A case study on airflow characteristics in greenhouses with adaptive wall-based attachment ventilation

School of Building Services Science and Engineering, Xi’an University of Architecture and Technology, 710055 Xi’an, China

^* Corresponding author: liag@xauat.edu.cn

Abstract

Modern greenhouses require not only heat preservation in winter but also temperature control in summer to provide a suitable growth environment. The efficiency and homogeneity of ventilation and cooling systems for greenhouses have always been challenges for facility agriculture engineering. This paper proposes the application of adaptive wall-based attachment ventilation (AWAV) in greenhouses. The case study on airflow characteristics and thermal environment of a typical greenhouse under AWAV mode are investigated numerically with the standard k-ε turbulent model, a solar ray tracing algorithm, and a surface-to-surface (S2S) radiation model. The ventilation performance of AWAV for greenhouses is examined and evaluated by air velocity and temperature distribution, non-uniformity coefficient, and ventilation efficiency. The results show that AWAV mode presents a more uniform airflow distribution (K_u=0.31, K_t=0.10) in the plant growth region, with relatively low temperature and an excellent cooling effect (E_T =1.39). In addition, another advantage of AWAV mode is that the height of the deflector can be adjusted as the plant grows to meet the required air environment of greenhouses.