Natural
Refrigerants
Information and case studies for Australian Businesses

CASE STUDIESPREPARED BY THE AUSTRALIAN INSTITUTE OF REFRIGERATION, AIR CONDITIONING AND HEATING,
with funding from the Department of Environment and Water Resources

Natural refrigerants case studies
Contents
Technology overviews

Ammonia

4

Carbon dioxide

6Hydrocarbons

8

Cascade / secondary loop systems

10

Case studies

Hydrocarbon refrigeration

12

Coles Gisborne

16

CRF Colac

20

Other resources

24

Writers:
Claire Heaney, Rick Swinard, Andrew Pang and Stuart West
Editor:Stuart WestTechnical committee:
Ray Clarke, Andrew Pang, Tony Kimpton, Ben Adamson,
Klaas Visser and Rick Ives

The views and opinions expressed in this publication are those of the authors and do not necessarily reflect thoseof the Australian Government or the Minister for the Environment and Water Resources.
While reasonable efforts have been made to ensure that the contents of this publication are factually correct, theCommonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not beliable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, thecontents of this publication.

Foreword
NaturalRerigerants

Much of the refrigeration and air conditioning equipment in Australia uses
fluorocarbon refrigerants to facilitate the heat transfer process. Fluorocarbon
refrigerants are synthetic chemicals which usually have a high global warming potential,
and some still have the potential to cause damage to the ozone layer as well if released
to the atmosphere.
Alternatives to these chemicals exist that can help to mitigate some of theenvironmental risks. Often referred to as ‘natural’ refrigerants because the substances
also occur in nature, these alternatives include ammonia, carbon dioxide and hydrocarbons.
These substances have been used as refrigerants for many years, however, they
are now finding their way into applications where previously fluorocarbons were
the preferred option.
This document has been put together to provide industry decision makers
with more information on the potential of ‘natural’ refrigerants. It includes an overview
of each of the alternatives, case studies on how they’ve been put to use in Australia,
and pointers to some sources of further information.
The case studies are written in plain English, and attempt to give a realistic
picture of how alternatives to fluorocarbon refrigerants were used in each case— the advantages they provided, the challenges that needed to be overcome,and the drivers behind each project.
Hopefully you will find them and the other resources provided herein useful,
and will consider alternatives to fluorocarbon refrigerants next time you haveto make a decision regarding air conditioning or refrigeration equipment.

Natural Refrigerants GuideAmmonia
GEA Grasso ammonia chiller
being installed on a building
roof in Sydney

Plant room of an ammonia
refrigeration plant room at acold storage facility in Victoria

Ammonia is a naturally-occuring substance that can be used as analternative to fluorocarbon refrigerants in refrigeration systems.

Potential applications

Indeed, ammonia has been in use as a refrigerant since long before
the invention of fluorocarbons – it was one of the refrigerants
Australian inventor, James Harrison specified for his groundbreaking refrigeration machine patented in 1856 [1].
Unlike carbon dioxide and hydrocarbons, ammonia has been used
as a refrigerant consistently since the invention of fluorocarbons,however, its use has largely been restricted to large industrial
applications.

Basic properties
Ammonia (chemical symbol NH3, refrigerant designation R717) is acolourless gas at atmospheric pressure, and has what many wouldview to be the ideal environmental properties for a refrigerant – ithas both a zero ozone depletion potential (ODP) and a zero global
warming potential (GWP) [2].
In isolation, these properties obviously make ammonia an attractive
prospect as a refrigerant, given that fluorocarbon refrigerants canhave global warming potentials as high as 3900 [2].
Many readers will be familiar with ammonia as an ingredient inhousehold cleaners, fertilizers and other products, and also befamiliar with its characteristic odour. Ammonia carries a B2 safetyclassification, meaning that it has a high toxicity, and also carries a
medium flammability risk [2].
Ammonia is compatible with some, but not all, commonly usedrefrigeration system lubricants. In particular, it is not suited foruse with polyol ester (POE) and poly vinyl ether (PVE) lubricants,
and it has only limited applications with poly alkylene glycol (PAG)
lubricants [2].

Natural Refrigerants Guide

As mentioned above, for many years ammonia has been the
refrigerant of choice in large industrial refrigeration applications(process cooling, cold storage, mining, etc).
In recent years, the focus has broadened to look at otherapplications that ammonia may be suitable for.
Chillers for building air conditioning, using ammonia as arefrigerant, have been released to the market in recent years,
though only a relatively small number of installations in Europe had
been reported at the time of writing [3] [4].
One possible reason for the small number of installations to date
could be the price of the equipment – estimated to be almost
250% of equivalent standard fluorocarbon refrigerant units [4].
It has also been suggested, however, that ammonia chillers could
operate more efficiently and result in cost savings over the whole
life of the equipment [3] [4].
While using ammonia in populated areas can bring about somesafety concerns (see section on safety below), ammonia chillers
designed for use in building air conditioning systems in Europe
have addressed these concerns with the introduction of systems
such as containment casings (erecting a structure around the chiller
to contain any leaks and ‘scrub’ the air inside before it is exhausted),ammonia absorption systems and flameproof electrical panels [4].
The additional safety equipment required will obviously increase
costs, however, manufacturers claim that operational energy andmaintenance savings will potentially outweigh the increased initialoutlay in the long run [4].
Ammonia’s traditional usage in industrial applications is also
evolving. Around the world, large ammonia systems are being
subjected to increasingly stringent safety regulations and pressure
is being placed on companies to reduce the size of ammonia
refrigerant charges [5].

One solution that is being embraced by a number of owners oflarge industrial plants is to use ammonia in conjunction with asecondary refrigerant such as carbon dioxide in a ‘cascade’ system,
meaning that less ammonia is required to do the same job, and thatthe ammonia charge can be contained in a plant room or othersafe environment. This solution is already in use in Australia, as
demonstrated by the case study on CRF Colac presented herein.

Conclusions

As with hydrocarbons, if ammonia is to be used in a systemdesigned for a different refrigerant (such as a fluorocarbon), it
should be noted that some modifications will probably be required
to ensure compatibility and address the issues associated withammonia’s flammability, toxicity and the standards applying to its
usage (see below). The system manufacturer should be consulted
before ammonia is substituted in an existing piece of equipment [6].

Its environmental properties (zero ODP and zero GWP) are also
highly favourable.

Safety issues
While ammonia is a toxic substance, it is also found in small
amounts in a number of substances we come in contact with ona regular basis. A glass of drinking water can contain as much as
1mg of ammonia, a 200g steak as much as 13mg, and some foodadditives can contain as much as 18mg [7]. Cigarette smoke andeven the air we breathe also contains ammonia in small amounts.

Ammonia has been in consistent use as a refrigerant since the1800s. It can be a very efficient alternative to fluorocarbon
refrigerants in a number of applications, and has been the
refrigerant of choice in areas such as industrial refrigeration
for many years.

Concerns do exist regarding the safe use of ammonia as a resultof its toxicity and flammability. Many advances have been madein recent years to minimise these risks, however, including using
ammonia in conjunction with other refrigerants in order to reduceand isolate the ammonia charge, and using advanced safety
equipment.

References1

Lang, W.R.; James Harrison – pioneering genius;
IMAG Digital Media, Melbourne, 2003

2

Lommers, C A; AIRAH Air Conditioning and Refrigeration
Industry Refrigerant Selection Guide; AIRAH, Melbourne,
2003 (also available online from www.airah.org.au)

3

In amounts of 300-400ppm, prolonged exposure will become
unpleasant, and in amounts over 700ppm it can cause burns
and serious damage to eyes. In amounts of 5000ppm or above,
exposure can be lethal to humans within five minutes [7] [8].

Rolfsman, L.; Reviewing current state-of-the-art systems using
ammonia; Alternative Cooling Technologies conference
presentation, London, February 1, 2005

4

Despite these issues, however, ammonia can be used with relative
safety in refrigeration systems provided the proper safety measures
are put in place.

Mundie, I.; Exploring the extent to which ammonia is viable
as a widespread commercial alternative to HFCs; Alternative
Cooling Technologies conference presentation, London,February 1, 2005

5

Ives, R.; The future of industrial refrigeration – a user’s view;
AIRAH natural refrigerants applications in refrigeration, airconditioning and heating conference paper, Sydney,
July 28, 2004

6

HB40.1-2001; The Australian Refrigeration and Air-conditioning
Code of Good Practice part 1: Reduction of emissions offluorocarbon refrigerants in commercial and industrial
refrigeration and air-conditioning applications; Australian
Fluorocarbon Council, 2001 (available online fromwww.saiglobal.com)

7

Lindborg, A.; Evaluating progress towards developing
safe, cost-effective ammonia cooling systems; Alternative
Cooling Technologies conference presentation, London,February 1, 2005

8

A-Gas; Ammonia- anhydrous material safety data sheet;produced by A-Gas Australia, dated December 7, 2005

9

AS/NZS 1677.2-1998; Refrigerating systems part 2: Safety
requirements for fixed applications; Standards Australia,
Sydney, 1998 (available online from www.saiglobal.com)

This demonstrates that the human body can deal with ammonia insmall quantities. Generally, any amount in the atmosphere below 20
parts per million (ppm) is regarded as not dangerous. At amounts of
up to 53 ppm, ammonia’s characteristic odour will be noticeable [8].

Australian Standard AS/NZS 1677.2-1998 Refrigerating systems
part 2: Safety requirements for fixed applications [9] sets out a numberof restrictions on the use of B1 and B2 classified refrigerants, which
cover ammonia, to promote safety.
In particular, the standard places restrictions on the amountof ammonia that can be used in a system dependent upon its
location, the locations where machinery can be installed and thedensity of occupants allowed in a room containing an ammonia
refrigeration system [9].
In addition to this, AS/NZS 2022-2003 Anhydrous ammonia – storage
and handling [10] sets out specific requirements for the use ofammonia, including the provision of safety equipment, preparationof emergency plans and the requirement for personnel to beproperly trained in handling and emergency procedures.
(Please note: this section quote terms which are defined as having
specific meanings within the standard – the full standards [9] [10]should be consulted before acting on the above information.
Note also that the restrictions above apply only to stationary
refrigeration and air conditioning systems – different restrictions
apply to ammonia used in vehicle air conditioning systems.)

