ISHS Acta Horticulturae 399: Greenhouse Environment Control and Automation
MODELLING LEAF CONVECTIVE HEAT TRANSFER |
| Authors: | B.J. Bailey, J.F. Meneses |
| Keywords: | convection, heat transfer, leaves, greenhouse |
| Abstract:
Convective heat transfer from two artificial leaves, arranged in a vertical plane, was measured in a wind tunnel for parallel flow, at different air velocities and several leaf-to-air temperature differences. At zero Reynolds number, values for the Nusselt number calculated from the measured data agreed with values obtained from the literature for free convection from vertical surfaces. At Reynolds numbers above 300, the experimental Nusselt numbers agreed well with those for forced convection. Over the Reynolds number range 0 to 1000, all experimental Nusselt numbers were represented well by an equation for mixed convection obtained by combining the Grashof number with an equivalent Grashof number derived for forced convection. Although these measurements were made using vertical leaves, which is not the normal attitude for real leaves, the results indicate that it may not be appropriate to consider that convective heat transfer between leaves and the greenhouse air occurs by free convection. | |
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