Analysis of the soil heat balance of a solar-ground source absorption heat pump with the soil-based energy storage in the transition season

In order to solve the problem of the soil heat imbalance due to the year-round operation of the solar-ground source heat pump in regions with the large gap between cooling and heating loads, this paper proposes to collect and store solar energy in the soil in the transition season. Based on the heating and cooling design of a solar-ground source double effect LiBr-H2O absorption heat pump for an office building, the heat pump system considering the solar energy stored in the soil has been built on TRNSYS platform. The long-term operating simulation has been conducted. The soil-based energy storage effect has been evaluated with taking the soil heat balance as the objective. The necessity of using the soil-based energy storage in the transition season has been discussed based on dynamic performance analysis results. The results show that the average soil temperature in the single heating condition rises to 16.49 degrees C, which is stable around 15 degrees C in the double cooling and heating condition after 10-years operation. The soil heat imbalance rates under two conditions are 18.32% and 11.64%, respectively. It can be seen that soil heat imbalance can be solved by the soil-based energy storage in the transition season.