Abstract:
A hydrogen generation system comprising solid hydrogen fuel, a liquid absorbent material, and a phase-change material is provided. When the liquid (usually water, alcohol, or aqueous solution of alcohol, aqueous solution of salt or aqueous solution of acid) in the absorbent material contacts with the solid hydrogen fuel, the solid hydrogen fuel will react with the liquid to release hydrogen and generate heat. The heat as generated will accumulate to increase the reaction temperature, and then boost the hydrogen-releasing rate. The phase-change material is adjacent to the solid hydrogen fuel for absorbing and storing the reaction heat, so as to stabilize the reaction temperature. Therefore, the hydrogen-releasing rate is kept as constant to achieve a steady hydrogen flow.

Description:
[0001]    This application claims the benefits of U.S. provisional application No. 61/285,467, filed Dec. 10, 2009, and Taiwan application Serial No. 099113137, filed Apr. 26, 2010, the subject matters of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The disclosure relates in general to a hydrogen generation system, and more particularly to the hydrogen generation system capable of providing hydrogen to a fuel cell at a stabilized hydrogen-releasing rate. 
         [0004]    2. Description of the Related Art 
         [0005]    Fuel cell is a device capable of converting chemical energy into electrical energy. The fuel cell can generate electrical energy continuously while fuel and oxidant are provided constantly. As to the hydrogen fuel cell, the fuel is hydrogen, and the oxidant is oxygen. 
         [0006]    Take a conventional hydrogen production system in a hydrogen fuel cell and sodium borohydride (NaBH 4 ) solution used as hydrogen source in the hydrogen production system for example. A pump transports sodium borohydride solution (liquid fuel) to a catalyst bed. After hydrogen is released, sodium perborate solution is extracted from the catalyst bed. A hydrogen releasing reaction reacted from sodium borohydride and water is catalyzed by the catalyst bed. The chemical equation (1) is as follows: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0007]    The chemical reaction of equation (1) is accompanied by the release of heat, which is an exothermic reaction. It is not easy to sustain the temperature of the hydrogen generation apparatus at which the hydrogen-releasing reaction occurs at a certain value or range. When the hydrogen-releasing reaction is processing, the accumulated heat increases the temperature of the hydrogen generation apparatus, in turn causing the hydrogen-releasing rate of reaction to be evolved even more quickly. Thus, the hydrogen-releasing rate of the conventional hydrogen generation apparatus would not be stably maintained in a certain value or range.  FIG. 1  shows the relationship between the hydrogen-releasing rate and the temperature of the reaction, which is high-positively related. 
         [0008]    Moreover, the fuel cells with different powers have different hydrogen consumption rates. The fuel cell could not generate the maximum power if the hydrogen generation system of the fuel cell provides hydrogen gas with the hydrogen-releasing rate under the demand. However, it would be energy waste that the hydrogen-releasing rate of the hydrogen generation system is higher than the standard value required for the fuel cell. Thus, it is an important subject to provide a hydrogen generation system (i.e. hydrogen source) with a stable hydrogen-releasing rate for the fuel cell. 
         [0009]    A mechanical design has been disclosed by the people skilled in the art for stabilizing the hydrogen-releasing rate. Taiwan application serial No. 96121493, entitled “Microcartridge Hydrogen Generator”, has disclosed a hydrogen generator, using solid hydride as a hydrogen fuel and a chamber containing a catalyst, for controlling and stabilizing the hydrogen-releasing rate. This hydrogen generator has a very complicated mechanical design with a bulky dimensions and weight, is, which is expansive and not easy to carry for daily use. 
         [0010]    Applicant has disclosed a flexible solid hydrogen fuel (Taiwan application serial No. 98108205), using a crushed mixture of a solid hydride and a solid catalyst uniformly dispersing in a polymer matrix. The flexible solid hydrogen fuel could be further deformed into various geometric shapes and put into suitable vessels. Hydrogen can be stably and highly released when water or adequate solution is added into the vessels and reacted with the solid hydrogen fuel.  FIG. 2  is a hydrogen-releasing curve of flexible solid hydrogen fuel according to the related art of TW ASN. 98108205. The curve of  FIG. 2  is obtained by using a crushed mixture of 3 g of NaBH 4  (solid hydride) and 0.6 g of Co 2+ /IR-120 (solid catalyst) uniformly dispersing in 2.5 g of silicone rubber (polymer matrix). 
         [0011]    In addition, Applicant has disclosed a hydrogen supply device (Taiwan application serial No. 98112619) with solid water, for solving the problem of leakage of water or liquid from the hydrogen supply device in use. Water absorbs the heat generated from the hydrogen releasing reaction because of its high specific heat capacity.  FIG. 3  is a hydrogen-releasing curve of solid hydrogen fuel and solid water according to the related art of TW ASN. 98112619. The curve of  FIG. 3  is obtained by using a crushed mixture of 2 g of NaBH 4  (solid hydride) and 0.4 g of Co 2+ /IR-120 (solid catalyst) uniformly dispersing in 1.6 g of silicone rubber. Solid water is exemplified as gel-forming water. However, solid water such as gel-forming water could not rapidly absorbs the heat generated from the hydrogen releasing reaction, so that the hydrogen releasing rate of the reaction is varied (with the increasing temperature) and could not be sustained at a certain value, as shown in  FIG. 3 . 
       SUMMARY 
       [0012]    The disclosure is directed to a hydrogen generation system and a method for generating hydrogen. The hydrogen generation system of the disclosure uses the phase-change material for keeping a temperature of the hydrogen generation system as a constant in a sufficient long time, thereby maintaining a reaction temperature of the hydrogen releasing reaction reacted by the solid hydrogen fuel and the liquid, and consequently stabilizing a hydrogen releasing rate of the hydrogen releasing reaction. 
         [0013]    According to a first aspect of the present disclosure, a hydrogen generation system is provided, comprising a solid hydrogen fuel, an absorbent material and a phase-change material. The absorbent material absorbs a liquid in the system. Examples of the liquid include water, alcohols and aqueous solutions thereof, aqueous solutions of salts, aqueous solutions of acids, and a mixture thereof. The phase-change material is disposed adjacent to a position at which a hydrogen releasing reaction occurs, for absorbing and storing the reaction heat generated from the hydrogen releasing reaction reacted by the solid hydrogen fuel and the liquid, thereby maintaining the reaction temperature. Consequently, the hydrogen releasing rate of the hydrogen releasing reaction can be controlled, and a hydrogen flow can be stabilized. 
