Installation of separate-type inverter-controlled fridge showcase
for convenience store(s)Additional Information
1.

Introduction

This methodology evaluates the reference emission of separate type fridge showcase, taking into accountthe impact of the difference of the coefficient of performances (COPs) and performance degradation effectof ON/OFF cycles of the constant speed compressor. In calculating the performance degradation effect ofincremental electricity consumption caused by frequent of ON/OFF cycles by the absence of the inverter,
Part load fraction (PLF) is applied considering the condition called “part load conditions” under which thecooling load is smaller than the rated cooling load. On the other hand, the effect of the inverter at the part
load condition where separate type fridge showcases frequently operate and the efficiency drastically
improved against reference non-inverter separate type fridge showcase is not considered. Therefore themethodology achieves the net emission reductions.

2.

Estimation of emissions from reference separate-type fridge showcase using Part Load Fraction

Reference emissions of the separate type fridge showcase is calculated by the multiplying electricity
consumption of the reference separate type fridge showcase and CO2 emission factor for the consumedelectricity.

Where,

ܴ‫ܧ‬௜,௝,௣ = ‫ܥܧ‬௥௘௙,௜,௝,௣ × ‫ܨܧ‬௘௟௘௖ ⋯ (1)‫ܥܧ‬௥௘௙,௜,௝,௣

Electricity consumption of the reference separate type fridge showcase‫ܨܧ‬௘௟௘௖

CO2 emission factor for consumed electricity [tCO2/MWh]݆݅

j at store i during the monitoring period p [MWh/p]

Identification number of the convenience store [-]Identification number of the separate type fridge showcase [-]Therefore, the formula for calculating the reference emissions of the reference separate type fridge showcase
is as follows.
ܴ‫ܧ‬௣ = ෍ ෍ ൣ‫ܥܧ‬௥௘௙,௜,௝,௣൧× ‫ܨܧ‬௘௟௘௖ ⋯ (2)௜௝In this methodology, the reference electricity consumptions are calculated by considering PLF which is acoefficient of part load ratio (PLR). PLR is generally calculated by the ratio of cooling load to rated cooling
capacity as follows. Since cooling load can be replaced by cooling capacity, the basic concept is shown inEquation (3).
1ܲ‫= ܴܮ‬‫[݀ܽ݋݈ ݈݃݊݅݋݋ܥ‬kܹ ]‫[ݕݐ݅ܿܽ݌ܽܿ ݈݃݊݅݋݋ܥ‬kܹ ]≅⋯ (3)ܴܽ‫[ݕݐ݅ܿܽ݌ܽܿ ݈݃݊݅݋݋ܿ ݀݁ݐ‬kܹ ] ܴܽ‫] ܹ݇[ݕݐ݅ܿܽ݌ܽܿ ݈݃݊݅݋݋ܿ ݀݁ݐ‬Cooling capacity required for the monitoring period is calculated by multiplying the averaged electricity
consumption and the COP of the project separate type fridge showcase as shown in Equation (4)‫ݕݐ݅ܿܽ݌ܽܿ ݈݃݊݅݋݋ܥ‬௣௝,௜,௣ =ா஼೛ೕ,೔,ೕ,೛
௧೛ೕ,೔,ೕ,೛

As the result, Equation (3) can be converted to Equation (5)Where,

ܲ‫ܴܮ‬௜,௝,௣ =ா஼೛ೕ,೔,ೕ,೛ ×ଵ଴య௧೛ೕ,೔,ೕ,೛

×× ‫ܱܲܥ‬௣௝,௜,௝ ⋯(4)஼ை௉೛ೕ,೔,ೕ஼௔௣ೝ೐೑,೔,ೕ

⋯(5)ܲ‫ܴܮ‬௜,௝,௣

Part Load Ratio of the separate type fridge showcase j in‫ݕݐ݅ܿܽ݌ܽܿ ݈݃݊݅݋݋ܥ‬௣௝,௜,௝,௣

Cooling capacity of the separate type fridge showcase j in‫ܥܧ‬௣௝,௜,௝,௣

Electricity consumption of the project separate type fridge

convenience store i during the monitoring period p[-]convenience store i during the monitoring period p [kW]showcase j in convenience store i during the monitoring periodp[MWh/p]‫ݐ‬௣௝,௜,௝,௣‫ܱܲܥ‬௣௝,௜,௝‫݌ܽܥ‬௥௘௙,௜,௝

Operating time of the project separate type fridge showcase j inconvenience store i during the monitoring period p[hour]
Energy efficiency of the project separate type fridge showcase
j in convenience store i
Rated capacity of the reference separate type fridge showcase jin convenience store i [kW]Rated capacity of the reference separate type fridge showcase is assumed to be same as the rated capacity of
project separate type fridge showcase, therefore the following equation can be obtained.

