塑料连栋温室不同通风机构的通风率（英）

为了提高对塑料连栋温室环境的认识水平，必需研究连栋塑料温室各种通风机构的通风性能和通风率。因此，通过运用气体浓度衰减示踪技术，研究了连栋塑料温室中卷膜通风系统和天窗开启式系统的通风性能，确定了模拟通风率的相关系数。研究表明，在试验条件下，当通风口完全打开时，卷膜通风系统比天窗开启式具有可高达2.32倍的通风率；在风速为3 m/s时，位于拱顶脊部的通风口比位于拱底部的通风率大60%；在同样条件下，防虫网可把通风率减少18%～22%。研究还发现，它们在相似的开启程度变化过程中，通风率的变化趋势也有显著的差异。另外，为简化研究，引入了描述通风系统结构性能的流量系数Cd和风力影响系数Cw。在实验条件下，以风力为主导通风时Cd 和Cw的相关参量C的参考值对天窗开启式系统为0.178，对卷膜通风式系统为0.318；而在以温度为主导通风时Cd的参考值对天窗开启式系统为0.667，对卷膜通风式系统为0.863。

Ventilation rate of various vents in plastic covered multi-span greenhouse

In order to better understand the microclimate inside a plastic covered multi-span greenhouse, it is essential to investigate the ventilation rate for the performances of various vents in it. For determining and modeling the ventilation rate, the experimental investigation was conducted by making use of the tracer gas technique and decay rate method in the greenhouses with continuous roof vent or with rolling-up roof vent. It was found that the rolling-up vent had a higher ventilation rate (up to 2.32 times) than the continuous roof one, the better ventilation (more than 60% at the wind speed of 3.0 m/s) could be achieved with vents near the ridge of the roof instead of near the gutter, and the obvious reduction (18%-22% at the wind speed of 3.0 m/s) in the rate values when an insect-proof screen was fitted to it, in the case of full opening of the vents. And the experiments confirmed the significant differences in the rate values when they were opened in the different known spaces by comparison between the two vents. Furthermore, for the simplification of the study, the wind effect coefficient Cw and discharge coefficient Cd were introduced and determined in values for this kind of greenhouse. The C, in relation to Cw and Cd, was obtained with the consultable value of 0.178 for the continuous roof vent, 0.318 for the rolling-up roof vent for the rates due to wind forces, and Cd was obtained with the consultable value of 0.667 for the continuous roof vent, 0.863 for the rolling-up roof vent for the rates due to buoyancy effect in related situations.