A recently published report has detailed a range of potential refrigerant blends designed to replace R134a, which could serve as more environmentally friendly alternatives.
The research, carried out by the US Government’s National Institute of Standards and Technology (NIST) laboratory, was focused on finding less harmful non- or marginally flammable R134a alternatives for military applications.
According to the report’s abstract, 16 refrigerant blends were identified that offered similar performance to R134a while, at best, simultaneously offering a reduction in global warming potential (GWP) of 54 per cent. Seven “marginally flammable” blends were also created, which offered GWP reductions as high as 99 per cent.
The use of R134a by the military is understandable, given the refrigerant’s performance and effectively non-flammable nature. However, its comparatively high GWP of 1430 will result in R134a being banned in many applications, with use and availability to become increasingly restrictive, motivating the search for suitable alternatives.
Although the results were notable, no blend documented in The Hunt For Non-flammable Refrigerant Blends to Replace R-134A met all of the targets. R134a is often stated to have a high GWP of 1430, for example, and even reducing its GWP by 54 per cent still leaves it falling short of many a modern regulation. To it in perspective, the 2008 European Directive on mobile air conditioning systems requires manufacturers to use refrigerants with a GWP of less than 150.
The marginally flammable low-GWP blends are perhaps of more interest as while they were not as efficient, due to their increased chemical complexity, they could be ideal for non-military refrigeration and air-conditioning systems.
“The military is insistent about wanting non-flammable blends, but the civilian applications are moving more and more toward at least marginally flammable mixtures,” NIST mechanical engineer and study lead author Ian Bell said.
“There is a fundamental trade-off,” he added. “If you really want non-flammability and efficiency, you won’t get both – you will get one or the other.”