A performance prediction model of variable frequency air source heat pump used for photovoltaic power generation scheduling in low-carbon buildings

Abstract

Recently, the photovoltaic-driven variable frequency air source heat pump (PV-VFASHP) space heating system has been widely used in low-carbon buildings. However, owing to the lack of performance prediction model for VFASHPs, the self-consumption rate of PV power generation is far lower than expected. To solve this problem, a simulation model and a test rig for VFASHP were built, and its heating performance under different conditions was investigated. A performance prediction model for heating capacity and COP was developed considering the joint effect of outdoor temperature, supply water temperature, and compressor speed. Then, this model was applied to a PV-VFASHP heating system in a low-carbon building in Beijing, and the application effect on sunny, cloudy, and rainy days was analyzed. Results show that the performance prediction model can predict the heating capacity and COP accurately. Experimental results of 13 VFASHPs from 8 manufacturers show that the relative errors are all within ±10 %. When regulating the PV-VFASHP system based on this performance prediction model, the self-consumption rate of PV power reaches 100 % on all the three days, contributing 77.26 %, 73.77 %, and 67.84 % of total power consumption. Additionally, the VFASHP operates efficiently, achieving an average COP of 3.59.