C021 -- Hydrocarbon Refrigerant Safety Considerations and Implications for Air Conditioning System Design

In 2016, Kujak presented a current state of how to apply hydrocarbon safely per standards consideration and methodologies for direct expansion air conditioning applications. Refrigerant charge limits at the time were very restrictive and did not allow for larger capacity direct refrigerant expansion systems. In recent years, the HVACR industry has been actively investigating the safety of flammable refrigerants by determining their risks, potential occurrences and severity of events and hydrocarbon refrigerant charges have increased significantly. This paper will provide an updated view of the selection challenges faced by air conditioning product designers and compare the various flammability characteristics of R290 compared to R454B. It will give an updated overview of standards methodology to determine the refrigerant charge and resulting cooling load to compare various flammable refrigerants for ASHRAE 34 Standard Class 2L, 2 and 3 refrigerants. In addition, the authors investigated the optimization of blends using R290, R1270 and RE170 to understand if there are possible optimization of properties and flammability limits to increase refrigerant charges.