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Evaporative cooling of a ventilated greenhouse rose crop
Year:
2006
Authors :
Dayan, Ehud
;
.
Fuchs, Marcel
;
.
Presnov, Eugene V.
;
.
Volume :
138
Co-Authors:
Fuchs, M., Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, The Volcani Centre, PO Box 6, Bet Dagan, 50250, Israel
Dayan, E., Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Gilat Experiment Station, Israel
Presnov, E., Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Gilat Experiment Station, Israel
Facilitators :
From page:
203
To page:
215
(
Total pages:
13
)
Abstract:
Greenhouse crops may suffer from excessive heat load in warm weather. A procedure is developed to evaluate latent heat cooling by means of crop transpiration and free water evaporation from a wet pad and fan system. The procedure uses concurrent external climatic factors as input data. It treats construction characteristics (dimensions and radiometric properties of the roof cover), plant foliage (leaf area, stomatal conductance) and ventilation rate as parameters to calculate heat transport coefficients. Measurements in a greenhouse rose crop (Rosa indica L cv 'Mercedes Long') show that the numerical solution of the energy balance equation predicts accurately crop transpiration, foliage temperature, air temperature and humidity inside the greenhouse. With ventilation rates of 30 volume changes per hour and external air humidity below 50%, transpiration of a plant well supplied with water, cools the foliage and the air in the greenhouse below external temperature even when solar radiation is at its maximum value. Cooling obtained with an evaporative wet pad at the air inlet lowers vapour pressure deficit in the greenhouse and decreases transpiration rate. Still, total latent heat dissipation added to pad evaporation and crop transpiration is higher than that obtained by crop transpiration without the wet pad. The combined solution of the energy balance of the air passing through the evaporative pad and of the crop predicts accurately transpiration of the rose crop and internal temperature and humidity. The evaporative pad cools the air considerably; but the lowering of transpiring leaf temperature is only minor. Evaporation from the pad decreases when external humidity increases. Crop transpiration rate when the wet pad operates is nearly independent of external humidity and ventilation rate. © 2006 Elsevier B.V. All rights reserved.
Note:
Related Files :
Climate control
COOLING
crop
humidity
latent heat flux
Rosa indica L
temperature
temperature effect
transpiration
Show More
Related Content
More details
DOI :
10.1016/j.agrformet.2006.05.002
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
18901
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:25
Scientific Publication
Evaporative cooling of a ventilated greenhouse rose crop
138
Fuchs, M., Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, The Volcani Centre, PO Box 6, Bet Dagan, 50250, Israel
Dayan, E., Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Gilat Experiment Station, Israel
Presnov, E., Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Gilat Experiment Station, Israel
Evaporative cooling of a ventilated greenhouse rose crop
Greenhouse crops may suffer from excessive heat load in warm weather. A procedure is developed to evaluate latent heat cooling by means of crop transpiration and free water evaporation from a wet pad and fan system. The procedure uses concurrent external climatic factors as input data. It treats construction characteristics (dimensions and radiometric properties of the roof cover), plant foliage (leaf area, stomatal conductance) and ventilation rate as parameters to calculate heat transport coefficients. Measurements in a greenhouse rose crop (Rosa indica L cv 'Mercedes Long') show that the numerical solution of the energy balance equation predicts accurately crop transpiration, foliage temperature, air temperature and humidity inside the greenhouse. With ventilation rates of 30 volume changes per hour and external air humidity below 50%, transpiration of a plant well supplied with water, cools the foliage and the air in the greenhouse below external temperature even when solar radiation is at its maximum value. Cooling obtained with an evaporative wet pad at the air inlet lowers vapour pressure deficit in the greenhouse and decreases transpiration rate. Still, total latent heat dissipation added to pad evaporation and crop transpiration is higher than that obtained by crop transpiration without the wet pad. The combined solution of the energy balance of the air passing through the evaporative pad and of the crop predicts accurately transpiration of the rose crop and internal temperature and humidity. The evaporative pad cools the air considerably; but the lowering of transpiring leaf temperature is only minor. Evaporation from the pad decreases when external humidity increases. Crop transpiration rate when the wet pad operates is nearly independent of external humidity and ventilation rate. © 2006 Elsevier B.V. All rights reserved.
Scientific Publication
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