Study On The Combined Operation Of Solar-ground Source Heat Pump System

In recent years,energy shortages and environmental degradation have seriously threatened the sustainable development of our country,and the development and utilization of renewable energy is imminent.The application of solar and geothermal energy has a certain degree of restrictions because of their own characteristics.The solar-ground source heat pump system has achieved the complementary effect of solar system and ground source heat pump,which can not only solve the problem of hot and humid imbalance of single ground source heat pump system but also overcome the intermittence of solar system.It has a great development potential in cold areas of northern China.This paper selects an office building in Taiyuan as the research object,using Design Builder software calculates cooling and heating load of the building by the time.Based on the thermodynamic parameters of rock and soil and the distribution of solar energy resources,a set of solar-ground source heat pump system was designed for the building under the premise of keeping the heat exchanger in the winter and summer heat dissipation.With TRNSYS for the simulation platform to build solar-ground source heat pump system simulation model,the solar collectors and ground heat exchanger system performance under two kinds of tandem mode is simulated and analyzed.The results showed that: two programs all contribute to soil temperature lifting,lifting effect is not obvious difference;the system of Scheme I operating of the whole year energy consumption than scheme II to save about 22999 k Wh;Scheme I is better than scheme II on improving the COP of the heat pump system.Therefore,the select of solar-ground source heat pump system is tandem mode scheme I(heat load fluid into the ground heat exchanger to exchange heat,and then through the solar collector).The system performance and soil temperature change of three kinds of solar collectors under the minimum temperature control,temperature difference control and load domain method were simulated and analyzed under the tandem mode scheme I.The results show that: the system operates the best of the year when the minimum temperature of the outlet borehole was set as 2 ℃.Under the four kinds of temperature control mode,system performance and soil temperature difference is small,the optimum temperature differences are △T_H = 8℃,△T_L = 3 ℃.Comprehensive comparison of these three operating strategy showed that when using the temperature difference between the lowest energy consumption control system,heat pump COP maintain a high value and good soil heat balance effect.