10 AS/NZS 2022-2003; Anhydrous ammonia – storage andhandling; Standards Australia, Sydney, 2003 (available onlinefrom www.saiglobal.com)

Natural Refrigerants GuideCarbon dioxide
Plant room of a cold storage facility using carbon dioxide refrigerant (above and right)

Carbon dioxide (CO2) is a substance that has been used in the
refrigeration industry since the 1860s [1].
The use of carbon dioxide as a refrigerant declined between the
1890s and 1930s for a number of reasons, including changes intechnology and the introduction of fluorocarbon refrigerants,
which were billed as ‘safety refrigerants’ at the time. Interest in theuse of carbon dioxide resurfaced in the 1990s, with discussion of
the phase out of ozone depleting refrigerants [1] [2].

When used as a refrigerant, carbon dioxide typically operates at ahigher pressure than fluorocarbons and other refrigerants [4]. While
this presents some design challenges it can usually be overcome
in systems designed specifically to use carbon dioxide – moreissues may be encountered if carbon dioxide is to be retrofitted to asystem designed for a different, lower-pressure refrigerant.

Basic properties

Carbon dioxide is compatible with some, but not all, commonly usedrefrigeration system lubricants. In particular, it is not suited for use with
polyol ester (POE) and poly vinyl ether (PVE) lubricants, and it only has
limited applications with poly alkylene glycol (PAG) lubricants. [3]Carbon dioxide has an ozone depletion potential (OPD) of zero anda global warming potential (GWP) of 1 [3].

Potential applications

It is generally regarded as a cheap and easily available refrigerant,
and many experts also regard it as having a ‘unique’ set ofproperties which make it an ideal refrigerant [1].

Carbon dioxide is already being used as a refrigerant in a number ofapplications around the world, including truck and bus cooling, car
air conditioning, in supermarkets and ice skating rinks, in industrial
freezers and in large cold storage applications [1].

In addition to its basic environmental properties, carbon dioxide is nontoxic. It carries an A1 safety classification (the same as most fluorocarbon
refrigerants), indicating that it has low toxicity and is non-flammable [3].
Some experts controversially argue that, although carbon dioxide
as a refrigerant carries a GWP of 1, this value should be ignored as
the carbon dioxide supplied as refrigerant is usually recovered fromthe exhaust of industrial processes and therefore would have beenreleased to atmosphere anyway if it were not reused [1].
Carbon dioxide is colourless, odourless and is also heavier thanair. It is the latter property that can cause some safety issues, as if
enough carbon dioxide builds up in an enclosed space it will begin
to displace oxygen and can cause asphyxiation in anyone present
within the space. As carbon dioxide is colourless and odourless, aperson in the space will not be able to tell it is filling with carbon
dioxide unless proper detectors and alarms are installed*.

Research has also been carried out on the potential for using
carbon dioxide as the refrigerant in heat pumps for air conditioning
and water heaters [4].
The availability of equipment rated for carbon dioxide’s higher pressure
has been an issue in the past, however, the technology is now catchingup and many companies offer compressors, evaporators and otherequipment suitable for use with carbon dioxide [5] [6].
Carbon dioxide is now being used commonly in what are referred
to as “cascade” or “secondary loop” systems, where it is used inconjunction with another refrigerant to maximise efficiency. The
Australian case studies presented later provide two examples ofthis – in cascade with a fluorocarbon refrigerant in a supermarket(Coles Gisborne) and in cascade with ammonia in a freezing andcold storage facility (CRF Colac).

* It should be noted that in this respect, carbon dioxide it is no different to fluorocarbon refrigerants, which are also heavier than air and can cause
asphyxiation in similar circumstances.



Natural Refrigerants Guide

While there are relatively few installations of this nature currently
in Australia, they are becoming more and more commonplace inEurope where companies such as Nestlé have embraced its use [7] [8].
In his address to the June 2004 “Refrigerants Naturally” conference,
Jeff Seabright, vice president of environmental and water resourcesat the Coca Cola company, stated that “On the basis of the work
done over these past four years, we have come to the conclusionthat CO2-based refrigeration is currently the best option for the
global needs of Coca-Cola’s sales and marketing equipment, ourcoolers and vending machines. CO2 is a natural gas, it is safe andnon-hazardous, and its global warming potential is dramatically lessthan HFCs” [9].
Seabright also stated that the company’s preliminary field tests
proved the technology to be reliable, in real life circumstances theequipment often used less energy than equivalent equipmentusing HFC as a refrigerant [9].

In 2000, the International Institute of Refrigeration (IIR) identified
carbon dioxide’s high working pressure as the main drawback
to its use, stating that appropriate equipment needed to be
developed for its use to spread [12]. This has since taken place, andcarbon dioxide refrigeration systems are indeed beginning to gain
popularity.
As with other refrigerants, all applications need to be consideredon their merits by experts. Its favourable environmental andoperational properties make carbon dioxide a competitive option
in a number of applications.

References
1

Pearson, A; Carbon dioxide – refrigerant of the future; Alternative
Cooling Technologies conference presentation, London,February 1, 2005

As of 2006, the company was market testing a range of drinks
fridges and vending machines using carbon dioxide refrigerants [10].

2

Bellstedt, M., Elefsen, F., Jensen, S.S; Application of CO2 (R744)
refrigerant in industrial cold storage plant; EcoLibrium Vol. 1 No. 5
p.25-30 (also available online from www.airah.org.au)

Safety precautions

3

As carbon dioxide falls into the A1 safety classification, AS/NZS
1677.2:1998 Refrigerating systems part 2: Safety requirements for
fixed applications [11] treats it in the same manner as A1-classified
fluorocarbon refrigerants.

Lommers, C A; AIRAH Air Conditioning and Refrigeration Industry
Refrigerant Selection Guide; AIRAH, Melbourne, 2003 (alsoavailable online from www.airah.org.au)

4

Neksa, P.; CO2 as refrigerant for systems in transcritical operation– principles and technology status; AIRAH natural refrigerants
applications in refrigeration, air conditioning and heating conference
paper, Sydney, July 28, 2004 (Also published in EcoLibrium Vol 3
No.8-9, available for download from www.airah.org.au)

5Ono, M.; Transcritical CO2 heat pump and CO2 application; AIRAH
natural refrigerants applications in refrigeration, air conditioning
and heating conference paper, Sydney, July 28, 2004

6

Lozza, G.; Overcoming the challenge of heat exchange inusing CO2 as a refrigerant; Alternative Cooling Technologies
conference presentation, London, February 1, 2005

7

Page, A.; Analysing the commercial viability of CO2 as a real
alternative to HFCs; Alternative Cooling Technologies conference
presentation, London, February 1, 2005

8

Ives, R.; The future of industrial refrigeration – a user’s view; AIRAH
natural refrigerants applications in refrigeration, air conditioning
and heating conference paper, Sydney, July 28, 2004

9

Seabright, J.; presentation to Refrigerants Naturally conferencein Brussels, Belgium during June 2004. Transcript of speech lastaccessed at http://www.refrigerantsnaturally.com/speeches/
The%20Coca-Cola%20Company%20speech.pdf on
January 12, 2007

Some restrictions are placed on the size of the refrigerant charge,
with additional allowances made for systems with detectors andalarms fitted, and as carbon dioxide is heavier than air the standard
requires “suitable precautions” to be taken to prevent the undue
accumulation of refrigerant in occupied spaces in the event of aleak [11].
As with fluorocarbon refrigerants, the standard also requires thesystem to be designed to withstand the refrigerant’s maximum
operating pressure [11].
(Please note: the full standard [11] should be consulted before acting
on the above information. Note also that the restrictions above
apply only to stationary refrigeration and air conditioning systems– different restrictions apply to refrigerants used in vehicle air
conditioning systems.)

Conclusions
A number of experts believe carbon dioxide systems will become
more prevalent in the coming years. This is the opinion offeredby one expert, Andy Pearson of Star Refrigeration in the United
Kingdom [1]:“I believe that they (carbon dioxide systems) will be cheap
and they will be very common. We have already seen thatthe systems installed in all applications show extremely
good reliability, and they are also of comparable efficiency to
traditional designs. Ongoing research and development will
provide further improvements in these areas . . . carbon dioxide
refrigeration systems are here to stay for the foreseeable future.”

10 Coca Cola company; CO2 equipment in European market testing;PowerPoint presentation, October 2006, available fromwww.refrigerantsnaturally.com
11 AS/NZS 1677.2-1998; Refrigerating systems part 2: Safety
requirements for fixed applications; Standards Australia, Sydney,1998 (available online from www.saiglobal.com)
12 International Institute of Refrigeration; 15th informatory noteon refrigerants – carbon dioxide as a refrigerant; International
Institute of Refrigeration, Paris, 2000. Available onlinefrom www.iifiir.org

Natural Refrigerants GuideHydrocarbons
Part of hydrocarbon refrigeration system
for making liquid ethylene at temperatures as low as -100°C

Ethylene-propylene cascade system used for recoveryof petrol vapour at -80°C. It uses hermetic compressors(green items visible at the edge of the unit)

Hydrocarbons are refrigerants that can be used as an alternative tofluorocarbon refrigerants in some refrigeration and air conditioning
applications.

As most readers will be aware, an important property of all thesesubstances in their other applications is that they are flammable.

Along with ammonia and carbon dioxide, hydrocarbons
were commonly used as refrigerants before the invention offluorocarbon refrigerants in the 1930s.

Hydrocarbon refrigerants are also flammable, and as a result they
carry an A3 safety classification – this means they have a low
toxicity, but are in the higher range of flammability [1]. This does
not stop hydrocarbons being used as refrigerants, however, someprecautions need to be taken when they are.

Interest in hydrocarbon refrigerants has been revived in recent
years with discussions on the phase out of ozone depleting
refrigerants and high-profile publicity campaigns fromorganisations such as Greenpeace, although they have long beenused widely in the oil, gas and petrochemical industries, particularly
in very large refrigeration systems.

Hydrocarbon refrigerants are fully compatible with nearly all
lubricants commonly used in refrigeration and air conditioning
systems. One major exception to this rule is lubricants containing
silicone and silicate (additives which are commonly used as antifoaming agents) – lubricants containing these substances are notcompatible with hydrocarbon refrigerants [1].

Basic properties

Potential applications

The term ‘hydrocarbon’ encompasses a range of substances. The
hydrocarbons most commonly used as refrigerants are ethane(known as R170), propane (R290), butane (R600), isobutane (R600a)
and propylene (R1270).

Hydrocarbon refrigerants can be used either in systems designed
specifically for their use, or as a replacement in a system designed
for a fluorocarbon refrigerant.

