Solar Water Heater

Abstract

A low-cost absorber panel for a solar hot water heating system is provided. An aluminum absorber plate, under exposure to solar radiation, makes an efficient transfer of heat to water circulating within the collector panel by direct contact with the medium in an optimized area-to-volume configuration. An innovative use of fasteners makes it possible to accommodate expansion for freezing and to allow for disassembly and maintenance. Additionally, a low-cost heat exchanger and a low-cost solar hot water system are presented using common structures.

1 . A low-pressure absorber panel for solar hot water systems, comprising:
 an essentially rectangular aluminum absorber plate;   an essentially matching aluminum companion plate in spaced relationship to the absorber plate to which it is joined below by a means for binding;   a means for spacing to create an internal space between the absorber and companion plates for a flow of water there through, the means for spacing providing a water-tight seal;   a means for channeling to create a serpentine flow path for the water; and   at least one port through one of the absorber and companion plates for water to enter the internal space and at least one other port through one of the absorber and companion plates for water to exit, the at least two ports located so as to maximize the serpentine flow path, wherein the water flowing in contact with the absorber plate receiving solar radiation is heated by it and forms a medium for transferring heat.   
     
     
         2 . The low-pressure absorber panel of  claim 1 , wherein the means for spacing is an elastic gasket of substantially rectangular cross-section which is arrayed along the periphery edges of the absorber and companion plates and tensioned to provide a compression seal. 
     
     
         3 . The low-pressure absorber panel of  claim 1 , wherein the means for spacing is an elastic gasket of substantially circular cross-section which is arrayed along the periphery edges of the absorber and companion plates and adjustably tensioned to provide a compression seal. 
     
     
         4 . The low-pressure absorber panel of  claim 2 , wherein the means for binding is an extruded clip having arms angled so as to form a narrowed opening, the extruded clip covering the elastic gasket of substantially rectangular cross-section along the length of each periphery edge, the elastic gasket compressed between the arms to form a wedge shape which resists removal of the extruded clip from the periphery edge. 
     
     
         5 . The low-pressure absorber panel of  claim 3 , wherein the means for binding is machine screws and nuts straddling the gasket of substantially circular cross-section along the extent thereof, the machine screws optionally provided with o-ring seals for positioning in the internal space. 
     
     
         6 . The low-pressure absorber panel of  claim 5 , wherein the spacing of the machine screws is at sufficient interval as to prevent bulging of the plates under pressure. 
     
     
         7 . The low-pressure absorber panel of  claim 1 , wherein the means for channeling is a plurality of elastic baffles of substantially rectangular cross-section extending in alternation from one end or the other of the gasket at the periphery, beginning with the end closest to the entry port and ending with the end closest to the exit port, to a point short of the opposite end, whereby the parallel channels thereby formed are connected to adjacent channels by alternating passages, the elastic baffles held in place and in compression by bolts and nuts sealed with o-rings spaced along the length thereof. 
     
     
         8 . The low-pressure absorber panel of  claim 1 , further comprising a pressure differential of not more than 2 psi to urge the flow of water through the internal space. 
     
     
         9 . The low-pressure absorber panel of  claim 1 , further comprising a pressure differential of not more than 1 psi to urge the flow of water through the internal space 
     
     
         10 . The low-pressure absorber panel of  claim 7 , further comprising a means for volume expansion of not less than 9% to accommodate freezing water. 
     
     
         11 . The low-pressure absorber panel of  claim 10 , wherein the means for volume expansion is the loosening of screws and nuts interim the internal space to permit bulging therein. 
     
     
         12 . The low-pressure absorber panel of  claim 1 , wherein the rectangular aluminum absorber and companion plates each substantially measure 32 square feet. 
     
