2017 ASHRAE Annual Conference

Today’s societal demands to control climate change are forcing HVAC&R equipment designers to consider new lower GWP refrigerants, some of which are slightly flammable under certain conditions. This paper supports setting a safety factor as low as 2 to 1 (50% of LFL) when setting the charges limits for A2L flammable refrigerants depending on the HVACR products application refrigerant charge and application height. Computational fluid dynamic (CFD) analysis was performed to support the justification of setting the safety factor. Numerous fast leak scenarios, 4 min leaks, were evaluated at various heights, room areas and refrigerant charge sizes. Maximum refrigerant charges for a large number of ASHRAE 34 classified refrigerants will be summarized for comparison purposes at various LFL endpoints.

Demands to control climate change are forcing HVAC equipment designers to consider new lower GWP refrigerants to replace traditional higher global warming potential (GWP) refrigerants, for example R134a and R410A. Understanding the environmental tradeoffs of using these new low GWP alternatives in HVAC products is becoming well understood but what uncertainty remains in understanding how they impact the on building sustainability. This paper provides an understanding of the impacts on total building sustainability through using building model simulations employing products using new lower GWP alternatives R513A and R452B to replace R134a and R410A.

There is significant interest in the adoption of low global warming potential (GWP) refrigerants. However, the heat transfer performance of these refrigerants is not well documented. This paper investigates alternate R410A refrigerants such as R32 and R452B. Fewer than 10 papers have been located which report heat transfer and pressure drop data for R32 and no papers have been located which report heat transfer and pressure drop data for R452B. The predicted performance of low GWP R410A alternatives will be compared to baseline values for R410A and impact on evaporator and condenser design will be discussed.

In recent years, the HVAC&R industry has been evaluating low global warming potential (GWP) alternatives to refrigerants such as R410A because of rising concerns over climate change due to their high direct GWPs. The industry is working to identify candidates that optimize performance, safety (flammability), and environmental impacts (GWP). R452B and R32 are two of the candidates under consideration. This paper presents measurements of system performance made on an R410A-based 100 RT air-cooled packaged water chiller with R410A (as baseline), R452B, and R32 refrigerants. The chiller comprised scroll compressors, a brazed plate evaporator, and microchannel condenser.