While each of these substances has a different chemicalcomposition, they all share the same basic environmental
properties – an ozone depletion potential (ODP) of zero and a
global warming potential (GWP) of 3 [1].

If a hydrocarbon refrigerant is to be used in a system designed
for a different refrigerant (such as a fluorocarbon), it should be
noted that some modifications will probably be required to ensurecompatibility and address the issues associated with hydrocarbons’
flammability. The system manufacturer should be consulted before
a hydrocarbon is substituted in an existing piece of equipment [1] [2].

It is these properties that have caused a resurgence of interestin hydrocarbons as refrigerants in recent years – fluorocarbon
refrigerants can have global warming potentials as high as 3900
[1]
, so hydrocarbons would pose a much lesser threat to theenvironment in the event of a leak.

Another issue that needs to be addressed when replacing any
refrigerant is its compatibility with the lubricant being used in thesystem. As mentioned above, lubricants containing silicone andsilicate cannot be used with hydrocarbons.

While the refrigerant designations (the “R” numbers) may not befamiliar, many readers will be familiar with the common names of
the refrigerants listed above. Hydrocarbons are also used, amongst
other things, as barbecue gas and as LPG in our cars.

Natural Refrigerants Guide

Hydrocarbons are already being used in a number of applications.
In Europe, many models of domestic refrigerators are charged withhydrocarbon refrigerant in the factory. It is estimated that there
are at least 100,000,000 household refrigerators in use around theworld containing hydrocarbon refrigerants [3].

According to another report, hydrocarbons have also been used insmall air conditioning systems and cold drinking water dispensers,though not in the same numbers as domestic refrigerators [4].

Flammability concerns and usage
restrictions

Hydrocarbon refrigerants are also commonly used in large process
refrigeration systems in the oil and gas industries.

As mentioned above, hydrocarbon refrigerants are flammableand therefore certain restrictions are placed on their use to ensure
safety.

Various theoretical studies have been carried out on the potential
for hydrocarbon refrigerants, or blends of hydrocarbon refrigerants
and hydrofluorocarbon (HFC) refrigerants to replace commonlyused fluorocarbon refrigerants.

Australian Standard AS/NZS 1677.2-1998 Refrigerating systems part
2: Safety requirements for fixed applications [8] sets out a number ofthese restrictions.

In 2005, Lee et al compared the performance of hydrocarbon
refrigerants R290, R600a and R1270 to that of the commonly-used
HCFC refrigerant R22 in a test rig, and found that “in comparison to
R22, hydrocarbon refrigerants have similar or better ability and arealso environmentally friendly other than flammability” [5].
In 2003, Sekhar, Premnath and Lal conducted experiments on a
new refrigerant blend comprising R134a (an HFC) and hydrocarbon
refrigerants R600a and R290, with a view to finding a replacement
for the CFC refrigerant R12 in domestic refrigerators. They concluded
that the blend “has been identified as a promising alternative to be
used as a refrigerant in a conventional R12 system” and that, overall,
the blend reduced energy consumption by 4 to 11% [6].
Calm and Domanski noted in 2004 that “hydrocarbon refrigerants
generally are compatible with the materials used in systems
designed for R22 and often can use the same or similar lubricants,
however, their substitution requires significant attention to safetyissues including application specific considerations” [7].
Some of these considerations are discussed in the following
section. Calm and Domanski also make the important point in
the conclusion of their paper that “no (one) refrigerant has been
identified as a suitable alternative for most applications,” though
they identify that some refrigerant blends “offer good options” [7].
Blends can be HFC/HFC or HFC/HC.
While Calm and Domanski’s research was examining all refrigeranttypes (HFCs as well as natural refrigerants), their point is an
important one that is backed up by much of the other research– there is no one solution or ‘magic bullet’. Hydrocarbons may besuitable in some applications, and may not be in others, so every
application needs to be carefully assessed on its merits.

The standard states that, for any hydrocarbon system:• All electrical contacts must be sealed or non-sparking• The refrigerant charge in a system below ground level must notexceed 1.0 kg• Sealed systems not exceeding 0.25 kg can be sited in any
location• Systems with charges exceeding 0.25 kg must not be locatedanywhere where a sudden loss of refrigerant will raise theconcentration in the room or occupied compartment above thepractical limit (0.008 kg/m³)• Piping for systems exceeding 1.5 kg must be restricted to theroom containing the refrigerant
There are also additional restrictions placed on systems that fall into
certain categories:
Category

Additional requirements•	Refrigerant charge must not
Hospitals, prisons,exceed 1.5 kg per sealed systemtheatres, supermarkets,
schools, hotels,•	Refrigerant charge must notrestaurants, dwellings
exceed 5.0 kg in special machinery
rooms for indirect systems
Offices, small shops,
small restaurants,
places for generalmanufacturing andwhere people work•	Refrigerant charge must notexceed 2.5 kg per sealed system

Industrial, cold stores,
dairies, abattoirs,
non public areasof supermarkets•	Refrigerant charge must not exceed
10.0 kg in humanly occupied spaces•	Refrigerant charge must not exceed
10.0 kg in special machinery rooms
for indirect systems•	Refrigerant charge must notexceed 25.0 kg for systems
with high pressure sidein special machinery rooms•	No restrictions are placed on the
charge size if all parts of the system
containing refrigerant are in a special
machinery room or in open air

A hydrocarbon ice cream freezer from the Unilever field test at the Sydney Olympics(Please note: the above requirements quote terms which
are defined as having specific meanings within the standard– the full standard [8] should be consulted before acting on theabove information. Note also that the restrictions above apply
only to stationary refrigeration and air conditioning systems– different restrictions apply to hydrocarbons used in vehicle
air conditioning systems.)

Natural Refrigerants GuideSome Australian states place additional restrictions on the use ofhydrocarbons as refrigerants – in particular, state occupational
health and safety (OH&S) regulations.

3

Colbourne, D; Reviewing HCs to replace HFCs in mainstream
applications; Alternative Cooling Technologies conference
presentation, London, February 1, 2005

Particular attention should be paid to service practices whenworking on equipment containing hydrocarbon refrigerant – one
study notes that most incidents with hydrocarbon refrigerants
result from poor service practices [3].

4Cox, N; Reviewing which applications currently use HCs andwhere HCs could be used in the future; Alternative CoolingTechnologies conference presentation, London, February 1, 2005

5

Lee, H.S., Yoon, J.I., Kim, J.D., Bansal, P.; Evaporating heat transfer
and pressure drop of hydrocarbon refrigerants in 9.52 and12.70mm smooth tube; International Journal of Heat and Mass
Transfer 48 (2005) p.2351-2359

6

Sekhar, J.S., Premnath, R.R., Lal, M.D; On the performance of
HFC134a/HC600a/HC290 in a CFC12 compressor with mineral oil
as lubricant; EcoLibrium Vol. 2 No. 4 p.24-28 (also available onlinefrom www.airah.org.au)

7Calm, J.M, Domanski, P.A; R22 replacement status;
ASHRAE Journal August 2004 p.29-39

8

AS/NZS 1677.2-1998; Refrigerating systems part 2: Safety
requirements for fixed applications; Standards Australia, Sydney,1998 (available online from www.saiglobal.com)

Conclusions
Hydrocarbon refrigerants have a number of favourable properties,
and in the event of a leak they pose a much lower direct threat tothe environment than fluorocarbon refrigerants.
Care needs to be taken to ensure that the their flammability will notpose a safety risk, however, when the appropriate precautions aretaken hydrocarbon refrigerants can be used effectively in a range
of applications.
If a hydrocarbon is to be used as a replacement in a systemthat wasn’t originally designed for a flammable refrigerant, theequipment manufacturer should be consulted to ensure that thesystem will be compatible.
In some applications, a hydrocarbon refrigerant may be more
efficient and use less energy than a fluorocarbon. Each case should
be assessed on its merits by an expert, however, and emissions
from both direct refrigerant emissions and the energy the system
uses should be considered.

References

101

Lommers, C A; AIRAH Air Conditioning and Refrigeration
Industry Refrigerant Selection Guide; AIRAH, Melbourne,
2003 (also available online from www.airah.org.au)2

HB40.1-2001; The Australian Refrigeration andAir-conditioning Code of Good Practice part 1: Reductionof emissions of fluorocarbon refrigerants in commercial andindustrial refrigeration and air-conditioning applications;
Australian Fluorocarbon Council, 2001 (available onlinefrom www.saiglobal.com)

Natural Refrigerants Guide

Fluorocarbon-reducing
technologies
This summary will vary slightly from the three that it follows –up to this point, we have addressed specific natural refrigerants
and their uses.
In this section, however, we will address some technologies thatcan be used with a number of refrigerant types, and are either
allowing for the increased uptake of natural refrigerants or allowing
for the reduced usage of fluorocarbons in various market sectors.

Secondary loop systems
Most refrigeration and air conditioning systems use only one
type of refrigerant. There is only one “loop” – the system has
an evaporator, where the system absorbs heat from the space
being cooled, and transfers it via the refrigerant in the loop to thecondenser, where the heat is expelled.
A secondary loop system is made up of two refrigeration circuits
or ‘loops’, working together as a single system. One loop uses a
primary refrigerant, and the other uses a secondary refrigerant.
The primary system has all the same features as a single loop
system – the difference is that, at the evaporator, instead of
exchanging heat with the space that is being cooled, heat is
exchanged with the secondary refrigerant, which in turn isremoving heat from the space.
This can work with a range of equipment – supermarket cabinets,
air conditioners and various other systems. Generally, thesecondary refrigerant that is used is non-toxic.
Using a secondary loop configuration can have a number ofbenefits, including:• Less primary refrigerant is required, which can in turn reduce
costs. If the primary refrigerant is a fluorocarbon, there will beless risk to the environment in the event of a leak.
• As the secondary refrigerant is generally non-toxic, safetyconcerns in the event of a leak can be reduced.
• The primary refrigerant can be isolated in areas of the buildingthat reduce the risk to people in the event of a leak (such as aplant room).
Other advantages that may also be available include reduced
installation times, simplified control systems, improved safety,
reduced service costs and better temperature control.

