Method of modulated exothermic chemical systems through phase change materials

The chemical reactions modulation of temperature and dissipate heat through using phase change materials (PCM). Hydration of a mixture composed of encapsulated and/or non-encapsulated oxides such as calcium oxide and/or magnesium oxide and dehydrated and/or hydrated zeolite coupled with control of pH of mixture through compounds such as Citric acid, or combination exothermic mixes, such as Cao and Mg—Fe, provide sustained heat release and heat retention tailored by addition of PCMs. The modulation may include timed/controlled release from encapsulated reactants and may include particles with tailored size distribution and different burn characteristics. The phase change materials used include organics (paraffins, non paraffins and fatty acids) and inorganics (salt hydrates). The selection of PCM is based on compatibility with the reacting mix, added reacting aqueous medium, and the desired temperature the system is to be held constant or temperature range it is desired to be modulated.