         [0014]    According to a second aspect of the present disclosure, a method for generating hydrogen using solid hydrogen fuel is provided, comprising steps of: 
         [0015]    providing a solid hydrogen fuel, at least comprising a solid hydride powder and a solid hydrogen releasing catalyst; 
         [0016]    providing an absorbent material, mixed with the solid hydrogen fuel in a fuel pack; 
         [0017]    providing a liquid pack comprising a liquid of water, alcohols and aqueous solutions thereof, aqueous solutions of salts, aqueous solutions of acids, or a combination thereof. 
         [0018]    providing a phase-change material, disposed adjacent to the solid hydrogen fuel; and 
         [0019]    conducting water or aqueous solution of the liquid pack into the fuel pack for bringing about a hydrogen releasing reaction; wherein the absorbent material is capable of absorbing the liquid of water, alcohols and aqueous solutions thereof, aqueous solutions of salts, aqueous solutions of acids, or the combination thereof, and the phase-change material is used for stabilizing a temperature of the hydrogen releasing reaction reacted by the solid hydrogen fuel and the liquid. 
         [0020]    According to a third aspect of the present disclosure, a method for applying solid hydrogen fuel to fuel cell is provided, comprising steps of: 
         [0021]    providing a solid hydrogen fuel as disclosed in the second aspect; 
         [0022]    providing an absorbent material, mixed with the solid hydrogen fuel in a fuel pack; 
         [0023]    providing a liquid pack comprising a liquid of water, alcohols and aqueous solutions thereof, aqueous solutions of salts, aqueous solutions of acids, or a combination thereof; 
         [0024]    providing a phase-change material, disposed adjacent to the solid hydrogen fuel; 
         [0025]    conducting water or aqueous solution of the liquid pack into the fuel pack for bringing about a hydrogen releasing reaction; and 
         [0026]    providing a fuel cell applied with the hydrogen released from the solid hydrogen fuel; wherein the absorbent material is capable of absorbing the liquid of water, alcohols and aqueous solutions thereof, aqueous solutions of salts, aqueous solutions of acids, or the combination thereof, and the phase-change material is used for stabilizing a temperature of the hydrogen releasing reaction reacted by the solid hydrogen fuel and the liquid. 
         [0027]    The above and other aspects of the disclosure will become better understood with regard to the following detailed description of the non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  shows the relationship between the hydrogen-releasing rate and the temperature of the reaction, which is high-positively related. 
           [0029]      FIG. 2  is a hydrogen-releasing curve of flexible solid hydrogen fuel according to the related art of TW ASN. 98108205. 
           [0030]      FIG. 3  is a hydrogen-releasing curve of solid hydrogen fuel and solid water according to the related art of TW ASN. 98112619. 
           [0031]      FIG. 4  illustrates a method for generating hydrogen using solid hydrogen fuel of hydrogen production system according to the first embodiment of the present disclosure. 
           [0032]      FIG. 5  illustrates a hydrogen production system with the solid hydrogen fuel according to the second embodiment of the present disclosure. 
           [0033]      FIG. 6  illustrates a fuel cell using hydrogen from the hydrogen production system of the second embodiment of the present disclosure. 
           [0034]      FIG. 7A  shows the hydrogen releasing curves of the solid hydrogen fuel, using Na 2 SO 4 . 10H 2 O as the phase-change material, according to the embodiment of the present disclosure. 
           [0035]      FIG. 7B  shows the enlarged hydrogen releasing curves (c) and (d) of  FIG. 7A . 
           [0036]      FIG. 8  shows the hydrogen releasing curves of the solid hydrogen fuel, using Na 2 HPO 4 . 12H 2 O as the phase-change material, according to the embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    A hydrogen generation system, a method for generating hydrogen using solid hydrogen fuel and a method for providing hydrogen for a fuel cell using the solid hydrogen fuel are provided in the present disclosure. The phase-change material is used for keeping a temperature of the hydrogen generation system as a constant in a sufficient long time, thereby maintaining a reaction temperature of the hydrogen releasing reaction reacted by the solid hydrogen fuel and the liquid, and consequently stabilizing a hydrogen releasing rate of the hydrogen releasing reaction. 
         [0038]    The embodiments are provided to demonstrate the hydrogen generation system, the method for generating hydrogen using solid hydrogen fuel and the method for providing hydrogen for a fuel cell using the solid hydrogen fuel. Also, the embodiments are described with reference to the related experiments. However, the compounds, materials and steps for providing hydrogen illustrated in the embodiments are not intended to limit the invention. The modifications and variations can be made without departing from the spirit of the invention to meet the requirements of the practical applications. 
       First Embodiment 
       [0039]    In an embodiment, a hydrogen generation system, capable of generating hydrogen for a fuel cell, comprises a solid hydrogen fuel, an absorbent material, a phase-change material and a liquid such as water, alcohols (ex: methanol or ethanol) or aqueous solutions thereof. The absorbent material is mixed with the solid hydrogen fuel and absorbs the liquid such as water, alcohols and aqueous solutions thereof, aqueous solutions of salts, or aqueous solutions of acids. The phase-change material is disposed adjacent to a position at which a hydrogen releasing reaction occurs. The phase-change material absorbs and stores the reaction heat generated from the hydrogen releasing reaction reacted by the solid hydrogen fuel and the liquid, so as to maintain a reaction temperature. Consequently, a hydrogen releasing rate of the hydrogen releasing reaction is controlled and a hydrogen flow is stabilized. 
         [0040]    In the first embodiment, the phase-change material, the solid hydrogen fuel and the absorbent material are disposed in the same pack. 
