ISHS Acta Horticulturae 148: III International Symposium on Energy in Protected Cultivation
THERMAL ANALYSIS OF GREENHOUSES WITH HEAT TRANSFER MATRIX AND ENERGY EFFICIENCY |
| Authors: | K. Tachibana, H. Minagawa |
| Abstract:
Heat consumption is a major factor for the design of greenhouses. Overall heat transfer coefficient is one of the fundamental values for the environmental design. It was theoretically analyzed with heat transfer matrix. Required energy depends on solar energy accumulated in floor soil in the daytime and released in the nighttime. By the use of Laplace transform of heat transfer matrix equation, the diurnal change in the heat accumulated in soil in the daytime is found for greenhouses both with and without artificial heating system. From the result, the ratio of the heat released from soil through the nighttime to the amount of hot air heating energy can be calculated. The ratio of the amount of accumulated energy to solar radiation per day, namely the efficiency of solar energy utilization is discussed. The result shows that the efficiency decreases when any means raising inside air temperature, e.g. heating system or double grazing, are available. | |
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