nment in the long term, especially the contribution to global warming. In the ope ning speech to the IIR conference on “Applications for Natural Refrigerants”, Aar hus, Denmark (1996) the Danish Minister for Environment and Energy, Svend Auken, in hi s conclusion said: “It is therefore my sincere hope that in ten years’ time, not a single fridge, freez er or cooling plant is being built in Denmark that requires HFCs or other greenhouse gases.” Recently an announcement (in Danish; Bekendtgørelse, BEK nr. 552 of July 2., 2002) has been issued which forbid the use of certain industrial warming potential gasses, which includes the HFC ́s. From January 1, 2006 the use of HFC’ s is no longer allowed in new products. Exemptions are the use in refrigeration pl ants, heat pumps, air conditioning plants and dehumidifiers with refrigerant charge between 0.15 kg and 10 kg and compact heat recovery plant factory assembled with charge less than 50 kg. According to this rule conventional multiplex refrigeration systems cannot be used in supermarkets after January 2006.26 Besides the phase out in 2006 for ne w plants HFCs are charged a CO 2 tax. In Denmark emission of carbon dioxide (CO 2 ) has been taxed since May 15, 1992. Starting January 1, 2001 following the Kyoto protocol Denmark extended the CO 2 tax to include industrial greenhouse gasses (HFCs, PFCs and SF 6 ) based on the global warming potential (GWP) of each gas. The tax is US$ 0.0127 (DKK 0.10) pr. kg CO 2 with CO 2 by definition having the GWP of 1 with a maximum tax of US$ 50.95 (DKK 400) pr. kg (Danish law #49 of December 21, 2000).
In view of what is stated above it is obvious why the Danes are searching for natural refrigerant substitutes for HFCs. Se veral supermarket case studies have been done in Denmark with a primary focus on in creasing energy efficiency and applying natural refrigerants (like hydrocarbons, ammonia, and CO 2 ). In one small Danish supermarket the old refrigeration plant was replaced with a cascade plant. Propane was used as the high temperat ure refrigerant (-14/+30 ° C) while CO 2 was used at the low temperature level (-32/-11 ° C). Direct expansion of CO 2 is used in the freezer cases while a brine circuit with propylene glycol is us ed in the coolers. Total energy consumption decreased by 10% with the new plant, however it must be noted th at the old plant was
worn out. Based on the results from this initial demonstration a second propane/ CO 2 cascade plant was built in a medium-size supermarket and just started operation in late 2001. The test supermarket is part of a chain of about 250 similar s hops so it has been possible to compare the propane/carbon dioxide plant with newer traditional plants with the same cooling capacity. Energy use of the demonstration store has been compared to that of eight similar stores in the same chain and found to be about the same as that of the
most efficient of the newest conventional stores . It is estimated that the additional cost for a propane/ CO 2 cascade plant for a medium sized Danish supermarket (30 kW freezing load and 60 kW cooling load) will amount to approximately 10% or less of the total
installation. Details of th is second demonstration ar e included in Appendix A. A third demonstration plant has recently been started in a new supermarket in
which carbon dioxide is used in both the low temperature and medium temperature cases. This approach eliminates the secondary propyl ene glycol circuit with its thermodynamic efficiency penalty. The plant has 190 kW cooling capacity and 60 kW freezing capacity, and the condenser heat is utilized to supply the shop with all of its space heating and sanitary hot water needs. Th e refrigeration plant is a casca de plant with R404A in the high temperature stage and CO 2 in the low temperature stage. R404A is used in this plant because the equipment is installed in the baseme nt of the store where it is difficult to get permission to install flammable or toxic re frigerants. Both the freezer cases and fresh food cases are cooled by direct evaporation of CO 2 . Liquid CO 2 is pumped directly to the
fresh food cases while CO 2 is direct expanded into the freezer cases. The amount of R404A in this demonstration is only about 10% of that needed by conventional direct expansion systems for stores of this size. Taking into account the Danish tax on R404A
this reduction reduces the investment in refrigerant by about US$ 37,000. (DKK 290,000). The total investment in the refriger ation plant is approximately 10% higher than a conventional HFC-plant taking into account the reduced refr igerant cost. This demonstration has been underway since Febr uary 2002. A comparison with similar shops in the area with conventional refrigerati on systems shows significantly lower energy consumption. In November 2002 a second plant bui lt in according with this concept has been set in operation.27 In the future a project with title, ”Ene rgy efficient design and control of the secondary side of an indirect refrigerati on system with natural refrigerant” will be performed.

Sweden
Swedish activities for Annex 26 have been aimed at improving supermarket energy efficiency in several different ways . These have included development of a detailed computer model and analyses of full stores to examine different secondary loop system designs and heat recovery approa ches including impact of climate effects particularly relative humidity. Several fu ll-scale demonstration projects have been undertaken examining different secondary loop systems and display cases with advanced features such as automatic night covers. Increased sales in supermarkets, stricter environmental legislation for CFC and HCFC refrigerants and a major consideration of the use of energy and the effect on the environment have influenced the supermarket se ctor during the last ye ar in Sweden. Sales in supermarkets have increased 4.6 % during year 2001 in comparison with the year 2000 [30]. The consumption of deep-frozen pr oducts in supermarkets during 2001 was 231788 metric tons while during 2000 it was 216427 metric tons, which is an increase of 7%. The increase in sales in supermarkets places a demand on more cabinets, cold rooms and refrigeration systems that increase th e energy consumption from food stores. Supermarkets are using large amounts of en ergy; approximately 3% of the electric energy consumed in Sweden is used in s upermarkets (1,8 TWh/year). A breakdown of the energy usage shows that, typically, 47% is used for medium and low temp refrigeration, 27% for illumination, 13% for fa ns and climate control, 3% for kitchen, 5% for outdoor usage and 5% for other uses. Refrigeration systems, display cases, indoor climate contro l and illumination are the areas with the greatest potential for improvement. Since the energy systems of a supermarket are relatively complex, impr ovements in one subsystem affects other systems, thus making an analysis of potential improvements non-additive. Typical efficiency improvements may invol ve refrigeration systems, heat recovery, more efficient illumination, more efficient display cases with night lids, more efficient control, floating
condensation etc. Several new system solutions such as co mpletely, partially and cascade secondary loop (or indirect) systems have been develope d and introduced in recent years in Sweden to lower the refrigerant charge and, at the same time, minimize potential refrigerant leakage. Growing interest in secondary loop syst ems has led to the development of some new secondary refrigerants based on potassium formate and potassium acetate alone or mixed. Another very promising development is CO 2 as a secondary refrigerant. This technology is implemented in more than 30 supermarkets throughout Sweden. CO 2 systems require much lower tube diameters and the pressure drop is negligible when compared to conventional systems. A third pr omising development in this field is ice slurries. These systems offer additional advant ages with enhanced thermal capacity and a “built-in” thermal storage in th e system without increased pre ssure drop if ice-slurry with the right consistence is produced.28 Secondary systems and the minimization of refrigerant charge may lead to an unwanted trade off in overall energy efficien cy. Theoretical calculati ons confirm this due to the obvious extra temperature differences introduced in the system. An evaluation using a concept like TEWI (Total Equivalent Warming Impact) may be used to estimate the overall environmental impact. In 1998 the Department of Energy Technology of the Royal Institute of Technology of Sweden started a project in co-operation with different companies and the Swedish National Energy Administration. M odelling and field measurements of supermarket energy systems have been undertak en in the research project “The energy efficient supermarket” for more than four years. The results have been part of the
Swedish contribution to the IEA Annex 26

. The overall aim of the project “The energy efficient supermarket” is to develop a sound simulation model where different system solutions can be compared in detail with focus on energy usage, environmental impact (TEWI) and LCC (Life Cycle Cost). The program, “CyberMart” is built in modul es dealing with subsystems such as in- and outdoor climate, display cases, co oling and freezing rooms, refrigeration machinery, the building envelope etc. CyberMar t is a day-to-day simulation program that
allows the user to see the variation of di fferent variables such as compressor power, refrigeration capacity and temperatures in the supermarket during one year. The model is currently under validation w ith four different supermarkets in Sweden in cooperation with COOP and ICA, two major Swedish supermarket chains. The model development activit ies are now treating issues such as illumination, indoor climate and heat recovery, comfort cooling etc. Interesting issues to study are the potentials in heat recovery in the winter, moisture control/dehumidification and floating condensation. Additional Field measurements intended to validate data are currently being set up. A window for calculation of en ergy consumption is shown in Figure11. The diagram shows the results from the si mulation of the compressor power of the intermediate and low temperature systems during one year.29 Figure 11 - Results from CyberMart

The influence of the outdoor temperature on the indoor relative humidity of air is an important factor to take in considerat ion when dimensioning refrigeration and heat recovery systems in supermarkets. Lower out door temperature and moisture affect the compressor power and the dry cooler fluid approach temperature.30 Figure 12 - Indoor temperature, outdoor te mperature and indoor relative humidity
in Hedemora and Sala

Measurement of indoor temperatures, out door temperatures and indoor relative humidity from two supermarkets in the cities of Hedemora and Sala are shown in Figure 12. The distance between the cities is about 60 km. The results confirm the dependence of relative humidity on out door temperature. The indoor relative humidity in both supermarkets follows the variation of outdoor temperature during the period of study. Sala - Hedemora Aug 2000 - Feb 2001

-30 -20 -10

0 10 20 30 40 50 60 70

aug-00 aug-00 sep-00 okt-00 okt-00 nov-00 nov-00 dec-00 jan-01 jan-01 feb-01

Timetemp[°C], RH[%] Indoor Temp. Hedemora
Outdoor temp. Hedemora

RH. Hedemora
Indoor Temp. Sala

RH. Sala
Outdoor Temp. Sala31 Figure 13 - Temperatures, relative humid ity and compressor power in Sala

The variations of temperatures, moistu re and compressor power during week 32 in August 1999 in the supermarket in the city of Sala are shown in Figure 13. In the figure it is possible to see the influence of night covering of the display cases and defrosting on the compressor power. The cabinet s are defrosted with electrical defrost. The compressor power is reduced between 10 and 20 % by the night covering of the cabinets. The covering occurs automatically when the supe rmarket closes at 21.00 and ends at 8.00 in the morning. The positive effe ct on energy saving of night covering is dependent on the quality of the curtains. Night covering is an effi cient method to reduce
infiltration and radiation loss in cabinets. The influence of high indoor temperatures on compressor power has been studied in the supermarket in the city of Hedemo ra. The high investment cost of the air conditioning system and a short period of higher outdoor temperatures during the summer
have affected the decision of install AC in many supermarkets in Sweden. Sala

