Performance Comparison And Analysis Of Different Thermal Storage Wall Solar Greenhouse In Yangling

Solar greenhouse is one of the main agricultural facilities in China. It is widely used in the northwest area. The wall plays an important role in the heat storage and heat preservation, which has a direct impact on the thermal environment of the greenhouse. In this paper, four kinds of greenhouses: new type of gravel heat storage wall, active heat storage wall, porous brick composite wall and ordinary brick wall as the research object, detected the environmental parameters of the greenhouse, analyzed the performance of different greenhouse, and through the experimental verification and theoretical analysis, the heat storage mechanism of the new heat storage wall solar greenhouse was studied. Research results show that:(1) The environment in the greenhouse is affected by the outside weather, and the changes of the indoor environment parameters of the four kinds of greenhouse are similar, but there are some differences. The average transmittance of four solar greenhouses is about 50%, the difference is not significant. The average temperature of the new heat storage wall is about 4~5 higher than that of ordinary solar greenhouse, and about12 higher than outside. The ℃ ℃average ground temperature of the heat storage wall compared to ordinary brick wall and porous composite wall greenhouses, under different weather conditions are higher than 3~4℃. Indoor average relative humidity of the gravel heat storage, active heat storage, porous brick composite wall greenhouses about 10% lower than the ordinary brick wall greenhouse. In summary, the heat storage wall greenhouse has good heat preservation and low relative humidity, which is favorable for the growth of crops.(2) Compared the temperature in the wall, the two kinds of heat storage wall in the 20 cm, 40 cm depth are higher than ordinary brick wall and porous composite wall greenhouse, especially in the continuous cloudy and snowy conditions, in 20 cm, active storage wall temperature respectively is 8.1℃、7.3 higher than the porous brick wall℃ 、the common brick wall. Gravel heat storage wall temperature respectively is 5.4℃、4.6 hig℃ her than the porous brick wall、the common brick wall. In 40 cm, the two kinds of heat storage wall are about 5 ℃higher than ordinary brick wall and porous composite wall. It can be known that the heat storage wall solar greenhouse can save more heat by autonomous or passive mode.(3) Compared with the common brick wall greenhouse, the improved yield of gravel thermal storage wall, active heat storage wall, porous brick composite wall greenhouses respectively is 43%、35%、17%.(4) In view of the new type of gravel heat storage wall, analyzing its heat storage area and according to the porous medium model, the gas temperature and flow field distribution are simulated in Fluent, the mechanism and process of heat storage were analyzed.