University of South Florida

Sermin G Sunol

Aydin K Sunol

Kyle Louis Cogswell

Pamela Alvarez Moreno

Emilee Chassanne Bannister

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&#x2014;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.

Method of modulated exothermic chemical systems through phase change materials

Self-heating apparatus and methodology for customizing a time-temperature profile thereof. The layered apparatus includes at least a layer of phase change material and a layer of air- or oxygen-activated material. When the air- or oxygen-activated material is activated, heat is released rapidly and is absorbed by the phase change material. The phase change material then releases the absorbed heat over a long period of time. Time-temperature profiles can be adjusted based on type, amount, and configuration of phase change and air-activated materials used. The apparatus and methodology allows rapid heat-up of times of a few minutes and lasts several hours at near constant tunable temperatures.

Self-heating apparatus and method of customizing a time-temperature profile thereof

Exothermic reactions are used in self heating products, such as food, beverages, and clothing. Temperature peaks are important as heat can cause user injuries or increase pressures within the heating container to unsafe levels. Disclosed is a composition that modulates chemical reactions by control of the reaction initiation. Solid exothermic reactants, like calcium oxide and zeolite, are wetted with a combination of water and at least one surfactant, such as polyethylene glycol. The use of surfactants limits the initial rate of wetting, and also provides modulation of the reaction by changing phase. Optional addition of weak acids or acid salts modulated temperature and pH.

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Sermin G Sunol