Week32

0 10 20 30 40 50 60 70

1999-08-09 1999-08-10 1999-08-11 1999-08-12 1999-08-13 1999-08-14 1999-08-15 1999-08-16

Timetemp[°C], power[kW], RH[%] Indoor temp.
Outdoor temp.
Comp. Power

RH32 Figure 14 - Temperatures in a deep fr eeze cabinet and indoor and outdoor temperatures during four days in July in Hedemora

Figure 14 presents indoor temperatures, outdoor temperatures and air return temperatures in four sections of a deep-fr eeze cabinet during four days in July 2001. The outdoor temperatures are above 30°C during a long part of th e day and this affects the indoor temperatures. The values of indoor temperatures dur ing the day are above 25°C, which is the dimensioning indoor temperatur e of the display cases. The maximum indoor temperature is 28°C, which occurs on the 5 th of July at around 17: 00 o’clock. The air return temperatures in three sections are above –20°C and one of them has air return temperatures higher than -15°C during the da y. If the temperature of the products is assumed 1°C higher than the air return temper ature, which is a reasonable supposition, then the temperature of the product should be about –14°C at an air return temperature of -15°C. According to the National Food Admi nistration, which regulates and supervises the food area in Sweden, the maximum temper ature of freeze products is –18°C. The date for the minimum durability, or use-by date, of frozen food is calculated at a temperature of –18°C. Higher product temperature implicates a risk of the multiplica tion of bacteria in the frozen food that might cause illness to the consumers. The results from Figure 12 confirm the necessity of air conditioning during the warmer days in the summer in
Sweden. The economy and overall energy efficiency of supermarkets, in cold climates, benefit from heat recovery. In theory, the n ecessary heat can always be supplied from the condensers. Practical experien ces show that in real systems only 40 % – 70 % of the necessary heat is recovered. There are many re asons for this but the most important are on/off regulation, low cooling lo ad during cold days, poorly designed heat recovery systems and non-communication control systems for refrigeration and HVAC. Hedemora 3 - 6 July 2001

-30 -20 -10

0 10 20 30 40 50

00:00 12:00 00:00 12:00 00:00 12:00 00:00 12:00 00:00
TimeTemp [°C], RH[%] Indoor Temp.
Outdoor Temp.

DFsec1

DFsec2

DFsec3

DFsec4

RH33 United Kingdom Storing and displaying refrigerated goods accounts for a considerable amount of energy use in the UK. Figure 15 shows the breakdown of the end use of refrigeration energy. Of the total of 24,000 GWh, refrigerated retail display cabinets overall consume some 7,740 GWh per year in the UK. This provides a great incentive to improve the energy efficiency of refrigerated supermarket display units. In addition to this there is also the requirement to reduce the emission of environmentally damaging refrigerants
that contribute to the total equivalent warming impact.

Figure 15 - Refrigeration energy usage in The United Kingdom by end use

Reported here are a summary of the Phase 2 studies and the overall analysis of the current position regarding th e available technologies. Full details of the Phase I technology review and Phase 2 detailed studies are included in the UK country report. The second phase of the UK contribu tion covered four research areas:

• secondary refrigerant systems

• alternative defrost approaches

• interactions between the store en vironment and the cabinet case

• combined heat and power and combined heating, cooling and power applications in supermarkets. This summary records the main points that were concluded from each of the four
studies carried out. Each area of research wa s carried out by an or ganisation specialising in refrigeration technology. The areas where fu rther research may be useful have also
been identified. Secondary Systems. Secondary refrigerant systems offer the potential of reduced total equivalent warming impact (TEWI) as a consequence of reduced refrigerant leakage of high ozone depleting potential (ODP) refrigerants. However, it is recognised that there34 may be additional energy requirements to operate this type of system because of greater temperature gradients and increased pumping power. Field monitoring data from a typical supermarket was used to validate a refrigeration simulation model, and a detail ed investigation of the thermal and fluid properties of secondary refrig erant fluids was made. This enabled simulations to be
carried out to assess the feasib ility of a wide rang e of secondary systems and refrigerants in a typical supermarket. A key finding of th e simulation was that the energy use of the secondary systems simulated w ould typically be greater than for other systems and as a consequence they would deliver higher operational CO 2 emissions. In terms of overall TEWI, the secondary system using R290 (propane) would re duce the TEWI by 8% over a 15-year life compared to an R 22 direct system with 15% refrigerant leakage. The benefit of a reduced TEWI of a secondary system is lessened as the le akage rate of the equivalent direct system decreases. The project has shown that there is sufficient knowledge of secondary fluid properties to be able to design an effective system. However, careful optimisation will be needed for a secondary system to become more attractive both financially and in terms of TEWI, so further research is recommended in to the optimisation of secondary systems.
Further research needs. Secondary systems using pumpable ice have been tried in
the UK but further work is needed to establ ish if it is a viable option. Research is
also needed to address the issues of st ore layout and pipework arrangements with the specific aim of reducing the capi tal cost of the secondary system.
The use of CO 2 as the secondary refrigerant ne eds to be researched in the
UK context. The current situation is not clear with respect to the health and safety issues and the performance of the systems in operation. Cascade systems have been used in the USA and may have some energy benefits and the possibility of using these in the UK should be investigated. If changes in legislation force th e adoption of lower Global Warming Potential (GWP) refrigerants then retail ers may wish to in vestigate secondary systems further. The options for improve ment include: system design (store layout to reduce pipework capital costs); pumpable ice; CO 2 ; and cascade systems. Reference should be made to experience in North America and Scandinavia where some of these approaches have been adopted.

Defrost. The energy used for defrosting evaporator coils in supermarkets can amount to 30% of the operating energy. Altern ative means of reducing the defrost energy have been researched by labor atory studies of different de frosting techniques and control strategies. Studies were carried out in both high and low temp erature applications and the following defrost techniques were considered:

• off-cycle

• hot/cool gas

• electric. However, not all techniques can be used in all circumstances, for example, offcycle is not appropriate in low temperatur e applications, leaving a choice of gas or
electric defrost. The findings showed that, for high temp erature applications, the cheapest and least energy consuming means of defrost is ‘off-cycle’. This method of defrost is widely35 used in the industry. For low temperature appl ications, the use of gas defrosting is more energy efficient than electric defrost but the considerable ex tra capital costs lead to long payback periods, up to 28 years. Consequently , electric defrost is most commonly used for low temperature applications in the UK. The length and frequency of the defros t cycle has a significant effect on the energy use of a refrigerated cabinet. The nor mal procedure of a fixed number of cycles per day is wasteful of energy because the time period between defrosts may be either too long - thereby reducing the frosted evaporator efficiency before defrost - or too short which provides unnecessary defrost events. In addition, the length of defrost can be excessive and this wastes further energy, a nd risks adverse effect s on the produc t quality and life. Optimised defrost cycles could reduce energy use by between 25 and 50%, where electric defrost is employed. Work is under way to develop controls to achieve
this. The optimum defrosting cycle will depend on the cabinet type and store
conditions and a means of control that rela tes to these paramete rs would lead to significant energy savings.
Further research needs. A number of issues for further research were revealed by these studies. Liquid defrosting for low temp erature applications should be further researched as it is potentially a more effective and energy efficient technique. Methods of determining the need fo r defrosting should be investigated and
these should take into account the avoidance of simultaneous defrosting of a number of units leading to high electrical loads. Evaporator design has an
influence on the formation of ice and shoul d also be researched in order to avoid or reduce the incidence of frosting.

CHP/CCHP. Combined heat and power and combined cooling, heat and power are potentially efficient methods of providi ng the energy for supermarkets. A simulation model has been developed that allows the en ergy and heat flows in a supermarket to be modelled and will predic t energy and cost savings arising from a range of measures taken to improve efficiency of supply or use of energy. The model was tested against a store using CHP and then used to evaluate a range of options. The studies showed that currently availabl e equipment can be used satisfactorily but needs to be carefully optimised for the specific store in which it is being installed.
The cost effectiveness of CHP/CCHP is sensit ive to the fuel costs and in particular the ratio of the gas and electricity costs. Additionally the number of hours for which the plant operates in a year is a key determinant of the cost effectiveness.
Further research needs. Determining the heat and power load profiles of a wider range of stores would assist in developi ng a clearer view of the potential for CHP in supermarkets. The design of the refrigeration syst em with the use of CHP and CCHP needs to be investigated as novel appro aches may provide a better match of heat and power usage. For example, gas engi ne prime movers for vapour compression machines can be attractive and the pote ntial for their use should be examined. The simulation model that has been developed in the context of this
research could be made available for retail ers and other interested parties to carry out feasibility studies on future stores.36 Case and Store Environment Interaction. This project was based on the premise
that the internal environment of the store, in which the refrigerated display cabinet is located, can have a significant bearing on the energy use and performance. The temperature and humidity of the air and its movement around the cabinet are all likely to influence the energy use. A store environm ent was measured and the conditions were recreated in the laboratory. Tests were then carried out with these different internal environmental parameters to investigate thei r impact on energy use. Two different cases were tested in the laboratory – an integral (self-contained open front chiller unit and an open well (coffin-type) freezer with a row of half-height glass door shelves above the open well (see Figure 16).

Figure 16 - Example of freezer case type tested by UK team in environmental chamber to determine impact of sto re temperature, relative humidity and ventilation mode (conventional or displacement) on performance

The results showed that for the freezer tested varying the store’s temperature, relative humidity and ventilation mode a nd rate had little im pact on the energy consumption of the unit. It may be surmised that although the rate of frost formation on the evaporator was dependent on the ambi ent relative humidity, whilst the defrost initiation and duration were pr eset, no significant impact on the energy use for defrost
was observed.37 For the chilled cabinet the energy consum ption was more dependent on the store conditions. A change of stor e temperature from 19 to 22 o C increased the energy use by up to 20%. At the higher temperature of 22 o C the relative humidity of the store environment increased the energy consumption by 15%, when raised from 35%rh to 50%
rh. Increased ventilation around the chiller could also lead to some increase in energy use. Overall, relative humidity is not as much of a significant factor in energy use as was initially expected from the literature revi ew. This is probably because the rh values in the UK are typically much lower than in the USA, where the other research had been
carried out. An additional finding was that reduction of the voltage supply to the cabinet had a large effect on the electricity use. Reducing the voltage from 240 to 220 volts resulted in a saving in energy of approximately 10% without any loss in performance. This effect has also been observed in stores, and current practice is to reduce voltage supply to the whole store in order to make savings.
Further research needs. The use of high velocity air s upply in aisles in order to mix the stagnant cool air needs to be i nvestigated particularly to ascertain the impact on customer comfort. This needs to be studied in the context of customers’ expectations of comfort leve ls in stores and particular ly adjacent to refrigerated display areas. Research is required into controllin g anti-sweat heaters by methods other
than time control. The control of the anti-s weat heaters is an area in which there is a potentially large energy saving to be made. The design and manufacture of cabinet s is a major issue that warrants further examination. The tendency is to provide standard solutions that are not being developed in line with the ai ms of improving energy efficiency. To overcome this needs the active participa tion of manufacturer s in the realistic testing and measurement of in-sto re operation in future trials.

