Articles
THERMAL CHARACTERISTICS OF SCREENHOUSE CONFIGURATIONS IN A WEST-AFRICAN TROPICAL CLIMATE
Article number
443_4
Pages
39 – 46
Language
Abstract
The Biological Control Program (BCP) for Africa operates from Cotonou, Benin, which is part of the International Institute of Tropical Agriculture (IITA). Its present mandate includes the provision of Biological Control Labs to African National Biological Control Programs.
Thirty tropical countries are targeted.
The challenge presently faced by the BCP is to develop biological control structures adapted to the climatic and economic conditions of those countries.
Specifically, structures such as greenhouses, screenhouses and growth chambers must provide, at reasonable expense, protection of experimental material against insects and airborne pathogens, as well as close to ambient temperature and sunlight.
A recent innovation, the "screenhouse", is a promising technology with respect to its inherent capacity of providing near-ambient conditions by passive cooling (natural ventilation, radiation absorption and evaporative cooling) alone.
However, overheating is still a problem in many conditions.
In order to characterize the thermal performance of such structures, and to optimize their cooling performances, various screenhouse architectural configurations, screen types and water cooling options were evaluated during three seasons at the IITA, BCP research station.
Thirty tropical countries are targeted.
The challenge presently faced by the BCP is to develop biological control structures adapted to the climatic and economic conditions of those countries.
Specifically, structures such as greenhouses, screenhouses and growth chambers must provide, at reasonable expense, protection of experimental material against insects and airborne pathogens, as well as close to ambient temperature and sunlight.
A recent innovation, the "screenhouse", is a promising technology with respect to its inherent capacity of providing near-ambient conditions by passive cooling (natural ventilation, radiation absorption and evaporative cooling) alone.
However, overheating is still a problem in many conditions.
In order to characterize the thermal performance of such structures, and to optimize their cooling performances, various screenhouse architectural configurations, screen types and water cooling options were evaluated during three seasons at the IITA, BCP research station.
Results show that in the climatic conditions tested, the architectural configuration is the most influential factor affecting the inside temperatures of the screenhouse followed by the type of screen used.
Water cooling had more effect in the rainy season.
Heat transfer models were formulated for every screenhouse configuration and set of options tested.
Computer simulations generated the predicted inside temperatures of the screenhouses using the heat transfer characteristics calculated from the experimental data.
The research aimed and succeeded at establishing fundamental understanding of the heat transfer of the screenhouse system in order to develop criteria for better designs.
Authors
G. Desmarais, G.S. Vigaya Raghavan
Keywords
Tropical greenhouse, insect proof screens, biological control, natural ventilation, evaporative cooling, low energy greenhouse
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