Screening And Comprehensive Performance Analysis Of Greenhouse Thermal Insulation Materials

This paper intends to analyze and evaluate the performance of common heat preservation and insulation materials,and select the best materials and combinations for heat preservation and insulation of the back roof and wall of solar greenhouse in theory,so as to provide the basis for the optimization of heat preservation and insulation materials in solar greenhouse.In this paper,14 kinds of composite materials,such as ordinary polystyrene board,expanded polystyrene board,extruded polystyrene board,polyurethane foam board,polyurethane foam,aerogel felt,vacuum insulation board,pearl cotton board and rock wool board and their 14 composite materials,are taken as test materials.Through analysis and determination of the performance indexes of single material such as bulk density,water absorption,tensile strength,compressive strength and heat insulation,etc.The thermal insulation and heat transfer coefficients of different composites were measured and analyzed,and the prices of each material were counted.Entropy weight method was used to evaluate the material comprehensively.The main results are as follows:1.In the single material,the extruded polyphenyl board is the high quality material.From the bulk density,water absorption,tensile strength,compressive strength,thermal insulation and price,it can be seen that the extruded polystyrene board has a moderate bulk density of 28.22 kg/m3,which guarantees a certain strength of itself and does not affect the convenience of use because of the greater self-weight;the water absorption rate is only 34%,which can resist the adverse effects of rain and water vapor to a certain extent,and insulate most of the heat preservation.The material guarantees a certain durability;the tensile strength and compressive strength are 0.613 MPa and 265.97 kPa,respectively,which can provide good mechanical strength in use;at the same time,it has good thermal insulation and low price,about 30.5 yuan/m2,which is conducive to promotion and popularization.Through the comprehensive analysis of the function of the entropy weight method,the relative superiority of the nine kinds of single thermal insulation materials reaches 0.955,ranking first.For the best material,the single thermal insulation material is the most suitable thermal insulation material for the back roof and the back wall.2.Composites made of rock wool board and extruded polyphenylene board have the best performance,and show excellent performance in all aspects.Rock wool board and extruded polystyrene board both have good thermal insulation,ranking first and second in the thermal insulation test;Rock wool board in its own tensile and compressive performance is poor,but extruded polystyrene board has good tensile and compressive properties,to a certain extent,to make up for the lack of strength of rock wool board;Rock wool board water absorption rate is high,can reach 3.26%of the tested materials can only rank fifth;but the price of rock wool board is relatively low,only 20 yuan/m~2;comprehensive entropy weight function analysis shows that the relative superiority of rock wool board+extruded polyphenyl board combination is 0.770,which is the best of the 14 materials tested.The combination of rock wool board and extruded polyphenylene board is the most suitable one for thermal insulation of back roof and back wall.