UK Overall Conclusions. These projects have c onfirmed that many of the practices the retailers currently have in place are the mo st cost effectiv e e.g. the use of DX systems at low leakage rates, and electric and off-cycle defrosting. However, some of the more expensive and/or innovative tec hnologies could further reduce the TEWI of supermarket refrigeration.
A number of issues remain to be addre ssed in order to achieve these potential savings in all applications. There also appear s to be great scope for considering the whole system – from power supply to refrigerated goods display in a store environment – as a single system to be optimised; rather than a collection of indi vidual components each acting in isolation. Of particular note are:

• Defrost methods and control strategies – which has great retrofit potential

• Secondary system optimisation

• Store environmental conditions for comfort and cabinet energy use

• Variable speed compressors.

United States
The US contribution to the Annex include d an analysis of several low-charge refrigeration system options, a field test of a distributed compressor refrigeration system,38 and development of a spreadsheet-based refrig eration system model. Summaries of the analyses and the field test re sults are given below. The spreadsheet model is described briefly below and more fully in the US country report. Full details of the analyses and field test projects are given in the US country report. Appe ndix A provides some summary information on the field tests as well. There are over 100,000 retail food markets in the United States. Of these almost 33,000 are supermarkets – stores with over $2 million in sales annually and generally having much more than 1000 m 2 of sales floor area. Total annual electricity consumption for refrigeration alone in all US superm arkets combined is about 35-40 billion kWh. System analysis summary. A 3720 m 2 supermarket based on the layout in Figure 1 was simulated and energy consumption estimat es were made for a baseline air-cooled multiplex refrigeration system which uses R22 for the medium temperature compressor rack and R404A for the low temperature comp ressor rack and four advanced, low charge systems (Walker and Baxter, 2003). The advanced systems investigated included distributed compressor (R404A), secondary l oop (R507, primary refrigerant), low-charge multiplex (same refrigerants as baseline), and advanced self-cont ained (R404A). The secondary loop system modeled included four separate temperature loops operating at temperatures of -30, -18, -7, and -1 ° C with a potassium formate brine in the lowest temperature loop and propylene glycol brine in the higher temperature loops. The lowcharge multiplex system modeled was ba sed on the system described in Figure 7. Total refrigeration load was 328 kW ( 82 kW for frozen foods and 246 kW for fresh foods). The baseline system char ge was 1360 kg or 4.15 kg/kW load. Both the distributed compressor system (with secondary loop for heat rejection and evaporative cooling tower) and the secondary loop system (with evaporative condensing) achieved
similar results with annual energy savings of 11.3% and 10.4%, respectively, compared to the baseline for a Washington, DC locati on. The low-charge multiplex refrigeration system (with an evaporative condense r) showed annual energy savings of 11.6% compared to the baseline system. No ener gy savings were estimated for the advanced, self-contained system. Refrigerant charge reductions were 67% for the distributed compressor system, 85% for the secondary loop system, and 33% for the low-charge multiplex system. Energy savings results are summarized in Table 1.39 Table 1 - Predicted Energy Consumption for Low-Charge Refrigeration Systems System Heat Rejection Annual Energy (kWh) Energy Savings (kWh) % Savings vs
baseline

Multiplex (baseline) Air-Cooled
Condenser 976,800 - -

Multiplex Evap. Condenser 896,400 80,400 8.2 Low-Charge Multiplex Evap. Condenser 863,600 113,100 11.6

Distributed Water-Cooled Condenser, Evap Rejection 866,100 110,700 11.3

Secondary Loop Evap. Condenser 875,200 101,600 10.4
Advanced SelfContained Water-Cooled Condenser, Evap Rejection 1,048,300 - -

Secondary Loop Water-Cooled Condenser, Evap Rejection 959,700 17,100 1.8

Results for supermarket at Washington, DC location

Use of evaporative heat re jection (evaporative condens er or cooling tower) was the principal driver for energy savings for a ll of the advanced systems compared to the baseline case. The energy consumption of the multiplex baseline system would be about 8.2% lower if equipped with an evaporativ e condenser instead of the air-cooled
condenser.
An environmental assessment of these refrigeration systems was also made through a TEWI analysis for a 15-year life. The lowest TEWIs were achieved by the distributed compressor system and the secondary loop systems with estimated CO 2emission reductions compared to the baseline multiplex system (multiplex with aircooled condensing) of 13- 14 million kg, or about 57 - 60%. The low-charge multiplex system had estimated TEWI reductions of a bout 43% compared to the baseline system for a 15% annual refrigerant loss rate. Repl acing the air-cooled condenser with an evaporative condenser on the baseline system resulted in an estimated TEWI reduction of about 3% due to the energy savings from ope ration at lower condensing temperatures.
TEWI results are summarized in Table 2.40 a Conversion factor = 0.65 kg CO 2 /kWh

b 1/3 R404A (low temp), GWP = 3260; 2/3 R22 (medium temp), GWP = 1700

c R507, GWP = 3300

One observation from this study is that further efforts to reduce total global warming impacts for the distributed and s econdary loop systems would benefit more from reduction in energy usage (through effici ency increases or load reductions) than from further reduction in direct impact (from refrigerant losses). This based on the fact that the direct (refrigerant loss) portion of the estimated TEWI for these systems only comprises about 10% of the total. Payback estimates. A simple payback analysis was conducted based on the results from the analysis project. Estimated installed cost premiums for the distributed compressor, secondary loop, and low-charge multiplex refrigeration systems were $60,000 (about 15%), $147,000 (about 35%), and $0, respectiv ely compared to the baseline air-cooled multiplex DX system. These estimates were based on actual construction budgets supplied by the engineering departments of two supermarket chains.
It should be noted that the actual installe d cost of any refrigeration system will vary greatly, depending upon many factors, such as: purchasing arrangements between the supermarket and refrigeration equipment ve ndors; whether or not display cases are purchased in conjunction with the refrigerat ion system; special system features or configuration requested by the supermarket; and unique installation requirements of each
site. The cost premium for the water-source he at pumps used for heat recovery in refrigeration systems that use a secondary fl uid heat rejection loop was estimated to be$25,000 (about 30%) over a conventional system consisting of roof top airconditioners/gas heaters. Th e cost premium includes water piping for the heat pumps and Table 2 - Total Equivalent Warming Impact (TEWI) for Supermarket Refrigeration TEWI (million kg of
CO 2 ) System Condensing Charge, kg/kW Primary Refrigerant Leak (%) Annual
kWh
Direct Indirect a Total Multiplex Air-Cooled (baseline) 4.15 30 (15) 976,800 13.62 (6.81) 9.52 (9.52) 23.14 (16.33) Evaporative 4.15 R404A
/R-22 b
30 896,400 13.62 8.74 22.36 30 863,600 9.08 8.42 17.50 Low-Charge Multiplex Evaporative 2.77 R404A
/R-22 b 15 863,600 4.54 8.42 12.96

Distributed Compressors Water-Cooled, Evap. Tower 1.24 R404A 5 866,100 1.00 8.44 9.44

10 875,200 1.13 8.54 9.67 Secondary Loop Evaporative 0.69 R507 c 5 875,200 0.56 8.54 9.10 5 959,700 0.23 9.36 9.59 Water-Cooled, Evap. Tower 0.27 R507 c 2 959,700 0.09 9.36 9.45

Results for Washington, DC lo cation – 15 year service life41 over-sizing of the refrigeration heat rejection system to allow heat pump heat rejection during space cooling. Simple paybacks for refrigeration operat ion only were estimated for each of the low-charge systems at four different locations in the US. Operating cost savings for the refrigeration systems include the savings obt ained for reduced energy use and refrigerant leakage. Water costs are included for all sy stems employing evaporative heat rejection. The payback period for the low-charge multiplex system is immediate, since no installed cost premium exists. Paybacks for the distributed compressor system ranged from 3.4 to 7.0 years, while the payback for the secondary loop system ranged from 8.3 to 16.8 years. In addition simple payback was estimated for a distributed refrigeration system in combination with water-source heat pumps for store HVAC compared to a baseline multiplex refrigeration system with air-c ooled condensers and rooftop air-condensers with gas heat for HVAC. These pay back periods ranged from 4.2 years to 7.8 years depending upon local outdoor climate cond itions. The combined payback for refrigeration and HVAC savings was less than that for refrigeration savings alone for
cold climate locations because of increased space heating savings. Combined paybacks were lower for refrigeration system alone in the warmer climate locations because space heating is not as significant at these locations. Field test summary . A field test was conducted to compare the performance of a conventional multiplex system and a distribu ted compressor refrigeration system. Two supermarkets in the vicinity of Worcester, Massachusetts were the sites utilized for the field test. One store was equipped with a multiplex refrigeration system that had three compressor racks and air-cooled condensers. At the second store, a low-refrigerantcharge distributed refrigeration system wa s installed that consisted of 10 compressorcabinets. Heat rejection for the compressor cabinets was accomplished through watercooled condensers piped to a fl uid loop that used dry fluid co olers. The second store also had water-source heat pumps for space heating a nd cooling that were piped into the fluid loops. Both sites were instrumented to de termine energy consumption, refrigeration and heating, ventilating and air conditioning ( HVAC) loads, and numerous system state points to characterize operation. Energy consumption of the two refrigerati on systems was compared for winter and summer time periods from May 2001 through Febr uary 2002. The data show that overall energy consumption for the tested multiplex system was about 8% lower than that of the distributed compressor system tested in winter and 14% lower in summ er – in contrast to the analytical projections. For summer operation the multiplex system efficiencies (COPs) were 34.7 and 18.5% higher than thos e of the distributed system for low and medium temperature refrigeration, respectively. For winter operation the multiplex system COPs were higher than those of th e distributed system by 12.1 and 22.2% for low and medium temperature refrigeration, resp ectively. These results are disappointing because the distributed compressor system di d not perform as well as the analytical results suggested it could. This does not mean the advanced system is fatally flawed, but
there are several reasons for its poor performance relative to the baseline system tested. First, the tested distributed system used dry cooling towers for heat rejection rather than wet towers as assumed in the analysis. Second, the technique used to provide subcooling for the scroll compressors in the low temper ature cabinets of the distributed system simply did not work. Finall y, the baseline multiplex system tested was more efficient42 than the one modeled in the analytical case st udy. This had the effect of degrading the relative performance of the advanced vs. baselin e system in the field test as compared to the analysis. A one-year TEWI analysis of each test system was conducted. The charge sizes were estimated at 1360 kg of refrigerant for the multiplex system and 454 kg for the distributed system. Actual refrigerant leak age rates for the systems were not known so rates of 20% and 5 % were used in the analysis for the multiplex and distributed systems, respectively. The analysis showed that th e distributed system had about a 40% lower TEWI than the multiplex system over the co mbined summer and winter test periods despite its higher energy consumption.
Field test results for the water-source h eat pumps show that the amount of heat recovered from the refrigeration system was ab out 25.9% of the total he at rejection. This amount is considerably less than the capabilit y of the heat pumps, which can recover as much as 59.8% of the rejected heat from the refrigeration system. The ambient conditions during this time period were very mild so that the amount of space heat needed for the store was much less than normally seen. Despite limited operation, the water-source heat pumps were able to displace approximately 37,346 m 3 of natural gas usage at the test store for the winter period evaluated. The va lue of this displacement is dependent upon the utility rates for electricity and gas. For this particular site, the estimated energy cost savings seen over this winter period were $3,171.

