日光温室夜间后墙不同高度放热量差异的理论分析

Theoretical analysis on the heat-releasing volume differences of back walls at different heights in solar greenhouse at night

针对日光温室夜间后墙不同高度放热量差别较大的现象,运用物理学矢量原理、气体分子动理论,对外界低温通过覆盖面在后墙形成的放热机理进行推导,结合放热机理和后墙不同高度温度差别对后墙不同高度放热量差别的影响进行研究。结果表明:1)外界低温驱动力水平分量大小随后墙高度降低不断增大,外界低温驱动力水平分量密度随后墙高度降低不断减小,后墙放热驱动是外界低温驱动力水平分量大小和密度乘积的函数,随后墙高度降低不断增大。2)后墙放热后温度不断下降,后墙放热量自上而下逐渐增多,下侧放热量是上侧放热量的2~3倍。3)推导出的后墙放热机理能够解释后墙不同高度放热量差异,后墙不同高度放热量差异主要是由于外界低温通过覆盖面在后墙产生的放热驱动不同造成的;后墙放热是外界低温驱动下的被动放热。4)后墙温度较高时,后墙放热量受后墙温度和后墙放热驱动共同作用,此时后墙中部放热量也会较多;后墙温度较低时,后墙放热量主要受后墙放热驱动作用。

Aiming at the phenomenon that the heat-releasing volume of back wall at different heights in solar greenhouse are quite different,this study first deduce the heat-releasing mechanism of the back wall formed by the outer low temperature through greenhouse cover by using physics vector principle and the gas molecular movement theory as foundation and then carry out the research on heat-releasing difference of different heights of the back wall in combination with the heat-releasing mechanism and the differences of the temperature of back walls at different heights.The results show that the horizontal component of the external low-temperature driving force increases and the density of the horizontal component of the external low-temperature driving force in the back wall decreases with the decreasing of the back wall height.The heat-releasing drive formed by the outer low-temperature is the function of the product of driving force with the driving force density,and it increases with the height of the back wall decreasing.The temperature of the back wall decreases continuously after releasing heat.The heat-releasing volume from the back wall increases gradually from the top to the bottom,and the heat-releasing volume from the bottom side are 2-3 times higher than that from the top side.The deduced exothermic mechanism can explain the heat-releasing difference of different height back walls,and the heat release of the back wall is a passive heat-releasing process driven by the external low temperature.The difference of heat-releasing volume is mainly due to heat-releasing drive caused by external low temperature.The heat-releasing volume is affected by the heat-releasing drive and the temperature of the back wall when the temperature of the back wall is high and the heat-releasing volume in the middle of the back is also high;The heat-releasing volume of the back wall is mainly driven by the heat-releasing drive of the back wall when the temperature of the back wall is low.