         [0041]      FIG. 4  illustrates a method for generating hydrogen using solid hydrogen fuel of hydrogen production system according to the first embodiment of the present disclosure. First, a solid hydrogen fuel  11 , an absorbent material  13  and a phase-change material  15  are provided. A fuel pack  21  is formed by mixing the solid hydrogen fuel  11  and the absorbent material  13  with addition of the phase-change material  15 . Then, a liquid package  31  containing liquid, such as water, alcohols and aqueous solutions thereof, aqueous solutions of salts, or aqueous solutions of acids, is provided. Afterward, the fuel pack  21  and the liquid package  31  are disposed into a hydrogen releasing apparatus  41 . When water or aqueous solution of the liquid package  31  is conducted into the fuel pack, a hydrogen releasing reaction occurs, and hydrogen generated from the solid hydrogen fuel  11  could be discharged from the gas outlet  412  for providing the power of a fuel cell. The absorbent material  13  is capable of absorbing water or aqueous solution, and the phase-change material  15  is used for stabilizing a temperature of the hydrogen releasing reaction reacted by the solid hydrogen fuel  11  and the liquid, so as to maintain a hydrogen releasing rate at a certain range in a sufficiently long time. 
         [0042]    In an embodiment, the solid hydrogen fuel at least comprises a solid hydride powder and a solid hydrogen releasing catalyst. The solid hydride powder reacts with the liquid, such as water, alcohols and aqueous solutions thereof, aqueous solutions of salts, aqueous solutions of acids, or a mixture thereof, to bring about the hydrogen releasing reaction. The solid hydrogen releasing catalyst catalyzes the hydrogen releasing reaction for producing hydrogen. In another embodiment, the solid hydrogen fuel further comprises a flexible polymer matrix as a molding agent, for providing flexibility of the solid hydrogen fuel. 
         [0043]    In an embodiment, solid hydride powder could be boron hydride, nitrogen hydride, carbon hydride, metal hydride, nitrogen borohydride, carbon borohydride, nitrogen carbon hydride, metal borohydride, metal nitrogen hydride, metal carbon hydride, metal nitrogen borohydride, metal carbon borohydride, metal nitrogen carbon hydride, nitrogen carbon borohydride, metal nitrogen carbon borohydride, or a combination thereof. Examples of the solid hydride powder include sodium borohydride (NaBH 4 ), lithium aluminum hydride (LiAlH 4 ), sodium aluminum hydride (NaAlH4), magnesium aluminum hydride (Mg(AlH 4 ) 2 ), calcium aluminum hydride (Ca(AlH 4 ) 2 ), lithium borohydride (LiBH 4 ), potassium borohydride (KBH 4 ), beryllium borohydride (Be(BH 4 ) 2 ), magnesium borohydride (Mg(BH 4 ) 2 ), calcium borohydride (Ca(BH 4 ) 2 ), lithium hydride (LiH), sodium hydride (NaH), magnesium hydride (MgH 2 ), or calcium hydride (CaH 2 ). 
         [0044]    In another embodiment, the solid hydride powder is a hydride or a chemical compound represented by the formula BxNyHz. Examples of compound represented by the formula BxNyHz include ammonia borane (H3BNH3), diborane, H2B(NH3)2BH4, poly(amine-borane), borazine (B3N3H6), borane-tetrahydrofuran complex, and diborane and the likes. 
         [0045]    Moreover, the solid hydrogen releasing catalyst may comprises solid acid, or metal salt including at least one of ruthenium, cobalt, nickel, copper and iron, or metal nano-particles/micro-particles including at least one of ruthenium, cobalt, nickel, copper and iron, or a plurality of catalyst metal carriers covered by metal irons/metal atomics/metal nano-particles/meta micro-particles including at least one of ruthenium, cobalt, nickel, copper and iron. 
         [0046]    In the embodiment, the absorbent material comprises an absorbing cotton and at least an absorbent polymer. Examples of the absorbing cotton include tissues, absorbent cotton fabric, cosmetic cottons and any cotton products. Examples of the absorbent polymer include at least one or more of polyacrylate, poly(vinyl alcohol), vinyl acetate copolymer, poly urethane, poly(ethylene oxide), and starch graft copolymer/rubber blend. 
         [0047]    In the embodiment, the solid hydrogen fuel comprises a flexible polymer matrix having a hydrophobic polymer elastomer such as silicone, rubber, and silicon rubber, for providing a flexibility and deformation of the solid hydrogen fuel. 
         [0048]    It is noted that the compounds of the solid hydride powder, the solid hydrogen releasing catalyst and the flexible polymer matrix of the solid hydrogen fuel are not limited to the any specific aforementioned compounds. Also, the solid hydride powder, the solid hydrogen releasing catalyst and the flexible polymer matrix could be the ground or un-ground powders, dispersed or pressed as the tablets, depending on the requirements of the practical application. 
         [0049]    In the embodiment, the phase-change material could be the compound selected from the groups of inorganic or organic phase-change materials, phase-change materials of eutectic system or solid-liquid system. Examples of the organic phase-change materials include any or more materials of aliphatic compounds, polyhydric alcohols and paraffin waxes. Examples of the inorganic phase-change materials include acids and hydrated slats (ex: with melting points ranged from 15˜120). 
         [0050]    Table 1˜Table 4 respectively list various compounds selected from the inorganic phase-change materials, the organic phase-change materials, the phase-change materials of eutectic system and the phase-change materials of solid-liquid system, and the melting points and the latent heats thereof. The suitable phase-change material could be selected from the compounds listed in Table 1˜Table 4 according to relationship, and the practical requirements of the application (ex: the hydrogen releasing rate of the solid hydrogen fuel required to be sustained in a certain range), with reference to the relationship between the temperature and the hydrogen releasing rate of the hydrogen releasing reaction. 
       Second Embodiment 
       [0051]      FIG. 5  illustrates a hydrogen production system with the solid hydrogen fuel according to the second embodiment of the present disclosure. The system composition of the second embodiment is identical to that of the first embodiment. The hydrogen releasing apparatus  43  of  FIG. 5  has a fuel pack and a liquid package  31 . However, only a mixture of the solid hydrogen fuel  11  and the absorbent material  13  is disposed in the fuel pack. The phase-change material  15  is disposed outside the fuel pack and directly contacts a container at which the fuel pack is placed (i.e. the hydrogen releasing apparatus  43 ). The phase-change material  15  is used for absorbing and storing the reaction heat generated from the hydrogen releasing reaction via heat conduction. Please also refer to the descriptions in the first embodiment for the compounds of the solid hydrogen fuel and the process for hydrogen releasing reaction in details. 
         [0052]    Similarly, the hydrogen production system of the second embodiment achieves the object of maintaining a reaction temperature of the hydrogen releasing reaction and consequently stabilizing a hydrogen releasing rate thereof using the phase-change material. In the second embodiment, the phase-change material  15  disposed outside the fuel pack is reusable. Practically, the hydrogen production system of the second embodiment is good for environmental conservation and also cost saving. 