Supermarket energy use screening level model

The model discussed herein was developed by the US as part of its role as the Annex operating agent.
The model consists of a set of Excel ® spreadsheets and was developed to provide tools to assist supermarket planners and engineers to co mpare the relative energy and refrigerant requirements for alternative designs of their refrigeration systems. The spreadsheets have been completed for multiplexed direct expansion and secondary loop refrigeration systems; an additional spreadsheet may be developed in the future for distributed refrigeration systems.
A users’ manual for the model is include d Volume 2 as part of the US country report. Users must specify or select info rmation about the display cases and walk-in coolers/freezers, secondary loop piping and fluids, and type of condenser. All calculations of fluid viscosity , friction factors, pressure drops, compressor power, and secondary fluid loop pumping pow er are built into the model. Model validation exercises have been performed using data from the baseline multiplex DX system tested in
Massachusetts. Results of the validation ar e included in the users manual in the US
country report.

Overall Summary

The five participating countries in Anne x 26 have carried out a significant amount of research on supermarket refrigeration and heat recovery system s – an estimated $543 million US total effort. A few major conclu sions and observations are noted (by country along with some summary comments) in this section from the analyses and testing programs conducted. Before proceeding, howe ver, it must be noted that these conclusions are subject to the assumptions used in the analyses and the particular
locations and insta llations of the field test systems. These specific results should not be considered to be generalizable to all store sizes and locations . However, they do provide a good relative indicatio n of the energy savings and TEWI reduction potential of the lowcharge refrigeration systems.

Canada Hydro Quebec’s laboratory (LTE) is field-testing two advanced systems and a baseline multiplex DX system. One advanced approach uses a multiplex DX system with heat reclaim for space and water heating and ground water to supplement heat rejection. The other has heat pumps integrated to provi de space heating for the store and subcooling for the refrigeration system. In winter , the discharge gas from the refrigeration compressors goes first through th ree plate heat exch angers that serve to desuperheat and precondense the gas. The three heat exchange rs also serve as evaporators for rooftop heat pumps that supply space heating to the st ore. Using heat pumps for heat recovery places no minimum limit on refrigeration system condensing pressure, as is the case for traditional heat recovery approaches. A fourth rooftop heat pump is integrated with the liquid line exiting the air-cooled condenser via a fourth plate heat exch anger. This heat pump subcools the refrigerant l eaving the condenser and uses the recovered heat for store space heating. Initial baseline tests in 1999- 2000 showed that both advanced approaches achieved about 6% lower speci fic energy consumption (kWh/m 2 /yr) compared to the
baseline store. In addition CETC-Varennes is partneri ng with Loblaws (Canadian supermarket chain) to install a refrige ration showcase in a new 9000 m 2 store in 2003. Refrigeration for all cases will be provided by a secondary loop system (the frozen food cases will have self-contained refrigeration systems with horizontal scroll compressors and will reject heat to the main secondary loop system). Re frigeration heat recove ry will be used for store heating.

Denmark A propane/carbon dioxide demonstration pl ant has been built in a medium-size supermarket. Propane is used as th e high temperature refrigerant (-14/+30 ° C) while carbon dioxide is used at the low temperature level (-32/-11 ° C). Carbon dioxide is used directly to perform the cooling in the freezer s while a brine circuit with propylene glycol is used in the coolers. Energy consumption in the test store is simila r to that of other new
stores in the same chain of markets with c onventional systems. The additional cost for a propane/carbon dioxide cascade plant for this si ze store is estimated at approximately
15% of the total installati on. A second test store (190 kW chilled food load, 60 kW frozen food load) with a cascade system usi ng R404A as the high temperature refrigerant and R744 (carbon dioxide) fo r the lower stage has been monitored also. The CO 2 is used
to cool both frozen food and chilled food cases, thus the amount of R404A required is only about 120 kg or about 10% of what a conventional DX system would require resulting in initial refrigerant cost savi ngs of about $37,000US due to high Danish taxes44 on HFCs. The total system cost was a bout 10% more than a conventional DX but showed 15-20% lower energy use than similar stores with R404A DX systems. The store used recovered heat from the refrigeration system for heating and required no back up during the test period.

Sweden Sweden’s work for the Annex is part of their national program Eff-Sys under a project “Energy Efficient Solutions for Supe rmarkets in Theory and Practice.” They have developed a computer model (Cybermart) for system predesign and have carried out field measurements in four supermarkets to validate the model. Sweden’s analyses
indicate that well de signed advanced secondary loop sy stems do not compromise energy efficiency compared to conventional DX systems. The analyses also show that two-loop secondary systems with subcooling of the lo w temperature loop are more efficient than cascade systems. Major conclusions from th e field test results include the following. - Standard secondary loop systems with subcooling of the low temperature loop primary refrigerant by the medium temperature brine have efficiency advantages over cascade systems. - Night covering of display cases reduces energy consumption by 10-20% - Practical experience with he at recovery to date show that only about 40-70% of stores’ heating needs are supplied by refrig eration heat recovery, primarily due to very low refrigeration loads during wint er and unoptimized control systems.

- Air-conditioning is needed in Swedish stores even if the cooling season is very short to avoid food quality problems. When the store ambient exceeds 25 ° C food in display cases will exceed code minimum temperatures and shelf life is halved.

United Kingdom
Four research activities have been co mpleted. The first is an evaluation of combined heat and power, and combined cooling, heating, and power schemes for supermarkets. CCHP has an improved load match compared to CHP, when used with absorption chilling. Cascade vapor compression systems integrated with the absorption system provide case refrigeration. Primary en ergy savings are around 15%, and there is a
TEWI reduction of more than 50%. A second study involved comparison of various secondary systems with standard DX systems. Results from that study indicated that secondary loop systems use about 30% more energy mostly due to secondary pumping power. TEWI for secondary systems was esti mated to be 8% lower than a DX baseline system, assuming the reference case had a 15% annual refrigerant l eakage rate and a 15 year service life. Capital co sts were estimated to be about 20% higher for the secondary approach. The third study wa s an investigation of the eff ect of various store conditions on case performance. Environmental chamber tests of low and medium temperature case systems show that an increase in ambient temperature from 19 to 22 ° C increases system energy use by 20%. Increasing RH from 35 to 50% at an ambient of 22 ° C increased the medium temperature case energy use by 15% but had no effect on the freezer case. Large savings were observed when the voltage was dropped from 240V to 220V, with no negative impact on product temperature. Finally analytical and experimental investigations of defrost met hods and alternative control st rategies were carried out. Studies looking at the frequenc y and duration of defrost cycl es showed that the current45 cycles are suited to relatively warm internal temperatures and high relative humidities (22 o C and 60% RH), and for different internal conditions, a lower frequency would be sufficient. For electric defrost, optimized cycles and controls c ould reduce energy use by 25-50%, and better termination controls on co mpletion of defrosting would reduce energy
use still further.

United States
A 3720 m 2 supermarket was simulated and TEWI and energy consumption estimates were made for a baseline air-cooled multiplex refrigeration system and advanced systems. Total refrigeration load was 328 kW with a refrigerant charge of 4.15 kg/kW load. The distributed compressor, low-charge multiplex, and secondary loop systems (with four independent secondary l oops) all achieved esti mated annual energy savings of about 11%. Use of evaporative h eat rejection was the principal driver for these energy savings - baseline system en ergy consumption was 8.2% lower with an evaporative condenser. The lo west TEWIs were achieved by the distributed system and the secondary loop systems with CO 2 emission reductions of about 13 - 14 million kg, or 57 - 60%. The low-charge multiplex system had estimated TEWI reductions of about 24% or 43% depending upon the refrigerant loss assumption. An analysis of an integrated water source heat pump and di stributed compressor refrigeration system showed about 13% operating cost savings comp ared to a baseline air-cooled multiplex refrigeration system with conventional rooftop HVAC units.

Summary comments Analyses carried out under the Annex 26 project and i ndividual country programs have shown that both energy savings (ove r 10%) and TEWI reductions (up to 60%) are possible with low-charge refrigeration system s as compared to the most prevalent type baseline -- a multiplex DX system with air-cool ed condensers. Savings are possible with distributed compressor systems, secondary loop systems, and low-charge multiplex systems. The secondary loop system opti on was the most thoroughly investigated advanced low-charge alternative in this A nnex (all participants studied this option to some extent). Energy consumption comparis ons with the baseline ranged from up to 30% greater energy use to about 10% saving s. Use of evaporative heat rejection approaches (condensers or cool ing towers) to reduce condensi ng temperatures is a key to obtaining maximum energy savings for all of the systems studied. Evaporative condensers (or cooling towers) will impose greater maintenance efforts and costs, however. Proper design and implementation of advanced low-charge systems is essential if energy savings are to be realized. In general further efforts to reduce tota l global warming im pacts (TEWI) of the advanced low-charge systems examined he re would benefit more from reduction in energy usage (through efficiency increases or load reductions) than from further reduction in direct impact (f rom refrigerant losses). Recovery of refrigeration system rejected heat was shown to be able to provide from about 40% to all of space and water heat needs for the test stores examined in this
Annex. The amount of waste heat that is eff ectively applied to the space and water heat requirements at a given site will depend upon the size of the coincident refrigeration load and the refrigeration/HVAC control system’s ability to effectively manage the heat46 recovery process. The integr ation of heat pumps with refr igeration systems was shown to be an excellent means for recovering refrig eration waste heat and reducing overall store energy use. Heat-pump-based heat recovery does not require the refrigeration system condensing temperature to be maintained artifi cially high to facilita te heat recovery.
Available cost studies show installed cost premiums for secondary loop systems range from 0% to about 35% while distri buted compressor systems show about a 15% premium. The low-charge multiplex approach is estimated to cost no more than current multiplex systems. It should be noted that the actual installed cost of any supermarket refrigeration system will be highly dependent upon many fact ors, not the least of which are the complex relationships between superm arket companies and equipment suppliers. These factors include negotiate d purchasing arrangements, inclusion of display cases with system purchase, special system featur es, and unique installation requirements (site specific). If/when any of the advanced syst ems studied begin to obtain increased market share, the price differential with the curre nt baseline can be expected to decrease somewhat due to the pressures of these market forces.

