Solar water heater

Abstract

Solar water heater using the phase-change principle including a collector, a condenser, and .[.an accumulator.]. .Iadd.a vapor release drum .Iaddend.joined to form a natural circulation system .[., including a pressure accumulator and a vapor release drum.]..Iadd.. .Iaddend.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is: 
     
       1. Solar water heater making use of phase-change heat transfer, comprising: (a) a condenser having an .Iadd.upper .Iaddend.inlet and .[.an.]. .Iadd.a lower .Iaddend.outlet, which condenser is in contact with the water to be heated,   (b) a solar collector having a bottom inlet and a top outlet and .[.having an.]. .Iadd.at least one .Iaddend.inner conduit that connects the inlet and the outlet, the conduit being suitable for exposing a heat-transfer medium .[.in.]. .Iadd.within the length of .Iaddend.the conduit to solar energy, the collector outlet being located below the condenser,   (c) .[.conduits joining.]. .Iadd.a second conduit connecting .Iaddend.the outlet of the collector .Iadd.directly .Iaddend.to the inlet of the condenser and .Iadd.a third conduit connecting .Iaddend.the outlet of the condenser directly to the inlet of the collector to form a closed circuit, .[.(d) A.]. .Iadd.said closed circuit adapted to be charged with a .Iaddend.phase-change .[.liquid.]. heat transfer medium .[.located within the circuit.]., .Iadd.   (d) means for limiting the pressure in said closed circuit during normal operation of the heater, and   .[.(e) an accumulator having means for regulating the pressure therein and having an inlet that is connected to the circuit below the collector, and.].   .[.F.]. (.Iadd.e.Iaddend.) a vapor-release drum connected in the circuit .[.between the outlet of the solar collector and the inlet of the condenser.]., .Iadd.upstream of said condenser and downstream of said inner conduit, said inner conduit having its outlet at a point in said drum which is during normal operation of the heater below the liquid-vapor interface within said drum so as to receive heat transfer medium from said inner conduit and, .Iaddend.wherein the vapor-release drum has sufficient volume that the upper surface of the heat transfer medium .[.always.]. remains within the confines of the drum so that, during normal operation of the heater only the heat transfer medium which becomes vaporized is released into the inlet of the condenser .Iadd.whereby all heat transfer takes place due to the conversion of the vapor to the liquid phase.Iaddend..  .[.2. Solar water heater as recited in claim 1, wherein the solar collector has a generally rectangular configuration with an upper horizontal edge on which the collector outlet is located, and wherein the vapor-release drum has an elongated cylindrical configuration that extends parallel to and spaced upwardly from the said upper horizontal edge of the solar collector..]. .[.3. Solar water heater as recited in claim 2, wherein the heat transfer medium is a fluorinated hydrocarbon..]. .[.4. Solar water heater as recited in claim 3, wherein   
     
     
        the heat transfer medium is Freon 114..]. 5. Solar water heater as recited in claim 1, wherein .[.the accumulator is a bladder-type.]. .Iadd.said means for limiting pressure in said closed circuit comprises a bladder-type accumulator having means for regulating the pressure therein and having an inlet that is connected to the circuit below the collector.Iaddend..  .[.6. Solar water heater as recited in claim 5, 
     
     
        wherein the bladder is formed of Neoprene..]. 7. Solar water heater as recited in claim 1, wherein the condenser is located within an insulated water tank, the water tank having a lower water inlet and an upper water outlet the condenser and tank being formed of stainless steel.  .[.8. Solar water heater as recited in claim 1, wherein the solar collector, the conduits, the drum, and the condenser are arranged so that no vapor traps exist within them which would restrict the flow of vapor..]. .[.9. Solar water heater as recited in claim 1, wherein the conduits are comprised of deoxidized copper tubing and deoxidized forged copper fittings which are silver soldered..]. .[.10. Solar water heater as recited in claim 1, wherein the drum is provided with a liquid level observation window..]. 
     
     
            Solar water heater as recited in claim .[.1.]. .Iadd.5 .Iaddend.wherein a shut-off valve is located adjacent the accumulator inlet to permit it to be disconnected from the circuit without loss of 
     
     
        pressure or of fluid. 12. Solar water heater as recited in claim 11, wherein the accumulator is capable of independently containing a supply of 
     
     
        fluid under pressure before initial installation. 13. Solar water heater as recited in claim .[.11.]. .Iadd.5.Iaddend., wherein the accumulator consists of a container separated into two parts by a flexible bladder, the container being provided with a valved inlet into one part for the introduction and retention of an inert gas under pressure and with a valved inlet into the other part for the introduction and retention of the fluid.  .[.14. Solar water heater as recited in claim 1, wherein the drum is of elongated cylindrical conformation and is initially charged with the heat transfer fluid before incorporation into the circuit with integral nipples for field-connection to the conduits..].