Additional Informationon the Proposed Methodology “ Energy Saving by Introducing High Efficiency
screw chiller for freezing and refrigeration”
1. Identification of reference cooling system
A research was conducted to identify cooling system that supply cold water for freezing andrefrigeration at manufacturing factories in Thailand. In general, ice storage system withreciprocation type compressor (refrigerant: Ammonia) is widely installed at manufacturing
factories for freezing and refrigeration purpose to treating wide range of heat load, while somefactories newly install water/brine chilling system with screw type compressor instead ofinstalling ice storage system .
According to the interview, it is expected that the installation of energy efficient screw typewater chiller as well as brine chiller will be gradually increased in Thailand. In addition, theidentified chiller is regarded as non-inverter type because the water/brine chillers marketed in
Thailand are not equipped with inverter.
From the above reason, reference chilling system for freezing and refrigeration in thismethodology is identified as non-inverter type screw brine chiller.
2. Research on COP value for available reference screw chiller and identification ofreference COP
Research on COP of reference chiller was conducted through collecting catalogues ofscrew chiller that correspond to brine chilling1. As the result, 2 companies (3 models) wereidentified and 24 COP values are collected as shown in Figure 1 below within the range thatcooling capacity is s less than or equals to 1,000 kW.
Although COP values by manufacturer’s testing under the temperature condition based on
JIS B 8613-19942, they are standardized with the equation as indicated in Criterion 2 on theproposed methodology.
COP value varies according to cooling capacity, it is observed that those COP values(around 4.70) with cooling capacity of less than 520 kW show clearly smaller thanthose ranging more than 520 kW. On the other hand, the value is lower than 4.72 of
the COP value for screw type chiller recommended by Thai government under the
standardized condition. So, 4.97, the COP value for cooling capacity of 520kW in
1

Premium type chilling units which are applicable to down to lower than -10 °C leaving fluid temperature are notincluded for available data.
2 JIS B 8613-1994 Water chilling unit (http://kikakurui.com/b8/B8613-1994-01.html)

Company B model 2, is adopted as the reference one for smaller category for cooling
capacity in conservative manner.
Therefore, two cooling capacity ranges are set to determine the reference COP values
for each range.
The most efficient COP, which has the largest value, in each capacity range isselected as the reference COP and shown in Table 1 below in red circles.
Under temperature condition(Cooling Water in: 32˚C out:37˚C

Chilled Water in: 12 ˚C out 7˚C)

5.5

max: 5.02
max: 4.97

COP

5.0

4.5

4.00200

400

600

800

1000

Cooling Capacity(kW)Company A Model 1
Company B Model 1
Company B Model 2

Figure 1: Standardized COP values of screw type water chiller
The reference COP of screw chiller for each cooling capacity range is determined and shown in
Table 1 below. (“x” in the table represents cooling capacity per unit.)
Table 1: Established COPRE,i of screw chiller for the proposed methodology

Cooling capacity per unit (kW)x≤520

520<x≤1,000

COPRE,i

4.97

5.02