Greenhouse water spray cooling system using subterranean water. (Part 1)-Analysis of the cooling load in summer nighttime.:Analysis of the cooling load in summer nighttime

概要

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Greenhouse water spray cooling system is developed for night cooling treatment for raising seedling in summer time. This system adopts a closed-type water curtain cooling system, adding fog spraying of cold subterranean water as a cold source. The relationship is analyzed among the environmental factors, such as inside, outside and ground temperatures of greenhouse and volume and temperature of sprayed water. In the initial period of cooling when the greenhouse is shut and water is sprayed, the heat load for cooling inside the greenhouse, especially vapor condensed heat load is very large. At the steady period late at night, the main heat load for cooling is the heat transmission from the roof of the greenhouse. This water spraying system is able to quickly remove the large amount of initial heat load to lower the inside temperature, and proves to be useful for greenhouse cooling at night in summer. To control the inside temperature by spraying subterranean water, multiple regression analysis calculates the inside temperature from the outside temperature and the temperature and volume of sprayed water. It shows that controlling the volume of sprayed water makes the inside temperature optimum for night cooling of strawberry seedling. Moreover, controlling the volume of water saves subterranean water, leading to energy saving, and this system proves to have high potential to spread for practical use.
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