Carbon Dioxide
Compressor

Ammonia
Oil separator Cascade
condensor

Oil return filter
Lowtemperatureevaporators

Expansion valve
Liquid pump

Oil separator

Compressor

Condensor

Oil return filter
Suction accumulator
Expansion valve

Suction accumulator

Schematic of a carbon dioxide / ammonia cascade system (courtesy of Grasso)

Secondary loop systems have been around for many years, but therefrigerants employed in them have changed over the years.
They are commonplace in air conditioning for multi-storey
buildings, where chilled water is used as the secondary refrigerant
that is circulated around the building, and the primary refrigerant(usually a fluorocarbon, in the case of building air conditioning)is contained within a plant room.
Secondary loop systems using a variety of refrigerants have also
been used in the dairy and meat industries and in ice cream
cabinets.
A variety of substances can be used as secondary refrigerants,
including water, ice slurries, brines, glycols, alcohol, silicon oil and liquidcarbon dioxide. Different substances will suit different applications,guided largely by the operating temperature of the system.
Historically, water has been used as a secondary refrigerant because
it is cheap and readily available. It is unsuitable as a secondaryrefrigerant in a system operating below 0°C though, as it would
freeze in the pipes. As a result, it is most often used in building air
conditioning systems, and some process cooling applications.
Brines (a mixture of water and inorganic salts such as calcium
chloride or sodium chloride) have been employed as secondaryrefrigerants as well, but because of their corrosive properties they
can shorten the life of pipework and other equipment, reducing
efficiency and increasing maintenance costs.
Ice slurries are formed by adding chemicals to water resulting insmall ice particles being formed in the fluid. Ice slurries are mostcommonly used in applications where temperatures between 0
and -5°C are required.

Natural Refrigerants Guide

11

One advantage of using ice slurries is that cooling energy can be
stored and “burned off” later as the ice melts. For example, somesecondary loop systems generate their ice slurries overnight,
making use of cheaper off-peak electricity, for use the nextday. Sometimes, this storage can even mean that the primaryrefrigeration system can be turned off during the day.
Ice slurries are also often employed in the food industry for
immersion freezing of fruits, for the production of “desert” frozen
fruits such as strawberries. In these cases, the ice slurry is based ona sugar-ethanol solution and research has found that this method
reduces losses of valuable fruit enzymes [1].
There are two types of glycol that are commonly used as secondaryrefrigerants: ethylene glycol is toxic, and so is commonly used in
non-food applications, and propylene glycol, which is non-toxic
and actually sometimes used as a food additive. As it is non-toxic,
propylene glycol can be used in food applications and will notpresent a risk to produce in the event of a leak.
Glycols can be used in conjunction with a corrosion inhibitor, andas a result they have become popular in applications that would
previous have employed brines.
In very low temperature applications such as freeze drying,
substances such as pure silicon oil or methanol have been employed
as secondary refrigerants, reaching temperatures as low as -70°C.
One of the advantages of the abovementioned substances is thatthey all have a zero ozone depletion potential (ODP) and a zeroglobal warming potential (GWP), so the risk to the environment isgreatly reduced in the event of a leak.
One other substance that has been used as a secondary refrigerant
in recent years, liquid carbon dioxide, has a GWP of 1. It has beenfinding applications as a secondary refrigerant in supermarkets,
circulating to the frozen food cabinets on the shop floor.

Conclusions
While not strictly speaking a natural refrigerant technology,
secondary loop and cascade system technology is enabling
fluorocarbon refrigerant charges to be reduced and naturalrefrigerants to be used in new market segments.

References
1

Fikiin, K., Tsvetkov, O., Laptev, Y., Fikiin, A., Kolodyaznaya, V.;
Thermophysical and engineering issues of the immersion
freezing of fruits in ice slurries based on sugar-ethanol aqueous
solution; EcoLibrium Vol 2 No 7 p.10-15 (also available onlinefrom www.airah.org.au)

2

American Society of Heating, Refrigerating and Air
Conditioning Engineers; ASHRAE refrigeration handbook– ultra-low temperature refrigeration section; ASHRAE, Atlanta
USA, 2002 p39.3

3	Gigel, A; The technical and commercial potential of water andair as refrigerants; Alternative Cooling Technologies conference
presentation, London, February 1, 2005.

Bibliography

Cascade systems

Bellstedt, M; Why secondary refrigerants should be a primary focus;
Climate Control News, November 2004, p.21

The cascade system is another alternative to a single-refrigerantsystem, and is similar in design to a secondary loop system.

Egolf, P.W; Technical note on refrigerating technologies – ice slurry:a promising technology; International Institute of Refrigeration,
Paris, 2004. Available online from www.iifiir.org

A cascade system is made up of two separate but thermallyconnected refrigeration systems, each of which have a primaryrefrigerant [2]. The refrigerants work in concert to reach the desired
temperature, which can sometimes be as low as -100°C inbio-medical applications.
Air and water as refrigerants [3]
In addition to ammonia, carbon dioxide and hydrocarbons, air and water are often cited as
potential alternatives to fluorocarbon refrigerants.
They are non-toxic, non-flammable and have zero ozone depletion potential and global
warming potential. They are also cheap and readily available. They can be used as either
secondary refrigerants (as described above) or as the sole refrigerant in a system.
Water is a highly efficient refrigerant over small or medium temperature differentials (0-30°C,
for example), however, it has two major disadvantages – in its pure form it can’t be used inapplications below 0°C (as it will freeze solid) and it requires very large compressors if used as
the sole refrigerant in a system.
As a result, water has only been used as the sole refrigerant in a few examples around the world,
and all are in very large applications (including a 7MW mine cooling plant in Botswana, and a

12

Cascade systems have been used in industrial applications inAustralia for some time, and are now starting to be used incommercial situations as well. A common situation is using carbon
dioxide as the ‘low stage’ refrigerant in concert with a fluorocarbon,
a hydrocarbon or ammonia as the ‘high stage’ refrigerant.
CRF Colac (see the case study following) is an example of thisarrangement.

Natural Refrigerants Guide

ASHRAE Refrigeration Handbook – System practices for ammonia
refrigerants, Chapter 3, Page 3.1.2002. ASHRAE, Atlant

2MW chilled water plant at the Lego factory in Denmark – the Lego system uses a compressor
with a 1.8 metre diameter).
Water is commonly used as a secondary refrigerant, however, especially in commercial building
air conditioning systems.
Air-cycle systems work by compressing air, increasing its pressure and temperature, thencooling and expanding the air. The cold, low-pressure air is used for refrigeration before it isrecompressed and the cycle begins again.
Air-cycle cooling systems are used in most commercial and military aircraft, and have also beenused in high-speed trains. They are rare in stationary applications, although prototype units
have been used at cold stores in Japan.
One of the major barriers to the further adoption of air and water systems is the lack ofequipment – at the time of writing, equipment for air or water systems is only being producedin small quantities.

Natural
Refrigerants
CASE STUDIESNatural Refrigerants Guide

13

Hydrocarbon
refrigeration at the
Sydney Olympics

C ASE S TUDY

(L–R) Data loggers inside and outside the Unilever ice cream cabinets, and an electricity meter placed on the bottom of the cabinets

Introduction
Two major hydrocarbon refrigeration projects took place during theSydney Olympics in 2000 – one was carried out by multi-national
company Unilever in its ice cream freezers, and the other at the
Sydney Superdome by a much smaller company.

Unilever – hydrocarbon
ice cream freezers
Multi-national food company Unilever is probably best known by
ice cream lovers for its Streets range, with its distinctive heart logo.
The company, which makes everything from toiletries to tea bags,
owns around two million ice cream freezers throughout the world
and is the global market leader in ice cream sales.
In 2000, in line with its corporate commitment to take on moreenvironmentally sustainable practices, the company pledgedthat it would not buy ice cream freezers that were charged withhydrofluorocarbon (HFC) refrigerants after 2005 in countries wherelegal and commercially viable alternatives were available [1].
Like fellow global business giants McDonalds and Coca Cola, Unileverhad been challenged by Greenpeace and the United Nations
Environment Programme (UNEP) to take the environmental lead.

14

Natural Refrigerants Guide

The company’s Code of Business Principles at the time stated that
it was “committed to running its business in an environmentallysound and sustainable manner” [2].
In recognition of concern about chlorofluorcarbons, it stopped
using ice cream cabinets charged with CFC refrigerants in 1995. Allof the company’s major refrigeration installations use ammonia [3].
The company states that it was interested in using the naturalrefrigerant hydrocarbon in “green” ice cream freezers, the subject of
this case study, from early on.
Hydrocarbons were favoured because they have zero ozone
depletion potential and very low global warming potential (GWP
– hydrocarbons have a GWP of 3 - some synthetic refrigerants are
as high as 3900 [4]).
Unilever’s supply chain director Alan Gerrard says that the company
started trialling hydrocarbon refrigerants in India in 1996 andDenmark in 1998 [3].
The move for hydrocarbon freezers coincided with a push by the2000 Sydney Olympics organisers to embrace ‘green’ principles
in all aspects of the games staged in Australia: guidelines for the
Sydney Games stated that CFC, HCFC and HFC-free refrigerants
should be used [5].

As a result, Unilever had 50 hydrocarbon ice cream freezers
manufactured for the games.
The company stated that it opted for hydrocarbon because it
already had some internal experience with it. It was alreadyavailable for the domestic market, it has a very similar technology
and supplier base and was likely to meet the company’s time frameand be within its cost targets [1].
The hydrocarbon chosen was propane, or R290, and the freezers
were situated at Sydney’s Olympic Park during the Olympics andthe subsequent Paralympics.
To compare the operation of the hydrocarbon charged ice cream
freezers, Unilever also commissioned 25 freezers using the HFC
refrigerant R404A, which is standard in refrigeration systems of thiskind. R404A has a GWP of 3800 [4].
Unilever decided to compare their operation in a field test overseenby the Danish Technological Institute.
The test was divided into two parts; the Olympics phase, and asubsequent test phase in which the performance of the freezers
was assessed under normal retail use.

The field tests
Once the freezers had completed their duty at the Olympic Park,
from the beginning of September 2000, to the end of October
2000, they were taken to a warehouse in Sydney [1].
There the Danish Technological Institute (now known as the CSIRO
Energy Centre) and a subsidiary of Denmark’s Danish Technological
Institute and Unilever gave the cabinets a thorough inspection.
Data was collected and the data loggers were re-programmed.
Measuring equipment to measure the temperature outside thecabinet, temperature inside the cabinet and energy consumptionof the cabinet in kWh was used. During the test period thetemperature data loggers took a measurement every two hours.
A device used to measure energy was mounted in the compressor
compartment of the freezers.
The second phase of the field test saw the freezers placed in
shops, supermarkets and service stations. In the Sydney area 25hydrocarbon and 12 R404A freezers were used.
In Brisbane 19 hydrocarbon and 12 R404A freezers were used [1].
According to head of the research, Dr Frank Elefsen, the first
freezers were placed in shops from early December, 2000 until midJuly, 2001.

