ASHRAE OR-16-C015

Abstract

<em>Lower global warming potential (GWP) refrigerant replacements for R410A have been extensively studied over the past few years with limited success in finding an optimal replacement. Refrigerant candidates offered to date have been a trade-off of GWP to performance, but so far candidates have not been offered that trade GWP to flammability while preserving or improving performance of R410A to allow for quick and orderly transition to lower GWP refrigerants. These refrigerants have been either pure R32 or blends of R32 with various new olefin refrigerants, like R1234yf and R1234ze(E), along with other traditional hydrofluorocarbons. Pure R32 has good performance, but would require significant hardware redesign to accommodate fluid properties differences, the GWP is one of the highest (GWP=675), as well as being one of the more flammable refrigerants (burning velocity 6.7 cm/sec). Performance modelling, unit performance testing, and flammability studies were conducted to guide the best refrigerant design to optimize GWP to flammability for blends of R32, R1234yf and R125. This study determined that in fact flammability can be minimized while allowing for a R410A &#8220;design compatible&#8221; refrigerant that improves on the performance of R410A while balancing GWP.</em>