         [0053]      FIG. 6  illustrates a fuel cell using hydrogen from the hydrogen production system of the second embodiment of the present disclosure. As shown in  FIG. 6 , the hydrogen releasing apparatus  43  ( FIG. 5 ) incorporating with the phase-change material  15  would stably and continuously provide hydrogen to the fuel cell  51  in an sufficient long time. The temperature of the fuel cell  51  is kept at a certain range since the phase-change material  15  absorbing and storing the reaction heat generated from the hydrogen releasing reaction. It is very convenient for the user that the phase-change material  15  and/or the fuel pack of the hydrogen releasing apparatus  43  are/is replaceable after the fuel cell used for a (long) while. 
         [0054]    Several experiments are conducted in the embodiments of the present disclosure for observing the effects of the phase-change material on the hydrogen releasing rate. Two experiments and the results thereof are disclosed below. 
       Relative Experiment 1 
       [0055]    Please also referred to  FIG. 4 . 4 g of the flexble solid hydrogen fuel, comprising 2 g of NaBH 4  (solid hydrogen powder), 0.4 g of cobalt ion catalyst (Co 2+ /IR-120, solid hydrogen releasing catalyst) and 1.6 g of silicone subber (i.e. molding agent), is divided into 96 pieces and blended with the absorbing polymer (absorbent material); then, the phase-change material Na 2 SO 4 . 10H 2 O is added into this mixture for manufacturing a fuel pack. A liquid package is provided by adding water into a plastic bag with enclosure. The fuel pack and the liquid package are disposed into a hydrogen releasing apparatus. Afterwards, water in the liquid package is conducted into the fuel pack by piercing the plastic bag, and the hydrogen releasing rate is measured.  FIG. 7A  shows the hydrogen releasing curves of the solid hydrogen fuel, using Na 2 SO 4 .10H 2 O as the phase-change material, according to the embodiment of the present disclosure.  FIG. 7B  shows the enlarged hydrogen releasing curves (c) and (d) of  FIG. 7A . 
         [0056]    As shown in  FIG. 7A  and  FIG. 7B , curves (a)˜(d) represent the hydrogen releasing curves of the solid hydrogen fuel with addition of 0 g, 0.3 g, 0.5 g and 1.0 g of the phase-change materials, respectively. The results have indicated that the hydrogen-releasing rate quickly reaches the maximum values in the absence of the phase-change material, and hydrogen is completely released in a short time. Addition of 0.3 g of the phase-change material has the effect on the hydrogen-releasing rate and sustaining time. The results have indicated that the hydrogen releasing rate and sustaining time have been greatly improved while 0.5 g of the phase-change material has been added. Also, the results of  FIG. 7B  have indicated that additions of 0.5 g and 1.0 g of the phase-change materials have very similar effects on the hydrogen-releasing rate and sustaining time. Accordingly, when a certain ratio of the phase-change material has been added, the temperature of the reaction system could be controlled and a hydrogen releasing rate could be maintained at a certain range in a sufficiently long time. 
       Relative Experiment 2 
       [0057]    The procedures of the relative experiments 1 and 2 are similar, except the uses of Na 2 SO 4 .10H 2 O as the phase-change material in the relative experiment  2 . 
         [0058]    First, 2.5 g of the flexble solid hydrogen fuel (from the composition of 10 g of NaBH 4  (solid hydrogen powder), 3 g of cobalt ion catalyst (Co 2− /IR-120, solid hydrogen releasing catalyst) and 6 g of clay (i.e. molding agent) is divided into 96 pieces and blended with 1 g of sodium polyacrylate (the absorbent material); then, the phase-change material Na 2 HPO 4 .12H 2 O is added into this mixture for manufacturing a fuel pack. A liquid package is provided by adding water into a plastic bag with enclosure. The fuel pack and the liquid package are disposed into a hydrogen releasing apparatus. Afterwards, water in the liquid package is conducted into the fuel pack by piercing the plastic bag, and the hydrogen releasing rate is measured.  FIG. 8  shows the hydrogen releasing curves of the solid hydrogen fuel, using Na 2 HPO 4 .12H 2 O as the phase-change material, according to the embodiment of the present disclosure. 
         [0059]    As shown in  FIG. 8 , curves (e) and (f) respectively represent the hydrogen releasing curve of the solid hydrogen fuel and the temperature curve of hydrogen releasing reaction without addition of the phase-change materials. Also, curves (g) and (h) respectively represent the hydrogen releasing curve of the solid hydrogen fuel and the temperature curve of hydrogen releasing reaction in the addition of 2 g of the phase-change materials. The results of  FIG. 8  have indicated that using Na 2 HPO 4 .12H 2 O as the phase-change material has similar effect on the stabilization of the hydrogen releasing rate as well. 
         [0060]    According to the aforementioned description, the hydrogen generation system, a method for generating hydrogen using solid hydrogen fuel and a method for providing hydrogen for a fuel cell using the solid hydrogen fuel, as presented in the present disclosure, use the phase-change material for keeping a temperature of the hydrogen generation system as a constant in a sufficient long time, thereby maintaining a reaction temperature of the hydrogen releasing reaction (reacted by the solid hydrogen fuel and the liquid), and consequently stabilizing a hydrogen releasing rate of the hydrogen releasing reaction. Compared to conventional ways for generating hydrogen with complicated and bulky mechanical structure, the hydrogen production system of the disclosure is much smaller and easier to be carried. The required space of the hydrogen production system of the disclosure is reduced effectively, and the weight of the product is lowered. Moreover, electricity of the applied product can be generated from the hydrogen-releasing reaction by just contacting the solid hydrogen fuel with water. Thus, the hydrogen production system using solid hydrogen fuel and methods for generating hydrogen and providing hydrogen for fuel cell according to the embodiments have several advantages. It is easier to match the mechanical design of the system and product, which simplifies the design of hydrogen production system. Furthermore, solid hydrogen fuel releases hydrogen stably in a sufficiently long time. Above advantages increase users&#39; willingness to use the product and widen the application field of the product. 
         [0061]    While the disclosure has been described by way of example and in terms of the exemplary embodiment(s), it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Inorganic Phase-Change Materials 
               
