Patent Application
20070012314
The present invention relates to a solar heating system, and more particularly to a solar water heating system for swimming pools.
Solar heating systems employ solar radiation to heat a fluid medium to transfer heat for a heating application, such as heating of a residential or commercial building, heating of a swimming pool, or other applications. Commonly, the fluid medium is a liquid, such as water. In a typical arrangement, a solar heat exchanger employs an upper manifold and a lower manifold, the manifolds being connected by at least one fluid passage wherein a liquid is heated by solar radiation as the liquid travels along the fluid passage between the manifolds.
Generally, a liquid flows either from the lower manifold to the upper, or from the upper manifold to the lower. In either case, air bubbles collect within the manifolds, within the fluid passages connecting the manifolds, and within other parts of a solar heating system that incorporates the solar heat exchangers. Formation of air bubbles is found particularly within the solar heat exchanger as the liquid is heated.
Air trapped within the solar heating system prevents optimum heating of the liquid, and contributes to mechanical stresses on the solar heat exchangers that may ultimately cause the heat exchanger to leak or fail.
Air within a heat exchanger may become trapped against an upper part or surface of the heat exchanger and thus insulate the liquid from the heating of solar radiation. This prevents the maximum transfer of solar energy to the liquid, decreasing the efficiency of the solar heat exchanger.
Vibrations caused by air bubbles traveling through a solar heating system, and exiting the solar heating system such as into a swimming pool, result in vibration of various components of the solar heating system including the heat exchangers. These vibrations cause wear on the components of the solar heating system, and particularly on the heat exchangers, contributing to a shortened useful life of the solar heating system. Additionally, vibrations caused by air within the system causes noise during operation of the system.
A solar water heating system for heating a liquid drawn from and returned to a liquid source, such as a swimming pool, employs at least one solar heat collector to heat the liquid using solar energy. The solar heat collector has an upper manifold and a lower manifold, and at least one fluid passage between the upper and lower manifold in a generally conventional arrangement. The upper and lower manifolds each are inclined, each having an upper end and a lower end, so that air bubbles within the solar heat collector will travel to the upper ends of the upper and lower manifolds.
A liquid reservoir is located at an elevation above the solar heat collector, the reservoir having an outlet at a bottom portion of the reservoir and a supply inlet at an upper portion of the reservoir. The outlet is coupled to the upper end of the upper manifold so that liquid within the reservoir may flow by gravity into the solar heat collector. A float valve may be employed within the reservoir to maintain a constant hydrostatic head pressure at the reservoir output.
An air venting conduit is connected between the solar heat collector and the reservoir so that air bubbles trapped or formed within the solar heat collector are vented to the reservoir.
A fluid supply conduit has a first end in fluid communication with the supply inlet of the reservoir and a second end in fluid communication with the liquid source, to supply a liquid medium from the liquid source to the reservoir, and a fluid returning conduit has a first end in fluid communication with the solar heat collector and a second end in fluid communication with the liquid source to return heated liquid to the liquid source.
A metering valve may be disposed inline of the fluid returning conduit to vary the flow rate of liquid from the solar heat collector, and to thereby vary the dwell time of liquid within the solar heat collector.
A pump may be provided to draw liquid from the liquid source and pump the liquid to the reservoir.
These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.
The present invention is a solar water heating system, designated generally as 100 in the drawings. A liquid is supplied to the solar water heating system 100 from a liquid source, heated by the solar water heating system 100, and returned to the liquid source. Referring to
It can be appreciated that, in alternative embodiments, the solar water heating system 100 may be readily adapted to other heating applications, including closed circuit applications wherein a liquid is contained and circulated within a closed circuit that includes a heat transferring apparatus to conduct heat from the solar water heating system 100 for a heating application.
In a typical configuration, a swimming pool 110 may be associated with a hot tub or spa 112 or the like, the swimming pool 110 and spa 112 being serviced together by a filtration system including a conventional pump 114 and a filter 116. In the configuration shown in
The solar water heating system 100 comprises at least one solar heat collector 120, and a pressure regulator 140. While the solar water heating system 100 is illustrated with a single solar heat collector 120, additional solar heat collectors 120 may be employed. An example of a suitable solar collector useful for this invention is marketed under the name SunGrabber™ by FAFCO, Inc. Corporation of Chico, California, model 07295. The pressure regulator 140 regulates the hydrostatic head pressure of liquid that is fed, by gravity, into the solar heat collector 120. A liquid is supplied to the pressure regulator 140 from a liquid source. In the presently illustrated embodiment, liquid is supplied from the filter return conduit 117 to the solar water heating system 100 by a supply conduit 118 that is connected to a supply valve 119 of conventional design connected inline of the filter return conduit 117. It can be understood that the supply conduit 118 may be alternately configured to draw liquid from a liquid source. Thus, opening the supply valve 119 allows some of the liquid pumped by the pump 114 to be fed into the solar water heating system 100, thereby supplying the pressure regulator 140 with liquid from the liquid source, such as, in the illustrated embodiment, water from the swimming pool 110.
The solar heat collector 120 comprises an upper manifold 122 and a lower manifold 132, the upper manifold 122 being positioned at an elevation above the lower manifold 132. The upper manifold 122 is connected to the lower manifold 132 by at least one fluid passage 130 in a generally conventional manner whereby a liquid supplied to the upper manifold 122 is heated by solar heating as the liquid passes through at least one fluid passage 130 to the lower manifold 132.
Each of the upper and lower manifolds 122, 132 are inclined, such that the upper manifold 122 has an upper end 124 and a lower end 126, and the lower manifold 132 has an upper end 134 and a lower end 136. Because of the incline of each of the manifolds 122, 132, air within the solar heat collector 120 will move toward the upper ends 124, 134 of the upper and lower manifolds 122, 132 respectively as the air bubbles tend to rise along the inclined manifolds 122, 132.
