Materials Effect Of Underground Ventilation Pipe On The Thermal Environment Of Solar Greenhouse

In this study,the heat exchange system of stainless steel,HDPE,promoted PVC material,as the research object,compared with traditional PVC material system.determination and analysis different depth of soil temperature,inlet and outlet temperature and humidity of four systems.The results showed that:(1)From temperature control aspect,13:00~14:00,four groups of heat exchange to achieve the best results in temperature control,in sunny days stainless steel group could cool more 0.9? than the control,improved PVC was 1.4?,stainless steel group could cool more 0.9? in cloudy,the promoted PVC group was 2.3?;(2)From humidity control aspect,in sunny day,improved PVC humidity increased was 2.5% higher than the control increased,stainless steel was 3.4% in the day,at night,PVC more reduced by 3.4%,stainless steel group decreased by 1.6%;in cloudy day,improved PVC increased humidity was 3.9% higher than the control increased,stainless steel was 2.8% in the day,at night,PVC more reduced by 2.1%,stainless steel group decreased by 1.2%;(3)From soil temperature control aspect,in depth of 30 cm,in sunny day,stainless steel group was temperature increased 1.2?more than control group temperature increased,HDPE and promoted PVC were less increased 0.5?and 0.7?,at night,the promoted PVC was less reduced 1.2?,in cloudy day,stainless steel group was temperature increased 1.3? more than control group temperature increased,at night,the promoted PVC was less reduced 1.0?.stainless steel group was 0.6?;in the depth of soil 20 cm,in sunny day,stainless steel group was temperature increased 1.0?more than control group temperature increased,promoted PVC were less increased 0.6?in day,at night,the promoted PVC was less reduced 0.7?,and stainless steel was less reduced 0.4?,in cloudy day,stainless steel group was temperature increased 0.7?more than control group temperature increased,at night,stainless steel was more reduced 0.6?;in the depth of 10 cm,three groups had no differences in the aspect of soil temperature effect.(4)In sunny day,heat storage capacity of stainless steel group and the improved group PVC system was 4 times and 3 times compared with the control group,in cloudy day,the heat storage capacity of the four systems were greatly reduced,and the storage and stainless steel performance of promoted PVC group had obvious advantages,was 3.3 times and 1.6 times compared with control group.(5)Performance of HDPE had no obvious difference from control group.(6)From the cost aspect,when the system was 6m,stainless steel was 2.6 times of CK,HDPE was 1.4 times,improved PVC was 1.1 times,when the system was 12 m,stainless steel,HDPE and improved PVC was 3.0 times,1.5 times and 1.1times.(7)Considering of promoting the thermal insulation effect,indoor temperature,dehumidification effect and cost,improved PVC was the better choice to be material of underground ventilation pipe.