             
          
           
               
                   
                 Chemical 
                 Melting 
                 Latent 
                   
               
               
                 Material 
                 Formula 
                 point ( ) 
                 Heat (kJ/kg) 
                 Notes 
               
               
                   
               
             
          
           
               
                 Acids 
                   
                   
                   
                   
               
               
                 Acetic acid 
                 CH 3 COOH 
                 16.7 
                 184 
               
               
                 Polyethylene 
                 H(OC 2 H 2 )n_OH 
                 20-25 
                 146 
               
               
                 glycol 600 
               
               
                 Capric acid 
                 CH 3 (CH 2 ) 8     —   COOH 
                 36 
                 152 
               
               
                 Eladic acid 
                 C 8 H 7 C 9 H 16     —   COOH 
                 47 
                 218 
               
               
                 Lauric acid 
                 CH 3 (CH 2 ) 10     —   COOH 
                 49 
                 178 
               
               
                 Pentadecanoic 
                 CH 3 (CH 2 ) 13     —   COOH 
                 52.5 
                 178 
               
               
                 acid 
               
               
                 Tristearin 
                 (C 17 H 35 COO)C 3 H 5   
                 56 
                 191 
               
               
                 Myristic acid 
                 CH 3 (CH 2 ) 12     —   COOH 
                 58 
                 199 
               
               
                 Palmatic acid 
                 CH 3 (CH 2 ) 14     —   COOH 
                 55 
                 163 
               
               
                 Stearic acid 
                 CH 3 (CH 2 ) 16     —   COOH 
                 69.4 
                 199 
               
               
                 Acetamide 
                 CH 3 CONH 2   
                 81 
                 241 
               
               
                 Methyl 
                 (CHCO 2 NH 3 ) 2   
                 102 
                 242 
               
               
                 furmarate 
               
               
                 Salts 
               
               
                   
                 K 2 HPO 4     —   6H 2 O 
                 14.0 
                 109 
               
               
                   
                 FeBr 3     —   6H 2 O 
                 21.0 
                 105 
               
               
                   
                 Mn(NO 3 ) 2     —   6H 2 O 
                 25.5 
                 148 
               
               
                   
                 FeBr 3     —   6H 2 O 
                 27.0 
                 105 
               
               
                   
                 CaCl 2     —   12H 2 O 
                 29.8 
                 174 
               
               
                   
                 LiNO 3     —   2H 2 O 
                 30.0 
                 296 
               
               
                   
                 LiNO 3     —   3H 2 O 
                 30 
                 189 
               
               
                   
                 Na 2 CO 3     —   10H 2 O 
                 32.0 
                 267 
               
               
                   
                 Na 2 SO 4     —   10H 2 O 
                 32.4 
                 241 
               
               
                   
                 KFe(SO 4 ) 2     —   12H 2 O 
                 33 
                 173 
               
               
                   
                 CaBr 2     —   6H 2 O 
                 34 
                 138 
               
               
                   
                 LiBr 2     —   2H 2 O 
                 34 
                 124 
               
               
                   
                 Zn(NO 3 ) 2     —   6H 2 O 
                 36.1 
                 134 
               
               
                   
                 FeCl 3     —   6H 2 O 
                 37.0 
                 223 
               
               
                   
                 Mn(NO 3 ) 2     —   4H 2 O 
                 37.1 
                 115 
               
               
                   
                 Na 2 HPO 4     —   12H 2 O 
                 40.0 
                 279 
               
               
                   
                 CoSO 4     —   7H 2 O 
                 40.7 
                 170 
               
               
                   
                 KF_2H 2 O 
                 42 
                 162 
               
               
                   
                 MgI 2     —   8H 2 O 
                 42 
                 133 
               
               
                   
