Global warming, impact on refrigeration
The UK saw its highest ever temperature of 40.3°C in Coningsby on the 19th July this year. Provisional figures from the Met Office show that in July the mean UK temperature was 16.6°C which is 1.3°C above the long term average (Met Office link).
Eight of the hottest days on record in the UK have been since 2000 and 5 of these have been since 2015. It is clear that extreme temperature events are becoming more common, and this is having an impact on refrigeration systems. Many reports can be found on supermarket refrigeration systems breaking down due to the hot ambient temperatures or not being able to maintain the temperature of food at safe levels. This has meant that many of the top retailers have had to empty cabinets and have been unable to sell refrigerated products. Even if the refrigerated cabinets can continue to keep working, the warmer ambients are having a major impact on costs to run a supermarket. A recent report from Imperial College has indicated that a 2°C increase in average UK summer temperature increased refrigeration energy demand by 6% (link to report). The same report also found that refrigerated cabinets broke down more in hotter weather increasing maintenance bills. All of this is bad news for supermarkets, consumers and the environment as the additional costs will have to be absorbed and food may be wasted if cabinets can no longer cope with the warmer conditions.
Ultimately most cabinets and refrigeration systems are not designed to operate at 40°C which may become the new norm. Systems that can cope with higher ambient temperatures are possible but add cost and complication to the design. However, these concepts may prove viable if increased energy costs and the loss in food sales are considered.
A number of options are available to prevent refrigeration breakdowns. Good maintenance and monitoring can make sure cabinets and refrigeration plant have the best operational performance before they are stressed by warm conditions. Adiabatic condensers may help reduce temperatures onto condensers reducing energy consumption of the compressors. Thermal storage may be able to directly cool or reduce condensing temperatures in the few hours of maximum ambient temperatures. Reducing refrigeration loads can also have benefits. Using doors or other energy saving technologies can significantly reduce refrigeration loads. Much of the work at RD&T involves independent assessment of refrigerated cabinets and often new technologies which may save energy and reduce refrigeration load. We believe that independent assessment of technologies in a controlled environment is essential to validate performance of new or add on technologies. This ensures that energy and load reductions work when it really matters when refrigeration plant is stressed in high ambient conditions.
Design of both the refrigerated cabinets themselves and refrigeration systems need to be considered in a new light if we regularly have to cope with conditions which exceed the original design temperatures. As supermarket refrigeration systems are expected to have an operating lifetime of 15-20 years there is a need to make sure new systems are able to cope with what is likely to become common rather than rare high ambient temperature events. At RD&T we provide independent expertise on design and operation of refrigerated cabinets and systems. If you would like to discuss how refrigerated cabinets could be made more future proof please contact Judith Evans (firstname.lastname@example.org) or Alan Foster (email@example.com) at RD&T.