Solar energy collector

Claim 1

A device for collecting solar energy comprising: a closed first envelope filled with a fluid at saturating vapour pressure, comprising at least an evaporator and a condenser, said evaporator being exposed to the incident solar radiation, said fluid therein passing to the vapour state, said vapour condensing in said condenser which is placed outside said incident radiation for giving up the heat to the surrounding medium; means for returning the fluid in a liquid phase to the evaporator, said means being placed inside said first envelope; a closed second envelope located around said first envelope at least in the evaporator part therof; thermal insulation means between said evaporator and an outer surface of said second envelope; and wherein at least the evaporator of said first envelope is covered with a material which absorbs said incident radiation; said absorbent material consists of one material selected from the group constituted by zinc, molybdenum and tungsten; said thermal insulating means comprises a gaseous medium between the evaporator and an outer wall of said second envelope at a pressure lower than atmospheric pressure; said pressure of said gaseous medium being lower than 1.3 10 -2 Pascal; said thermal insulating means comprises, at least on the part exposed to the incident radiation of the inner surface of the second envelope, a filtering layer which transmits said incident radiation and reflects the infrared radiation coming from said evaporator; said filtering layer is constituted by indium oxide In 2 O 3 ; said thermal insulating means comprises, in a part of the inner surface of the second envelope which is opposed to that exposed to the incident radiation, a layer reflecting said incident radiation; said fluid consists of one fluid selected from a group constituted by water, glycol, alcohol, ammonia and a mixture of said fluids; said means for returning the fluid comprises a capillary system disposed along the inner wall of said first envelope, and said capillary system is constituted by sintered material.

Claim 2

A device for collecting solar energy comprising: a closed first envelope filled with a fluid at saturating vapour pressure, comprising at least an evaporator and a condenser, said evaporator being exposed to the incident solar radiation, said fluid therein passing to the vapour state, said vapour condensing in said condenser which is placed outside said incident radiation for giving up the heat to the surrounding medium; means for returning the fluid in a liquid phase to the evaporator, said means being placed inside said first envelope; a closed second envelope located around said first envelope at least in the evaporator part therof; thermal insulation means between said evaporator and an outer surface of said second envelope; and wherein at least the evaporator of said first envelope is covered with a material which absorbs said incident radiation; said absorbent material consists of one material selected from the group constituted by zinc, molybdenum and tungsten; said thermal insulating means comprises a gaseous medium between the evaporator and an outer wall of said second envelope at a pressure lower than atmospheric pressure; said pressure of said gaseous medium being lower than 1.3 10 -2 Pascal; said thermal insulating means comprises, at least on the part exposed to the incident radiation of the inner surface of the second envelope, a filtering layer which transmits said incident radiation and reflects the infrared radiation coming from said evaporator; said filtering layer is constituted by indium oxide In 2 O 3 ; said thermal insulating means comprises, in a part of the inner surface of the second envelope which is opposed to that exposed to the incident radiation, a layer reflecting said incident radiation; said fluid consists of one fluid selected from a group constituted by water, glycol, alcohol, ammonia and a mixture of said fluids; said means for returning the fluid comprises a capillary system disposed along the inner wall of said first envelope, and said capillary system is constituted by sintered material.