References

Danish law #49, December 21, 2000. Act amending the Act on taxes on certain chloroflouro-carbons and halons (CFC tax) . (Tax on the industr ial greenhouse gasses HFCs, PFCs and SF 6 ).

Bashtrash, S., 2002. Personal communicati on to Annex 26 participants during supermarket system tour near Montreal, April.

Horton, W. T., 2002. Modeling of secondary l oop refrigeration systems in supermarket applications, HL 2002-3, Report # 52571-1, Purdue University, W. Lafayette, IN, April.

Hrnjak, P., 1996. “Secondary Coolants for Low Temperature Supermarket Refrigeration”, presentation given at EPRI Supermarket Refrigeration Design Review Panel Meeting, ComEd Commercial Center, Oak Brook, IL. May 3.

Hrnjak, P., 2000. “Heat transfer issues in laminar flow of single-phase secondary refrigerants through the pipes,” Proceedings of the IEA Annex 26 Workshop, Stockholm, Sweden, October. P. Lundqvist, ed.

Kantchev, J., 2002. . Personal communica tion to Annex 26 participants during supermarket system tour near Montreal, April.

Kazachki, G., E. Bayoglu, and C. Gage, 1997. “C omparative Evaluation of Heat-Transfer Fluids for Secondary Loop Systems”, presentati on given at the International Conference on Ozone –Protection Technologies, Baltimore, MD, November 13.47 Lundqvist P., ed 2000. Proceedings of the IEA Annex 26 Workshop: Advanced Supermarket Refrigeration/Heat Recovery Sy stems, IEA Heat Pump Centre, Sittard, The Netherlands. (Cd-rom format only), ISBN# 90-73741-39-4.

Melinder, A., 2000. “Update on Secondary Refrigerants for Indirect Systems”, Proceedings of the IEA Annex 26 Works hop, Stockholm, Sweden, October. P. Lundqvist, ed.

Sand J. R., Fischer S. K., and Baxter V. D., 1997. Energy and global warming impacts of HFC refrigerants and emerging technologies, Alternative Fluorocarbons Environmental Acceptability Study and U. S. Depart ment of Energy, Washington, DC, USA.

Sherwood, G. J., 1999. Design and analysis of secondary refrigeration systems, MS Thesis, University of Minnesota, March.

Vana, J., 2000, “Comparison of secondary and multiplex DX equipment,” Proceedings of the IEA Annex 26 Workshop, Stockholm, Sweden, October. P. Lundqvist, ed.

Walker D. H. and Baxter V. D., 2003. “Analy sis of advanced, low-charge refrigeration systems for supermarkets,” ASHRAE Trans. V. 109, pt. 1.

Acknowledgements

The Annex Operating Agent gratef ully acknowledges the support and contributions of the lead investigators from each Annex 26 participant: V. Minea and D. Giguère of Canada; Prof. H. J. H. Knudsen of Denmark, Prof. P. Lundqvist of Sweden, and A. Crompton and J. Palmer of the United Kingdom. Thanks are al so expressed to US
contributors S. Fischer and D. Walker. The US Department of Energy, Office of Building Technology, State and Community Progra ms sponsored U. S. activities for IEA
Annex 26 under contract DE-AC05- 00OR22725 with UT-Battelle, LLC.48 Appendix A – Case Study Summaries

This appendix is included to give the reader some summary details for a few of the stores that were the objects of cas e studies under Annex 26. For fu ll details on the studies one
should consult the individual c ountry reports in Volume 2.

Canada – LTE

Test store 1 (“System1-phase1”) -- METRO – Messier , Montreal Test store 2 (“System2-phase1”) -- IGA – Crevier , Montreal Conventional store (“CON”) -- METRO – Bordeleau , Montreal

- “System1-phase1” – multiplex system with reciprocating compressors for low temperature loads and screw compressors for medium temperature loads. New total heat reclaim technique for space a nd hot water heating. High speed hot gas
defrost method.

- “System2-phase1” – improved multiplexed system with reciprocating compressors. Cascade heat pumps coupled with the refrigeration system to recover rejected heat for store heati ng in winter. Dedica ted heat pump for mechanical sub-cooling. Re frigerant liquid pumping.

- “CON” – multiplex, conventional heat reclaim and defrost.

Store and system design details

Store Areas and Refrigeration Capacities as function of Saturated Suction Temperatures
System Total
Area Sale
Area Low/Dual Temperatures Medium Temperatures

- - - 37 °C - 32 °C - 29 °C -26 °C -12 °C -9 °C -7 °C -1 °C 7 °C
ft 2 ft 2 kW kW kW kW kW kW kW kW kW System1 38,000 28,302 7.15 28.34 8.54 13.63 - 82.77 134.4 11.58 35.43 System2 40,900 30,838 4.61 9.02 56.33 - 3.61 118.0 155.3 9.50 -

CON 18,000 12,200 - 35.57 - - - 45.70 78.61 - -

- store operating hours (hours open per day): 14 hours/day.
- total traffic or sales vol ume: average traffic - 10 000 per week

- estimated total primary refrigeran t charge (estimate): R-22, 1500 – 1800 kg

- estimate of annual loss of prim ary refrigerant: 15% of charge49 ” System1-phase1 ”: Display Cases and Walk-in Boxes – Low Temperature Rack

(SST - Saturated Suction Temperature; CST - Condensing Saturated Temperature)

No Dimensions Description Capacity SST CST

- ft - Btu/h °F °F

1 8’ Frozen Tomb 10 860 -25 105

2 12’ Frozen Tomb 13 380 -25 105

3 15 doors Ice Cream 25 500 -25 105

4 12 doors Grocery 18 000 -15 105

5 14 doors Meat 21 000 -15 105

6A 5 doors Fish 7 500 -15 105

6B 3 doors Bakery 4 500 -20 105

7A 26’x15’x8’ Grocery 12 500 -25 105

7B 26’x15’x8’ Grocery 12 500 -25 105

8 20’x13’x8’ Meat 15 900 -20 105

9 11’x8’x8’ Bakery 8 750 -20 105

10 12’ Frozen Tomb 3 960 -25 105

11 Spare 10 % 18 000 -25 105

13A 8’+2 (bouts) Ice Cream 12 200 -35 105

13B 8’+2 (bouts) Ice Cream 12 200 -35 10550 ” System1-phase1 ”: Display Cases and Walk-in Boxes – Medium Temperature (SST - Saturated Suction Temperat ure; CST - Condensing Saturated Temperature)

No. Dimensions Description Capacity SST CST

- ft - Btu/h °F °F

20 28 Fresh Meat 44 800 15 110

21 36 Fresh Meat 57 600 15 110

22A 14 Delicatessen 15 400 15 110

22B 14 Delicatessen 15 400 15 110

23A 14 Cheese 10 850 15 110

23B 14 Cheese 10 850 15 110

24A 8 Pizza 9 600 15 110
24B 8 Spare 10 600 15 110
24C 8 Spare 2 400 20 110
24D 8 Spare 2 400 20 110

25 36 Delicatessen 52 800 15 110

26A 8 Fich 9 600 15 110
26B 8 Bakery 9 600 15 110
27 12 Start-up 9 300 15 110
28 Spare 10 % - 26 000 15 110

29 A/C AC offices 79 800 45 110

30A 30’x20’x10’ Meat 17 550 20 110

30B 30’x20’x10’ Meat 17 550 20 110

31A 10’x9’x8’ Fish 8 200 20 110

31B 10’x9’x8’ Delicatessen 8 200 20 110 31C 12’x8’x8’ Bakery 8 000 20 110

32A 8 Meat 3 040 20 110

32B 24 Delicatessen Service 9 120 20 110

33A 26’x18’x8’ Milk 11 300 20 110

33B 26’x18’x8’ Milk 11 300 20 110

34A 36 Milk 47 700 20 110

34B 12 Wine 15 900 20 110

35 38 Milk 50 360 20 110

36 40 Milk 53 000 20 110

37 44 Beer 63 800 20 110

38A 8 Fruits 3 800 20 110

38B 20 Fruits 26 500 20 110

39 48 Fruits 37 440 20 110

40 24’x15’x8’ Fruits 20 150 20 110
41A 608 Preparing 19 760 30 110
41B 608 Preparing 19 760 30 110
42 Spare 10 % - 41 000 20 110 43 - Sub-cooling 41 084 40 110

TOTAL - - 901 514 - -51 ” System1-phase1 : Characteristics of the Low Temperature Compressors

Compressor SST Model Power Capacity THR RLA kW

- °F - hp Btu/h Btu/h A -

Copeland -25 3DA3-0600-TFE 6 28 661 44 545 10,5 4,6

Copeland -25 4DA3-1000-TSE 10 48 307 75 860 17,5 8

Copeland -25 4DL3-1500-TSE 15 64 685 101 098 20,9 10,7

Copeland -25 3DS3-1000-TFE 10 46 399 71 891 16,8 7,4

Copeland -35 3DF3-0900-TFE 9 29 470 49 160 16,5 5,7

TOTAL - - 50 217 522 342 554 82,2 36,4

” System1-phase1 : Characteristics of the Medium Temperature Compressors

Compressor TSS Model Power Capacity THR RLA kW

- °F - hp Btu/h Btu/h A -

Carlyle 15 06TAH078C2EA 40 323 173 408 548 51,4 37,2

Carlyle 15 06TAH078C2EA 40 323 173 408 548 51,4 37,2

Carlyle 15 06TAH078C2EA 40 323 173 408 548 51,4 37,2

TOTAL - - 120 969 519 1 225 644 154,2 111,6

” System1-phase1 : Characteristics of the Air-Cooled Condensers

Low Temperature Medium Temperature

Model CLD057 FDFCT-180-R

Capacity 424 800 Btu/h 1 800 000 Btu/h

AC Circuit; Control 8,4 A; 575 V/3 ph; 120 V/30 A 575 V/3 ph; 120 V/30 A52 ” System 1-phase 1 ”: Example of Monitored Parameters

Type of Parameter Observation

Store Total Power (kW) -

Compressor’s Power (kW) Both DT and MT Compressor

Total Electrical Power (kW) LT and MT Compressor

Suction Pressures (psig) Both DT and MT Refrigeration Line

Discharge Pressures (psig) Both DT and MT Refrigeration Line

Suction Temperatures (°C) Both DT and MT Refrigeration Line

Discharge Temperatures (°C) Both DT and MT Refrigeration Line

Liquid Temperatures (°C) Both DT and MT Refrigeration Line

Liquid Pressures (psig) Both DT and MT Refrigeration Line

Cold Water Temperatures (°C) Entering/Leaving Storage Tank

Groundwater Temperature (°C) Enteri ng/Leaving Plate Heat Exchanger

Control Valves Status (on/off) Defrost, Heat Recovery, Flushing, etc.

