日光温室不同闷棚覆盖材料的光热特性研究及综合评价OA

In order to study the regulatory effect of the covering materials used in the solar greenhouse shading cover on the surface micro-environment of the soil in Yinchuan City,an experiment on the light and heat properties of the covering materials was conducted.The transmittance,insulation property,infrared transmittance,ultraviolet shielding effect of different thicknesses of PE(polyethylene)ordinary film,PE(polyethylene)drip-free film,PO(polyolefin)film,and EVA(ethylene-vinyl acetate copolymer)film were tested,as well as the light and heat characteristics such as the light intensity under the film and the soil temperature and humidity.A comprehensive evaluation was carried out.The results showed that from the perspective of radiation transmittance,the ultraviolet transmittance of 0.08 mm PE ordinary film was the highest and the temperature rise speed was the fastest.However,with the extension of time,a large number of water droplets would be produced inside the film,causing a decrease in the transmittance,and the ultraviolet transmittance of 0.12 mm EVA film was the lowest.From the perspective of light intensity,0.10 mm EVA film had the strongest capture ability of light flux and the average light intensity was the highest,154 65.5 lx.0.10 mm PE drip-free film had the lowest average light intensity,7 467.7 lx.In terms of insulation property,the average soil temperature after the 0.1 mm EVA film shading was the highest,44.9 ℃,with the best insulation effect.PO film came second,and 0.12 mm PE ordinary film had the lowest average soil temperature,42.4 ℃.From the perspective of the droplet flow performance of the film,except for the PE ordinary film which would produce a large number of water droplets,the flow performance of the other films was good.From the price survey,the price of PE film was the lowest,EVA film was the highest,and PO film was in between.The prices decreased from high to low in the order of 0.12 mm,0.10 mm,and 0.08 mm thickness.The comprehensive evaluation results analysis showed that EVA film performed the best among all the different material shading cover materials and could be used as the preferred material for high-temperature shading.PE ordinary film came second,0.10 mm EVA film was the best in thickness,0.12 mm PE ordinary film was the best choice for PO film,and PE drip-free film had the worst effect.It is not recommended to be used as the shading cover material.