Design and Adjustment of Shed Greenhouse Environment with Double Covers and Air Gap in Taiwan
Date Issued
2005
Date
2005
Author(s)
Tu, Tien-Tun
DOI
zh-TW
Abstract
This research emphasizes on the improvement of recent single-layer greenhouse structures in Taiwan, by building real greenhouses that own the characteristic of double-cover air gaps to test the environment inside the structures. For heating and cooling, used operators to achieve the economically suitable terms of planting under Taiwan’s climate. Probe into the proper design of bio-production equipments in Taiwan from two parts, one is from the economic benefits of the greenhouse structures and the other is from the environmental adjustment capability. Test two sample greenhouses on different environmental regions, one sample is in high elevation in MeiFeng and the other is in the level ground in Taipei. As to the material and structure, the two single-shed, double-layer PVC, light steel structures are built with 20cm and 25cm air gaps separately, 30cm interval and external vents, outdoor double-layer black nets with 50% and 20% transparency, cooling fans, and 1mm blue PVC sheets. The frameworks of the two greenhouses are 99.4 kg/m² and 132.5 kg/m² separately, and the spaces are 38.7 kg/m³and 52.4 kg/m³. As to the environmental experiment, calculated and measured the two greenhouses on the basis of different seasons and analyzed the temperature reduction ability in summer daytime, the heat preservation capacity in winter nights and the facility conditions under other seasons. Findings in summer experiments indicate that the perfect mode, which can reduce the inner temperature about 3.1℃ and has a close inside-outside temperature, is achieved under 25cm air gap, both black nets blocking, cooling fans on and vents opened. Moreover, data suggests that the black nets and cooling fans have similar effects on temperature reduction ability. In winter experiment shows that the temperature in the daytime can increase 6 to 14℃, and be 1 to 2℃ higher than outside at winter nights when the two different thicknesses of air gaps are closed. As to the heat prevention experiment of air gaps, results conclude that the 25cm air gap with open vent which gets the minimum thermal energy can apply to the purpose of heat prevention in summer; the 20cm air gap with closed vent which gets the maximum calorific capacity can apply to that of heat preservation in winter. Finally, the two sample greenhouses can meet the needs of the medium or low light demanded plants by using double-layer blue PVC sheets as the cover materials, which have a lower than 30% transparency.
Subjects
溫室
熱收支
空氣層
雙層被覆
Greenhouse
Double-layer covers
Air gap
Heat flux
SDGs
Type
thesis
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