Where,‫݌ܽܥ‬௣௝,௜,௝‫݌ܽܥ‬௥௘௙,௜,௝ = ‫݌ܽܥ‬௣௝,௜,௝ ⋯(6)
Capacity of the project separate type fridge showcase j at store i during themonitoring period p[kW]2

According to the manual of EnergyPlus(1), a typical part load fraction (PLF) correction is calculated as follows.

Where,

ܲ‫ܨܮ‬௜,௝,௣ =‫ݕ݂݂ܿ݊݁݅ܿ݅݁ ݀ܽ݋݈ݐݎܽ݌‬= 1 − ‫ܥ‬஽ ൫1 − ܲ‫ܴܮ‬௜,௝,௣ ൯⋯ (7)‫ ݕ݀ܽ݁ݐݏ‬− ‫ݕ݂݂ܿ݊݁݅ܿ݅݁݁ݐܽݐݏ‬ܲ‫ܨܮ‬௜,௝,௣

Part Load Fraction of the separate type fridge showcase j in convenience storeCୈ

Degradation Coefficient is a parameter used in calculating the part loadi during the monitoring period pfraction-]

As shown in the equation (7) above, PLF is led by the formula using degradation coefficient (CD). The
degradation due to ON/OFF cycles by the absence of the inverter is assumed to be equivalent since theseparate type fridge showcase is similar with the air conditioner in terms of the operation except for thesetting of evaporating temperature. As shown in Table 1, the survey of air conditioner standard in thecountries indicated in Table 1, the values of degradation coefficient CD are identified from 0.20 to 0.25.
Therefore, in this methodology, CD is set to be 0.15, which is applied in Energy Plus, in order to achieve net
emission reductions.

Table 1 The comparison with CD in each country
Degradation
CountryStandards
coefficient (CD)JapanJIS B 8616:20150.25
USA
ARI 210/240,0.2
CanadaASHRAE 116-1995
EUBS EN 14825
0.25
China
GB/T 7725-2004
0.25
Hong Kong
Voluntary Energy Efficiency Labelling
0.25
Scheme for Room Air Conditioners
Chinese Taipei Draft-2008
0.25
Korea
KS C 9306-2007
0.25
New Zealand
AS/NZS 3823.4.1:2014
0.25(Source)

APEC Energy Working Group, Reducing Barriers to Trade through Development Of A Common
Protocol For Measuring The Seasonal Energy Efficiency (SEER) Of Air Conditioners.
JIS B 8616：2015 Package Air Conditioners
BS EN 14825:2016 Air conditioners, liquid chilling packages and heat pumps, with electricallydriven compressors, for space heating and cooling. Testing and rating at part loadconditions and calculation of seasonal performance

In addition, the part-load fraction correction should be normalized to a value of 1.0 when the PLR equals to1

EnergyPlus is an open-source whole building energy simulation program funded by the U.S. Departmentof Energy's (DOE) Building Technologies Office (BTO), and managed by the National Renewable Energy
Laboratory (NREL). https://energyplus.net/
3

1.0 (i.e., no efficiency losses when the compressor run continuously). For PLR values between 0 and1(0<PLR<1), the following rule applies.
ܲ‫ܨܮ‬௜,௝,௣ ≥ 0.7 , ܲ‫ܨܮ‬௜,௝,௣ ≥ ܲ‫ܴܮ‬௜,௝,௣
In the case of the calculation of the electricity consumption of the reference separate type fridge showcase
without consideration of the incremental electricity consumption caused by frequent ON/OFF switching
control of constant speed compressor, it is calculated by the multiplying ratio of COPs of the project andreference separate type fridge showcase. The formula for obtaining the power consumptions of the referenceseparate type fridge showcase is as follows.

Where,‫ܥܧ‬௥௘௙,௖௢௡௧௜௡௢௨௦,௜,௝,௣ = ‫ܥܧ‬௣௝,௜,௝,௣ ×஼ை௉೛ೕ,೔,ೕ஼ை௉ೝ೐೑,೔,ೕ

⋯ (8)Electricity consumption of the reference separate type fridge‫ܥܧ‬௥௘௙,௖௢௡௧௜௡௢௨௦,௜,௝,௣

showcase j in convenience store i with operating continuously
during the monitoring period p [MWh/p]

Therefore if PLR is equal to and larger than 1 (PLR≧1), the formula for obtaining the power consumptionsof the reference separate type fridge showcase is as follows since the constant speed compressor of thereference separate type fridge showcase runs continuously.

