Adsorption solar heating and storage system

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Drawings

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in the process commonly known to this art. Thus the air

ADSORPTION SOLAR HEATING AND STORAGE in the panel is warmed and in turn warms the zeolite SYSTEM bed. The zeolite is also warmed by its own absorption of the solar energy. The continuous heating by the sun in

This invention relates to solar energy systems em 5 concert with the relatively dry air blown through the ploying radiant energy collector plates and is concerned more particularly with a new means of energy storage collector by the blower causes the 13X to release the water adsorbate. The final water content of the zeolite from such systems through utilization of zeolites. is determined by its temperature, the relative humidity One of the most formidable problems of solar energy of the purgative air, the speed of the air flow, the time devices to be overcome is the efficient storage of the O heat collected from such systems for use during the duration of this drying process, and the pellet size of the 13X. The heated air from the collector circulates down night and on sunless days. Several storage schemes have through the radiator(s), releasing heat to the building as been advanced, some of which are: insulated water any conventional forced hot fluid system does. The storage tanks, insulated rock piles, or insulated storage resultant cooled water-laden air passes from the radia tanks filled with some type of antifreeze. Each of these 15 tor(s), where storage schemes has some disadvantage, such as ex ground-cooledmost of the water condenses out into a reservoir for later use by the water spray pense, size of volume needed, efficiency of extracting injector.

the stored energy, and decay of the stored energy with energy is Hence, during this phase of the cycle, solar time due to heat losses. In accordance with the present 13x zeolitestored in the form of heat of adsorption in the bed. As long as the circulating air is kept free teachings, however, the above problems are eliminated 20 of water adsorbate, the solar energy can be stored in through the utilization of a zeolitic process. As a back definitly.

ground for insuring a sufficient understanding of the At night, or on cloudy days, this stored energy present invention as claimed, zeolites are a family of is released by injecting atomized water into the blower. chemical compounds that are capable of reversible ad This water circulates through the zeolite bed in the sorption. Typically, heat is released during the adsorp 25 collector and is adsorbed, releasing the heat of adsorp tion process (heat of adsorption); the adsorbate is re tion and warming the circulating air. This warm air leased by applying heat to the zeolite adsorbent while then flows through the radiator(s) to warm the building purging the zeolite with a dry gas. Lifetimes of syn in the same manner as above. The heat extracted from thetic zeolites are on the order of 2000 cycles of adsorp the zeolite bed in the panel is regulated by the amount of tion/release. A representative text applicable to this 30 water injected into the airflow and the rate at which it subject is: Molecular Sieves Charles K. Hersh; Reinhold is injected. This can be controlled automatically by a Publishing Corp., New York; 1961. Also, reference to thermostatically controlled hydraulic valve. The entire U.S. Pat, Nos. 2,306,610; 2,882,243; and 2,882,244 is adsorption/release cycle described above is repeatable recommended. up to 2000 times, indicating a lifetime of over 6 years By way of preferred teaching, the zeolite used is a 35 for the zeolite. The size of the collector and zeolite bed synthetic type marketed by the Linde Co. under the required is of course dependent on the heat requirement name "13X'. It has an alumina-silicate base with sodium of the building.

cation. The primary adsorbate for 13X is water. The The blower fan should be reversible, as the system is 13X adsorbent will be described in the form of in. more efficiently purged on the water adsorbate if the pellets by preferred design, though it will be clear that purgative airflow is opposite in direction to the water the process will work to varying degrees of success in injected airflow during the sunless hours, Thus the powder form, bead form, or other size pellets. Also, regeneration of the zeolite bed will be more complete, other zeolites, both natural and synthetic, will work to A bonus feature of the zeolite storage system, espe varying degrees of success with their respective adsor cially when 13X is the zeolite, is its affinity for hydro bates; for example, Linde Co.'s "LMS type 4A" with carbons. If instead of the closed-loop forced hot air water as the adsorbate, or activated chabazite (natural) system described above an open loop system is used, i.e. with water. Because this teaching relates specifically to the radiator is a simple the use of zeolites as energy storage for thermal flat wer/water injector takesblower vent, and the inlet blo plate solar collectors, and is not concerned with a new interior, then the hydrocarbon affinityfrom air directly the building's the zeolite bed type of such collectors, the collector described will be would serve to purify the interior air of hydrocarbon of the most basic type so as to exemplify the preferred pollutants.

