This paper is based on findings resulting from ASHRAE Research Project RP-1580.

Comprehensive risk assessments of 2L refrigerants are needed to evaluate the use of alternative refrigerants in stationary HVAC and refrigeration applications. This study uses CFD simulations, concentration mapping tests, and ignition tests to determine which leak scenarios for HFC-32 and HFO-1234yf may result in flammable concentrations. We simulated 17 different residential and light commercial leak scenarios, and selected 6 distinct scenarios for ignition testing. The simulations and testing showed that tightly enclosed spaces, such as closets, were the most likely to create flammable concentrations, but modifications, such as louvered doors, can greatly minimize the likelihood of creating flammable scenarios.OurCFDsimulations also showed that while refrigerant selection did not have alarge role in determining whether a flammable concentration would occur, the choice of refrigerant did affect the severity of the resulting ignition event. In the future, the data should be combined with additional field studies to conduct full risk assessments of HVAC and refrigeration equipment.