| 摘要 |
<p>PURPOSE:To prevent thermal efficiency from being lowered due to dew condensation on the inside surface of a cover glass by a method wherein the distance between a sunlight-transmitting film and a heat-collecting plate is maintained at a fixed value by a supporting stand and the volume of an air layer between the cover glass and the film is changed according to the sunshine condition. CONSTITUTION:Studs 7, 8 of the supporting stand 9 are mounted on a heat insulating material 3 and so supported that the distance between the film 13 and the heat- collecting plate 1 is constant. Since the film 13 is flexible and has deflections 14 at its periphery, even when the volume of an air layer 16 is increased by heating, the air layer 17 is kept at the same pressure as the air layer 16 and the layer 16 is kept at the atmospheric pressure by the function of a pressure-equalizing passage 5. Accordingly, the air layer 17 is kept in a sealed condition by a simple sealing of ribs 6. Since convection is prevented perfectly by the double-cover structure, dew condensation on the inside surface of the cover glass 15 is prevented however low the temperature of the glass may be. The dew condensation is prevented also when the sunshine is lost and the temperature of the plate 1 is lowered.</p> |
