ISHS Acta Horticulturae 633: XXVI International Horticultural Congress: Protected Cultivation 2002: In Search of Structures, Systems and Plant Materials for Sustainable Greenhouse Production
GREENHOUSE STRUCTURES AND PLANT GROWTH CONTROL SYSTEMS FOR ENERGY EFFICIENT CROP PRODUCTION |
| Author: | T.H. Short |
| Keywords: | computational fluid dynamics, CFD, fan-pad cooling, fan ventilation, natural ventilation, controlled environment agriculture, energy conservation, decision model |
| Abstract:
Designing greenhouse glazing systems for high solar radiation transmission is essential for most crops, especially during the low light conditions. Framing and glazings, however, must also be designed to reduce air infiltration and increase thermal insulation. With night curtains, a daytime glazing is maintained and insulation is added when it is most needed at night. A summary of annual heat use due to structural choices is illustrated. Techniques such as pumping insulative pellets into and out of double-wall glazing panels is also illustrated for both night insulation and selective summer shading. Both central boiler systems and unit space heaters are discussed in terms of fuels, the amount of greenhouse space to be heated, and the level of capital investment desired. Each heating system should be designed and installed to optimize heat recovery from both the burners and delivery systems. New aerodynamic design techniques for naturally ventilated greenhouses are illustrated. Structural variables such as greenhouse width, roof and side vent locations, vent opening widths, aerodynamic profiles, internal and external shading systems, and benching for various wind speeds and directions are discussed. A decision support system for growing hydroponic tomatoes is shown to integrate air and root temperatures, air humidity, nutrient solution pH and EC, and solar radiation. An automated one-page processor is illustrated that can be found on the Internet at: http://www.oardc.ohio-state.edu/hydroponics/. | |
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