Temperature And Humidity Control Of Solar Greenhouse Based On Active-passive Phase Change Thermal Storage Wall

To study the effects of phase change materials and solar air collectors on the greenhouse thermal environment and humidity environment.By testing a series of indicators such as heat flux,temperature and humidity of the passive phase change heat storage trapezoidal wall greenhouse(described briefly below as passive heat storage greenhouse),active-passive phase change thermal storage ventilated trapezoidal wall greenhouse(described briefly below as active-passive thermal storage greenhouse),and control trapezoidal wall greenhouses(described briefly below as control greenhouses).It aims to improve the wintering cultivation environment of melons and vegetables,the heat storage and release performance of greenhouse walls,and improve the greenhouse heat environment.The main findings are as follows:1.Study on thermal environment of passive thermal storage solar greenhouse.Regardless of the sunny and cloudy days,the heat absorption and heat release of the passive heat storage greenhouse wall were higher than the control greenhouse,and there was a significant difference;In winter sunny days,the energy utilization efficiency of the passive heat storage greenhouse wall and the control greenhouse wall were 87.9%and 82.3%,respectively.There was a certain difference in the temperature of the same part of the passive heat storage greenhouse and the control greenhouse wall at the same typical time.This difference gradually decreased with the increase of the wall depth,and the difference between 0-300 mm was the most obvious.The average daily cumulative calorific value of the passive heat storage greenhouse wall was 8.1%higher than that of the control greenhouse,and the monthly cumulative calorific value was 14.8%higher than that of the control greenhouse.The monthly mean temperature at the surface of the passive heat storage greenhouse wall and the wall within 0.3m was significantly different from that of the control greenhouse.The average monthly temperature of the passive heat storage greenhouse,the control greenhouse and the outdoor air were 9.9℃,8.6℃ and-8.9℃,respectively.2.Study on dehumidification effect of active-passive thermal storage ventilation in solar greenhouse.The dehumidification system was operated for 1 h,1 h,1.5 h,2 h and 2.5 h before dehumidification.According to the comparative analysis,On sunny days,the active-passive thermal storage greenhouse started the thermal interaction dehumidification fan for 1 h in the first 1 h of the operation mode,and the effect was relatively good.The relative humidity was 9.57%lower than that of the control greenhouse,the indoor temperature was 2.0℃ higher than the control greenhouse,the absolute humidity was 0.09 g·m-3 lower than the control greenhouse,and the enthalpy was 2.32 kJ·kg-1 higher than the control greenhouse.The the moisture content was 0.11 g-kg-1 lower than the control greenhouse.On cloudy days,the active-passive thermal storage greenhouse started the thermal interaction dehumidification fan for 1 h in the first 2 h of the operation mode,and the effect was relatively good.The relative humidity was 10.38%lower than the control greenhouse,and the average relative humidity was 10.38%lower than the control greenhouse,and the indoor temperature was 1.4℃higher,and the absolute humidity was 0.23 g·m-3 lower than the control greenhouse,and the enthalpy was 1.05 kJ·kg-1 higher than the control greenhouse,and the moisture content was 0.16g·kg-1 lower than the control greenhouse.3 Study on thermal environment of active-passive heat storage ventilation greenhouse.Thermal environment.During the test period,the daily average temperatures of indoor air temperature,soil temperature and wall surface temperature of the active-passive thermal storage greenhouse were 1.1℃,0.9℃,and 0.7℃ respectively,and night-time average temperature compared with the control greenhouse.They were:1.3℃,1.0℃,and 0.8℃ higher,respectively.Store heat and heat storage layer.Compared with the control greenhouse,the daytime heat absorption and night-time heat release of the wall and soil of the active-passive thermal storage greenhouse were significantly higher than that of the control greenhouse,no matter whether it was sunny or cloudy.The active-passive thermal storage greenhouse and the control greenhouse wall thermal storage layer were 400-500 mm,300-400 mm,respectively.The phase change heat storage hybrid material and the solar air collector combined to play the role of peaking,filling the valley for storing and releasing heat of the wall,and increasing the heat storage capacity of the original trapezoidal wall and improving the thermal environment in the greenhouse.