Patent Publication Number: US-7213409-B1

Title: Reconfigurable hydrogen transfer heating/cooling system

Description:
ORIGIN OF THE INVENTION 
   The invention described herein was made in the performance of official duties by an employee of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon. 
   FIELD OF THE INVENTION 
   The invention relates generally to heating and cooling systems based on hydrogen transfer, and more particularly to a hydrogen transfer based system that can be configured to heat or cool small human-occupied environments. 
   BACKGROUND OF THE INVENTION 
   Small human-occupied, man-made environments that are used or immersed in harsh ambient environments may require heating or cooling in order to provide safe and comfortable temperature conditions for their human occupant(s). For example, garments worn by divers, firefighters, chemical “hazmat” workers, etc., frequently must be heated or cooled depending on ambient environmental conditions. In addition, small chambers such as dive chambers or hyperbaric chambers must also be heated or cooled. In each of these cases, constraints on size, weight, power availability and/or power consumption limit the types of heating or cooling systems that can be used. Furthermore, since some applications of these human-occupied environments may require heating while other applications may require cooling, it is advantageous to have a single system that is capable of being configured for heating or cooling as dictated by the particular application conditions. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a system for effecting temperature changes. 
   Another object of the present invention is to provide a system that can be configured to heat or cool small human-occupied environments. 
   Still another object of the present invention is to provide a system that can be configured for heating or cooling without the need for a power supply during the operation thereof. 
   Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
   In accordance with the present invention, a system is provided for effecting temperature changes in an environment. A first thermally-conductive container stores a metal hydride at ambient temperature and a storage pressure that is greater than ambient pressure. A second thermally-conductive container stores a metal alloy at ambient temperature and ambient pressure. The metal alloy is one that is capable of absorbing hydrogen atoms at a pressure that is less than the storage pressure of the metal hydride. A conduit, coupled between the first and second thermally-conductive containers, is in communication at a first end thereof with the metal hydride and in communication at a second end thereof with the metal alloy. A valve is disposed in the conduit for controlling communication between the first end second end thereof. A thermal insulator is disposed about one of the first and second thermally-conductive containers depending on whether the system is to be used for cooling or heating. A circulating fluid is (i) placed in thermal communication with the one of the first and second thermally-conductive containers that is insulated by the thermal insulator, and (ii) adapted to be in thermal communication with an environment requiring temperature changes. As a result of this system structure, when the valve is opened, hydrogen atoms desorbed from the metal hydride are transported through the conduit and are absorbed by the metal alloy. Desorption of the hydrogen generates a cooling effect while absorption of the hydrogen generates heat. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the preferred embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
       FIG. 1  is a schematic view of a reconfigurable hydrogen-transfer heating/cooling system configured for cooling in accordance with the present invention; 
       FIG. 2  is a schematic view of the reconfigurable hydrogen-transfer heating/cooling system configured for heating in accordance with the present invention; and 
       FIG. 3  is an isolated view of a metal hydride or metal alloy canister with a fluid-carrying heat transfer coil wrapped thereabout in accordance with an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, simultaneous reference will be made to  FIGS. 1 and 2  where a reconfigurable system for effecting temperature changes in a small human-occupied, man-made environment  100  is illustrated generally by reference numeral  10 . In  FIG. 1 , system  10  is configured for cooling environment  100  while, in  FIG. 2 , system  10  is configured for heating environment  100 . By way of non-limiting examples, environment  100  can be a garment such as that worn by a diver, firefighter, chemical or biological “hazmat” worker, military personnel, etc. Environment  100  could also be a small chamber used to temporarily house humans as is the case with dive chambers, submarine rescue chambers, hyperbaric chambers, etc. 
   Whether used for heating or cooling, system  10  generally includes the following: 
   a thermally-conductive container  12  for storing a charged metal hydride  14  therein; 
   a heat exchanger  16  thermally coupled to container  12 ; 
   a thermally-conductive container  22  for storing a metal alloy  24  therein, a heat exchanger  26  thermally coupled to container  22 ; 
   a conduit  30  that is open on either end thereof with one open end exposed to metal hydride  14  and the other open end exposed to metal alloy  24 ; 
   a user-controllable valve  32  disposed in conduit  32  with valve  32  being closed until system  10  is to be used for heating or cooling; 
   a thermal insulator  40  disposed about one of (i) container  12 /heat exchanger  16  when system  10  is used for cooling, or (ii) container  22 /heat exchanger  26  when system  10  is used for heating; and 
   a fluid circulation system  50  coupled to one of (i) heat exchanger  16  when system  10  is used for cooling, or (ii) heat exchanger  26  when system  10  is used for heating. 
