Abstract: There is provided a solar collector comprising a solar heat absorber plate thermally conductively connected to the evaporator section of a metal heat pipe. The absorber plate and the evaporator section are surrounded by an evacuated glass envelope joined to the heat pipe at the open end of the evaporator section by a glass-metal seal. The condenser section of the heat pipe is spaced from the evaporator section and is formed for installation in a heat transport system. A flexible portion joins the respective open ends of the evaporator section and the condenser section, such flexible portion having an outer diameter smaller than the inner diameter of the evaporator section and that of the condenser section. The moment of resistance of this flexible portion is smaller than the moment that can be withstood by the glass-metal seal.

Abstract: A solar collector comprises a flat absorber and an associated evaporation/condensation system. The evaporation zone, which is in thermal contact with the absorber, has a number of outwardly and downwardly extending protrusions which are spaced along its length and which serve for collecting heat transport medium condensate returning to the evaporation zone under the influence of gravity.

Abstract: A solar collector comprising a heat exchanger duct through which a heat transport liquid is conducted is arranged during operation at an angle relative to the horizontal. An upper portion of this heat transport liquid duct thereby provides a gas collecting reservoir, downstream whereof such duct is formed with a constriction in which a lower pressure prevails. An exhaust duct is in open communication between the gas collecting reservoir and such constriction and removes gas from the reservoir by the passage of the heat transport liquid through the constriction due to the resulting Venturi effect.