ISHS Acta Horticulturae 578: International Symposium on Design and Environmental Control of Tropical and Subtropical Greenhouses
ENVIRONMENT-CONTROLLED HYDROPONICS INSIDE SUBTROPICAL AIR-INFLATED GREENHOUSES |
| Authors: | C.-H. Wu, H.-S. Chang, T.-C. Kao, W.-S. Wu |
| Keywords: | environmental control, hydroponics, double-layer greenhouse, subtropical, anti-typhoon |
| Abstract:
To enhance the cooling capability for the double-layer greenhouses, which were used in Taiwan, imported from North America, the original design for cooling purpose was strengthened through the enlargement of the watering pad and the augment in air flow rate for ventilation. These double-layer polyethylene greenhouses having same size, same orientation, same material, same construction and same control system equipped with a dynamic root floating hydroponics system planting leafy vegetables, tomato and cucumber under controlled environment. To investigate the thermal removing ability on excessive heat for these remodeled double-glazing greenhouses, various temperature control modes are operated and observed to understand the resulted extent of cooling. The acquisited data from one greenhouse adopting forced-convection mode using two fans, or evaporative-cooling mode driven either by double fans or single fan were compared with the values of corresponding parameters collected in another plastic house employing the same equipment under the same atmospheric conditions except that it is not shaded. In the case that the unshaded greenhouse employed purely ventilated control mode with double fans, the average indoor temperature was only 1°C higher than that outdoors in the shiny noon of August. The uniformity in temperature distribution is acceptable. If the watering pad was actuated at the same time, the average temperature indoors could be 3.4°C lower than that of the case mentioned above. It quantitatively showed the heat removal ability of the pad. Inside the shaded greenhouse, the average temperature of eighteen sensing points was 3.3°C cooler than atmospheric temperature at noon in the shiny day in August in case that the fan-and-pad system was operated. Under the similar conditions except the greenhouse is unshaded, the temperature was 2.4°C low than the outdoor level, however, the distribution in relative humidity is not so uniform as that in another compared shaded-greenhouse. | |
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