The results – Sydney Olympics
A paper produced by the team headed by Dr Elefsen, titledField Test of 75 R404a and R290 Ice Cream Freezers in Australia andpublished in EcoLibrium® magazine [1] outlines the results derived
from the two field tests.
The authors of the report note that two of the hydrocarbon
freezers were damaged in the first few days, a power meter did notwork on another and a freezer charged with R404A went missing.

Graph showing the energy efficiency of the different ice cream cabinets

It was also noted that the energy consumption on some of thehydrocarbon freezers varied, however, it was suggested that
this was a result of each of the hydrocarbon freezers being built
manually (essentially, 50 prototype freezers were made – greater
consistency would be expected from cabinets mass-produced in a
manufacturing environment).
When the data from the cabinets was assessed, however, it was
found that the overall energy consumption of the hydrocarbon
freezers was considerably less than the R404A freezers. The
hydrocarbon average was 2.9 kWh per 24 hours compared with 3.6
kWh per 24 hours for the R404A freezers [1].
The authors also noted that the operating conditions during
the Olympics were not typical of normal shop conditions, as thehuge numbers of people being serviced resulted in high productturnover and high thermal loads.
Constant opening and closing of the freezers will let outside heatin, and high product turnover means that the freezers had to berestocked with slightly warmer products regularly. Both of thesefactors meant that the freezers had to work harder than they would
normally be expected to, and therefore consumed more energy.
“The energy consumption results are, therefore, not representative
for normal use,” the Elefsen team concludes. “The fact thatthe hydrocarbon freezers functioned well during these toughconditions confirms their reliability, however.” [1]The results – Sydney
and Brisbane store tests
As mentioned above, for the second part of the field test thefreezers were placed in service stations, supermarkets and shops in
Sydney and Brisbane.
There were 44 hydrocarbon freezers used in the field test. The
review found that of them 37 (or 84 per cent) of the freezers operated
satisfactorily. Gas leaks and electrical failures were blamed for the failureof the seven remaining freezers. For various reasons the data loggers
and measuring equipment did not work on some of the machines.
Sixteen of the 24 R404A freezers used in the field test wereregarded to have worked satisfactorily - again, there were some
failures with the data loggers and measuring equipment.
The field test team concluded that the hydrocarbon freezers had aconsumption of 2.6 kWh per 24 hours compared with 3.1 kWh per
24 hours for the R404A freezers.

Natural Refrigerants Guide

15

One of the test ice cream cabinets

Dr Elefsen’s team concluded that based on the two field tests, the
new hydrocarbon freezers operated satisfactorily and once otherdata was taken into consideration the team concluded that theenergy consumption of the hydrocarbon freezers was 9 per centless than the R404A freezers [1].
The results also confirm that the freezers used less energy whenreturned to normal operating conditions.

Sydney superdome –hydrocarbon drink fridges
Unilever was not the only company embracing the use ofhydrocarbon refrigerants during the Sydney Olympics.
Sunshine Coast-based refrigeration company Maslen Australia
worked with the major Games contractor Abigroup to comeup with 62 400-litre drink fridges that were used in corporate
entertaining areas at the Sydney Superdome.
Company owner John Maslen says he was approached to get
involved because of his “long-term interest in environmentallysound refrigeration”.
Prior to commencing the project, Maslen and Jan Goedhart ofrefrigeration consultancy Nutech had already been experimented withretrofitting some standard refrigerators with hydrocarbon refrigerant.
He says that his early results were promising and he waspredisposed to using hydrocarbon refrigerants when he wasapproached to join the Superdome project.
Maslen had meetings with project managers and then began
experimenting further with the design.
He says that one drawback was the price of $2200 per unit – a pricetag that looked like it could sink the project before it had reallybegun. He went back to the drawing board and came up with asimple design featuring a roof-mounted (forced draft) evaporator
connected to an R12 compressor and a fan cooled condenser
controlled by a domestic thermostat and capillary tube expansion
device.
This simpler design reduced the price per unit, $1600, though it wasa sticking point.
“I had very little profit margin to play with, this was very much alabour of love as this was certainly not our core business and I had
no plans to make it so,” he recalls of the project.

16

Natural Refrigerants Guide

Eventually, Maslen got some support in the form of a $5000
sponsorship and free gas from Boral in exchange for badging
rights.
Maslen says the team studied the regulations and came up with ways
to comply with various standards regarding the use of hydrocarbon
refrigerant. In many cases, he says, it meant ‘leave it out’.
He says the main issue, due to the flammability of hydrocarbon,
was to remove potential sources of ignition.
“We replaced anything with electrical contacts with encapsulated
electronics and enclosed them in IP (ingress protection) rated
boxes - double safety, if you like,” he says.
He says the only exception was the thermostat, which was
mounted in a sealed IP-rated box but had electrical contacts.
“We simply could not fit electronic thermostats into the budget,”he says.
“I made the prototype by hand and loaded it into the back of a ute
and drove from Caloundra to Sydney and proudly showed it to the
Abigroup. They came back with a list of changes they would likeand then we were given the contract.”“I eventually got the prototype back and it is still the best beer
fridge I ever owned.”

Construction
The final product had an outer shell that was 1mm powder coatedgalvanised steel.
The inside was made of interlocking Armacell panels made byvacuum forming part recycled PET plastic over part recycled
polystyrene insulation and recycled white cardboard to give asmooth finish.
He says the door was a standard Maslen Australia aluminium
doorframe with recycled polystyrene insulation and vacuum
formed inner liner.
Adjustable shelving was built on a free-standing ladder system.
Maslen notes that there was no warranty on the compressor
because of the use of hydrocarbon.
There was a hydrocarbon refrigerant charge of 60 grams.

“No lighting was installed in the single-door fridges and no heater
cables were used, to remove potential ignition sources in the eventof a refrigerant leak,” he says. “It also helped reach our price target.”To further minimise any potential ignition sources, all joints in thesystem were soldered.

Benefits
While Maslen stresses that any of the findings are anecdotal rather
than being measured in controlled conditions, he points to someadvantages in choosing hydrocarbon.
“It is interesting to note that the hydrocarbon molecule is quite
large and is less prone to small leaks than the more popularrefrigerants and requires only about 60 per cent of the gas charge
by weight,” he says.
He says a smaller charge of a cheaper refrigerant was required, thefridges’ compressors ran cooler and the current draw was between
15 and 20 per cent less.

Coronato also stated that other alternatives to fluorocarbon
refrigerants were being tested, including freezers running using
thermo-acoustics (using sound pressure instead of the traditional
refrigeration cycle).
“Alternatives such as thermo-acoustics will continue to be tested,particularly in the US where hydrocarbons have not yet been
approved for use in domestic or commercial appliances of thistype,” he says [8].
For his part, John Maslen argues that the use of hydrocarbon“sounded more troublesome than it is”.
He says people overlooked the fact that a home barbecue gas
cylinder can hold up to 9kg of hydrocarbon, much more than the
60 grams in his 400-litre fridges.

References1

He says refrigeration mechanics, mindful of the concerns about
flammability, were more careful when they were doing their hookups, which in Maslen’s view resulted in a lower failure rate for themachines than might otherwise be expected.

Elefsen, F., Nyvad, J., Gerrard, A. and Van Gerwen, R.; Field Test of
75 R404A and R290 Ice Cream Freezers in Australia; EcoLibrium®,
November 2003.

2

Unilever; Social Review 2000; last accessedat www.unilever.com on December 14, 2006

Conclusions

3

Unilever’s experience with hydrocarbon-charged ice cream
refrigerators didn’t end at the Sydney Olympics – indeed, thecompany continued to explore the potential for non-fluorocarbon
refrigerants.

Gerrard, A.; Exploring the Policies of Major End Users towards
HFCs and their progress towards making the transition to
HCF-free Refrigeration; presentation to the Alternative CoolingTechnologies conference, London, UK, February 1, 2005.

4

After the Sydney and Brisbane field tests, Unilever conducted
another, much larger scale trial in Denmark during 2003, in which
800 cabinets were used [3].

Lommers, C A; AIRAH Air Conditioning and Refrigeration
Industry Refrigerant Selection Guide; AIRAH, Melbourne,
2003 (also available online from www.airah.org.au)

5

Olympic air-conditioning – Cooling the 2000 Summer Games,
accessed at www.greenpeace.org.au

6

The company took the Sydney Olympics principle one step further atthe 2004 Athens Olympics, where it trialled five similar hydrocarboncharged ice cream refrigerators powered by solar cells [7].

Europe: hydrocarbon ice cream cabinets cut impact on
climate change; case study last accessed at http://www.
unilever.com/ourvalues/environmentandsociety/casestudies/climateChange/hydrocarbon_icecream_cabinets.asp on
December 14, 2006

7

The vice president of global marketing for Unilever ice cream,
Gino Coronato, summed up the situation at the 2004 “Refrigerants
Naturally” conference [8]:Chilled by the sun; case study last accessed at
http://www.unilever.com/Images/Chilled%20by%20the%20
Sun%5B1%5D_tcm13-18809.pdf on December 18, 2006

8

Coronato, Gino; presentation to Refrigerants Naturally
conference in Brussels, Belgium during June 2004. Transcriptof speech last accessed at http://www.refrigerantsnaturally.
com/speeches/Unilever%20speech.pdf on December 16, 2006

By the end of 2004, around 15,000 of the cabinets has been
installed in 17 European countries. According to the company,
laboratory trials have found these models to be 15% more efficientthan equivalent HFC refrigerant models [6] – an improvement on
the 9% efficiency increase observed in the Australian trials.

“Why would a Unilever marketing man be talking about working
together with competitors such as Coke and McDonalds onrefrigeration? And why would consumers be remotely interested insomething as boring as freezer technology?” he asks.
“Because, I believe it makes good environmental and marketing
sense,” he says. “This premise is based on the belief that greatbrand design appeals to both the rational and emotional side ofour consumers. Unilever’s ice cream business operates nearly two
million freezers around the world and we require excellence inrefrigeration as a means to remain competitive.”