                 CaI 2     —   6H 2 O 
                 42 
                 162 
               
               
                   
                 K 2 HPO 4     —   7H 2 O 
                 45.0 
                 145 
               
               
                   
                 Zn(NO 3 ) 2     —   4H 2 O 
                 45 
                 110 
               
               
                   
                 Mg(NO 3 )_4H 2 O 
                 47.0 
                 142 
               
               
                   
                 Ca(NO 3 )_4H 2 O 
                 47.0 
                 153 
               
               
                   
                 Fe(NO 3 ) 3     —   9H 2 O 
                 47 
                 155 
               
               
                   
                 Na 2 SiO 3     —   4H 2 O 
                 48 
                 168 
               
               
                   
                 K 2 HPO 4     —   3H 2 O 
                 48 
                 99 
               
               
                   
                 Na 2 S 2 O 3     —   5H 2 O 
                 48.5 
                 210 
               
               
                   
                 MgSO 4     —   7H 2 O 
                 48.5 
                 202 
               
               
                   
                 Ca(NO 3 ) 2     —   3H 2 O 
                 51 
                 104 
               
               
                   
                 Zn(NO 3 ) 2     —   2H 2 O 
                 55 
                 68 
               
               
                   
                 FeCl 3     —   2H 2 O 
                 56 
                 90 
               
               
                   
                 Ni(NO 3 ) 2     —   6H 2 O 
                 57.0 
                 169 
               
               
                   
                 MnCl 2     —   4H 2 O 
                 58.0 
                 151 
               
               
                   
                 MgCl 2     —   4H 2 O 
                 58.0 
                 178 
               
               
                   
                 CH 3 COONa_3H 2 O 
                 58.0 
                 265 
               
               
                   
                 Fe(NO 3 ) 2     —   6H 2 O 
                 60.5 
                 126 
               
               
                   
                 NaAl(SO 4 ) 2     —   10H 2 O 
                 61.0 
                 181 
               
               
                   
                 NaOH_H 2 O 
                 64.3 
                 273 
               
               
                   
                 Na 3 PO 4     —   12H 2 O 
                 65.0 
                 190 
               
               
                   
                 LiCH 3 COO_2H 2 O 
                 70 
                 150 
               
               
                   
                 Al(NO 3 ) 2     —   9H 2 O 
                 72 
                 155 
               
               
                   
                 Ba(OH) 2     —   8H 2 O 
                 78 
                 265 
               
               
                   
                 Mg(NO 3 ) 2     —   6H 2 O 
                 89.9 
                 167 
               
               
                   
                 KAl (SO 4 ) 2     —   12H 2 O 
                 91 
                 184 
               
               
                   
                 MgCl 2     —   6H 2 O 
                 117 
                 167 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Organic Phase-Change Materials 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Material 
                 Composition/ 
                 solidification 
                 Latent 
                   
               
               
                 Paraffin waxs 
                 Product 
                 point ( ) 
                 Heat (kJ/kg) 
                 Notes 
               
               
                   
               
               
                   
                 No. 6106 
                 42-44 
                 189 
                 Ter Hell 
               
               
                   
                   
                   
                   
                 Paraffin 
               
               
                   
                   
                   
                   
                 Hamburg, 
               
               
                   
                   
                   
                   
                 FRG 
               
               
                   
                 No. 5838 
                 48-50 
                 189 
                 Ter Hell 
               
               
                   
                   
                   
                   
                 Paraffin 
               
               
                   
                   
                   
                   
                 Hamburg, 
               
               
                   
                   
                   
                   
                 FRG 
               
               
                   
                 No. 6035 
                 58-60 
                 189 
                 Ter Hell 
               
               
                   
                   
                   
                   
                 Paraffin 
               
               
                   
                   
                   
                   
                 Hamburg, 
               
               
                   
                   
                   
                   
                 FRG 
               
               
                   
                 No. 6403 
                 62-64 
                 189 
                 Ter Hell 
               
               
                   
                   
                   
                   
                 Paraffin 
               
               
                   
                   
                   
                   
                 Hamburg, 
               
               
                   
                   
                   
                   
                 FRG 
               
               
                   
                 No. 6499 
                 66-68 
                 189 
                 Ter Hell 
               
               
                   
                   
                   
                   
                 Paraffin 
               
               
                   
                   
                   
                   
                 Hamburg, 
               
               
                   
                   
                   
                   
                 FRG 
               
               
                   
                 No. P116 
                 45-48 
                 210 
                 Sun 
               
               
                   
                   
                   
                   
                 Company, 
               
               
                   
                   
                   
                   
                 USA 
               
               
                   
               
             
          
           
               
                   
                 Paraffin 
                 Carbon 
                 Melting 
                 Latent 
                   
               
               
                   
                 Waxs 
                 Number 
                 Point ( ) 
                 Heat (kJ/kg) 
                 Notes 
               
               
                   
                   
               
               
                   
                   
                 14 
                 5.5 
                 228 
               
               
                   
                   
                 15 
                 10 
                 205 
               
               
                   
                   
                 16 
                 16.7 
                 237.1 
               
               
                   
                   
                 17 
                 21.7 
                 213 
               
               
                   
                   
                 18 
                 28.0 
                 244 
               
               
                   
                   
                 19 
                 32.0 
                 222 
               
               
                   
                   
                 20 
                 36.7 
                 246 
               
               
                   
                   
                 21 
                 40.2 
                 200 
               
               
                   
                   
                 22 
                 44.0 
                 249 
               
               
                   
                   
                 23 
                 47.5 
                 232 
               
               
                   
                   
                 24 
                 50.6 
                 255 
               
               
                   
                   
                 25 
                 49.4 
                 238 
               
               
                   
                   
                 26 
                 56.3 
                 256 
               
               
                   
                   
                 27 
                 58.8 
                 236 
               
               
                   
