low GWP, flammable refrigerants
Environmental concerns raised by high global warming potential (GWP) refrigerants have triggered a series of activities around the world to curtail the use of hydrofluorocarbons (HFCs). Many of the promising alternative refrigerants being investigated are mildly flammable and fall under the A2L safety classification of ASHRAE 34. In an effort to properly address A2L refrigerants in safety standards, the Air-Conditioning, Heating, and Refrigeration Technology Institute (AHRTI) undertook a research project to investigate refrigerant leaks and ignition testing under whole scale room conditions. This paper summarizes refrigerant leak and ignition tests for A2L refrigerants R-32, R-452B, R-455A and R-457A. The work included two main tasks. The first involved testing R-32 and R-452B under a controlled environment to explore factors affecting the refrigerants’ ignition. These factors include refrigerant leak rates, leak locations, leak opening size and oil effect. In the second task, tests were conducted under whole room scale for typical air-conditioning and refrigeration configurations. The whole room testing simulated large refrigerant leaks with ignition sources present from a packaged terminal unit, a residential split AC, a rooftop unit, a reach-in cooler and a walk-in cooler under various scenarios. Key observations will be summarized and future research work will be discussed.