Natural Refrigerants Guide

17

Coles Gisborne
CO2 /R404A supermarket
refrigeration system

C ASE S TUDY

Coles Gisborne supermarket.

Don Griffiths outside the store

Introduction
Coles Myer Ltd is a company listed on the Dow Jones Sustainability
Index. Each of its businesses is implementing an energy
management plan, with the aim of reducing their overall energy
consumption by 2-4% by 2010 and taking steps to introduce lower
carbon solutions and offsets [1].
But the company took another very practical step a few years
ago when it commissioned a 2500 square metre environmentally
sustainable supermarket at Gisborne in Victoria, 50 kilometers
north-west of Melbourne. The supermarket was opened in April
2005 and featured a number of sustainable design initiatives,
including the use of natural refrigerants in the refrigeration systems.
This supermarket would come to be known as “G1”.
“What is learned from this project will be a guide for the future
design of Coles Supermarkets. The company is seeking to reduceenergy demand and consumption, reduce water and waste
billing, meet corporate goals and of course meet our customer
expectations,” said Don Griffiths, Coles refrigeration and building
services design engineer on the project just prior to its opening [2].
The project was carried out in cooperation with the Federal
Department of Industry, Tourism and Resources’ Energy Efficiency
Best Practice Program, which “worked in partnership with industry,
consultants and other government and research agencies, to18

Natural Refrigerants Guide

demonstrate that significant and additional energy efficiency savings
could be delivered in a range of businesses and industries” [3].
Architects McGauran Giannini Soon state the project has “developed
new standards for energy performance in a supermarket, with theresulting G1 store achieving projected energy savings of over 40%.
This is a significant achievement in reducing Australia’s carbon
emissions having the impact of reducing emissions by nearly 1% if
applied across all supermarkets” [4].
The results were such that the project won a 2005 Royal AustralianInstitute of Architects (RAIA) award for sustainable architecture [5]for its integration of day lighting, recycled water and various othersustainable building strategies– but it’s the refrigeration and air
conditioning systems that will be of the most interest to readers of
this case study.
This case study will examine how a number of aspects of thesupermarket’s design work together to improve sustainability.
While the refrigeration system is the major focus of this study,
readers will note that factors external to the refrigeration system
also need to be considered to ensure the best possible outcomes.

Building fabric
The building ‘fabric’ (walls and roof) comprises 75mm recycledconcrete panels in the walls to increase the building’s thermalmass and insulated sandwich-panel roofing. The insulation andincreased thermal mass makes the store’s interior less susceptible tochanges in the ambient temperature outside, meaning in turn thatthe air conditioning system (and refrigeration systems) shouldn’t
have to work as hard.
Supermarkets can also have problems with temperature
differentials between shopping and service areas or between thestore and the air outside – warm air from outside or even inside thestore itself leaking into cool rooms can create extra work for the
refrigeration system, for example. The most common example ofthis taking place is when the doors are opened.
The G1 store has tried to minimise this problem by installing ‘airlocks’ at both the front customer entrance to the store, and also
to the loading dock at the rear of the store. The loading dockalso features quick action roller shutters, and the effect of these
combined with the air lock concept is to reduce the effect oftemperature differentials, creating less work for the refrigeration
and air conditioning systems and therefore reducing overall energy
consumption.

Refrigeration system
Background
Even before Coles came to them, Frigrite Refrigeration Pty Ltd,
based at Cheltenham in Victoria, was looking at ways in which
natural refrigerants could be employed to replace synthetic
refrigerants.
The Frigrite Alternative Refrigerant Program began in 1999
with wide-ranging aims to investigate natural refrigerants and“get ahead of the game” according to the company’s national
engineering manager Paul Sheahen.
Sheahen says that Frigrite, an Australian-owned company, didn’t
want to be “caught with its pants down”. To this end, the company
teamed up with Sustainability Victoria to carry out research on
alternatives to the systems on the market at the time. Bitzer
Australia, Danfoss Controls and the CSIRO’s Energy Technology
division were also brought on board for the project, sitting down to
discuss ways in which they could avoid using synthetic refrigerants
in preference to natural refrigerants.
“Several approaches are in play – in Europe the trend is towards
using carbon dioxide (CO2) in cascade systems (ie: in conjunction
with another refrigerant)” says Sheahen.

Overseas experiences
The Coles G1 store is the first of its kind in Australia, andthe use of natural refrigerants in supermarket applications
is starting to take off overseas as well.
As early as 1993, Wal-Mart opened an “Eco-Mart” store in Kansas,
USA which used ice storage as part of its refrigeration system.
Sheahen viewed a number of systems during his research overseas.

He travelled extensively to see what was on offer overseas andinvestigate natural refrigerant systems, however, he believed thateach system he saw had its failings so the company decided todevelop its own CO2 system.
The project resulted in the development of a pilot refrigeration
cabinet suitable for supermarkets, which could be tested using
R507A (a synthetic, hydrofluorocarbon or HFC refrigerant with a
global warming potential of 3900 [6]) and carbon dioxide (CO2,which has a global warming potential of just 1).
According to Sheahen, a medium temperature meat case and afreezer case were selected for the test. They were initially run using
CO2 as the refrigerant, then modified to run on R507A (a direct swap
is not possible, as R507A requires the use of a polyol ester lubricant
which is incompatible with CO2 [6]. As a result, some modifications to
the equipment are required before the refrigerant can be swapped).
The performance and energy consumption of the equipment wasmonitored for both refrigerants. Sheahen states that, when operating
using CO2, the system used less energy than when operating using
R507A: 4.11kWh, as opposed to 5.24kWh. In addition to the potential
environmental benefits of using a refrigerant with much lower global
warming potential, the energy saving made CO2 a very attractive option.

The Coles G1 system
The system that was eventually installed at the Coles G1 store in
Gisborne was a product of this research – a “cascade” system using
R507A and CO2.
“The conventional hydrofluorocarbon refrigeration plant is replacedwith a cascade hydrofluorocarbon (R507A) stage that works inconjunction with a liquid CO2 stage to reduce fugitive emissions,”
says Sheahen.
The result of this is that, even though fluorocarbon refrigerants arestill used, they are needed in much lower quantities when usedin conjunction with CO2. The amount of fluorocarbon refrigerant
required to operate the system is 90% lower than it would be with a
R507A-only system according to Sheahen (a charge of 120kg, downfrom around 1200kg for a similar-sized R507A only system). Lower
charges mean that, even if there is a leak, less refrigerant will be lost
and the CO2 equivalent released from the leak will be much lower.
CO2 is used for the low-temperature frozen food cases and coldrooms, and R507A is used for the remaining systems. R134a (a HFC)
is used in the building’s air conditioning system, and R407C (also aHFC) air conditioners are used in the food preparation areas, backrooms and staff areas [7].

In South Africa, France and the UK there are supermarkets
operating using a combination of R404A and either propylene
glycol or a proprietary non-fluorocarbon heat transfer fluid. Thereis also a Sainsbury supermarket in the UK using a combination ofhydrocarbon and proprietary non-fluorocarbon heat transfer fluids.
Sheahen says that in Denmark he came across a systemusing R404A in its high stage and carbon dioxide in its low stage,and it was this system that was the inspiration for theColes G1 system.

Natural Refrigerants Guide

19

Why CO2?
Don Griffiths says that in an assessment of the alternative naturalrefrigerants, he believes CO2 came out with a number of attributes
in its favour.
“It is a natural refrigerant known and used in the past. It has a
low replacement cost, is available locally and is not imported like
synthetic refrigerants,” he says.
He also adds the fact that CO2 is non-toxic and non-flammablewere characteristics that he viewed as “more acceptable” in a
shopping centre setting.
Sheahen says that hydrocarbon refrigerants were consideredearly in the process, but they were eliminated based on theirflammability and the need to install extra detection alarms.
While it is true that CO2 operates at a higher pressure than mostother refrigerants [8], Sheahen says that the problem was avoided
in this installation by installing more smaller pipes that effectively“spread the load”.

System description
To aid efficiency, the refrigeration cabinets feature twin air screens,
single row fluorescent tubes with parabolic reflectors for lighting,motorised (automated) night blinds, high-efficiency electronicallycommutated fan motors, low energy glass doors (on cabinets withdoors) and dual pane glass on deli cases.
The fluorescent lighting configuration produces less heat than standard
systems, meaning less energy is expended by the refrigeration systemremoving lighting-generated heat from the cabinet.
The automated night blinds are also something of an innovation.
While Sheahen says that night blinds are certainly not a newconcept, automating them ensures their use is not left to chance.
He says that when the blinds are controlled manually, they may
not be used for days or weeks at a time because staff often forget
to lower them. When the blinds are lowered, more cool air iscontained within the cabinet and the system doesn’t have to work
as hard to maintain its temperature overnight.

Illustrating the piping example, Sheahen points out that a typicalinsulated copper pipe for use with R134a (another fluorocarbon
refrigerant) would need to be 215mm in diameter. A pipe for thesame application using ammonia (a natural refrigerant) would need
to be 133mm in diameter. By contrast, the pipes required for CO2
were only 69mm in diameter. All other things being equal, thesmaller pipe will be cheaper.
Sheahen also claims that CO2 allows for a smaller refrigeration plant
which operates more quietly than an equivalent fluorocarbon
system and has less vibration, and that as a refrigerant CO2 isseven times more efficient per kilogram in this application than asynthetic refrigerant like R507A.

Conclusions
The project’s backers are treating it with cautious optimism now
that it is in operation, though the level of financial and energy
savings couldn’t be quantified at the time of writing.
“We do not want to put hard figures on it at this stage as it is earlydays,” says Coles Myer’s Paul Lang. “We are fine tuning it – when
you have new technology and new equipment there are going to
be teething issues and we are monitoring them and continually
making improvements.”
The lessons from the G1 store have already been used elsewhere
though, with much of the technology developed being put towork at another Coles supermarket in Winmalee, New South Wales- indeed, Sheahen states that some of the lessons learned fromdoing a second system have allowed for retrofit improvements to
be made to the G1 store.

References
1
2
3

Reclaimed heat from the refrigeration system is also used toprovide hot water and to warm the air in front of the refrigeration
cabinets, minimising the problem of customers feeling chilly as
they walk past the cabinets.
All of the refrigerated display cases meet minimum energy
performance standards (MEPS), and Sheahen believes that thesystem overall has the potential to cut power consumption by
about 20 per cent.