use of the zeolite storage process. The advantages of this zeolitic storage system are A thermal flat plate solar collector consisting of a flat many. The solar energy is stored with high chemical rectangular box whose top is double pane glass, plexi glas, or some other transparent material, and whose 55 efficiency as long as the zeolite bed is kept dry. The base is flat black or dark green, is filled with 13X zeolite stored chemical energy can be released as heat in an in the form of in. pellets so as to form a layer of zeolite easily controllable manner with the common, non-toxic, about an inch in depth or less. An inlet manifold is non-flammable, non-polluting, inexpensive adsorbate, connected to an air blower to which is attached a water water. The zeolite bed is easily integrated with current atomizer/injector. The use of a multiple duct manifold designs of solar thermal collectors, precluding the need causes a more uniform distribution of air flow through for large insulted thermal storage tanks, etc. The 13X the entire zeolite bed. The outlet manifold is connected chases,zeolite itself is common and economical in large pur via insulated ductwork or pipe to a heat exchanger(s) especially considering its 2000 plus cycle life (any radiator currently used in forced hot air systems) time, inside the building to be heated. The radiator(s) is in 65 It is an object, therefore, of the present invention to turn connected to a condenser and then the blower to provide a chemical storage of energy from solar ther complete the circuit. During a sunny day, the panel mal collectors by means of dehydrating a zeolite bed collects the Sun's radiant energy and converts it to heat with solar heat and purgative airflow.

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Another object is to provide an energy storage sys The solar energy collected by the solar collector is tem for solar thermal collectors that is mutually com functional in two ways: first, the air circulated through patible and beneficial to a forced hot air heating system. the collector volume is heated, thus allowing heating of Another object is to provide a chemical energy stor the house in the manner just described and; second, the age system for solar energy that is easily integrable with 5 heat within the collector, in conjunction with the dry solar thermal flat plate collectors. airflow through the collector caused by blower (item 5 A further object is to provide an energy storage sys in FIG. 1), purges the zeolite 13X bed of much of its tem for solar thermal flat plate collectors that is efficient adsorbed water and is thus chemically stored in the over long periods of sunless days (i.e., allows very little potential heat of adsorption of the 13X. The efficiency energy loss). 10 of this storage process depends on the temperature of Still another object is to provide an energy storage the zeolite bed, the humidity of the purgative airflow, system for solar thermal flat plate collectors that allows and the speed of the purgative airflow. easily contollable and efficient release of energy from Now, the air emerging from the radiator 3 is cooler storage for heating. and of high humidity because of the purging of the Yet another object is to provide an energy storage 15 water adsorbate from the zeolite bed. When this air system for solar thermal flat plate collectors that is flows through insulated pipe 2C, it makes contact with economically attractive for the individual home-owner a protruding metal rod that is cooled by way of heat in comparison to current and projected costs for home sinking to the ground below the building. The water heating by conventional means. vapor in the air condenses for the most part onto this A final object is to provide an energy storage system 20 cool metal rod (item 4B in FIG. 1) and flows into the for solar thermal flat plate collectors that also provides reservoir 4. The air, now fairly dry, enters blower fan 5 air purification by means of adsorbing hydrocarbon and is pushed up insulated pipe 2D to enter the inlet pollutants from the building's interior air. manifold 1E, which like the outlet manifold 1D, is an Other objects, advantages, and novel features of the insulated branched pipe. A manifold such as this serves invention will become apparent from the following 25 to distribute the airflow uniformly throughout the zeo detailed description of the invention when considered in lite bed and so prevents build-up of adsorbate along conjunction with the accompanying drawings, wherein: restricted paths through the zeolite bed. And so the FIG. 1 represents the entire zeolitic storage system, entire heating/purging cycle is repeated. with the solar thermal flat plate collector in pictorial Now,during the sunless hours (night-time and cloudy view and a cross section shown to reveal the zeolitic 30 days), the dry zeolite bed in the solar collector is a bed; the remainder of the closed-loop heating circuit source of stored chemical energy which is readily shown in schematic form. changed into thermal energy by allowing water into the FIG. 2 represents the entire zeolitic storage system as system's airflow. Item 4C is a water atomizer and injec in FIG. 1 but in the air purification mode; again, the tor that, at the control of a thermostat or otherwise, solar collector is shown in pictorial and the heating 35 sprays fine droplets of water into the airflow. The water circuit is shown in schematic form. is taken from the reservoir 4 by way of pipe 4A in FIG. Referring to FIG. 1, item 1 shows a typical solar 1. Blower 5 forces the water laden air into the dry zeo energy thermal flat plate collector. Item 1A is a glass, lite bed contained in the solar collector, where some of plexiglas, or other transparent material in sheet form. the water is adsorbed, resulting in released heat of ad Together with box 1C, they form a volume whose sorption. For the 13X zeolite, the heat released is about width and length are much greater than its height. Box 1800 BTU’s per pound of water adsorbed. Thus the air 1C can be constructed typically of treated wood, corru flowing through the collector is heated, and in turn gated aluminum, plastic, or other material known to the heats the building as it flows through the radiator 3. The art of solar collectors. All interior surfaces of the box supply of heat only terminates when the zeolite bed is are flat black or flat dark green to maximize absorbant 45 completely water-loaded and cannot adsorb any more efficiency of the solar collector to the solar radiation. Water.

