A flameless heater apparatus and method whose heating capacity and performance can be selected and tuned at the time of manufacture, and which is easily used and has a long shelf life. The apparatus and method may be used in flameless ration heaters, such as may be used in military or emergency situations. There is provided a flameless heating method and apparatus in which the solid reactive ingredients (not including liquid reactant, typically water) are not all blended or mixed together at the time of apparatus fabrication. Rather, at least one key ingredient (typically a super-corroding alloy of magnesium and iron) in a dry powder form is kept physically segregated from all the other ingredients, such as catalysts (normally acids such as acetic or tartaric acid or acidic mixtures) and surfactants. The exothermic chemical reaction is initiated only after at least one (typically a dry powder catalyst) goes into aqueous solution after the application of water (saline or non-saline). The catalytic solution flows out, through, and about and among water-permeable pockets in the pouch-like apparatus which contain one or more other ingredients, including the active ingredient (e.g., the Mg-Fe alloy). Thus, the catalyst and the active ingredient do not come into effective contact until a flowing aqueous saline solution carries a reactive catalytic-saline solution to the active ingredient alloy, and then mixes the inter-reactive ingredients to generate the desired heat.