” System 1-phase 1 ”: Example of Calculated Thermodynamic and Energy Parameters

Type of Parameter Observation

Mass Enthalpies (kJ/kg) Both DT and MT Line (Suction, Discharge, Liquid)

Total Refrigerant Flow-rate (kg/s) Bo th DT and MT Refrigeration Line

Title of Two-phase Refrigerant (%) Bo th DT and MT Refrigeration Line

Refrigeration Power (kW) Both DT and MT Refrigeration Line

Condensing Power (kW) Both DT and MT Refrigeration Line

Refrigeration Load (kWh) Both DT and MT Refrigeration Line

Energy Rejected from Condensers (kWh) Both DT and MT Refrigeration Line

Refrigeration Efficiency Both DT and MT Refrigeration Line

Saturated Suction (SST) and Discharge (SDT) Temperat ures (°C) Both DT and MT Refrigeration Line

Compressor Consumed Energy (kWh) Both DT and MT Refrigeration Line

Energy Consumption (kWh) Both DT and MT Refrigeration Line

Operating Time: Heat Reclaim, Defrost; Condens er; Geothermal Space and Water Heating Systems

Defrost Cycle Status and Operating Time (sec/hr; hr s/day) Fresh Meat Case and Cold Room; Ice Cream53 “ System2 – phase1 ”: Characteristics of Dual (Low & Medium) Temperature Compressors (THR - Total Heat Rejection; EER – Energy Efficiency Ratio)

Compressor TSS Model Condensing temperature SUCTION Capacity THR EER

- °F - °F Btu/h Btu/h -

COP/Discuss (22) L/T -35 2DA3-060E-TFE-200 100 16 000 27 270 5,07

COP/Discuss (22) L/T -25 3DB3-075E-TFE-200 100 37 000 55 490 6,76

COP/Discuss (22) L/T -20 2DL3-040E-TFE-200 100 25 000 36 380 7,07

COP/Discuss (22) L/T -20 3DS3-100E-TFE-200 100 56 000 82 320 7,1

COP/Discuss (22) L/T -20 3DS3-100E-TFE-200 100 56 000 82 320 7,1

COP/Discuss (22) L/T -20 4DA3-100E-TSE-200 100 59 000 88 510 6,93

COP/Discuss (22) M/T 15 3DB3-100E-TFE-200 100 107 000 136 100 12,71

COP/Discuss (22) M/T 15 3DS3-150E-TFE-200 100 142 000 181 100 12,32

COP/Discus (22) M/T 15 4DA3-2000-TSE-200 100 150 000 190 800 12,54

Total -35 - - 16 000 - -

-25 - - 37 000 - -

-20 - - 195 000 - -

15 - - 399 000 - -

Total Unit - - - - 880 200 -

“ System2 – phase1 ”: Characteristics of Medium Temperature Compressors (THR - Total Heat Rejection; EER – Energy Efficiency Ratio)

Compressor TSS Model Condensing Temperature SUCTION
Capacity THR EER

- °F - °F Btu/h Btu/h -

COP/Discuss (22) M/T 20 2DA3-075E-TFE-200 100 83 000 103 600 13,78

COP/Discuss (22) M/T 20 3DB3-100E-TFE-200 100 120 000 149 300 13,82

COP/Discuss (22) M/T 20 3DL3-150E-TFE-200 100 159 000 199 200 13,34

COP/Discuss (22) M/T 20 4DH3-2500-TSE-200 100 222 000 276 800 13,69

Total 20 - - 584 000 - -

- - - - 729 000 -54 “ System2 – phase1 ”: Display Cases and Walk-in Boxes –Low Temperature

No. Description Capacity SST

- - Btu/h °F

13 Ice Cream 15 720 - 35

11 Pastry and Frozen Meat 5 280 - 25

4 Ice Cream 5 doors 25 500 - 25

10 Bakery and Frozen Crus taceous 16 680 - 20

8 Frozen Meat and Fish 21 720 - 20

3 Frozen Products 10 860 - 20

5 Frozen Products 23 160 - 20

6 Frozen Meat 17 640 - 20

7 Frozen Bakery 20 760 - 20

9 Frozen Meat and Fish 27 000 - 20

2 Frozen Products 24 000 - 20

1 Frozen Products 22 500 - 20

12 Spare 7 894 - 2055 “ System2 – phase1 ”: Display Cases and Walk-in Boxes – Medium Temperature (SST : Saturated Suction Temperature)

No. Description Capacity SST

- - Btu/h °F

41 Combined Service. “BAS” 12 320 10

41 Shelves of Prepared Meals 7 200 15

41 Flowers 6 240 20

52 Prepared Meals 5 080 15

52 Delicatessen and mets préparés 12 420 20

31 Fresh Meat 30 280 15

30 Fresh Meat 44 800 15

32 Fresh Meat, Fish and Crustaceous 33 960 15

33 Delicatessen 52 800 15

34 Delicatessen 38 400 15

38 Prepared Meals 43 200 15

37 Pizza 31 200 15

38 Prepared Meals 11 670 20

35 Wine 26 500 20

35 Delicatessen 26 500 15

40 Vinaigrettes 37 100 20

46 Fruits and Vegetables 43 680 20

36 Fruits and Vegetables 18 720 20

42 Fruits and Vegetables 44 160 20

50 Milk Products 50 340 20

49 Milk Products 31 800 20

48 Milk Products 47 700 20

53 Milk Products 71 520 20

51 Beer 68 900 20

44 Milk 22 650 20

43 Fresh Meat and Fish 39 090 20

45 Bakery; Fruits and Vegetables 36 990 20

47 Preparation Area 32 400 3056 “ System2 – phase1 ”: Example of Monitored Parameters

Type of Parameter Observation

Store Total Power (kW) -

Compressor Power (kW) Each Low and Dual Compressor

Rack Power (kW) LT and MT Compressor

Heat Recovery and Sub-Cooling Heat Pump Power (kW) Each Unit

Suction Pressures (psig) Very Low, Low and Medium

Common Discharge Pressures and Defrost Discharge (psig) Each Rack

Suction Temperatures (°C) Very Low, Low and Medium

Common Discharge Temperatures (°C) DT/MT

Defrost Discharge Temperatures (°C) DT/MT

Liquid Defrost Return Temperatures (°C) DT/MT

Liquid Temperatures (°C) DT/MT

Liquid Pressures (psig) DT/MT

Liquid Pump Pressures (psig) Entering/Leaving each LP

Control Valves Status (on/off) Defrost, Heat Recovery, Flushing, etc.

Hot Gas Temperature at Plate Heat Exchangers Outlet (°C) Each Unit

Natural Gas Valve Status (on/off) Each Unit

“ System2 – phase1 ”: Example of Calculated Parameters

Type of Parameter Observation

Mass Enthalpies (kJ/kg) LT/DT (Suction, Discharge and Liquid0

Compression Mass Enthalpy Variation (kJ/kg) LT/DT

Saturated Suction and Discharge Temperat ures (°C) Low and Dual Temperature

Compressor Energy Consumption (kWh) Each Low and Dual Compressor

Total Energy Consumption (kWh) Each Low and Dual Compressors

Heat Pumps Operating Time (sec/hr; hrs/ day) Space and Water Heating Systems

Defrost Status and Duration (sec/hr; hrs/day) Fresh Meat Case and Cold Room; Ice Cream57 “System CON ” : Display Cases and Walk-in Boxes – Low Temperature

Circuit Description Capacity Operation Temperatures

- - Evaporation Condensing

Btu/h °F °F

1 Different
Products 25 500 - 25 105

2 Ice Cream 22 100 - 25 105

3 Different Product 11 500 - 25 105

4 Fish 25 680 - 25 105

5 Meat 2 640 - 25 105

7 Meat 19 260 - 25 105

8 Meat 9 000 - 25 105

9 Pastry 5 700 - 25 105

Total - 121 380 - -58 “ System CON ” : Display Cases (15 °F - Medium Temperature)

Circuit Description Capacity Operation Temperatures

- - Evaporation Condensing

Btu/h °F °F

19 Fresh Meat 57 600 15 110

11 Delicatessen 16 140 15 110

12 Fish 9 600 15 110

13 Mets cuisinés 24 000 15 110

14 Delicatessen 14 400 15 110

15 Cheese 10 800 15 110

20 Meat 23 400 15 110

Total - 155 940 - -

“ System CON ” : Display Cases (20 °F - Medium Temperature)

Circuit Description Capacity Operation Temperatures

- - Evaporation Condensing

Btu/h °F °F

17 Pastry 9 600 20 110

18 Farm Delicatessen 10 500 20 110

18 Milk 63 600 20 110

20 Beer 21 200 20 110

21 Jus/Vegetables 37 100 20 110

21 Refrigerated Table 5 600 20 110

22 Fruits/Vegetables 40 300 20 110

23 Milk 11 500 20 110

24 Delicatessen 4 500 20 110

25 Fruits/Vegetables 10 000 20 110

26 Beer 19 000 20 110

27 Meat 24 505 20 110

28 Fruits/Vegetables 10 800 20 110

Total - 268 20559 “ System-CON ”: Monitored Parameters

Type of Parameter Observation

Compressor Power (kW) LT and MT Compressors

Electrical Oven Power – Cook ing (kW) Ovens #1, 2 and 3

Suction Temperature (°C) Low and Medium Temperature Racks

Common Discharge Temperature (°C) Each Rack

Hot Gas Temperature – Heat Reclaim (° C) Entering and Leaving HR Coil

Defrost Valves Status (on/off) Freezing Products; Fresh Meat

Based on the measured parameters, several ther modynamic, energy and performance calculations were performed ( ).

