Simulation And Dehumidification Of Sinking Sunlight Greenhouse Based On CFD

Sunlight greenhouse is an important agricultural facility in northern China，whichprovides a way to riches for the majority of farmers. In order to improve the performance ofsunlight greenhouse and better for agriculture development，it should modify the structure ofgreenhouse. In recent years，researchers have proposed that the sinking sunlight greenhousehave the better insulation performance and higher land utilization. But there is excessivemoisture in this kind greenhouse. The purpose of this study is through ventilation to reducethe excessive moisture of the sinking sunlight greenhouse based on the environmentalparameters.In order to cut down the research period and cost，the study combined the methods ofcomputational fluid dynamics simulation and test monitoring. Test monitoring provided theinitial parameters，boundary conditions and verification for the simulation model. Theparameters’ distribution and changes inside greenhouse were got through numericalcalculation. It is better for analyzing the greenhouse environment，improving the structure andmanagement methods.The study used the Fluent (computational fluid dynamics software) to analyze the airtemperature，humidity，air velocity and other parameters of the greenhouses. After that，itshould be analyzed the influences of digging depth，cover curtain time and ventilation. Basedon the experimental investigation and numerical analysis，the results as follows:1) With the digging depth increases，the greenhouse’ insulation becomes better，butrelative humidity increases because the air flow becomes weaker. Considering thetemperature，humidity and crop conditions，1.0meters is the best digging depth of sinkingsunlight greenhouse in YangLing district.2) It is showed that inside the sinking sunlight greenhouse，air temperatures at night fromthe back wall and ground to light surface were layer reduced. The values between simulationand messured were agreed well. Under the condition of weak light and low air temperature，advance the cover curtain time can significantly increase the air temperature at night ofsinking sunlight greenhouse. 3) It is showed that，the mean of relative humidity of the greenhouses were all more than85%. There was excess and uneven distribution on humidity of the sinking sunlightgreenhouse. Inside the greenhouses，the top part was26.7%smaller than the bottom part，theeastern part was6.3%smaller than the western part，the southern part was3.7%smaller thanthe northern part.4) It is showed that， the forced ventilation was good for the ventilation anddehumidification. Ventilator set in front part was better for improving the sinking sunlightgreenhouse’ environment.5) Considering the crop，dehumidification and insulation needs，a reasonable program ofventilation was formulated.