3337 — Secondary Heat Transfer in Heat Pumps

The effects on heat pump performance of secondary heat transfer in heat pumps were investigated using numerical models. An interchanger was shown to improve heat pump performance by increasing the output by approximately 4% and the coefficient of performance (COP) by approximately 2%. The recovery of heat transferred from the compressor by enclosing the compressor together with the accumulator in an insulated housing was shown to improve heat pump performance by increasing the output by approximately 4% and the COP by approximately 1%. The reduction of heat transfer from a compressor using liquid injection into the compressor inlet was shown to have an adverse effect on compressor performance. It was shown that heat transfer within a compressor has a major effect on its performance. It was also shown that heat and mass transfer in a reversing valve has a small adverse effect on heat pump performance. The reasons for the beneficial or adverse effect were evident from the simulated detailed heat pump performance data.

KEYWORDS: heat flow, secondary, heat pumps, performance, coefficient of performance, calculating, compressors, casing, heat exchangers, finned tube heat exchangers.