Zhang Weijian School of Mechanical Engineering, College of Engineering, Universiti Teknologi MARA, Selangor, Malaysia.
Email: m15751010257@163.com
Nurnida Elmira Binti Othman School of Mechanical Engineering, College of Engineering, Universiti Teknologi MARA, Selangor, Malaysia.
Email: nurnida@uitm.edu.my
Azli Bin Abd Razak School of Mechanical Engineering, College of Engineering, Universiti Teknologi MARA, Selangor, Malaysia.
Email: azlirazak@uitm.edu.my

Abstract:

The Yangtze River Delta (YRD) is a densely populated region where the advancement of efficient and intensive agricultural practices is crucial. Glass greenhouses, particularly in areas such as Shanghai, frequently become unusable during the summer months due to excessive internal temperatures, primarily resulting from inadequate knowledge of cooling techniques. This study employs a time series comparative approach to evaluate the cooling performance under seven different operational conditions, utilising Computational Fluid Dynamics (CFD) to simulate and illustrate the greenhouse characteristics when subjected to external wind forces specific to the YRD. The findings reveal that, in glass greenhouses lacking side windows, the internal temperature distribution during summer—under the prevailing southerly wind conditions—exhibits a general pattern of lower temperatures in the south and west, and higher temperatures in the north and east. This indicates that the southwest quadrant achieves the most effective cooling, whereas the northeast quadrant performs poorly in this regard. Moreover, mechanical ventilation proved significantly more effective than natural ventilation, achieving a cooling reduction of up to 4.02°C compared to 1.53°C in naturally ventilated greenhouses. Natural ventilation still outperformed conditions with no ventilation at all. In addition, the implementation of multi-layer shading nets demonstrated notable cooling benefits. When outdoor radiation exceeded 800 W/m², the use of two shading layers achieved a temperature reduction of 4.5°C, whereas a single layer provided a reduction of 3.7°C in experimental settings. Based on these analyses, the study proposes specific strategies for the utilisation of glass greenhouses under the summer climatic conditions typical of the Yangtze River Delta.

Keywords:Greenhouse, Temperature Regulation, Time Series Comparison, CFD, Yangtze River Delta Region.