Articles
THE ROLE OF TRANSPIRATIONAL COOLING IN THE DESIGN OF GREENHOUSE VENTILATION
Article number
578_5
Pages
55 – 61
Language
English
Abstract
Transpiration is a major cooling mechanism of greenhouse crop canopies and makes latent heat a major energy dissipation component.
The larger this component, the smaller is the required ventilation rate.
The evaporation coefficient, namely the fraction of the radiation load dissipated as latent heat, is an important ventilation design parameter, of which designers often have no more than a qualitative knowledge.
In an attempt to overcome this difficulty, the present study proposes to incorporate the Penman-Monteith (P-M) evapotranspiration equation into the standard ventilation design formula.
With this modification the design adapts automatically to new environmental conditions.
The applicability of this approach depends, however, on the availability of reliable bulk P-M coefficients, which requires a concerted collection of data in different climatic regions.
The larger this component, the smaller is the required ventilation rate.
The evaporation coefficient, namely the fraction of the radiation load dissipated as latent heat, is an important ventilation design parameter, of which designers often have no more than a qualitative knowledge.
In an attempt to overcome this difficulty, the present study proposes to incorporate the Penman-Monteith (P-M) evapotranspiration equation into the standard ventilation design formula.
With this modification the design adapts automatically to new environmental conditions.
The applicability of this approach depends, however, on the availability of reliable bulk P-M coefficients, which requires a concerted collection of data in different climatic regions.
Publication
Authors
I. Seginer
Keywords
Penman-Monteith equation, climatic differences, radiation load.
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