4

5

System advantages
Sheahen states that this configuration also allows for a significant
cost saving on the refrigerant itself – R507A is more expensive
than CO2 so reducing the amount of R507A required by this muchprovides a substantial cost benefit.
He says that there were also savings made because the system uses
smaller pipes than a comparable fluorocarbon system and because
efficiency gains from the whole system allowed the number of fanson each evaporator to be reduced from four to two.

20

Natural Refrigerants Guide

6

7
8

Coles Myer Ltd; Corporate Social Responsibility Report 2006;
last accessed at www.colesgroup.com.au on December 7, 2006
McGowan, S; Grocery Goes Green; EcoLibrium® magazine,
Vol 4 No 3 (April 2005) p 10
Department of Industry, Tourism and Resources Energy
Efficiency Best Practice program website: last accessed at
http://www.industry.gov.au/content/itrinternet/cmscontent.
cfm?objectid=4797DE4D-9619-4C79-A10D935C6FE25ED1&in
dexPages=/content/sitemap.cfm?objectid=48A3EB59-20E068D8-ED2EA23BE5801384 on December 7, 2006
McGauran Giannini Soon project information sheet on
Gisborne Central Retail Centre, last accessed atwww.msgarchitects.com.au on December 7, 2006
www.architecture.com.au Gisborne Retail Centre award
summary, last accessed at http://www.architecture.com.au/awards_search?option=showaward&entryno=20053063
on December 7, 2006
Lommers, C A; AIRAH Air Conditioning and Refrigeration
Industry Refrigerant Selection Guide; AIRAH, Melbourne,
2003 (also available online from www.airah.org.au)
Griffiths, D; Coles: the ultimate in green grocers; Climate Control
News, May 2005 p 14, published by Yaffa Publishing Group Pty Ltd
Ives, R; The Future of Industrial Refrigeration – A User’s View;
AIRAH natural refrigerants: applications in refrigeration, airconditioning and heating conference, Museum of Sydney,
July 2004. Proceedings available from www.airah.org.au

C ASE S TUDY

CRF (Colac Otway) Pty Ltd
cascade CO2 / ammonia
freezing plant
Introduction
Lamb processing company CRF (Colac Otway) Pty Ltd is one of thebiggest employers in the Western Victorian district town of Colac,
providing work for more than 350 people.
It processes on average 6000 head of lamb per day, and bones
out on average 3000 head of lamb per day. Its plant is a service
provider for supermarket giant Coles, providing full carcases andcuts of lamb to their distribution centres throughout Australia andto overseas customers.

As work progressed, the team tapped into the Victorian State
Government’s Commercial Office Building Energy Innovation
Initiative (COBEII), which provided a $110,000 grant and support forthe project [2].
The facility, adjacent to CRF but on an independent site in Colac,
freezes, chills, and stores meat products and by-products such as
offal that are produced at the CRF plant. There also is provision infor products from other suppliers to be frozen at the facility on acontract basis.

But it took some time for the company to reach this position.

The cold storage facility opened in November, 2005, and employs
up to 13 people.

In the late 1990s, the owners saw a commercial opportunity forsupply chain principles to be applied to meat processing andbuilt a brand new facility using the latest design and technology
principles.

System overview

In 2000, a $9.8 million state-of-the-art processing plant was opened [1].
But despite this great leap forward, the company was still forced to send
any meat it wanted frozen to Melbourne, some 150km away.
In an effort to cut costs and increase efficiency, the company began
exploring the feasibility of building a cold storage facility so it could
freeze its produce on-site.
It was decided that Otway Fresh Pty Ltd, a separate entity but
related company, would build a $7 million cold storage facility toprovide this service.
Otway Fresh appointed a design team which included Melbourne
meat processing specialist Meateng Consultants and New Zealandcompany RealCold. Bendigo-based KAV Consulting also assisted in
the development of the refrigeration system.

The central piece of equipment in the project is an automatic air
blast-freezing tunnel (AABF), developed by RealCold.
The AABF installed at Otway Fresh is capable of freezing 1610 bulk
packed export meat cartons with a 24-hour turn around. The
design includes infrastructure to cater for an expansion should theneed arise. Under the plan, the AABF could be capable of being
expanded to freeze 3312 bulk packed export meat cartons, still witha 24-hour turn around [3].
The facility also includes two forklift-loaded carton blast freezing
cells, ‘palletising’ areas, chilled product storage and frozen productstorage.
The design makes provision for a three-fold increase in the cold
storage capacity and a future carton chilling facility, which could bein the form of an automatic storage and retrieval system.

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21

Meateng consultant Steve Baum says the AABF was selected dueto the varying sizes and depths of cartons handled in a single
production shift. The contents of these different carton sizes range
from 15kg to 25kg, which he says meant that plate freezing (analternative freezing method) was not suitable in this case.

Use of natural refrigerants
CRF says it was keen from the outset to use natural refrigerants forthe project.
The use of ammonia in cold storage and freezing applications suchas the one CRF were seeking to build is common in Australia. As
the team discovered, however, combining ammonia with anothernatural refrigerant would lead to greater efficiency and provide anumber of other benefits.
After some investigation it was decided that a ‘cascade’ carbon
dioxide (CO2) / ammonia system could be installed. The systemis the first of its kind in Australia to be built with this capacity andto be applied to an AABF, freezing cells and maintenance of cold
storage, with the cool storage temperatures around the freezing
point.
Baum says CO2 was chosen because it is a non-toxic, nonflammable gas that has good thermal properties. He says anotheradvantage is that if there were a refrigerant leak, it would not affect
the quality of the meat being processed.
Furthermore, Baum states that CO2 is an environmentally
sustainable choice because of its minimal global warming potential(GWP - CO2 has a GWP of 1, whereas synthetic refrigerants can have
GWPs of up to 1500 [4]).
Using CO2 in conjunction with ammonia instead of an ammoniaonly installation was also deemed to be a better option in terms ofoccupational health and safety (OH&S).
While ammonia has a GWP of 0 [4] and is very efficient in a number
of applications as a refrigerant, it is also toxic and leaks can be asignificant OH&S hazard. In the ‘cascade’ configuration used forthis project, however, where CO2 is used in the staffed areas, thesections of refrigeration plant using ammonia can be isolated in theplant room and more easily contained in the event of a refrigerant
leak.
Using CO2 also gave the team access to productivity increases– traditionally, AABFs in these applications have operated on a
48-hour freezing turn around. The design team found that using
CO2 in a cascade system with ammonia gave access to higher
system efficiencies which allowed the turn around time to be
reduced to 24 hours, and an operating cost analysis indicated that
this outcome could be achieved more economically and efficiently
than using ammonia alone.
Finally, the design team noted that CO2 systems operate under apositive pressure at all times (ie: the pressure inside the refrigeration
system is greater than the atmospheric pressure outside thesystem), meaning that air and other potential contaminants cannot
be drawn into the system [3].
Low temperature ammonia systems operate below atmosphericpressure, potentially allowing these contaminants to be drawn into

22

Natural Refrigerants Guide

the system. While these contaminants won’t cause immediate
system failure in most cases, their accumulation inside a system will
increase the condensing pressure and hence the running costs if
unattended.
The choice of this natural refrigerant configuration also broughtsome challenges though. In particular, the team needed to devoteconsiderable effort to be devoted to finding suitable materials forthe system, as the majority of commercially available materials were
not suited to applications of below -40°C, and there were somecost considerations. These challenges are discussed below.

Costs and system configuration
Using CO2 in combination with ammonia as opposed to anammonia-only system did have an effect on the cost of the system,
and various factors had to be weighed up during the design process.
One issue was with the cascade condenser, a component required
to make the CO2 / ammonia design function. The design teamsays that the condenser required for the CO2 / ammonia design
was more expensive than an equivalent ammonia-only model,
however, cost savings in other areas of the project cancelled out
the extra cost.
The condenser eventually chosen was a plate and shell design withit high performing capacity made by Vahterus, a Swedish company
with a track record in CO2 condensing applications [3].
CO2 systems also operate at a higher pressure than ammonia
systems, and this high pressure means that the vessels containing
the CO2 need to be designed for these higher pressures. As a result,they cost more than the vessels that would be required for anammonia system of the same capacity.
According to the design team, the capital cost of a carton-freezing
tunnel such as the one used at Otway Fresh is fairly constant for any
given number of carton spaces. Therefore, the comparative capital
cost per carton frozen is dependent on the number of cartonsfrozen per day [3].
For example; a freezing tunnel costing say $1 million and holding
5000 cartons has an effective capital cost of $200 per carton whenfreezing on a 24-hour cycle. The cost blows out to $400 when
operating on a 48-hour cycle.
Realcold’s Brian Edwards cautions that a 10,000-carton tunnel does notcost twice as much as a 5000 carton tunnel though. “Care must be
exercised in how the various costs are evaluated and compared,” he says.
A detailed study was undertaken to compare the capital cost of a AABF
CO2 system on a 24-hour turn around with that for a 48-hour turnaround in a conventional tunnel and ammonia refrigeration system.
There were four options considered:
OPTION 1:

A 48-hour freeze tunnel with a two-stage plant room
at a total cost of $2.55 million. Included in this figure
was the cost of building the AABF with a capacity tofreeze 3300 cartons over 48 hours, estimated at $1.2
million, and the cost of the plant room equipment
was $390,000. The plant in this configuration would
use 402 kW of power.

OPTION 2:

A 48-hour freeze tunnel with economised one-stage
plant room at a total cost of $2.48 million. The plantroom equipment would cost $320,000 and the AABF
$1.2 million. Power use was estimated at 452 kW.

OPTION 3:

A 24-hour freeze tunnel with two-stage ammonia
plant room with a total cost of $2.4 million. The plantroom equipment was put at $450,000 and the AABF
at $900,000. Energy consumption was estimated at
436 kW.

OPTION 4:

A 24-hour freeze tunnel with a cascade CO2 /ammonia plant room at a total cost of $2.18 million.
The cost of the plant room was put at $450,000 and
the AABF at $900,000. Energy consumption was
estimated at 401 kW.

Options 1 and 3 also included a glycol system, the cost of which
was estimated at $60,000. Cooling equipment inside the coldrooms common to all four options was priced at $200,000.

