ISHS Acta Horticulturae 229: Symposium on Biological Aspects of Energy Saving in Protected Cultivation
HEAT AND WATER VAPOR TRANSFER ACROSS THE BOUNDARY LAYER OF ARTIFICIAL LEAVES IN A GREENHOUSE |
| Authors: | A. Silva, R. Rosa, M. Candeias |
| Abstract:
One pair of black painted aluminium leaves and another pair of aluminium leaves covered with wet black tissue were made to study heat and water vapour transfer across the boundary layer of tomato leaves. One leaf in each pair is electrically heated from within and the steady state energy balance method was applied to determining the boundary layer resistance to heat and water vapour. Our experiment was carried out within the tomato canopy inside a greenhouse, so that the artificial leaves were subjected to a reallistic environmental situation. We found evidence that both heat and water vapor transfer take place in a mixed regime, between forced and natural convection, so that not only air velocity but also temperature and vapor pressure differences, between leaf surface and air, are important in determining the rate of sensible and latent heat loss from the leaves. The effective boundary layer resistance may be simulated by a parallel association of a forced and a natural resistance, for both heat and vapor transfer processes. | |
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