4436 -- Experimental Study of an R-407C Heat Pump Water Heater PDF

The purpose of this work was to investigate the possibility that R-407C can replace R-22 in existing heat pump water heaters (HPWHs). Several tests, including baseline tests and system tests with a counter-cross-flow evaporator, were conducted to evaluate the performance of R-407C in HPWHs. The HPWH studied was originally designed for R-22 but was modified for R-407C operation. The baseline test results indicated that the R-407C HPWH had a much higher water heating capacity than that of the R-22 unit with the same designed capacity. However, the R-407C unit also consumed more power, which resulted in lower COPs at higher water temperature region. However, when the HPWH was modified with a counter-cross-flow evaporator, the system performance improved. The COP increased by an average of almost 20% and heating capacity by 4% over the baseline case. The improved system COP is slightly higher than that of R-22. It is feasible that R-407C can be used to replace R-22 with improvement in water heating capacity without sacrificing the system energy efficiency.

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