Greenhouse microclimate and dehumidification effectiveness under different ventilator configurations

In this paper, the efficiency of two different greenhouse ventilation opening configurations on greenhouse microclimate during dehumidification process with simultaneously heating and ventilation was analysed by means of computational fluid dynamics (CFD) using a commercial program based on the finite volume method. The numerical model was firstly validated against experimental data collected in a tunnel greenhouse identical with the one used in simulations. A good qualitative and quantitative agreement was found between the numerical results and the experimental measurements. The results of the simulations performed for an outside wind direction perpendicular to the greenhouse axis show clearly the influence of ventilation opening configurations on the velocity, temperature and humidity distributions inside the greenhouse. With the first ventilation configuration (roll-up type) maximum air velocity inside the greenhouse was reached in the greenhouse near the ground, with the lowest values observed near the greenhouse roof. As a result, temperature and humidity decreased first near the ground and afterwards in the rest of the greenhouse volume during the dehumidification process. The exactly opposite pattern was observed with the second configuration (pivoting door type). The maximum air velocities were observed near the greenhouse roof where air temperature and humidity were decreased first during the dehumidification process. Energetically the first configuration is proven to be better since the ratio of latent to sensible exchanges during the dehumidification process was higher than the first configuration. (C) 2006 Elsevier Ltd. All rights reserved.