Journal of Zhejiang University SCIENCE
(ISSN 1009-3095, Monthly)
2005 Vol. 6B No. 6 p.523-529
Prediction and analysis model of temperature and its application to a natural ventilation multi-span plastic greenhouse equipped with insect-proof screen
LIU Shu-zhen†1,2, HE Yong†1, ZHANG Yu-bao3, MIAO Xiang-wen1
(1School of Biosystems Engineering and Food Science, zhejiang university, Hangzhou 310029, China)
(2Department of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016, China)
(3Information Engineering Department, Zhejiang Textile and Fashion Vocational Technology College, Ningbo 315211, China)
†E-mail: shuzhenl@163.com; yhe@zju.edu.cn
Received Dec. 31, 2004; revision accepted Mar. 13, 2005
Abstract: The natural ventilation widely used in greenhouses has advantages of saving energy and reducing expense. In order to provide information for climate control of greenhouse, a model was developed to predict the variation of air temperature in the naturally ventilated greenhouse equipped with insect-proof screen. Roof ventilation and combined roof and sidewall ventilation were considered in the model. This model was validated against the results of experiments conducted in the greenhouse when the wind was parallel to the gutters. The model parameters were determined by the least squares method. In the used model, effects of wind speed and window opening height on the air temperature variation were analyzed. Comparison between two types of ventilation showed that there existed a necessary ventilation rate which results in air temperature decrease in natural ventilation under special climatic conditions. In our experiments when wind speed was less than 3.2 ms−1, wind had a more gradual effect on greenhouse temperature for roof ventilation, compared with combined roof and sidewall ventilation, which had greater air temperature decrease than roof ventilation only.
Key words: Greenhouse, Natural ventilation, Temperature, Model
doi:10.1631/jzus.2005.B0523 CLC number: S625.3