LB-17-C049 -- Performance of an Air-Cooled Chiller with R410A Alternatives R-452B and R-32 PDF

In recent years, the HVAC&R industry has been evaluating low global warming potential (GWP) alternatives to refrigerants such as R410A becauseof rising concerns over climate change due to their high direct GWPs. The industry is working to identify candidates that optimize performance,safety (flammability), aand environmental impacts (GWP). R452B and R32 are two of the candidates under consideration. Both have similar GWPs(~ 675 per AR5). Both have an ASHRAE Standard 34 flammability classification of 2L with R32 having a burning velocity of 6.7 cm/s andR452B of 4.2 cm/s (WCFF) and 3.5 cm/s (WCF).

This paper presents measurements of system performance made on an R410A-based 100 RT air-cooled packaged water chiller with R410A (as baseline),R452B, R32, and a new experimental refrigerant. The chiller comprised scroll compressors, a brazed plate evaporator, and microchannel condenser. Testswere run at leaving chilled water temperatures of 44°F (6.7°C), 56°F (13.3°C), and 68°F (20°C) and ambient air temperatures ranging from 65°F(18°C) to 125°F (52°C).

R452B produced cooling capacities that were within 0 to 5% of R410A and COPs that were 0% to 5% higher over the operating range. The newexperimental refrigerant performed similarly. R32 produced higher cooling capacities (+5% to +13%), as expected from its thermodynamic properties, withCOPs running -2% to +6%. The refrigerant charge with R452B was 13% lower than R410A. The R32 charge was ~20% lower. Compressordischarge temperatures with R452B were moderately elevated over R410A while R32 produced significantly higher compressor discharge temperatures.R452B is seen to be a design-compatible alternative to R410A. The new experimental refrigerant behaved similarly to R452B, and so has prospects foralso being a design compatible alternative to R410A. Use of R32 would require changes in design to match compressor and heat exchanger capacities andto deal with its high compressor discharge temperatures and pressures.