“ System-CON ”: Thermodynamic, Energy and Pe rformance Calculated Parameters

Type of Parameter Observation

Energy Consumption of Compressor (kW) Low and Medium Temperature Compressors

Total Refrigeration Consumed Energy (kWh) Low and Medium Temperature Compressors

Cooking Energy Consumption (k Wh) Each Electrical Oven

Duration and Defrost Status (sec/hr; hrs/day) Four Refrigeration Display Cases60 Annual energy consumption

Total Store’s Natural Gas Consumption vs. Sale Area

Syste

m Sale
Area Total Consumption Equivalent Energy Total Natural Gas
Cost (CAN$)

2 ft 3 m /y 3 m / 2 ft GJ/y (kWh/y) GJ/ 2 ft /y
(kWh/ 2 ft /y) $/y $/ 2 ft /y

Syst-1 28,302 45,179 1.59 1.6 (4.4* 6 10 ) 5.6* 5 10

− (155) 22,534 0.80

Syst-2 30,838 35,625 1.15 1.27 (3.5* 6 10 ) 4.12* 5 10

− (113) 17,860 0.58

Total Store Annual Electrical Energy C onsumption and Costs (Including Demand Power Cost) vs. Sale Area (CAN$)

System Sale
Area Total Store Electrical Energy Consumption (including compressors and heat pumps) Total Store Electrical Energy Cost (Power : 11,97 $/kW)

2 ft kWh/y kWh/ 2 ft .y vs. CON.1

(%) $/y $/ 2 ft .y vs. CON.1 (%)

Syst-1 28,302 2,770,873 97.9 + 2.4 157,.704 5.6 - 12.5

Syst-2 30,838 2,768,775 89.8 - 5.7 163,411 5.3 - 17.2

CON.1 12,200 1,095,462* 95.5* - 78 440* 6.4* -
* Without Electrical Cooking61 Annual Compressor Electrical Energy Consum ption and Costs (Including Power Demand Cost) – vs. Sale Area (CAN$)
Syste

m Sale
Area Compressors Total Energy Consumption (Compressors only) Total Electrical Energy
Cost (Compressors only)

2 ft - kWh/y % of Total
Store
Cons. kWh/ 2 ft .y $/y $/ 2 ft .y

Syst-1 28,302 Low Temp. 264,906 9.6 9.4 15,077 0.53

Medium T. 637,299 23 22.5 36,262 1.28

TOTAL

compressors 902,205 32.5 31.9 51,339 1.81

Syst-2 30,838 Low/Dual T. 423,291 15.3 13.7 24,982 0.81

Medium T. 206,298 7.5 6.69 12,172 0.39

TOTAL

compressors 629,589 22.7 20.4 37,154 1.2

Heat Pumps 313,805 11.3 10.2 18,521 0.6

TOTAL 943,394 34.0 30.6 55,675 1.8

CON. 12,200 TOTAL

compressors 355,721 30.6* 29.2 23,995 1.97

* Excluding electrical cooking.62 Denmark

Fakta market in Beder, Denmark (newest store in the Fakta chain as of July 2001)

Store details
Size - 490 m 2 sales area (720 m 2 total area) Operating hours/day – 12 hours/day Lighting load – 12.18 kW indoor; 1 kW outdoor

Refrigeration system Type – This is a cascade system using pr opane as the refrigerant for the higher temperature loads (–14/25°C) and CO 2 as the refrigerant for the lower temperature loads (–32/–10°C). The propane cycle rejects heat through an air-cooled
condenser at the roof of the supermarket while the CO 2 condenses in a cascade heat exchanger that also serves as one of two evaporators for the propane cycle.
CO 2 is used directly (direct expansion) in the low-temperature (LT) cabinets and cold stores of the supermarket, while th e propane circuit chil ls propylene glycol brine in its second evaporator. The glycol is pumped in a closed system to the high-temperature (HT) cabi nets and cold stores. Design capacity - 33 kW at -14 ° C evaporating temperatur e, propane circuit (21 kW for HT cabinets, 12 kW for CO 2 circuit condenser); 10 kW at -32 ° C evaporating temperature, CO 2 circuit Primary refrigerant type and charge – 10 kg propane; 6 kg CO 2 Secondary refrigerant type and charge – 120 l propylene glycol Estimated annual losses – propane circuit, 2% of charge; CO 2 circuit, 15% of charge

Propane system components Description Supplier 2 compressors Bitzer, 4T-8.2P
Air-cooled condenser ECO FCE 071C63 Plate heat exchanger R 290/PGl: 21 kW, Swep, B25x70 Plate heat exchanger R290/R 744: 10 kW, Swep V27x80 HP Plate heat exchanger R 290/R290: 2 kW, Swep, B12x70 Plate heat exchanger R 290/PG: 3 kW, Swep B27x50 Electronic expansion valve Danfoss ETRE – 30 kW Electronic expansion valve Siemens Staefa – 14 kW

CO 2 system components Description Supplier Compressor for CO 2 Bitzer, X2KC-3.2, BSE 55 Expansion valve AKV (nozzle 2-4) Safety pressure switches KP 5 Filter dryer DU 30363 Display cases
Air on Refrigeration load [W] Dimensions

[°C] Medium (+2°C) Low (-20°C) LxBxH [mm 3 ]

Storage (glass doors to shop) -2°C 4500 - 5100x3300x2360 Storage, frozen food (doors) -26°C - 4200 3600x3300x2450 Storage, ice cream (doors) -28°C 2800 2100x3300x2450 Vertical cabinet (no doors) -2°C 14400 - 10 m in length
Horizontal case -27°C 2200 3750x1000x960
Horizontal case -27°C 800 1985x1000x960
Horizontal case -2°C 1400 3750x1000x960
Horizontal case -2°C 700 1985x1000x960
Total 21000 10000 * Type of defrost method: Electric resistance

HVAC system Type – ventilation only; 2.62 kW power input

System operating data Saturated discharge and suction temperatures Propane system: Condensation Temperature: Evaporation temperature: Capacity (design): 25°C (avg.)/ 22°C (min) / 30°C (max) -14°C (avg.)
33 kW CO2 system: Condensation Temperature: Evaporation temperature: Capacity (design): -11°C (avg.) -32,5°C (avg.)
10 kW Brine PG(40%): Outlet temperature: Return temperature: Capacity (design): -8°C
-2°C
21 kW

System energy use and weather conditions Total store energy consumption, July 2001

pcs kW/pcs Hours/day kWh/ July
Refrigeration plant 1 - 24 8682
In store lighting 210 0,058 12 4531
Out store lighting 10 0,1 12 372

Ventilation store 1 2,62 14 1137

Tellers 3 0,4 12 446

Bottle machine 1 1 1 31

Various 1 2 12 372

Total 1557164 Refrigeration system energy c onsumption detail, July 2001 Consumer Energy consumption [kWh for July] Propane compressor 1 3565 Propane compressor 2 1240

CO 2 compressor 605

Cases and cabinet: Lighting 107

Ventilation 487 Storage rooms: Lighting 391

Ventilation 744

Brine pump: 126 Heaters (Edge): 1116 Defrost (cases, cabinet and storage) 84

Ventilation condenser 140

Electronics 78

Total 8682

The average outdoor temperature during the Ju ly 2001 period was 17.9 oC. Store indoor temperature averaged 22.5 oC. Energy consum ption of the refrigeration system in the Fakta Beder store compared to eight sim ilar Fakta supermarkets with conventional R404A direct expansion refrigeration systems is illustrated in Figure A1. The time period plotted begins in July 2000 and ends in February 2002.65 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Ju

ly

S

ep

t emb er Novemb e

r

Janu a

r y M a

r t s May Jul y

S

ep

t emb er

N

o vemb er Jan u

aryEnergy consumption [kWh]

Lower 25% Upper 25%

New Fakta in Beder

Figure A1 – Comparison of energy use of Fakta Beder store (with cascade refrigeration system) to that of eight ot her Fakta stores (wit h conventional R404A DX refrigeration systems); July 2000 through February 2002.66 United States

Test store – Distributed compressor refrigeration system
Size – 4830 m 2 sales area Operating hours – 168 hrs/week

Refrigeration system

The system consists of several small comp ressor cabinets distributed throughout the store
and located close to the loads th ey serve. Heat rejection is done via a water/glycol loop that connects the compressor cabinets to roof-m ounted cooling towers (dry type). Water source heat pumps are integrated into th e condenser cooling loop and recover the refrigeration waste heat in wi nter to heat the store space.

Distributed Refrigerati on System Compressors (capacities are in kW for saturated evapor ating and condensing te mperatures shown) All compressor cabinets use refrigerant R-404A Cabinet A Low Temper ature Cabinet C Low Temperature Compressors Capacity: -32 o C & 41 o C Capacity: -27 o C & 41 o C
A-1 ZF15K4 4.8 C-1 ZF15K4 6.3
A-2 ZF15K4 4.8 C-2 ZF15K4 6.3
A-3 ZF15K4 4.8 C-3 ZF15K4 6.3
A-4 ZF18K4 5.7 C-4 ZF15K4 6.3
A-5 ZF18K4 5.7 C-5 ZF15K4 6.3 Cabinet B Low Temper ature Cabinet D Low Temperature Capacity: -32 o C & 41 o C Capacity: -32 o C & 41 o C
B-1 ZF13K4 3.9 D-1 ZF15K4 5.2
B-2 ZF13K4 3.9 D-2 ZF15K4 5.2
B-3 ZF15K4 4.8 D-3 ZF15K4 5.2 Capacity: -26 o C & 41 o C D-4 ZF15K4 5.2
B-4 ZF15K4 6.1 D-5 ZF15K4 5.2
B-5 ZF18K4 7.3 D-6 ZF18K4 6.2
B-6 ZF18K4 7.3
Cabinet E Medium Temperature Cabinet G Medium Temperature Capacity: -6.7 o C & 43 o C Capacity: -8.3 o C & 43 o C
E-1 ZS38K4 12.0 G-1 ZS38K4 11.3
E-2 ZS38K4 12.0 G-2 ZS38K4 11.3
E-3 ZS45K4 14.4 G-3 ZS38K4 11.3
E-4 ZS45K4 14.4 G-4 ZS38K4 11.3
E-5 ZS45K4 14.4 G-5 ZS38K4 11.3
E-6 ZS45K4 14.4 G-6 ZS45K4 13.567 Cabinet F Low/Medium Temperature Cabinet H Low/Medium Temperature Capacity: -6.7 o C & 43 o C Capacity: -15 o C & 43 o C
F-1 ZF09K4 H-1 ZS26K4E 6.2 Capacity: -8.3 o C & 43 o C H-2 ZS26K4E 6.2 F-2 ZS30K4 9.2 Capacity: 1.7 o C & 43 o C
F-3 ZS30K4 9.2 H-3 ZS38K4E 15.9
F-4 ZS30K4 9.2 H-4 ZS38K4E 15.9
F-5 ZS38K4 11.3 H-5 ZS45K4E 19.1
Cabinet I Medium Temperature Cabinet J Low/Medi um Temperature

