The Selection and Use of Low GWP Refrigerants

Even if you doubt that human activity impacts climate change, engineers are increasingly tasked with designing products for the global marketplace, and despite loosening regulations in the U.S., most industrial countries are attempting to limit or eliminate high global warming potential (GWP) gases as part of their commitment to theKyoto Protocol Agreement.

The European Union MAC Directive has mandated that residential air conditioning and refrigeration must use refrigerants of GWP of 150 or less by 2015. The same is true of new automobiles by 2017. In the EU, low GWP refrigerants have a GWP of 150 or less. Medium GWP refrigerants are between 150 and 2,500. High GWP gases have GWP greater than 2,500.

Carbon dioxide (CO2) has a GWP of 1, but a longer lifetime. CO2 has been used as a refrigerant in industrial and commercial applications, but specialized high pressure or transcritical systems are required, and the theoretical cycle efficiency is lower compared to HFCs