                   
                 28 
                 61.6 
                 253 
               
               
                   
                   
                 29 
                 63.4 
                 240 
               
               
                   
                   
                 30 
                 65.4 
                 251 
               
               
                   
                   
                 31 
                 68.0 
                 242 
               
               
                   
                   
                 32 
                 69.5 
                 170 
               
               
                   
                   
                 33 
                 73.9 
                 268 
               
               
                   
                   
                 34 
                 75.9 
                 269 
               
               
                   
                   
               
             
          
           
               
                 Non-Paraffin 
                   
                 Melting 
                 Latent 
                   
               
               
                 waxs 
                 Material 
                 point ( ) 
                 Heat (kJ/kg) 
                 Notes 
               
               
                   
               
               
                   
                 Formic acid 
                 7.8 
                 247 
               
               
                   
                 Caprilic acid 
                 16.3 
                 149 
               
               
                   
                 Glycerin 
                 17.9 
                 198.7 
               
               
                   
                 D-Lattic acid 
                 26 
                 184 
               
               
                   
                 Methyl palmitate 
                 29 
                 205 
               
               
                   
                 Camphenilone 
                 39 
                 205 
               
               
                   
                 Docasyl bromide 
                 40 
                 201 
               
               
                   
                 Caprylone 
                 40 
                 259 
               
               
                   
                 Phenol 
                 41 
                 120 
               
               
                   
                 Heptadecanone 
                 41 
                 201 
               
               
                   
                 1-Cyclo- 
                 41 
                 218 
               
               
                   
                 hexylooctadecane 
               
               
                   
                 4-Heptadacanone 
                 41 
                 197 
               
               
                   
                 p-Joluidine 
                 43.3 
                 167 
               
               
                   
                 Cyanamide 
                 44 
                 209 
               
               
                   
                 Methyl eicosanate 
                 45 
                 230 
               
               
                   
                 3-Heptadecanone 
                 48 
                 218 
               
               
                   
                 2-Heptadecanone 
                 48 
                 218 
               
               
                   
                 Hydrocinnamic acid 
                 48.0 
                 118 
               
               
                   
                 Cetyl alcohol 
                 49.3 
                 141 
               
               
                   
                 a-Nepthylamine 
                 50.0 
                 93 
               
               
                   
                 Camphene 
                 50 
                 238 
               
               
                   
                 O-Nitroaniline 
                 50.0 
                 93 
               
               
                   
                 9-Heptadecanone 
                 51 
                 213 
               
               
                   
                 Thymol 
                 51.5 
                 115 
               
               
                   
                 Methyl behenate 
                 52 
                 234 
               
               
                   
                 Diphenyl amine 
                 52.9 
                 107 
               
               
                   
                 p-Dichlorobenzene 
                 53.1 
                 121 
               
               
                   
                 Oxolate 
                 54.3 
                 178 
               
               
                   
                 Hypophosphoric acid 
                 55 
                 213 
               
               
                   
                 O-Xylene dichloride 
                 55.0 
                 121 
               
               
                   
                 b-Chloroacetic acid 
                 56.0 
                 147 
               
               
                   
                 Chloroacetic acid 
                 56 
                 130 
               
               
                   
                 Nitro naphthalene 
                 56.7 
                 103 
               
               
                   
                 Trimyristin 
                 33-57 
                 201-213 
               
               
                   
                 Heptaudecanoic acid 
                 60.6 
                 189 
               
               
                   
                 a-Chloroacetic acid 
                 61.2 
                 130 
               
               
                   
                 Bee wax 
                 61.8 
                 177 
               
               
                   
                 Bees wax 
                 61.8 
                 177 
               
               
                   
                 Glyolic acid 
                 63.0 
                 109 
               
               
                   
                 Glycolic acid 
                 63 
                 109 
               
               
                   
                 p-Bromophenol 
                 63.5 
                 86 
               
               
                   
                 Azobenzene 
                 67.1 
                 121 
               
               
                   
                 Acrylic acid 
                 68.0 
                 115 
               
               
                   
                 Dinto toluent (2,4) 
                 70.0 
                 111 
               
               
                   
                 Phenylacetic acid 
                 76.7 
                 102 
               
               
                   
                 Thiosinamine 
                 77.0 
                 140 
               
               
                   
                 Bromcamphor 
                 77 
                 174 
               
               
                   
                 Durene 
                 79.3 
                 156 
               
               
                   
                 Benzylamine 
                 78.0 
                 174 
               
               
                   
                 Methyl brombrenzoate 
                 81 
                 126 
               
               
                   
                 Alpha napthol 
                 96 
                 163 
               
               
                   
                 Glautaric acid 
                 97.5 
                 156 
               
               
                   
                 p-Xylene dichloride 
                 100 
                 138.7 
               
               
                   
                 Catechol 
                 104.3 
                 207 
               
               
                   
                 Quinone 
                 115 
                 171 
               
               
                   
                 Acetanilide 
                 118.9 
                 222 
               
               
                   
                 Succinic anhydride 
                 119 
                 204 
               
               
                   
                 Benzoic acid 
                 121.7 
                 142.8 
               
               
                   
                 Stibene 
                 124 
                 167 
               
               
                   
                 Benzamide 
                 127.2 
                 169.4 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Phase-Change Materials of Eutectic System 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Metal 
                   
                 Melting 
                 Latent 
                   
               
               
                 Eutectic 
                 Material 
                 point ( ) 
                 heat (kJ/kg) 
                 Notes 
               
               
                   
               
               
                   
                 Gallium-gallium 
                 29.8 
                 — 
               
               
                   
                 antimony 
               
               
                   
                 eutectic 
               
               
                   
                 Gallium 
                 30.0 
                 80.3 
               
               
                   
                 Cerrolow 
                 58 
                 90.9 
               
               
                   
                 eutectic 
               
               
                   
