Experiment of Heating & Heatstoring of the Underground Heat Exchange System in a Multispan Greenhouse

In China, the cost of production in multispan greenhouse is very high for its high energy consumption. It is necessary to develop the technology of energy saving for multispan greenhouse production. The heating experiment using underground heat storage system, replacing fuel to some extent, was carried out in a multispan greenhouse. It was showed that the solar heat can be stored during the daytime by circulating the warm greenhouse air through the pipes buried in the greenhouse soil, and the heat can be obtained effectively from the soil through the pipes at night. During the daytime, the warm greenhouse air was cooled down and decreased in temperature by 6～8 and in enthalpy by 13～20kJ/kg, after flowed through the pipes and stored heat into the pipes. During the nighttime, the greenhouse air was warmed up and increased in temperature by 4～5.5 and in enthalpy by 7～10kJ/kg, after flowed through the pipes and gained heat from the soil. When the system was run at night, it could give heat for about 60W/m^２ (greenhouse floor) and the inside air temperature of the greenhouse was 11 or higher than outside temperature.