The Operation Characteristics Study Of Hybrid Geothermal Heat Pump With Solar Collectors

The study object of the dissertation is hybrid geothermal heat pump with solar collectors. A hybrid geothermal heat pump to combine solar collectors, hot water tank and underground heat exchanger in the condition of insufficient area to arrange underground heat exchanger was proposed and the operation characteristics of the hybrid system were carried out. The main contents are as follows:1. The characteristics of the solar and soil energy were analyzed. The optimal obliquity of the solar collectors that towards south was obtained based on theoretical result of hour by hour solar energy intensity of clear sky in Handan. The temperature varying discipline of the underground soil in different depth was analyzed based on the soil temperature distribution equation with boundary condition of periodical temperature action.2. The theoretical study was performed based on combining the fitting curve of gas import coefficient and total efficient of compressor, the model of evaporator, condenser and solar collector. The variation condition of the compressor energy consumption along with the evaporation temperature, the inlet water temperature of the evaporator and the ratio of compressor pressure as well as the variation condition of COPh, the heat absorption of the evaporator and the energy supply of the condenser along with the evaporation temperature was discussed. In order to prevent a lower evaporation temperature and the indoor air temperature lower than the designed requirement because of the under capacity of the heat pump unit in the condition of insufficient area to arrange underground heat exchanger, the hybrid geothermal heat pump with solar collectors can be adopt where have relatively abundant solar energy resource.3. The experimental study of hybrid geothermal heat pump was launched. Firstly, the heating experimental study of geothermal heat pump in winter was carried on. Secondly, the problem that in the condition of insufficient area to arrange underground heat exchanger was verified. Finally, the heating experimental study of hybrid geothermal heat pump that combined underground heat exchanger, solar collector and hot water tank was carried on and the varying discipline of system parameters was analyzed. The experimental show that the hybrid system is feasible.4. The operation performance of the heat pump unit, underground loop heat exchanger and solar collector was related through the outlet circular fluid temperature of underground heat exchanger based on the cylindrical source theory at varied heat flux condition and the concept of"shape factor". The simulation model that coupling the operation performance of the heat pump unit, underground heat exchanger and solar collector of the R134a hybrid geothermal heat pump systems was built. The verification of the simulation result shows that the model is quite close to the experimental data. The simulation model can simulate the operation performance of the hybrid heat pump in winter and has guidance meaning on design and energy consumption analysis of the geothermal heat pump systems. By means of the simulation model, the operation characteristics of the geothermal heat pump with different area of solar collector are simulated.