In summary, it was found that 24 hour freezing using a CO2 /ammonia cascade system consumed less energy in this case than
24 hour freezing using a two-stage ammonia plant, but moreenergy than a 48 hour freezing cycle using a two stage ammonia
plant.
Edwards also concluded that using CO2 would allow for a costsaving on pipework, as CO2 needs small pipes than an ammoniaonly system and because copper can be used to make CO2 pipes
for -50°C systems.
The savings in capital costs between 24-hour and 48-hour carton
freezing tunnels exceeded the increased cost of the CO2 / ammonia
cascade refrigeration plant room when compared with the cost ofa conventional ammonia plant room.
Therefore, 24-hour freezing with cascade CO2 / ammonia wasshown to be a lower capital cost solution than 48-hour freezing
with ammonia.
Further, 24-hour freezing with a cascade CO2 system was provento be a lower cost than 24-hour freezing with ammonia, as using
ammonia only required compressors that were eight times larger
than theCO2 option to operate at -50°C.
The system also provides versatility which can allow for further costsavings in some circumstances.
The AABF as installed can be set to operate on a 48-hour cycle
rather than a 24-hour cycle, which uses less energy than the
24-hour cycle. This means that the system operator has the ability
to extend the freeze time in periods of low production and reducerunning costs.

Comparison of system costs

SafetyThe design team drew the following conclusions :[3]

1.

The cascade CO2 / ammonia system (Option 4) was estimatedto be $370,000 lower capital cost than the ‘conventional’
solution of 48-hour carton freezing and two-stage ammonia
plant room (Option 1).

2.

In this instance, the power drawn by the system’s compressors
at full load was similar between Options 1 and 4. In othercases, however, a 48-hour freezing cycle using a two stage
ammonia plant may consume less energy than a 24 hour
freezing cycle in CO2 / ammonia cascade configuration.

3.

The CO2 / ammonia cascade system (Option 4) running at–50°C had a much lower (around 20%) compressor drawn
power than the two-stage ammonia system. This came aboutbecause the high efficiency reciprocating compressors being
used on both stages of the cascade option.

While ammonia has long been used as a refrigerant, its toxicity isoften a stumbling block precluding it from widespread use in areas
where a lot of staff are working.
Australian Standard AS/NZS 1677.2 Refrigerating systems Part 2:
safety requirements for fixed applications [5] dictates various safety
precautions that need to be put in place for an ammonia-onlysystem in an application such as the CRF one, including limits on
personnel density and the amount of refrigerant that the system
can hold.
Theoretically, ammonia could have been used in several rooms
at the Otway Fresh facility, however, the size of the rooms andthe number of personnel expected to work in them would haveexceeded the safety requirements set out by the standard.

The ammonia option was based on screw compressors and thoseon the high stage were relatively small and had lower efficiencies,
especially at part load conditions. In other instances the reverse
could be true were small screw compressors required to operate on
the CO2 system and larger, more efficient screw compressors usedon the alternate ammonia system.
Edwards cautions that on this basis it was important to make fullevaluations of each particular application. What is most efficient forthis application may not necessarily work as well for other sites.

Natural Refrigerants Guide

23

Otway Fresh wanted to take a strong stand on OH&S, and as aresult tenders for the project dictated that no direct ammonia
would be used in the project’s occupied areas.

The 24-hour freezing cycle offered by the CO2 / ammonia cascadesystem has also allowed stock holding and inventory levels to be
reduced.

The tender noted that there had been “examples of large ammonia
leakages reported in the Australian meat industry and it seems aprudent move to avoid the use of ammonia in the field if there wasa cost-effective alternative available.”At the time of writing, it is early days but the team believe the plantis on track.

In addition to the personnel risks, if ammonia leaked in an area
containing meat products, the products would be contaminatedand would have to be disposed of. A CO2 leak, on the other hand,
would not result in product contamination.
Additionally, the tender suggested an alternative such as glycol,
which is not harmful to people, should be used. In the final design,
CO2 was used instead of glycol.
The use of CO2 also carries risks – while it is non-toxic and nonflammable, CO2 is heavier than air and displaces oxygen in a room,
so a large enough leak in a confined space can cause suffocation. It
is also odourless (unlike ammonia) so detectors need to be installed
to warn staff in the event of a leak.
The Otway Fresh plant at Colac has had leak detectors installed in
all areas to ensure early detection occurs, according to Baum.

“It certainly has attracted some interest,” says Baum says.
Realcold states it has fielded inquiries from other meat works
interested in the project.
The carton freezers and cold store will be monitored and tested
during operation.
There have also been other positive outcomes - in announcing
the $110,000 assistance grant, State Environment Minister John
Thwaites said the choice of CO2would cut greenhouse pollution by
as much as 900 tonnes each year [2].
This, he suggested, would be the equivalent of removing 210 carsfrom Colac’s roads or save enough energy to power almost 40
homes for the year in the town.
While the system won’t be right for all applications, it is certainly
worth evaluating for large freezing and refrigeration projects.

Risk minimisation

References

The use of CO2 at Otway Fresh has allowed the amount of ammonia
in the system to be minimised. The design team estimates that anammonia-only system would have had an ammonia charge about
90% higher than the CO2 cascade charge. The cascade system
adopted also allows the ammonia charge to be contained within
the plant room at a safer distance from personnel.

1

CRF (Colac Otway) Pty Ltd corporate website, last accessed atwww.crfco.com.au on December 13, 2006

2

Victorian Government medial release; First for Victorian
Industry Efficiency Stored in Colac; issued July 29, 2005

3

Edwards, B, Baum, S and Sexton, L; Carbon Dioxide andAmmonia Cascade Refrigeration System for Automatic Blast
Freezing Tunnel and Cold Storage Distribution Centre for
Otway Fresh Pty Ltd; project overview, prepared October 2005

4

Lommers, C A; AIRAH Air Conditioning and Refrigeration
Industry Refrigerant Selection Guide; AIRAH, Melbourne, 2003
(also available online from www.airah.org.au)

5Australian / New Zealand Standard AS/NZS 1677.2:1998
Refrigerating systems Part 2: Safety requirements for fixed
applications; Standards Australia, Homebush, 1998

6

Visser, K.; Total energy two stage transcritical CO2 systems
for food processing and total energy single or two stagetranscritical CO2 systems for air conditioning and heating;presented at AIRAH natural refrigerants conference, Museumof Sydney, July 28, 2004. Proceedings available, contact www.
airah.org.au

The plate and shell type condenser chosen for the system also
helps to minimise the ammonia charge as it has an extremely highperformance capacity per unit volume, meaning the charge ofammonia – used to condense the CO2 – is kept to a minimum.
Baum points out that if CO2 had not been used, the charge ofammonia on the site could have been as high as six tonnes.
Consultant Klaas Visser suggests that OH&S is one of the top threeissues facing the food processing industry, hence the shift awayfrom ammonia in staffed areas.
“The ready acceptance of CO2 / ammonia cascade systems was mainly
driven by the occupational health and safety issues, which is the number
three issue facing the food processing industries in general,” he says [6].

Conclusion
CO2 has offered CRF and Otway Fresh the ability to economicallyfreeze cartons in 24 hours using air blast systems.
The capital costs were proven to be lower than an equivalentammonia system, and the operating costs are expected to better
than an ammonia system operating on a 24 hour cycle.
CO2 is not toxic, will have no effect on the product in the event of aleak, and has been found to be safer to use in occupied spaces thanammonia.

24

Natural Refrigerants Guide

Acknowledgements
The authors would like to gratefully acknowledge the input of thefollowing people to this case study:•

Jack Barclay, Mark Westgarth and Laura Sexton (CRF)•

Brian Edwards (Realcold)•

Merv Jaensch and Steven Baum (Meateng)•

Klaas Visser (KAV Consulting)Other rescources

Air Conditioning and Refrigeration Institute

Natural Refrigerants Transition Board— www.ari.org— www.nrtb.org.au

The Air Conditioning and Refrigeration Institute (ARI) is a US-basedorganisation representing manufacturers of air conditioning andcommercial refrigeration equipment. Its website provides information on
product testing and international refrigeration equipment standards.

The Natural Refrigerants Transition Board (NRTB) is an Australian group
established to “assist in the wider acceptance of natural refrigerants inthe community.” Its website provides information on various information
sessions and programs run by the organisation, as well as links to further
reading.

Australian Institute of Refrigeration,
Air Conditioning and Heating

Refrigerants, Naturally— www.airah.org.au— www.refrigerantsnaturally.com

The Australian Institute of Refrigeration, Air Conditioning and Heating(AIRAH) provides training and technical information for the refrigeration
and air conditioning industry. Its website contains information onammonia refrigeration training programs and articles on naturalrefrigerants from the institute’s magazine, EcoLibrium®.

Refrigerants, Naturally is an initiative supported by the United Nations
Environment Programme (UNEP) and Greenpeace for large businesses,
including McDonalds, Coca-Cola, Unilever, PepsiCo, Ikea and Carlsberg, toimplement fluorocarbon-free refrigeration systems.

Standards Australia
Department of Environment and Water Resources— www.environment.gov.au
The Australian Government Department of the Environment and Water
Resources (formerly the Department of the Environment and Heritage)develops and implements national policy, programs and legislation toprotect and conserve Australia’s natural environment and cultural heritage.

— www.standards.org.au
Standards Australia is the body responsible for producing and publishing
Australian Standards. Its website provides information on the standards
writing process, opportunities to comment on draft standards, andopportunities to purchase relevant Australian Standards.

Workplace Safety Australia
International Institute of Ammonia Refrigeration— www.iiar.org
The International Institute of Ammonia Refrigeration (IIAR) is a US-basedorganisation representing users of ammonia refrigerant. Its website offers
information on conferences held by IIAR, safety and technical informationand general information on the use of ammonia as a refrigerant.

— www.worksafe.com.au
Workplace Safety Australia provides advice and information to Australiancompanies on occupational health and safety issues and strategies. Its
website provides various newsletters, publications and question andanswer forums (note: subscription may be required to access someof these services).

International Institute of Refrigeration— www.iifiir.org
The International Institute of Refrigeration (IIR) is an international,
intergovernmental organisation enabling pooling of scientific and industrial
know-how in all refrigeration fields. Its website offers explanatory notes on
various refrigeration technologies (including natural refrigerants) as well as
access to research databases for more in-depth information.

Note: all website links were correct at the time of publishing (April 2007)

Natural Refrigerants Guide

25

PREPARED BY THE AUSTRALIAN INSTITUTE OF REFRIGERATION, AIR CONDITIONING AND HEATING,
with funding from the Department of Environment and Water Resources