                 Bi—Cd—In eutectic 
                 61 
                 25 
               
               
                   
                 Cerrobend eutectic 
                 70 
                 32.6 
               
               
                   
                 Bi—Pb—In eutectic 
                 70 
                 29 
               
               
                   
                 Bi—In eutectic 
                 72 
                 25 
               
               
                   
                 Bi—Pb-tin 
                 96 
                 — 
               
               
                   
                 eutectic 
               
               
                   
                 Bi—Pb eutectic 
                 125 
                 — 
               
               
                   
               
             
          
           
               
                   
                   
                 Melting 
                 Latent 
                   
               
               
                 Organic-Inorganic 
                 Compositions 
                 point 
                 heat 
               
               
                 Eutectic 
                 (wt. %) 
                 ( ) 
                 (kJ/kg) 
                 Notes 
               
               
                   
               
               
                 CaCl 2     —   6H 2 O + 
                 45 + 55 
                 14.7 
                 140 
               
               
                 CaBr 2     —   6H 2 O 
               
               
                 Triethylolethane + 
                 38.5 + 31.5 + 30 
                 13.4 
                 160 
               
               
                 water + urea 
               
               
                 C 14 H 28 O 2  + 
                 34 + 66 
                 24 
                 147.7 
               
               
                 C 10 H 20 O 2   
               
               
                 CaCl 2  + 
                 50 + 50 
                 25 
                 95 
               
               
                 MgCl 2     —   6H 2 O 
               
               
                 CH 3 CONH 2  + 
                 50 + 50 
                 27 
                 163 
               
               
                 NH 2 CONH 2   
               
               
                 Triethylolethane + 
                 62.5 + 37.5 
                 29.8 
                 218 
               
               
                 urea 
               
               
                 Ca(NO 3 )_4H 2 O + 
                 47 + 53 
                 30 
                 136 
               
               
                 Mg(NO 3 ) 3     —   6H 2 O 
               
               
                 CH 3 COONa_3H 2 O + 
                 40 + 60 
                 30 
                 200.5 
               
               
                 NH 2 CONH 2   
               
               
                 NH 2 CONH 2  + 
                 53 + 47 
                 46 
                 95 
               
               
                 NH 4 NO 3   
               
               
                 Mg(NO 3 ) 3     —   6H 2 O + 
                 61.5 + 38.5 
                 52 
                 125.5 
               
               
                 NH 4 NO 3   
               
               
                 Mg(NO 3 ) 3     —   6H 2 O + 
                 58.7 + 41.3 
                 59 
                 132.2 
               
               
                 MgCl 2     —   6H 2 O 
               
               
                 Mg(NO 3 ) 3     —   6H 2 O + 
                 50 + 50 
                 59.1 
                 144 
               
               
                 MgCl 2     —   6H 2 O 
               
               
                 Mg(NO 3 ) 3     —   6H 2 O + 
                 53 + 47 
                 61 
                 148 
               
               
                 Al(NO 3 ) 2     —   9H 2 O 
               
               
                 CH 3 CONH 2  + 
                 50 + 50 
                 65 
                 218 
               
               
                 C 17 H 35 COOH 
               
               
                 Mg(NO 3 ) 2     —   6H 2 O + 
                 59 + 41 
                 66 
                 168 
               
               
                 MgBr 2     —   6H 2 O 
               
               
                 Napthalene + 
                 67.1 + 32.9 
                 67 
                 123.4 
               
               
                 benzoic acid 
               
               
                 NH 2 CONH 2  + 
                 66.6 + 33.4 
                 76 
                 151 
               
               
                 NH 4 Br 
               
               
                 LiNO 3  + NH 4 NO 3  + 
                 25 + 65 + 10 
                 80.5 
                 113 
               
               
                 NaNO 3   
               
               
                 LiNO 3  + NH 4 NO 3  + 
                 26.4 + 58.7 + 14.9 
                 81.5 
                 116 
               
               
                 KNO 3   
               
               
                 LiNO 3  + NH 4 NO 3  + 
                 27 + 68 + 5 
                 81.6 
                 108 
               
               
                 NH 4 Cl 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Phase-Change Material of Solid-Liquid System 
               
             
          
           
               
                   
                   
                   
                 Latent 
                 Specific Heat 
               
               
                   
                 Liquid 
                 Temperature 
                 Heat 
                 Capacity 
               
               
                 Material 
                 Phase 
                 Range ( ) 
                 (kJ/kg) 
                 (J/kg · K) 
               
               
                   
               
             
          
           
               
                 Rock 
                   
                 20 
                 2560  
                 879 
               
               
                 Brick 
                   
                 20 
                 1600  
                 840 
               
               
                 Concrete 
                   
                 20 
                 1900-2300 
                 880 
               
               
                 Water 
                   
                  0-100 
                 1000  
                 4190 
               
               
                 Caloriea HT43 
                 Oil 
                 12-260 
                 867 
                 2200 
               
               
                 Engine oil 
                 Oil 
                 Up to 160 
                 888 
                 1880 
               
               
                 Ethanol 
                 Organic 
                 Up to 78  
                 790 
                 2400 
               
               
                   
                 liquid 
               
               
                 Proponal 
                 Organic 
                 Up to 97  
                 800 
                 2500 
               
               
                   
                 liquid 
               
               
                 Butanol 
                 Organic 
                 Up to 118 
                 809 
                 2400 
               
               
                   
                 liquid 
               
               
                 Isotunaol 
                 Organic 
                 Up to 100 
                 808 
                 3000 
               
               
                   
                 liquid 
               
               
                 Isopentanol 
                 Organic 
                 Up to 148 
                 831 
                 2200 
               
               
                   
                 liquid 
               
               
                 Octane 
                 Organic 
                 Up to 126 
                 704 
                 2400 
               
               
                   
                 liquid