Study On Air Source Heat Storage Assisted Ground Source Heat Pump System To Eliminate Thermal Unbalance In The Cold Regions

In the light of the obvious advantages of high efficiency and environment-friendly,heat pump systems such as ground source heat pump(GSHP)and air source heat pump(ASHP)have been widely applied.However,in northern cold climate areas building heating load is much greater than the cooling load of air conditioning all the year round;if the ASHP system is adopted,the outdoor temperature is very low during the winter heating system,which will cause the frosting of the evaporator and be harmful to the operation of the heat pump system,consequently the whole system will not be able to work;while using the GSHP system will lead to imbalance of heat intake and heat emission and long-time running will decrease the average soil temperature with the heat pump energy efficiency dropping.However,the problem of soil thermal imbalance cannot be solved fundamentally by optimizing the structure of ground heat exchanger.If we can put forward integrated approaches in the design of GSHP systems,it is possible to reduce the initial cost of the GCHP systems,and also improve the overall efficiency of the system.The ASHP-GSHP system is proposed based on the principle of heat extraction and thermal balance with an air heat exchanger being used to transfer heat to soil.The mathematical model of the ASHP,GSHP,underground heat exchanger,water pump and the building load have been established on TYNSYS software simulation platform,and also the dynamic simulation and calculation of the combined system have been conducted for ten years.On account of the simulation results,the design method and optimization strategy of composite system are presented.The findings indicate that air heat exchanger can store the heat energy in the air in the soil around the buried pipe heat exchanger through the medium in the underground pipe when running in high efficiency period,which can effectively solve soil thermal imbalance problem caused by a single GSHP for heating and cooling in the northern region.Furthermore,both the air heat exchanger and GSHP run efficiently and steadily throughout the whole operation period with the energy ratio about 2.483,which proves that the scheme is feasible in general.