ALTERNATIVE REFRIGERANTS
Here, Stuart Corr, techno commercial director of refrigerants manufacturer and supplier Mexichem discusses the challenges the air conditioning industry faces in hot climates.
A
t higher temperatures such as those encountered in Southern Europe and the Middle East, it is universally true that the effi ciency of air conditioning systems decreases. In general, a system using a refrigerant having a higher critical temperature will perform better in these conditions: refrigerants with a lower critical temperature tend to have a steeper decline in capacity and effi ciency with increasing ambient temperature. With hot climates increasing the demand for cooling, any improvement in effi ciency can play a valuable role in reducing demands on energy supply. The Montreal Protocol set out to eliminate the production and use of ozone depleting HCFCs and CFCs and this phase out schedule was accelerated in some countries under Article 5, which detailed the diff erent time scales in each region for the phase down of ozone depleting gases. This has led to a switch in refrigerant choice to HFCs in the accelerated phase down Article 5 countries, which in turn creates some interesting technical challenges in alternative refrigerant choice.
Alternatives
Historically, R22 has been the refrigerant of choice for hot climates, but because it is due to be phased out due to its
ozone depleting eff ect, industry is looking for alternatives. A technical barrier to the phase down of R22 is that it is diffi cult to replicate its properties, and suggested alternatives having similar physical properties commonly have decreased cooling capacity and lower effi ciency. For decades, the chemical industry has struggled to fi nd an alternative that matches the performance and properties of R22. Rather than looking to match the physical properties of R22 (pressure and boiling point), an alternative approach has been to use a refrigerant with higher pressure where the heat-transfer benefi ts of higher fl uid density can mitigate any thermodynamic shortcomings.
Mexichem’s high-pressure alternative to R22, R410A, is a well established product that is already on the market. There are millions of existing refrigeration and air conditioning systems already in use that are specifi cally designed for use with R410A, making it an option for rapid transition for countries looking to phase out R22.
However, a longer-term concern with R410A is that it is perceived by some to have a high GWP and, as a general trend, the industry is trying to move away from high GWP refrigerants.
Some lower GWP alternatives, such as R32 and blends
36 December 2016
www.acr-news.com
Cooling in the heat
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