Author：Chen Ling-Hsi

Associate Agricultural Engineer, Taichung District Agricultural Research and Extension Station, COA

Abstract：

    Torrential rain, drought and higher temperature are threaten food security due to climate change. Protected culture acreage is increasing in the enhance food self-sufficiency rate policy in Taiwan. Taiwan’s climate patterns are rainy spring, high temperature and high humidity as well as typhoons in summer, and cold wave in winter. Local greenhouse emphasizes both reduce temperature in summer and insulation in winter, and also require moderate natural ventilation, shading or misting in the rainy and hot summer. So the activity roof-window that can protect crop from rain and vent in the sunny day has be taken seriously. Greenhouses mounted with activity roof-window are increasing. The activity roof-window has two kinds, retractable and rolling plastic cover, all need to be closed the roof-window when rainy. Rain sensor with electromechanical control technology can automatically close the roof-window when it rains. There are three types of rain sensors: weight, resistive and optical. The experiment was conducted in Tacun Township, Changhua County on 13th January, 2015. The best performance of rain sensor is optical type and weight type has the least sensitivity because it need take time to soak rain drop. The optical type is expensive, followed by imported weight type, and then resistive type.

Keywords: Rain, Sensing, Protected Cultivation, Roof-window.

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