Analysis Of Heat Flux Characteristics In Heliogreenhouse Under Wall And Cultivation Medium

The Wall and culture substrate heat flux of heliogreenhouse and daily air andsoil temperature were monitored in real time by PC-2R heat flux recorder in SuzhouDistrict, Jiuquan City. The wall and culture substrate heat flux in different position ofheliogreenhouse of different span was analyzed to provide theoretical basis formadding insulation measure and improving wall structure of heliogreenhouse. Themain results were as follows:1.The diurnal highest and nightly lowest heat flux of west wall of solargreenhouse appeared earlier than the east wall. The heat release time of west wallwas earlier than east wall, and the heat absorption per unit area of east wall and westwall in daytime was higher than heat release at night in greenhouse. The heatabsorption of backwall during the day was higher than heat release at night. The trendof surface heat flux appeared decreased at first and then increased after the curtainwas opened and closed.2.The daytime heat absorption and nightly heat release of the south of west wallon the same level was higher than that of the north. The daytime surface heatabsorption and nightly heat release of different positions of east wall was notsignificantly different. With the measure point rising, the difference of nightly heatrelease was increasing, and that of south of east wall was higher than the north.3.The arising time of the highest and lowest backwall heat flux was earlier thanthe east and west sides of the corresponding point. The nightly heat flux change ofeast side of backwall was same as the west side. The daytime heat absorption of thebottom of backwall was larger than the top, while nightly heat release was adeverse.4.The weather only affected the size of wall heat flux, but it did not affect thearising time of highest wall heat flux. The daytime heat absorption and nightly heatrelease of western and back wall in sunny day was higher than that in cloudy day.5.The gable wall of four span of greenhouse showed heat storage. The heatstorage capacity of10m span’s greenhouse was best. The order of daytime heatabsorption of unit area of backwall wash10m>h8m>h9m>h11m, whilethe gable wallwas h10m>h11m>h8m>h9m. The order of nightly heat release of unit area ofbackwall was h11m>h8m>h10m>h9m, while the gable wall wash11m>h9m>h8m>h10m.6.The difference of daytime heat absorption of different positions of substratewas larger than that of nightly heat release. The average heat absorption amount ofsubstrate surface was0.59MJ/m2; the average nightly heat release amount ofcultivation substrate surface was0.17MJ/m2. With the measure point deepening, theamplitude of heat flux variation decreased, the time of heat storage delayed. The substrate under15cm heat flux was negative value, and the amplitude of variationwas not obvious.7.The average heat release of unit area of back wall in sunny day was1.51MJ/m2,the average heat release of gable was0.85MJ/m2, and the substrate was0.51MJ/m2.The average heat release of unit area of back wall in cloudy day was1.12MJ/m2, theaverage heat release of gable was0.39MJ/m2, and the substrate was0.47MJ/m2. Insunny day, the heat release of unit area of gable wall was higher than that of substrate,while the result was adverse in cloudy day. The heat release of substrate and gablewall was lower than backwall both in sunny day and cloudy day.