ENERGY SAVING Case study:
Largest single circuit cold store installation in the UK using very low GWP R-454C refrigerant
Many small to moderate size chill stores have traditionally operated using relatively high GWP (>1000 GWP) refrigerants, due to this technology being the most cost-eff ective option, but with the F-Gas regulation phasedown encouraging users to move to using much lower GWP options, a change in refrigerant strategy is needed.
W
hen EJM Engineered Systems were presented with the challenge of off ering a very low GWP option for a 15,000m³ medium temperature
cold room for food storage, they contacted Climalife to discuss the refrigerant options available. EJM are very experienced in chill store refrigeration but the typical option of R-448A or R-449A was quite rightly not considered low enough GWP to be sustainable. A store of this size posed a challenge in fi nding a cost and energy effi cient solution with a suffi ciently low GWP to be considered sustainable for the expected lifetime of the equipment. Together EJM and Climalife were able to combine their areas of expertise to propose a very low GWP solution that was both cost and energy effi cient.
Considering energy effi ciency and energy consumption The options available to EJM were R-290 or R-717 with
a secondary heat transfer fl uid loop, a R-744 direct expansion system or a R-454C direct expansion system. Many chill store applications have been installed using either the R-290, R-717 or R-744, but none of this size have previously been installed using this type of refrigerant in a single circuit direct expansion system. By working together, EJM and Climalife were able to combine their engineering expertise and refrigerant knowledge to assess the various technology options for refrigeration system performance, standards, and legislation compliance. All options will of course provide the required cooling for the application, but theoretical performance calculations performed by Climalife, cross referenced with manufacturers published system data for the various options, revealed that R-454C delivered more than 20% higher energy effi ciency compared to R-744 and equivalent or lower energy consumption than the combined power from a R-290 or R-717 system with pumped secondary heat transfer fl uid loop.
System designs and costing
System designs and costings performed by EJM demonstrated that although it would be possible to follow the methodology employed in other projects and use energy ineffi cient R-744, or multiple refrigerant circuits with much lower refrigerant charges to achieve the desired cooling, this would greatly reduce the cost advantage of a single circuit system and would also erode some of the energy effi ciency advantage. Comparisons vs CO2
and multiple systems utilising
other refrigerants and secondary cooling circuits would see a circa 28% – 32% increase in cost due to capital plant, labour and materials along with multi power supplies.
22 January 2024 •
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