   Regardless of whether system  10  is used for heating or cooling, charged metal hydride  14  is any metal hydride that stores hydrogen atoms therein at an ambient temperature and a storage pressure that is greater than ambient pressure. Accordingly, container  12  is a housing or canister capable of retaining the storage pressure. Such metal hydrides as well as methods of charging or saturating same with hydrogen are well known in the art. Metal alloy  24  is any metal alloy that is capable of absorbing hydrogen atoms at ambient temperature and a pressure that is less than the pressure at which metal hydride  14  is stored. The lower the hydrogen absorbing pressure of metal alloy  24 , the greater the heating or cooling differential produced during operation of system  10 . 
   Container  12 /heat exchanger  16  and container  22 /heat exchanger  26  can be realized in a variety of ways without departing from the scope of the present invention. For example, as illustrated in  FIG. 3 , each container/heat exchanger combination could be realized by a thermally-conductive container  60  having a thermally-conductive conduit  62  coiled about and in thermal communication with container  60 . Container  60  and conduit  62  can be individual elements or integrated into a single element. To facilitate the quick installation and removal of container  60  from the system of the present invention, a quick connect/disconnect (“Q C/D”) coupling  64  can be used to couple container  60  to conduit  30 . 
   In general, fluid circulation system  50  can be any fluid-carrying system of pipes, ducts, or other conduits used to transport a fluid medium (e.g., a liquid such as water, a gas such as air, etc.) therein between environment  100  and heat exchanger  16  (in the case of a cooling operation) or heat exchanger  26  (in the case of a heating operation). More specifically, fluid circulation system  50  has (i) a conduit  50 A leading from environment  100  to one of heat exchanger  16  or  26 , and (ii) a conduit  50 B leading from one of heat exchanger  16  or  26  to environment  100 . A pump  52  can be included along one (or both) of conduits  50 A and  50 B to facilitate circulation of the fluid medium therein. Coupling/uncoupling of conduits  50 A/SOB can be accomplished in any of a variety of ways well known in the art. Typically, some form of quick connect/disconnect would be used to simplify reconfiguration of system  10 . 
   In most instances, environment  100  will include its own internal pipes, ducts, or other conduits  102  that facilitate the movement of the fluid medium (passed through circulation system  50 ) therethrough. For example, if environment  100  is a garment, conduit  102  represents a fluid circulation tube integrated into the garment. If environment  100  is a small chamber, conduit  102  could be ductwork for transporting a gaseous fluid medium (e.g., air) therethrough. If the fluid medium is air, conduit  102  could be vented into environment  100  to allow some of the heated or cooled air to be admitted into environment  100 . 
   In terms of a cooling operation, system  10  in  FIG. 1  begins to function when valve  32  is opened. The higher pressure in container  12  immediately drops due to the lower pressure in container  22  thereby allowing hydrogen atoms stored in metal hydride  14  to be released or desorbed. The hydrogen release is an endothermic reaction that causes a temperature drop in metal hydride  14 . This temperature drop is transferred (via heat exchanger  16 ) to the fluid medium circulating through circulating system  50 . At the same time, metal alloy  24  absorbs the hydrogen desorbed from metal hydride  14 . Such hydrogen absorption is an exothermic reaction that produces heat which, in turn, is transferred to heat exchanger  26 . The heat in heat exchanger  26  could be used for some purpose or could be “dumped”. For example, if environment  100  is a garment, it may be advantageous to place heat exchanger  26  in thermal communication with the ambient environment in order to dissipate the heat therein. 
   In terms of a heating operation, system  10  in  FIG. 2  similarly begins to function when valve  32  is opened. Just as in the cooling operation, the higher pressure in container  12  immediately drops thereby allowing hydrogen atoms stored in metal hydride  14  to be released or desorbed. The hydrogen release is an endothermic reaction that causes a temperature drop in metal hydride  14 . This temperature drop is transferred to heat exchanger  16  while the corresponding temperature increase in metal alloy  24  (due to the absorption of the hydrogen desorbed from metal hydride  14 ) is transferred to the fluid medium circulating through circulating system  50  (via heat exchanger  26 ). Similar to the cooling operation, if environment  100  is a garment, it may be advantageous to place heat exchanger  16  in thermal communication with the ambient environment. 
   The advantages of the present invention are numerous. The system can be readily configured for heating or cooling. 
   No power supply is required to initiate or maintain the heating or cooling operation. The system can be readily “re-charged” simply by installing new canisters of a pre-charged metal hydride and a metal alloy that can absorb hydrogen at a pressure that is lower than the hydrogen storage pressure of the metal hydride. The amount of heating or cooling can be increased by using a metal alloy having a lower hydrogen absorption pressure. 
   Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.