The volume enclosed by this box is filled with the 13X In actual practise, maximum cycle lifetime for the zeolite (item 1B) by preferred practise, though LMS zeolite can be achieved by circulating the airflow in the type 4A or other zeolite with water as its primary adsor opposite direction for the purging cycle than for the bate could be used instead. The entire solar collector 1 50 adsorption cycle. This requires blower 5 to be revers is aimed at the solar ecliptic, and may be mounted on ible.

the roof of a building, as shown in FIG. 1, or inside a Another advantage of this invention lies in the fact solarium structure integral to the building, as repre that the 13X zeolite also adsorbs hydrocarbons, and so sented in FIG. 2. The advantages of mounting the solar can purify the building's air of hydrocarbon pollutants. collector inside such a solarium are several: first, main 55 FIG. 2 illustrates the above zeolitic storage system in tenance is much easier to accomplish; second, the solar the air-purification mode. With the part of pipe section collector serves also as radiator by exchanging its ab 2C removed between radiator and reservoir 4, air from sorbed solar energy directly with the building's interior, the building's interior is circulated through the zeolite eliminating some extra radiators and decreasing heat bed in the solar collector, warmed as in the above speci loss from transport through ducts from the roof; and fication, and also purified of hydrocarbons, then is third, the economics are better than for the roof blown back into the house through pipe 2A as purified mounted version. warm air. Radiator 3 is omitted in this mode. The outlet manifold 2A in FIG. 1, consisting of insu By way of further specification, the following is a lated branched pipe, carries the heat-laden air from the sample calculation of the amount of zeolite needed for interior of the solar collector to the radiator 3 inside the 65 heat storage for a family of four living in the Boston house. Heat is exchanged from the piped hot air to the area. Such a family requires about 20,000 BTU's per day house interior through the radiator as with conven for space heating of a small house with four or five tional forced hot fluid systems. rooms. As stated previously, type 13X zeolite releases 6 about 1800 BTU's per pound of water adsorbed, and as fall within the true spirit and scope of the invention. about 5 lbs. of 13X zeolite are required to adsorb a What I claim as new and desire to secure by Letters pound of water. Hence approximately 56 lbs. of 13X are Patent of the United States is:

necessary to store 20,000 BTU's, an average day's heat requirement for this family. To allow for a cloudy spell 5 tem1. comprising,

A solar thermal energy storage and collector sys a collector housing having a gas inlet of a few days or an extremely cold winter, a factor of 4 and outlet, said housing having therein a bed of zeolite times this figure, or about 224 lbs. of 13X, is reasonable. material positioned to absorb heat produced by incident At $5.00/lb. of 13X, this results in an initial cash outlay solar for this family of $1120, less than the cost of an equiva gas through the heat exchanger,means energy; a heat exchanger, for circulating a the housing inlet, the lent tank storage facility of the above BTU capacity. 10

The 13X pellets have a density of about 39 lbs./cu. ft., zeolite material 1D and back to the heat exchanger in a so 224 lbs. would require a volume of 5.74 cu. ft., or an closed water gaseous flow path, means for injecting atomized into and condensing water vapor out of the area of 69 sq. ft. at a bed depth of 1". Hence a panel solar circulating gas in a mutually exclusive operation, said collector of 7 ft. x 10 ft. x 1" would satisfy the storage injecting and condensing means positioned in the flow volume requirement. 15

It will be evident to those skilled in the art that the path between the heat exchanger and the housing inlet, illustrated embodiments of this zeolitic storage system whereby the zeolite material releases the latent heat of for solar thermal energy may be altered for certain adsorption to the gas upon exposure of the material to purposes; in particular, the type of Zeolite used is vari the water adsorbate containing gas, and whereby the able. Accordingly, it should be understood, that the 20 zeolite material is purged of the adsorbed water by the specific constructional details here illustrated and de combined action of the incident solar energy, the circu scribed are presented for purpose of disclosure rather lating gas, and condensing means, thus completing the than as limitations, and that in the appended claims it is solar heating and storage cycle.

aimed to cover all such modifications and equivalencies 25