Self-Heating Chemical System for Sustained Modulation of Temperature

Abstract

A self-heating chemical system using one or more primary components for exothermic reactions (such as calcium oxide), one or more porous components that can serve as a heat sink and conductor of heat as well as under going chemical transformations that release heat (zeolite), a weak acid (citric acid) for sustained modulation of temperature and pH. Exothermic reactions, mixing of some chemicals, sorption of certain chemicals, phase changes in chemicals, and dissolution of some chemicals in solvents release heat during these operations. The rate of heat generation coupled with mass and energy transfer rates to or from system(s) allows modulation of the temperature of systems. The modulation can be further enhanced by controlled release and availability of some of the components. This method provides with a class of self-heating product applications and focuses on the modulation of temperature through sequestering of reactions with different rates, heat release through dissolution, heat release through mixing, heat release through sorption, heat release through phase change as well as controlling mass and heat transfer rates.

1 . A heat-producing composition comprising calcium oxide, zeolite and one or more weak acids.  
   
   
       2 . The composition according to  claim 1  wherein the one or more weak acids is citric acid.  
   
   
       3 . The composition according to  claim 2  wherein the weight ratio of the calcium oxide:zeolite:citric acid is about 8:1:1.  
   
   
       4 . The composition according to  claim 1  wherein the composition is encapsulated in a coating.  
   
   
       5 . The composition according to  claim 4  wherein the coating is water-soluble.  
   
   
       6 . The composition according to  claim 4  wherein the coating is selected from the group consisting of water-soluble polymers and sugars.  
   
   
       7 . A heating element to provide extended heat transmission comprising: 
 a containment member comprising water; and    a reaction mixture comprising calcium oxide and zeolite, wherein release of the water in the containment member allows contact with the reaction mixture thereby producing an exothermic reaction.    
   
   
       8 . The heating element according to  claim 7  wherein the reaction mixture further comprises one or more one or more weak acids to neutralize the calcium hydroxide produced by the reaction of the water with the calcium oxide and further regulate temperature.  
   
   
       9 . The heating element according to  claim 8  wherein the one or more weak acids is citric acid.  
   
   
       10 . The heating element according to  claim 9  wherein the weight ratio of the reaction mixture of calcium oxide:zeolite:citric acid is about 8:1:1.  
   
   
       11 . The heating element according to  claim 7  wherein the reaction mixture is encapsulated in a coating.  
   
   
       12 . The heating element according to  claim 11  wherein the coating is water-soluble.  
   
   
       13 . The heating element according to  claim 11  wherein the coating is selected from the group consisting of water-soluble polymers and sugars.  
   
   
       14 . A heating element to provide extended heat transmission comprising: 
 an inner containment member comprising water; and    an outer containment member comprising a reaction mixture comprising calcium oxide, zeolite and a weak acid, wherein release of the water in the inner containment member allows contact with the reaction mixture thereby producing an exothermic reaction.    
   
   
       15 . The heating element according to  claim 14  wherein the one or more weak acids is citric acid.  
   
   
       16 . The heating element according to  claim 14  wherein the contents of the outer containment member are under vacuum.  
   
   
       17 . The heating element according to  claim 14  wherein the inner containment member is at a pressure higher that the outer containment member.  
   
   
       18 . The heating element according to  claim 16  wherein the outer containment member is vacuum-sealed to the inner containment member.  
   
   
       19 . The heating element according to  claim 14  wherein the reaction mixture is encapsulated in a coating.  
   
   
       20 . The heating element according to  claim 19  wherein the coating is water-soluble.  
   
   
       21 . The heating element according to  claim 19  wherein the coating is selected from the group consisting of water-soluble polymers and sugars.  
   
   
       22 . The heating element according to  claim 15  wherein the reaction mixture is encapsulated in a coating.  
   
   
       23 . A self-heating chemical system for the production of warm towels comprising a pouch system containing one or more towels and a heating element, the heating element comprising an inner containment member comprising water and an outer containment member comprising a reaction mixture comprising calcium oxide, zeolite and a weak acid, wherein release of the water in the inner containment member allows contact with the reaction mixture thereby producing an exothermic reaction.  
   
   
       24 . The self-heating chemical system according to  claim 23  wherein the one or more weak acids is citric acid.  
   
   
       25 . The self-heating chemical system according to  claim 23  wherein the contents of the outer containment member are under vacuum.  
   
   
       26 . The self-heating chemical system according to  claim 23  wherein the reaction mixture is encapsulated in a coating.