喷雾降温联合自然通风在大跨度温室中的试验

为提高日光温室土地利用率、增大日光温室操作空间，设计了一种新型南北走向的大跨度温室。该温室在夏天种植作物时，室内温度较高，尤其在晴天，即便通风口全开进行自然通风，中午温室内温度亦可高达40 ℃以上。为降低大跨度温室内温度，该文提出了一种高压喷雾降温方法，高压喷雾装置由过滤器、储水箱、管道、高压泵、控制器解压阀和喷头组成。根据现有的研究理论，计算温室的喷雾量为0.27 g/（m2·s），选择锥心式喷头，喷头孔径为0.3 mm，雾滴直径为0.02~0.03 m，喷头流量为1.3~2.4 g/s，喷头安装密度为0.3个/m2。试验期间设置了60 s开300 s关、90 s开300 s关和120 s开300 s关的3种喷雾运行模式，并在夏季典型晴天开展了喷雾降温试验，选择室外环境差异小的3个典型晴天的3个时段进行比较。试验结果表明，3种喷雾系统运行模式下，试验温室与对照温室相比，气温分别要低3.0、5.1和6.0 ℃，空气相对湿度分别增加10.2%、20.1%和23.8%。同等室外环境条件下，3种喷雾系统运行模式下的喷雾蒸发冷却效率分别为26.3%、39.4%和47.2%，从降温效果、空气相对湿度增加量及喷雾蒸发冷却效率结合来看，系统运行120 s关闭300 s的喷雾模式的降温效果最为理想。综合认为，该研究为北方大跨度温室夏季降温调控奠定了基础。 

Experimental Investigation of High-pressure Fogging System Applied with Natural Ventilation in Large Span Greenhouse

In order to increase land use efficiency and operation space of solar greenhouse，a new type of long-span greenhouse with north-south trend was designed.When planting crops in summer，the indoor temperature of the greenhouse is higher，especially in sunny days.Even if ventilation vents are fully opened for natural ventilation，temperature in the greenhouse at noon can be as high as 40 ℃.In order to reduce temperature in a large span greenhouse，a high-pressure spray cooling method was proposed.The high-pressure spray device consisted of a filter，a storage tank，a pipeline，a high-pressure pump，a controller decompression valve and a sprinkler.According to previous research theory，spray volume of greenhouse was calculated to be 0.27 g/（m2·s），the nozzle was cone shaped，nozzle diameter was 0.3 mm，droplet diameter was 0.02~0.03 m，nozzle flow rate was 1.3~2.4 g/s，and nozzle mounting density was 0.3 /m2.During the test period，3 spray operation modes，60 s opening 300 s off，90 s 300 s off and 120 s opening 300 s off，were set up，and spray cooling experiments were conducted on typical sunny days in summer.Test results showed that temperature of experimental greenhouse was 3.0，5.1 and 6.0 ℃ lower than that of control greenhouse respectively under three operation modes of spray device，and relative humidity of air increased by 10.2%，20.1% and 23.8% respectively.Spray evaporative cooling efficiency of three spray operation modes was 26.3%，39.4% and 47.2% respectively under outdoor environment approaching condition.Combined with cooling effect of greenhouse，relative humidity of air and efficiency of spray evaporative cooling，cooling effect of 120 s intermittent 300 s spray system was ideal.It was concluded that this study provided a reference for regulation of summer cooling in large-span greenhouses in North China.