Capacity: -8.3 o C & 43 o C Capacity: -6.7 o C & 43 o C
I-1 ZS38K4E 12.0 J-1 ZF11K4E 3.6
I-2 ZS38K4E 12.0 J-2 ZF13K4E 4.2
I-3 ZS45K4E 14.4 J-3 Zf13K4E 4.2
I-4 ZS45K4E 14.4 I-5 ZS45K4E 14.4 Capacity: -9.4 o C & 43 o C
J-4 ZS38K4E 10.8
J-5 ZS38K4E 10.8
J-6 ZS38K4E 10.8 Primary refrigerant type and charge – R-404A; estimated at about 410 kg total Secondary refrigerant type and charge – ethylene glycol on condenser fluid loop; total charge unknown Estimated annual losses – primary refriger ant annual loss estimate d at 5% of total charge

Display case line ups, storage and preparation room areas, and miscellaneous loads connected to compressor cabinets Circuit Case Length, No. of Doors, or
Walk-in Floor Area Design Refrigeration Load (kW) Cabinet A Sat. Suction Temp -32 o C
Walk-in Freezer 94.1 m 2 22.3 Cabinet B Sat. Suction Temp -32 o C
Walk-in Freezer 47 m 2 11.1 Cabinet B Sat. Suction Temp -26 o C
Reach-in Frozen Food 23 Doors 10.1 Cabinet C Sat. Suction Temp -26 o C
Reach-in Frozen Food 52 Doors 19.8
Multi-Deck Frozen Food 2.4 m 3.5 Cabinet D Sat. Suction Temp -32 o C
Multi-Deck Frozen Meat 17 m 16.7
Multi-Deck Frozen Fish 8.5 m 7.0
Walk-in Frozen Fish 13.4 m 2 3.5 Cabinet E Sat. Suction Temp -6.7 o C Multi-Deck Dairy 36.6 m 47.1
Multi-Deck Cheese 4.3 m 5.568 Walk-in Dairy 79.6 m 2 18.2 Cabinet F Sat. Suction Temp -8.3 o C
Service Deli 25.6 m 7.6
Multi-Deck Cheese 6.1 m 8.4
Isle Deli 4.9 m 11.3
Walk-in Deli 14.2 m 2 4.5
Walk-in Raw 4.5 m 2 1.4 Cabinet F Sat. Suction Temp -29 o C
Walk-in Deli Freezer 7.5 m 2 1.8 Cabinet G Sat. Suction Temp 8.3 o C Single-Deck Meat 7.3 m 3.3
Multi-Deck Meat 20.7 m 26.9 Floral Display 7.3 m 9.1
Multi-Deck Deli 8.5 m 12.4 Single-Deck Fish 4.9 m 5.2
Walk-in Fish 10.2 m 2 3.2 Cabinet H Sat. Suction Temp 35 o F Meat Prep Room 6,144 ft 2 153,600 Cabinet H Sat. Suction Temp -15 o C
Ice Maker 10.6 Cabinet I Sat. Suction Temp -6.7 o C
Multi-Deck Produce 35.4 m 36.0
Table Fish 4.6 m 2.2
Walk-in Produce 91.4 m 2 19.5 Cabinet J Sat. Suction Temp -9.4 o C
Walk-in Meat 98.1 m 2 23.2 Walk-in Bakery 11.1 m 2 5.8 Cabinet J Sat. Suction Temp -29 o C
Walk-in Freezer Meat 9.3 m 2 2.2 Walk-in Freezer Bakery 13.4 m 2 3.2 Multi-Deck Bakery 4.3 m 4.6 All Compressor Cabinets employ R-404A as the refrigerant

Baseline store – Conventional multiplex direct expansion refrigeration system
Size – 4830 m 2 sales area Operating hours – 168 hrs/week

Refrigeration system

The system consists of three compressor rack s - one for the low temperature load with seven compressors and two for the medium temperatures loads with six compressors each. All compressors are reciprocating t ype and the rack with highest suction temperature (Rack C) supplies mechanical subcooling to the other two racks.69 Multiplex Refrigeration System Compressors Low Temp System Rack A

Main Compressors -29 o C SST R-404A Comp1 4DL3-150E-TSK Comp2 4DL3-150E-TSK Comp3 4DL3-150E-TSK Comp4 4DL3-150E-TSK

Satellite Compressors –34 o C SST R-404A Comp5 3DF3-090E-TFD Comp6 3DF3-090E-TFD Comp7 2DL3-040E-TFD

Medium Temp System
Rack B Main Compressors –6.7 o C SST R-22 Comp1 3DA3-0750-TFD Comp2 3DA3-0750-TFD Comp3 3DA3-0750-TFD Comp4 2DD3-0500-TFD

Satellite Compressors –8.3 o C SST R-22 Comp5 3DS3-1500-TFD Comp6 3DF3-1200-TFD

Medium Temp System
Rack C Main Compressors –6.7 o C SST R-22 Comp 1 3DS3-1500-TFD Comp 2 3DA3-0750-TFD

Satellite Compressors 1.7 o C SST R-22 Comp 3 3DS3-1500-TFD Comp 4 3DS3-1500-TFD Comp 5 3DF3-1200-TFD Comp 6 2DL3-0750-TFD70 Display case line ups, storage and preparation room areas, and miscellaneous loads connected to compressor racks Circuit Case Length, No. of Doors, or
Walk-in Floor Area Design Refrigeration Load (kW) Rack A Low Temperature - Sat. Suction Temp -29 o C Refrigerant - R404A
Reach-in Frozen Food 76 Doors 33.4
Multi-Deck Frozen Meat 12.2 m 17.7
Multi-Deck Frozen Fish 5.5 m 8.0 Multi-Deck Bakery 3.7 m 5.3
Walk-in Freezers 85.9 m 2 20.3
Ice Maker 10.6 Rack A Low Temperature - Sat. Suction Temp -34 o C
Coffin Ice Cream 31.6 m 21.9 Coffin Shrimp 4.9 m 1.7
Walk-in Ice Cream 16.7 m 2 5.0 Rack B Medium Temperature - Sat. Suction Temp -6.7 o C Refrigerant - R22 Reach-in Dairy 46 Doors 18.3 Single-Deck Produce 17.1 m 15.6
Multi-Deck Produce 7.3 m 9.4
Service Meat & Deli 19.5 m 6.9
Multi-Deck Deli 14.6 m 20.5
Coffin Cheese & Deli 4.9 m 7.3
Tables Fish 6.1 m 2.9
Cooler Floral 13 m 2 3.1 Floral Display 2.4 m 3.0 Rack B Medium Temperature - Sat. Suction Temp -8.3 o C Bakery Display 4.6 m 3.7
Multi-Deck Meat 20.7 m 26.9
Isle Cheese & Deli 17.1 m 18.6 Isle Ready Meals 15.8 m 16.8 Rack C Medium Temperature - Sat. Suction Temp -6.7 o C Refrigerant - R22
Walk-in Coolers 204.0 m 2 57.9 Rack C Medium Temperature - Sat. Suction Temp 1.7 °C Meat Prep Room 93.8 m 2 41.4 Produce Prep Room 48.3 m 2 11.4 Mechanical Subcooling 106.0 Primary refrigerant type and charge – R-404A in low temperature system; estimated at about 454 kg total R-22 in medium temperature system; estimated 908 kg total Estimated annual losses –refrigerant annua l loss estimated at 20% of total charge71 System operating data & measured energy use

Energy Consumption Comparison between Mu ltiplex and Distributed Refrigeration Systems – May 2001 through February 2002 Energy Consumption (kWh/day) Distributed Multiplex Difference %
Difference May-Aug

LT Compressor 1306.4 1290.2 16.2 1.2

MT Compressor 1594 1201.2 392.8 24.6

Heat Reject 702.7 608.4 94.3 13.4
Total 3603.2 3100.5 502.7 14.0

Nov - Feb

LT Compressor 863.2 957.9 -94.7 -11.0

MT Compressor 951.3 635.9 315.4 33.2

Heat Reject 316.1 364.4 -48.3 -15.3
Total 2130.5 1958.2 172.3 8.1

Average State Points, Refrigeration Loads, and efficiencies for the Multiplex and Distributed Refrigeration Syst ems – May 2001 through February 2002 May - Aug Nov – Feb Low Temp Distributed Multiplex Distributed Multiplex SST ( o C) -26.6 -28.4 -27.3 -29.0 SDT ( o C) 32.2 28.2 16.1 21.7 Return Temp ( o C) -11.4 -16.6 -8.7 -11.7 Liquid Temp ( o C) 26.2 14.3 13.8 10.2 Ref Load (kW) 100.0 133.5 90.6 113.1 Comp Power (kW) 54.4 53.8 36.0 39.9

COP 1.84 2.48 2.52 2.83

Med Temp Distributed Multiplex Distributed Multiplex SST ( o C) -8.8 -5.1 -10.3 -6.6 SDT ( o C) 33.6 28.5 22.3 19.4 Return Temp ( o C) 8.0 9.4 6.8 9.6 Liquid Temp ( o C) 29.4 20.1 19.5 14.6 Ref Load (kW) 213.9 191.4 158.6 129.8 Comp Power (kW) 66.4 50.1 39.6 26.5

COP 3.22 3.82 4.01 4.9072 TEWI Analysis for the Field Test Re sults – May 2001 through February 2002 Refrigerant Leakage Energy TEWI (kg CO2)

(kg) (kWh) Direct Indirect Total

R-404A R-22 May - August Multiplex 30.3 60.3 381,300 202,055 247,845 449,900 Distributed 7.7 443,169 24,895 288,060 312,954 Difference 136,046

Nov - Feb Multiplex 30.3 60.3 234,960 202,055 152,724 354,779 Distributed 7.7 255,600 24,895 164,034 188,929 Difference 165,850

Multiplex leak rate estimated at 20%/yr Distributed leak rate estimated at 5%/yr

Field Test Results for the Water-Source Heat Pumps Space Heating Performance (November 2001 - February 2002) Average Heat Recovered (kW) Average Space Heat Load (kW) Heat Pump Energy (kWh) Gas Displaced (m 3 )

November 01 72.7 95.6 17,236 8,076

December 01 86.0 111.7 20,531 9,807

January 02 88.5 115.7 21,004 10,080

February 02 90.0 118.6 20,295 9,383

Total 79,066 37,346

Amount of heat recovered estimated at 25.9% of total refrigeration system heat rejection during the period. The heat pumps could reco ver up to about 60% of the rejected heat.