ISHS Acta Horticulturae 578: International Symposium on Design and Environmental Control of Tropical and Subtropical Greenhouses
ENVIRONMENTAL CONTROL OF DOUBLE-LAYER GREENHOUSES IN TAIWAN |
| Authors: | C.-H. Wu, H.-S. Chang, J.-T. Shaw |
| Keywords: | double-layer, greenhouse, environmental control, typhoon, environmental |
| Abstract:
Two double-covering plastic houses were built at the experimental station on horticulture of National Taiwan University. Fan-and-pad cooling facility equipped with the necessary control unit was assembled on the two greenhouses. A number of control concepts including force convection, fan-and-pad evaporation, natural convection, and closed living environment were carried out and compared to find the effective means for eliminating the thermal load inside the double-covering greenhouses in the summer of Taiwan. The fan-and-pad facility attained the best performance on cooling than those obtained using free convection or forced convection. It was quite powerful to remove the excessive heat especially in the front region of the greenhouse where the temperature could be 7°C below the atmospheric temperature. Compared to the record of closed greenhouse, it might deduct 21°C in the same location. However, the cooling potential starting from the central part of the greenhouse was not enough and resulted a temperature gradient about 1.4°C/m which should be alleviated by some auxiliary mechanical equipment such as fog system or by enlargement of the ventilation capability of the centrifugal fan to improve the living environment. In the summer, Taiwan area was threatened by the typhoon alarms. Since they were built, many typhoons attacked Taipei in the typhoon seasons. No damage reported on our greenhouses up to now. | |
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