Analysis of ventilation characteristics for prevention of high temperature inside a commercial greenhouse

为了探讨大型Venlo大棚有顶无侧壁通风机的通风量比有顶无侧壁通风机的常规大棚通风量小的原因，进行了以下测量。在通风机（顶板通风机+侧壁通风机）总开敞面积相同的情况下，采用单跨温室试验了侧壁通风机开敞面积对温室通风量的影响。结果表明，在通风机开启面积相同的情况下，开启侧壁通风机和开启顶板通风机的通风量是开启顶板通风机的1.5 ~ 5倍。这些结果表明，侧壁通风机对烟囱效应有促进作用。为了研究侧壁通风机对大型Venlo温室室内温度分布和通风量的影响，以安装侧壁通风机的中型Venlo温室为研究对象进行了环境测量。假设中型文洛温室是大型文洛温室的一部分，所以在测量中打开了单侧的通风机。打开侧壁通风机后，侧壁附近温度降低，热平衡法计算的温室通风机附近通风量增大。而侧壁通风机对Venlo温室内环境的影响范围约为20m左右。从以上结果可以看出，在大型Venlo温室中，侧壁通风机促进了温室的通风率，但从侧壁向中心部分的影响减小。

In order to investigate the cause that the ventilation rate of large-scale Venlo greenhouse with roof ventilators and without side wall ventilators is smaller than that of conventional greenhouse with roof and side wall ventilators, the following measurements were done.1.In the case of total open area of ventilators (roof ventilators + side wall ventilators) was the same, the influence of open area of side wall ventilators on ventilation rate of the greenhouse was tested with single span greenhouse. As a result, in the spite of open area of ventilators was the same, the ventilation rate with side wall and roof ventilators opened was 1.5-5 times that with roof ventilators opened. These results suggested that the chimney effect is promoted by side wall ventilators.2.In order to investigate the influence of side wall ventilators on the inside temperature distribution and ventilation rate of the large-scale Venlo greenhouse, environmental measurement was done with medium-scale Venlo greenhouse which was equipped with side wall ventilators. It assumed that the medium-scale Venlo greenhouse was the part of the large-scale Venlo greenhouse, so the one side wall ventilators were opened in the measurement. Temperatures near the side wall decreased when side wall ventilators were opened, and the ventilation rate of greenhouse calculated by the heat balance method increased near the ventilators. However the range of the influence of side wall ventilators on environments inside the Venlo greenhouse was about 20m from the side ventilators.From these results, side wall ventilators promote the ventilation rate of the greenhouse, however the influence is decreased as departing from the side wall to central part in the large-scale Venlo greenhouse.