Aspects of CFD modeling of fan and pad evaporative cooling system in greenhouses

A methodology approach in order to simulate numerically(CFD) a greenhouse equipped with fan and pad evaporative cooling system is presented. Using the main aspects of evaporative cooling systems in terms of heat and mass transfer, the flow and boundary conditions of the simulation model are identified integrating both the external and internal climatic conditions. The crop (tomato)was simulated using the equivalent porous mediumapproach by the addition of a momentum source term. Preliminary calculations were carried out in orderthe pressure drop, occurred in crop model due to air flow, to be determined as a function of leaf area and stage of crop growth. The temperature and humidity of incoming air and the operational characteristics of fans were specified to set up the CFD model. The numerical analysis was based on the Reynolds-averaged Navier-Stokes equations in conjunction with the realizable k-? turbulence model. The finite-volume method (FVM) was used to solve the governing equations. The 3D full scale model was solved in several differencing schemes of various orders in order to examine its accuracy. The simulation approach was used mainly to identify the critical parameters of microclimate of greenhouse and the regions were these have to be measured during the upcoming experiments which will take place in Farm of Aristotle University of Thessaloniki. Results show the influence of the different airflow rates on greenhouse microclimate, indicating that the proper choice of ventilationrate is crucial factor in order to improve the efficiencyof evaporative cooling systems.