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

为了探讨大型文洛温室有屋顶通风器和不带侧壁通风器的温室的通风量低于常规有屋顶通风器和无侧壁通风器的温室的原因，采取了以下措施：1.在通风机总开放面积相同的情况下(屋顶通风器+侧壁通风器)，用单跨温室进行了侧壁通风器开口面积对温室通风率的影响试验。结果表明，在通风器开放面积相同的情况下，侧墙通风器和屋顶通风器打开时的通风量是打开屋顶通风器时的1.5~5倍。为了研究侧壁通风器对大型文洛温室室内温度分布和通风率的影响，对装有侧壁通风器的中型文洛温室进行了环境测量。假设中等规模的Venlo温室是大型Venlo温室的一部分，因此在测量中打开了单侧墙通风器。侧壁通风器开启后，侧壁附近温度降低，用热平衡法计算的温室通风量在通风口附近增加。而侧墙通风器对大棚内环境的影响距离侧墙通风器约20m，在大型文洛温室中，侧墙通风器提高了温室的通风率，但从侧壁向中央方向的影响有所减弱。

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.