a portable heat generating device in which fuel vapor and an oxygen supply are directed through channels contained within a thin , flexible and compliant elastomeric sheet of material . elongated catalytic heat elements , placed strategically within the channels , spontaneously interact with the fuel - air stream liberating heat energy . means and methods are defined that permit flameless catalytic combustion to be uniformly extended over the length of each heat element , lowering power density but maintaining the overall power generated , permitting the use of many types of low temperature materials like plastics , polymers , and elastomers in the construction of the heater . the heat generation process is started by pumping an air stream into a reservoir containing a fuel source thereby saturating the air stream with fuel vapor . the fuel vapor is mixed with a another stream of air to achieve a particular fuel / air ratio and directed into channels within the elastomeric sheet , reacting with the catalytic heat elements to produce flameless combustion . the warm exhaust gas is directed to a thermally controlled diverter valve . the valve senses the temperature of the liquid fuel supply and diverts some or all of the warm exhaust gas , as necessary , to heat the fuel and keep its temperature within a specified range . exhaust by - products are passed into a miniature scrubber module adjacent to the fuel module . the scrubber absorbs any noxious components in the exhaust stream that may occur during start - up or rapid changes in operating condition .