Study On Operation Mode And Optimization Configuration Of Combined Heating Solar-Ground Source Heat Pump

With the continuous development of China’s economy,the state strongly advocates the development of green renewable energy utilization technology,combined with the application characteristics of the current solar-ground source heat pump system,there are some problems that different climate,geological conditions,the collector distribution system and the buried pipe system bear different load distribution ratios.The subject is about operation mode and optimal configuration of the solar-ground source heat pump system in the cold regions of northern China,and purpose is improving system performance and reducing the initial investment.For a residential building in Baotou,firstly according to three different solar and ground source heat pump operation modes: mode one is for the collector to enter the inlet end of the buried pipe,mode two is for the collector to enter the outlet end of the buried pipe,mode three a part of the circulating fluid on the collector side is connected to the outlet end of the ground pipe and another part is connected to the outlet end of the heat pump unit,also described the system.The system simulation model is established based on TRSYS.Secondly,The solar-ground source heat pump system were simulated and analyzed performance,soil temperature and user side inlet temperature.optimized the well spacing,collector area parameters,and load ratio optimization,so determined the best working condition parameters.It puts forward that the load ratio is defined as the ratio of the total heat load of the solar collector.The split ratio β of the circulating fluid is defined as the ratio of the collector flowing through the outlet end of the buried pipe to the circulating fluid on the total collector side.Finally,the economics of a single ground source heat pump system and a solar-ground source heat pump system were analyzed and evaluated using two evaluation indicators: net present value and investment payback period.The study results show that the mode performance of the part of the collector side connected to the outlet end of the buried pipe to the outlet end of the heat pump unit is optimal.After 20 years of system operation,the COP value dropped from 5.48 to 4.99,a decrease of 9%.The soil temperature dropped 7.6% in 5 years.The user side inlet water temperature is maintained at 51 °C to meet heating requirements.In mode three,the best well spacing is 5m.The collector side is responsible for the highest efficiency at about 40% of the total heat load,and the COP value before optimization is increased by 14.5%.When the collector side split ratio β is 0.6,the average COP value of the unit is increased by 6.8% compared with the COP before optimization.A single ground source heat pump system doesn’t have the ability to resist risks,while the solar-ground source heat pump system has a net present value greater than zero over the operating life and is suitable for investment operation.When the benchmark discount rate is 7%,the investment recovery period of a single ground source heat pump system is 18 years,but the investment recovery period of a solar-ground source heat pump system is 8.5 years.This project optimizes the optimal system operation mode by simulating the solar-ground source heat pump system under different operation modes in Baotou,and optimizes the different load ratio and flow ratio of the collector side and the buried tube side.Achieve the purpose of improving system performance.The collector area and the well spacing have been optimized to reduce the initial investment.It provides certain guidance and reference significance for the actual project investment operation in the severe cold regions of northern China.