Porous oxygen activated heater

Abstract

An substrate heater includes at least a wet porosity of between 15-35% to allow for sufficient electrolyte solution and porosity for access of a reducing agent within the substrate and oxygen.

What is claimed is: 
     
         1 . A heater comprising:
 a composite heater substrate that exothermically reacts with oxygen, wherein the composite heater substrate has a wet porosity of between 15-35%.   
     
     
         2 . The heater of  claim 1  wherein the composite heater substrate has a dry porosity of approximately 60%. 
     
     
         3 . The heater of  claim 1  wherein the composite heater substrate has a dry porosity of approximately between 60-65%. 
     
     
         4 . The heater of  claim 1  wherein the heater comprises: a reducing agent, a binder, a promoter and an electrolyte. 
     
     
         5 . A heater comprising:
 a porous flexible substrate including a reducing agent, a binder, and a promoter, the porous flexible substrate being activated with an electrolyte solution; and,   a package surrounding the porous flexible substrate to selectively prevent oxygen access to the porous flexible substrate to control an exothermic reaction between the porous flexible substrate and atmospheric oxygen,   wherein the porous flexible substrate has a wet porosity of between approximately 15-35%.   
     
     
         6 . The heater of  claim 5  wherein the porous flexible substrate has a dry porosity of approximately 60%. 
     
     
         7 . The heater of  claim 5  wherein the porous flexible substrate has a dry porosity of approximately between 60-65%. 
     
     
         8 . The heater of  claim 5 , wherein the heater includes approximately 82% by weight of the reducing agent, approximately 6.5% by weight of promoter, and approximately 12% of binder. 
     
     
         9 . The heater of  claim 8 , wherein the heater has a dry porosity of approximately 60%. 
     
     
         10 . The heater of  claim 9 , wherein the heater includes between approximately 5-8 g of electrolyte solution. 
     
     
         11 . The heater of  claim 10 , wherein the electrolyte solution is a 20% by weight solution of potassium chloride. 
     
     
         12 . A heater comprising:
 a flexible substrate that includes a binder and a reducing agent that will produce heat in the present of oxygen;   the flexible substrate being porous;   the flexible substrate being activated by an electrolyte solution such that the flexible substrate includes a wet porosity sufficient to achieve a desired temperature in an acceptable amount of time.   
     
     
         13 . The heater of  claim 12 , wherein the desired temperature is 140° F. 
     
     
         14 . The heater of  claim 13 , wherein the acceptable amount of time is less than 15 minutes. 
     
     
         15 . The heater of  claim 12 , wherein the wet porosity is between approximately 15-35%. 
     
     
         16 . The heater of  claim 12 , wherein the desired temperature is approximately 100° F. than an initial temperature of the heater.