Testing the Flammability of Newly Developed, Low-GWP Automotive Refrigerants

Newly developed refrigerants with low global warming potential (GWP) for use in motor vehicle air conditioning systems are mildly flammable — but it's difficult to test that flammability in the real world. In a paper published by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), "New Developments on Investigating the Ignition Propensity of Mildly-Flammable Refrigerants," Exponent's Daniel Jaimes and Amir Jokar describe a new testing apparatus they developed to evaluate the flammability of these refrigerants. The apparatus is a one-cubic-meter metal chamber with an aluminum foil blow-out panel, as well as instrumentation to measure temperature and pressure, with digital high-speed camera capabilities to record the ignition process during the flammability experiments.

In their paper, Drs. Jaimes and Jokar describe how the apparatus can be used to simulate the passenger or engine compartment of a vehicle and re-create the potential ignition of mildly flammable refrigerants by utilizing various ignition sources, including an electrical wire-to-wire short, a headlight filament bulb, and a blower motor wire resistor. The paper also includes case studies and selected experimental results. Read more about this unique testing apparatus in this ASHRAE paper.

From the publication: "Despite establishment of these flammability testing methodologies, there is still no current standard for an experimental apparatus that can simulate real-world conditions, in which a refrigerant leak in the vehicle passenger compartment or in the engine compartment occurs."