Active solar heating system with soil heat storage for plastic film greenhouse and its effects

An active solar heating system with soil heat storage for plastic film greenhouses was studied. In the system, outside air was heated by solar air collector and then pumped into underground pipes. The heat carried by air was transferred through pipes to the soil and stored for use at night. In the night, heat rised slowly to the ground surface to maintain the soil at constant temperature. After continual running of the active solar heating system for four days, it showed that during the night, the average air temperature of the active solar plastic film greenhouse was 3.8℃ higher and the average soil temperature was 2.3℃ higher than those of the unheated one. The system could store a heat quantity of 228.9-319.1 MJ. The experimental results prove that using solar air heating system with soil heat storage can increase the air and soil temperatures for plastic film greenhouse effectively and has a good prospect for applications.