Analysis and Optimization of the Fan-Pad Evaporative Cooling System for Greenhouse Based on CFD

A CFD model was presented to simulate the distribution of air velocity and temperature in a greenhouse adopting the fan-pad cooling system in summer. The Boussinesq hypothesis was applied for the simulation of gravitation; the k-ε turbulent model and discrete ordinates model were selected to predict the distribution of air velocity and temperature inside greenhouse using the commercial software Fluent. The differences between simulated and measured air temperature varied from 0.9 to 4°C and the differences of air velocity were less than 0.15 m/s, which proved that the CFD method can estimate the distribution of air velocity and temperature in the greenhouse rationally and effectively. The validated CFD model was then used to evaluate the cooling effect and design the installment of fan and pad in terms of the crop size. The results implied that Case 3 and Case 5 should be chosen when the height of crop canopy varies from 2 m to 3 m. When it varies from 1 m to 2 m, all the cases can be effective except Case 1. When the canopy height is below 1 m, all the cases can be selected. This paper suggested that the CFD model can be used as an optimal tool for fan-pad evaporative cooling system in the greenhouse.