Research On Soil Wall Structure Optimization And New Type Wall In Sunlight Greenhouse

Sunlight greenhouses are widely used in northern China.Soil wall solar greenhouses are generally under-digging during construction,and the soil of the wall is the remaining soil when the ground is dug.The cost of the soil wall is low,and the thermal properties of the soil are more suitable for the greenhouse than most building materials.The soil has also become the material used in the construction of the solar greenhouse wall in rural areas in central Hebei.However,in the actual construction,due to the lack of relevant technical guidance,the insulation effect is over-emphasized by the builders,thereby ignoring the disadvantages caused by the excessive wall size.Therefore,in the experimental area,the soil wall size exceeding the normal production requirements will cause cultivated land resources a certain amount of waste.In order to optimize the reasonable thickness of the soil wall of the solar greenhouse in the experimental area,this paper conducted a temperature field experiment on a soil wall solar greenhouse in the central Hebei region,and found that there are heat storage layer,transition layer and insulation layer inside the soil wall of the solar greenhouse,it is located 0.5m～1.0m away from the inner wall of the wall,1.75m～3m away from the outer wall of the wall,and 0m～1.75m away from the outer wall of the wall.Eue to the limited heat released by the wall,the temperature farther away from the wall is lower than the temperature closer to the wall,but the temperature can still be maintained at a level suitable for the growth of crops,indicating the original size of the soil in the area The wall has a good effect on the thermal insulation of the greenhouse.Then use the computational fluid dynamics(CFD)numerical analysis software to simulate the built greenhouse model,extract the same temperature data as the actual measurement point location,and compare with the previous measurement results,the results are in line with reality.Using CFD software to analyze and calculate the solar greenhouses with different wall sizes,it is concluded that the indoor temperature decreases with the decrease of the wall size.The too thin wall size is not obvious because of its insulation layer,so the insulation effect is poor,The size of the soil wall is optimized.The optimized wall size is:upper thickness=1.5m,bottom thickness=3.5m,wall height=2.5m,and rear house slope elevation angle=45°.It is not as good as a thicker wall,but it can still meet the needs of plant growth and can increase the land saving rate.Through the test,concrete specimens with different sizes of recycled coarse aggregate,different polystyrene particles and different amounts of phase change materials were made,and the compressive strength and thermal properties were tested.On the basis of the test,numerical simulation software was used to calculate the thermal insulation wall and phase change thermal storage wall of polystyrene particles of 12 different sizes.The results show that from the thermal insulation effect and economic considerations,it is recommended to choose a wall combination of 100-thick polystyrene board+200-thick polystyrene particle recycled concrete+60-thick phase-change concrete wall board.