GREENHOUSE EVAPORATIVE COOLING - MEASUREM ENTS AND MODELING

Summer overheat in agricultural greenhouses generates plant stresses w hich decrease the productivity and the quality of crops. High saturati on deficits can be reduced by means of evaporative cooling. In order t o promote the use of trickle pads in large greenhouses, it is necessar y to have a detailed knowledge of the heat and mass transfers that tak e place inside a combination of such pads for various inlet temperatur e and humidity conditions. This was done in a wind tunnel equipped wit h commercial corrugated cellulose pads. A semi-analytic model, using a specific heat transfer coefficient valid for this geometry, and assum ing complete similitude between mass and heat transfers, accounts reas onably well with the measured data. With this model, it is possible to determine the efficiency of the cooling and humidifying process of va rious combinations of pads.