Where,‫ܥܧ‬௥௘௙,௜,௝,௣ = ‫ܥܧ‬௥௘௙,௖௢௡௧௜௡௢௨௦,௜,௝,௣ = ‫ܥܧ‬௣௝,௜,௝,௣ ×஼ை௉೛ೕ,೔,ೕ஼ை௉ೝ೐೑,೔,ೕ⋯ (9)Electricity consumption of the project separate type fridge‫ܥܧ‬௣௝,௜,௝,௣

showcase j in convenience i during the monitoring period p[MWh/p]On the other hand, if PLR is less than 1 (PLR<1), the electricity consumption of the reference separate typefridge showcase is calculated by dividing electricity consumption of the reference separate type fridge
showcase by PLF. The formula for obtaining the power consumptions of the reference separate type fridge
showcase in case that PLR is less than 1 (PLR<1) is as follows.
‫ܥܧ‬௥௘௙,௜,௝,௣ = ‫ܥܧ‬௥௘௙,௖௢௡௧௜௡௢௨௦,௜,௝,௣ ÷ ܲ‫ܨܮ‬௜,௝,௣

3.

= ‫ܥܧ‬௣௝,௜,௝,௣ ×‫ܱܲܥ‬௣௝,௜,௝
1×⋯ (10)‫ܱܲܥ‬௥௘௙,௜,௝ ܲ‫ܨܮ‬௜,௝,௣

Research on reference COP values for separate-type fridge showcase
4

Table 2 shows the market share of convenience store companies in Thailand. It is observed that CompanyX and Y are dominant in the convenience store market. In addition, according to the survey, convenience
stores in Thailand install lightings, air conditioners, and fridge showcases including condensing units that are
made by domestic companies, e.g. condensing unit equipped with constant-speed compressor. Furthermore,
floor area of convenience store is mostly less than 200 square meters in Thailand.

Table 2 Market size of convenience store in Thailand
Company
Number of stores
Market share
X
8,618
76.8%
Y

1,117

10.0%

Other

1,483

13.2%

Total

11,218100.0%(Source) Interview with convenience store Y (2015)

According to the interview from Company B, condensing units of fridge showcase installed in a convenience
store in Thailand are generally separate type showcase equipped with compressors whose output are generally
6 HP or 8 HP （1HP = 0.7457kW）depending on the number of open showcases or walk-in showcases
provided by store design. When determining the reference condensing units of separate-type fridge showcase,the standard conditions shown in Table 3 is applied. And also, the range of cooling capacity including thecondensing unit whose output of the compressor is 6 HP and 8 HP are widely selected. It is noted that therefrigerant of which ODP is zero is also considered.

Table 3 The rated condition of condensing unit
Condition
Refrigerant
Temperature condition

R404A
Ambient temperature 32°C
Evaporating temperature -10°C(source) Spec sheet, Engineering document, brochure from show case manufacturer

The interview results show that there are four companies, the Company A and Company B and C and D,
which sell the condensing unit for separate type fridge showcase in Thailand. The Company A and Company
B accounts for about 90% share of the estimated market of refrigerators in Thailand. Company A, Company
B, and Company D provide condensing units equipped with constant speed compressor. Among them,Company A provides the catalog of condensing unit for convenience stores. Taking the temperature
standardization of COP values into consideration, COP values of condensing unit are collected from thecatalog data shown in Figure 1 below. However, the 8 HP model is not available on the market in Thailand,so Company A’s models with the same refrigerant, similar compressor’s horsepower band including 6 HP
that are used for the same purpose and distributed in other areas are selected and are illustrated with light5

blue and blue dots in the figure. These units are versatile and introduced in Europe where the introduction ofhigh-efficiency condensing unit is progressing, and are considered to be reasonable as reference equipment.
Conm panyA (6HP)

C om panyA (6H P)

C om panyA (8H P)

2.40

2.20

2.00

COP

1.80

1.60

1.40

1.20
0

510

1520

25

C ooling capacity(kW )Figure 1 COP values of non-inverter type condensing unit for fridge showcase in Thailand
Two cooling capacity ranges, namely “3.0 ≤x≤ 15.0” and “15.0 <x≤ 25.0” are set to determine the reference
COP values for each range. The highest value of COP obtained from the survey with green dots for the rangeof “3.0 ≤x< 15.0” are set as a reference COP value for the 6 HP model. In addition, the highest COP valuewith blue dots for the range of “15.0 <x≤ 25.0” is set conservatively as a reference value for 8 HP model.
Accordingly, the COP values depending on the cooling capacity range shown in Table 4 below are applied
as the reference COP value in this methodology (x indicates the unit freezing capacity).

Table 4 Established COP of reference condensing unit for the proposed methodology
Cooling capacity [kW]Reference COP

3.0 ≤x≤ 15.0

2.20

15.0 <x≤ 25.0

1.836