Effects of Vapor Injected Compression, Hybrid Evaporator Flow Control, and Other Parameters on Seasonal Energy Efficiency

A companion paper (Bach et al. 2014) experimentally investigated the effects of vapor injected compression and hybrid evaporator flow control on capacity and COP. The goal of this paper is to provide insight into the effects of these technologies on heating seasonal performance (HSPF). HSPF was calculated using a modified version of the ANSI/AHRI 210/240 method, and parametric studies were performed to better understand the seasonal performance with a focus on comparing vapor injected and single stage system configuration. It was found that part load degradation and reduced capacity at low ambient temperature are factors that can degrade the seasonal performance. The increase in heat pump COP for the vapor injected configuration leads to only a small benefit the main contributor to the increased HSPF of the vapor injected system configuration is its increased capacity towards low ambient temperatures.