ENERGY SAVING EQUIPMENT
deliver the highest achievable energy efficiency and its high time this practice is addressed. For example, using theoretical cycle calculations for medium (-8°C mean, MT) and low temperature (-35°C mean, LT) refrigeration conditions it can be seen in table 2 that all the lower GWP like for like alternatives for R-404A have a higher energy efficiency. It can also be clearly seen in table 2 that using two different refrigerants in the MT and LT systems has the potential to significantly increase the energy efficiency even further.
Technology choice Choosing a refrigerant with low GWP does not necessarily mean good energy efficiency. Due to a F-Gas regulation ban which came into force in 2022, R-744 (GWP=1) has become a common choice for retail refrigeration systems of 40kW or larger cooling capacity, however, there is a growing body of evidence that shows the use of R-744 may not be the best choice for energy efficiency. A recent case study published by Chemours has presented results supplied by the retailer Asda from a store using several R-744 booster systems but has now been changed to modular systems using R-454A as the refrigerant. Using energy monitoring of the refrigeration systems before and after the change of technology, Asda reported a reduction in annual energy usage of 34% when using R-454A compared to the previous R-744 system. Similarly, the dominance of ammonia in industrial refrigeration is also being challenged. In a case study from Climalife, Optinenergie (a French engineering company specialising in industrial energy performance) reported that in a medium temperature fruit store, a R 1234ze chiller installed in 2020 can achieve up to 25% higher C.O.P. values than an equivalent ammonia installation that was installed in 2015 at the same site. It is very clear from these recent studies,
and several previous reports, that technology choice is a major factor in achieving the most energy efficient solution available.
Heat recovery
This is a hugely underutilised technique which has the potential to greatly reduce energy usage by re-using the waste heat produced from the refrigeration system, or indeed any process that produces excess heat, that in the past has been expelled to
Figure 1.
Figure 2.
the environment. A white paper published by Chemours in July 2021 considered heat recovery from a supermarket of approximately 2300m² sales floor area using either R-454C or R-744 and compared the results to a basic R 404A refrigeration system with either a gas boiler or air source heat pump (AS HP) for all the heating requirements. The results considering numerous heat recovery strategies for a typical UK climate (Leicester) are shown in figure 2 and demonstrate the huge potential for lowering total system emissions, the majority of which are achieved by reducing energy consumption. It is very clear from the results of this study that heat recovery will greatly decrease the energy consumption with any refrigerant and easily justifies the higher initial installation cost.
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With governments setting targets for
reduced emissions and energy usage, it is clear the refrigeration industry has an important role to play. To achieve the maximum reductions available, it is important to thoroughly investigate all the options and not just make decisions on a single parameter, such as refrigerant GWP. As shown in this article, low GWP does not necessarily mean high energy efficiency and a poor choice of refrigerant technology may even lead to an increase energy usage, operating cost and total lifetime emissions. Advice on which solutions best fit your requirements is readily available and the team at Climalife have the tools and knowledge to lead you to an eco-efficient future.
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www.acr-news.com • January 2023 23
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