Soil heat balance and heat utilization of system for SGCHPS

In severe cold zone, building's heating load is much bigger than cooling load. Heating performance of solar-ground coupled heat pump system (SGCHPS) declines year after year and even can't afford the heating load. In order to solve this problem, a method of depending on solar seasonal heat storage in soil was put forward to maintain soil heat balance and increase system efficiency. Relying on a demonstration project of solar-ground coupled heat pump for heating and cooling in severe cold zone, long-term experiment on heat storage, heating and cooling of 3 years was carried out. On the basis of ensuring heating and cooling effect, the experimental results showed that the soil temperature changed daily and annually. And the soil maintained heat balance in an annual cycle. Solar energy accounted for 85% of the total heat supply in winter. In the cooling season, the ratio of ground heat exchanger (GHE) for heat storage and cooling can be distributed according to heat transfer rates. Heat storage in soil solved the imbalance of heating and cooling loads in severe cold zone. The system could operate efficiently for a long period. Solar energy of the whole year was utilized, which saved a lot of conventional energy.