Investigation On A Solar-assisted CO₂Hybrid Heat Pump Air Conditioning System

In order to improve the deficiency of the existed solar thermalutilization system and the conventional CO₂heat pump, a solar-assistedCO₂hybrid heat pump air conditioning system was proposed. And thispaper carried out the experimental research and optimization analysis onthe proposed solar-assisted CO₂hybrid heat pump air conditioning systemby setting an experimental apartment as study case. The main researchwork was summarized as follows:1. Constructed the theoretical mathematical model of CO₂hybrid heatpump and carried out the analysis and comparison on the coolingperformance of CO₂hybrid heat pump based on the built model with EES.The results indicate that the refrigeration COP of CO₂hybrid heat pump is63.6%higher than the conventional CO₂heat pump when the ambienttemperature is35℃. In addition, the cooling capacity of the absorptionchiller would increase with the increase of the solar radiation, so thecooling performance of CO₂hybrid heat pump matches well with the building load.2. Carried out experimental test on the solar-assisted CO₂hybrid heatpump air conditioning system under various conditions. The experimentdata shows that: the COPSof the CO₂hybrid heat pump heating modecould reach2.24and the COP of CO₂hybrid heat pump could get2.63when the average ambient temperature is4.8℃; the COPSof the solarheating mode could reach12.3when the average ambient temperature andsolar radiation is6.9℃and605W/m2; the integrated absorption chilledcould really improve the cooling performance of the CO₂heat pump.3. The design and operation parameters of the system were optimizedby using the system model built with TRNSYS program, which includedthe volume of the storage water tank, the tilt angle of the solar collectorand so on. Results show that: after optimization, the heat output of thesolar collector loop increases31.8%and the solar fraction could reach75.1%in heating season.