A liquid is supplied to the solar heat collector 120 for heating from the pressure regulator 140. The pressure regulator 140 is located at an elevation above the highest point of the solar heat collector 120. The liquid is fed by gravity from the pressure regulator 140 at a hydrostatic head pressure that is determined by the liquid level within the pressure regulator 140.
The pressure regulator 140 comprises a reservoir 142 and a float valve 144. At least a float member 146 of the float valve 144 is disposed within the reservoir 142. The float member 146 is connected by an appropriate lever to the valve 144, for example a simple flapper valve or other suitable design, and is movable between a lower position 148a, where the float valve 144 is fully opened, and an upper position 148b where the float valve 144 is fully closed. At intermediate positions of the float member 146, the float valve 144 is partially open in relation to the position of the float member 146. Thus, liquid supplied to the solar water heating system 100 enters the reservoir 142 through the float valve 144 at a flow rate related to the liquid level within the reservoir 142.
The float valve 144 regulates liquid flow into the reservoir 142 to compensate for liquid flowing out of the reservoir 142 and into the solar heat collector 120 so that a constant hydrostatic head pressure is maintained within the solar heat collector 120. The liquid flows from an outlet 150 of the reservoir, located at the bottom or a lower portion of the reservoir 142, to the upper end 124 of the upper manifold 122 of the solar heat collector 120. The liquid flows from the upper manifold 122, through the fluid passage 130 wherein the liquid is heated, and out from the lower end of the lower manifold 132. The head pressure could be varied by adjusting the fluid level in reservoir 142 or varying the elevation of the reservoir.
A fluid return conduit 154 connects the lower end 136 of the lower manifold 132 of the solar heat collector 120 to the swimming pool 110 to return heated water to the swimming pool 110. A manually adjustable metering valve 156 of conventional design is provided inline of the fluid return conduit 154 so that the rate of flow of liquid from the solar heat collector 120 may be varied. By varying the rate of flow of liquid from the solar heat collector 120, the dwell time of the liquid within the solar heat collector 120 may be varied, allowing for control over the temperature of the liquid exiting the solar heat collector 120. Additionally, the metering valve 156 may be adjusted such as to decrease the flow rate from the reservoir 142 or through the solar heat collector 120 in the event that the flow rate through the float valve 144 into the reservoir 142 is less than the gravity flow rate through the reservoir 142 or through the solar heat collector 120.
In the illustrated embodiment, a two-way valve 166 of conventional design is employed in the fluid return conduit 154 to selectively deliver heated water from the solar heat collector 120 to either the swimming pool 110 or the spa 112, or both. It can be recognized that additional configurations are possible.
An air vent line 158 is connected to the upper end 124 of the upper manifold 122 to allow air to be vented from the system. Additionally, the air vent line 158 may be connected to the upper end 134 of the lower manifold 132 to allow air to be vented directly from the lower manifold 132, as shown in the illustrated embodiment. Alternate arrangements may be employed, such as a single air vent line in connection with both the upper and lower manifolds 122, 124, separate air vent lines for each of the upper and lower manifolds 122, 124, or an air vent line connected only to the upper end of the upper manifold 122, with a fluid passage provided between the upper end 134 of the lower manifold 132 and the upper manifold 122 such that air collected at the upper end 134 of the lower manifold 132 will pass to the upper manifold 122 rather than collect in the lower manifold 132.
The air vent line 158 vents air from the solar heat collector 120 into the reservoir 142. A float activated check valve 160 is located in the top, or an upper portion, of the reservoir 142. Under normal operating conditions, the float activated check valve 160 is open so that air vented from the solar heat collector 120 is allowed to exit from the reservoir 142 to the atmosphere.
An overflow conduit 162 is connected to the top, or an upper portion, of the reservoir 142. The overflow conduit 162 returns liquid overflow from the reservoir 142 to the swimming pool 110. In the event that the liquid flow into the reservoir 142 exceeds the liquid flow from the reservoir 142, such as if the float valve 144 malfunctions, an increase of the liquid level within the reservoir 142 as the reservoir 142 fills causes the float activated check valve 160 to close as the float is raised by the liquid, preventing liquid spillage from the reservoir 142. Excess liquid is then returned to the swimming pool 110 by way of the overflow conduit 162. An outlet end 164 of the overflow conduit 162 is preferably located above the water level of the swimming pool 110 to discharge the liquid overflow into the atmosphere above the water level of the swimming pool 110 so that a noise is created by the overflow liquid discharging into the swimming pool 110, audibly drawing attention to the overflow condition.
In a solar heating system 100 according to the present invention, mechanical stresses of the solar heating system, and particularly of the solar heat collector 120, are reduced by the elimination of air collected within the system, because vibrations caused by circulation of air and air bubbles is reduced or eliminated. Additionally, because liquid is delivered to the solar heat collector 120 by a gravity flow under a controlled hydrostatic head pressure, fluid pressures within the solar heat collector 120 are lower than in systems wherein a liquid is pumped under pressure through a solar heat exchanger.
A liquid level controlling device 170, such as of a type commonly known and used in swimming pool installations, may be used to maintain a proper, and constant, benchmark water level 172 in the swimming pool 110. When a liquid supply pressure is removed from the system, such as by deactivating the pump 114 or by closing the supply valve 119, the solar heating system 100 may be drained entirely down to the benchmark water level 172.
It will be understood that the above-described embodiments of the invention are illustrative in nature, and that modifications thereof may occur to those skilled in the art. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed herein, but is to be limited only as defined in the appended claims.