     
         13 . A low-pressure heat exchanger for hot water systems, comprising:
 an essentially rectangular aluminum absorber plate;   an essentially matching aluminum companion plate in spaced relationship to the absorber plate to which it is joined below by a means for binding;   a means for spacing to create an internal space between the absorber and companion plates for a flow of water there through, the means for spacing providing a water-tight seal;   a means for channeling to create a serpentine flow path for the water; and   at least one port through one of the absorber and companion plates for water to enter the internal space and at least one other port through one of the absorber and companion plates for water to exit, the at least two ports located so as to maximize the serpentine flow path, wherein the water flowing in contact with the absorber plate receiving solar radiation is heated by it and forms a medium for transferring heat.   
     
     
         14 . The low-pressure absorber panel of  claim 13 , wherein the means for spacing is an elastic gasket of substantially rectangular cross-section which is arrayed along the periphery edges of the absorber and companion plates and tensioned to provide a compression seal. 
     
     
         15 . The low-pressure absorber panel of  claim 14 , wherein the means for binding is an extruded clip having arms angled so as to form a narrowed opening, the extruded clip covering the elastic gasket of substantially rectangular cross-section along the length of each periphery edge, the elastic gasket compressed between the arms to form a wedge shape which resists removal of the extruded clip from the periphery edge. 
     
     
         16 . The low-pressure absorber panel of  claim 13 , wherein the means for channeling is a plurality of elastic baffles of substantially rectangular cross-section extending in alternation from one end or the other of the gasket at the periphery, beginning with the end closest to the entry port and ending with the end closest to the exit port, to a point short of the opposite end, whereby the parallel channels thereby formed are connected to adjacent channels by alternating passages, the elastic baffles held in place and in compression by bolts and nuts sealed with o-rings spaced along the length thereof. 
     
     
         17 . A low-pressure solar hot water system, comprising:
 a heat-exchange vessel containing a volume of water;   at least one low-pressure absorber panel irradiated by the sun comprising an essentially rectangular aluminum absorber plate, an essentially matching aluminum companion plate in spaced relationship to the absorber plate to which it is joined below by a means for binding, a means for spacing to create an internal space between the absorber and companion plates for a flow of water there through, the means for spacing providing a water-tight seal, a means for channeling to create a serpentine flow path for the water; and at least one port through one of the absorber and companion plates for water to enter the internal space and at least one other port through one of the absorber and companion plates for water to exit, the at least two ports located so as to maximize the serpentine flow path, wherein the water flowing in contact with the absorber plate is heated by conduction and forms a medium for transferring heat;   at least one low-pressure heat exchanger submerged in the heat-exchange vessel comprising a duplicate structure to that of the absorber panel, wherein heated water flowing in contact with the absorber and companion plates of the heat exchanger transfer heat by conduction there through to the volume of water;   a means for providing a fluid communication loop between the at least one low-pressure absorber panel and the at least one low-pressure heat exchanger by connecting respective entrance and exit ports; and   a means for creating a circulation current in the fluid communication loop to thereby transfer heat between the at least one low-pressure absorber panel and the at least one low-pressure heat exchanger.   
     
     
         18 . The low-pressure solar hot water system  claim 17 , wherein the means for spacing is an elastic gasket of substantially rectangular cross-section which is arrayed along the periphery edges of the absorber and companion plates and tensioned to provide a compression seal. 
     
     
         19 . The low-pressure solar hot water system of  claim 18 , wherein the means for binding is an extruded clip having arms angled so as to form a narrowed opening, the extruded clip covering the elastic gasket of substantially rectangular cross-section along the length of each periphery edge, the elastic gasket compressed between the arms to form a wedge shape which resists removal of the extruded clip from the periphery edge. 
     
     
         20 . The low-pressure solar hot water system of  claim 17 , wherein the means for channeling is a plurality of elastic baffles of substantially rectangular cross-section extending in alternation from one end or the other of the gasket at the periphery, beginning with the end closest to the entry port and ending with the end closest to the exit port, to a point short of the opposite end, whereby the parallel channels thereby formed are connected to adjacent channels by alternating passages, the elastic baffles held in place and in compression by bolts and nuts sealed with  0 -rings spaced along the length thereof.