Thermal performance and energy characteristic analysis of multiple renewable energy complementary heat pump system

Traditional space heating methods in cold regions have the disadvantages such as low efficiency, high energy consumption and serious pollution. Therefore, a multiple renewable energy complementary heat pump system (MREHP) with solar energy, biomass energy and air heat as the main heat source is proposed. The system is mainly composed of solar collector unit, constant temperature biogas pool unit and heat pump unit. There are three modes for the system: air source (Mode 1), solar-air energy (Mode 2) and solar-biomass-air energy (Mode 3). The experimental platform was built in Lanzhou city of China. The average outdoor and indoor temperatures in three modes are -8.64 degrees C, -12.43 degrees C,-11.18 degrees C and 17.91 degrees C, 21.31 degrees C, 20.17 degrees C, respectively. The averages coefficient of performances (COP) of the heat pump are 1.70, 2.32 and 2.26, respectively. In Mode 1, air heat input accounted for 41.09%. The proportion of air heat input in Mode 2 is greatly reduced, only 17.02%, but solar energy input system accounts for 40.32%. In Mode 3, the energy input of air heat, solar energy and biomass energy are basically equal, which are 20.31%, 15.81% and 19.55%, respectively. The utilization of renewable energy in the three modes of proposed system accounts for 41.09%, 57.34% and 55.67%, respectively. Therefore, the power consumption can be reduced, which could save energy. The system can be conducive to build the distributed heating system based on renewable energy in rural area and relieve the problems such as serious environmental pollution caused by traditional heating methods.