The Structure Design And Optimization Of Fully Enclosed Sunlight Greenhouse

Solar greenhouse is a unique type of facility agriculture in China,which develops rapidly in northern China.Greenhouse structure is the most important factors influencing the performances of the indoor environment.Due to the half closed property of greenhouse,there are so many problems which affect crop growth such as the indoor temperature is too high,the environmental factors which is needed for crop growth is not enough,and the greenhouse plant diseases and insect pests.The research on greenhouse structure can effectively improve indoor environmental factors,improve greenhouse production efficiency and resource utilization,and reduce cost.Based key scientific research project on the coal base in Shanxi Province-efficient carbon sequestration with facilities vegetables,the paper constructed a new type of totally enclosed sunlight greenhouse,in order to solve the problem of greenhouse plant diseases and insect pests,realize the carbon-rich crops production of greenhouse,we studied the structure of totally enclosed greenhouse,the main research contents include:(1)Structure design of a totally enclosed greenhouse.The greenhouse structure is designed mainly from three aspects:the overall structure of the greenhouse,the design of the greenhouse geometry and the greenhouse cooling system.Through the design,the solar greenhouse is converted from the traditional natural ventilation mode to forced ventilation,and the air in and out of the room is filtered to realize the relative isolation of the greenhouse.When the indoor temperature is too high in summer,the greenhouse cooling is achieved by adding the nano-oxide antimony permeable coating on the films outdoor which is pervious to light and heat and using the high-pressure spray indoor.(2)Mechanical analysis of the closed greenhouse steel structure.According to the relevant load specification of greenhouse structure,the value of greenhouse steel structure load was determined,combination these load,then get three kinds of the most unfavorable load:people operation on the roof after snow,people standing on the roof roiling straws under blowing south wind,people standing on the roof putting straws under blowing north wind.On this basis,the deformation and stress of steel structure under three adverse loads are analyzed based on ANSYS12.0,and the conclusion is drawn:under the three most unfavorable loads,the maximum displacement of the steel structure is located on the front roof,and the value of maximum deformation is less than 1.6%of the greenhouse span.The maximum joint stress of steel structure occurs at the front roof,and its value is less than the allowable stress of the steel,whose value is 235Mpa,which meets the deformation and load requirements of the steel structure.(3)Optimized design of the whole closed solar greenhouse steel structure.Based on ANSYS12.0,we use the section size of steel as the independent variable,the structural steel quantity as the objective function,the upper chord,lower limit and the abdominal rod of the whole closed solar greenhouse steel structure are optimized,the strength are checked and the analysis are carried out.After optimization,the steel amount of the structure is reduced by 13.4%,and the steel quantity can be saved 0.738kg per square meter after optimization.