На японском языке. Расширенное резюме на английском языке. Joual
of Agrıcultural Meteorology. – 1982. – V. 38(3). – P. 253-259.
Summary
The influence of the area ratio of floor surface to covering surface on the heat transfer of greenhouses was calculated with a mathematical model. Relations between the area ratios and the overall heat transfer coefficient of greenhouses covered with Glass, P VC and PE single layers, the heat resistance of their covering surfaces and the equivalent temperatures of radiative cooling were examined under the normal weather conditions during winter nights. The results are as follows: The area ratio of a greenhouse is a conversion coefficient of heat flux at the floor surface to that at covering surface. The heat flux between floor surface and covering surface consists of convective and radiative heat fluxes. Both fluxes have the same conversion coefficient in the normal greenhouses.
With an increase of the area ratio of a greenhouse the heat resistance of the covering surface reduced, but the equivalent temperature of radiative cooling for the greenhouse increased (Figs.2 and 3).
When the area ratio of a greenhouse increased, the overall heat transfer coefficient which is a
function of the heat resistance and the equivalent temperature of radiative cooling, also increased, resulting from 1 and 2.
The correlation between the area ratio and the overall heat transfer coefficient of a greenhouse was greater in PE-greenhouse than in PVC-greenhouse. And that was the lowest in Glass-greenhouse. Therefore at the low value of the area ratio the overall heat transfer coefficient of PE-greenhouse was smaller than those of PVC-and Glass-greenhouses (Figs.5 and 6).
When the measurement of the heat requirement or the overall heat transfer coefficient in the experimental or particular type greenhouses is done, the area ratios of those greenhouses should be considered.
The influence of the area ratio of floor surface to covering surface on the heat transfer of greenhouses was calculated with a mathematical model. Relations between the area ratios and the overall heat transfer coefficient of greenhouses covered with Glass, P VC and PE single layers, the heat resistance of their covering surfaces and the equivalent temperatures of radiative cooling were examined under the normal weather conditions during winter nights. The results are as follows: The area ratio of a greenhouse is a conversion coefficient of heat flux at the floor surface to that at covering surface. The heat flux between floor surface and covering surface consists of convective and radiative heat fluxes. Both fluxes have the same conversion coefficient in the normal greenhouses.
With an increase of the area ratio of a greenhouse the heat resistance of the covering surface reduced, but the equivalent temperature of radiative cooling for the greenhouse increased (Figs.2 and 3).
When the area ratio of a greenhouse increased, the overall heat transfer coefficient which is a
function of the heat resistance and the equivalent temperature of radiative cooling, also increased, resulting from 1 and 2.
The correlation between the area ratio and the overall heat transfer coefficient of a greenhouse was greater in PE-greenhouse than in PVC-greenhouse. And that was the lowest in Glass-greenhouse. Therefore at the low value of the area ratio the overall heat transfer coefficient of PE-greenhouse was smaller than those of PVC-and Glass-greenhouses (Figs.5 and 6).
When the measurement of the heat requirement or the overall heat transfer coefficient in the experimental or particular type greenhouses is done, the area ratios of those greenhouses should be considered.