TRNSYS optimization of control strategy and equipment parameters of a geothermal solar heating system

Abstract In this research, a typical building and four heating strategies were simulated in the TRNSYS environment to choose the optimized control strategy and equipment parameters of the geothermal solar coupled system to recover soil temperature in one year. The final optimized strategy and the original strategy of the GSHP heating system were compared. Research results show that the optimized control strategy of coupled system is transforming solar hot water from the storage tank to heating terminals in heating seasons and transforming solar hot water to the ground heat exchanger in non-heating seasons. The optimized operation strategy of the solar heating soil cycle is that the cycle starts when tank temperature is higher than 40°C and stops when tank temperature is lower than 20°C. Furthermore, the best pump flow at the heat exchanger collector side of the tank is 6.6 m3/h. The optimum length of the water tank heat exchanger is 120 m. The optimum collector area, tank volume, and heat exchanger area are 86 m2, 3.9 m3 and 0.4 m2, respectively. This study provides a solution for solving soil temperature reduction in one year during GSHP applications.