Exothermic Chemical Systems with Phase Change Materials for Temperature Modulation
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Solution Overview
Problem
Existing self-heating products face challenges in achieving sustained and controlled temperature modulation, often resulting in uneven heating, overheating, and safety issues due to the lack of effective regulation of exothermic reactions and heat distribution.
Innovation Solution
A method that combines exothermic chemical reactions with phase change materials to modulate temperature profiles, using a mixture of metal oxides, zeolites, and surfactants to control heat and mass transfer rates, allowing for extended heat release without encapsulation, and incorporating pH modulators for sustained temperature modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If exothermic chemical reactions are used for self-heating, then heat generation capability is improved, but temperature control and modulation deteriorate
Solution Approach 1:
The patent utilizes phase change materials (PCMs) that undergo phase transitions (solid-liquid-crystal) at specific temperatures to absorb and release heat. The PCM absorbs excess heat during phase transition, preventing temperature runaway, and releases heat when cooling down, thereby modulating the temperature profile of the self-heating system while maintaining high heat generation capability from the exothermic reaction.
Solution Approach 2:
The invention creates a composite system combining exothermic reactants (such as calcium oxide, magnesium perchlorate) with phase change materials (paraffins, fatty acids, plastic crystals). This composite structure allows the chemical reaction to generate heat while the PCM component actively modulates temperature, resolving the contradiction between heat generation and temperature control.
2Reliability
If dual chamber cans are used for self-heating, then chemical reaction control is improved, but heating uniformity deteriorates
Solution Approach 1:
The phase change material acts as an intermediary between the exothermic reaction and the substrate (food/drink). It absorbs and redistributes heat uniformly throughout its phase transition process, eliminating hot spots and ensuring uniform heating across the substrate while the dual chamber structure maintains reaction control.
3Productivity
If high temperature heating is used, then heating efficiency is improved, but safety issues worsen
Solution Approach 1:
The phase change material is pre-positioned in the system to counteract excessive temperature rise before it occurs. During the exothermic reaction, the PCM undergoes phase transition at a predetermined temperature, absorbing excess heat and preventing temperature runaway, thus preemptively addressing safety issues while allowing efficient heating to occur.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient, safe, and environmentally friendly sustained heat generation and distribution, preventing overheating and ensuring consistent temperature profiles, thus addressing the limitations of existing self-heating technologies.
Implementation Method 1
The present invention combines modulation of chemical reactions, thereby allowing tuning of substrate temperature profiles through sequestering of several exothermic reactions, regulation of reaction, heat and mass transfer rates, and control of the reaction initiation with melting the phase change materials with the heat provided through the chemical reaction and subsequently, utilizing the heat released during fusion of the phase change material
Implementation Method 2
utilizing the heat released during fusion of the phase change material
Implementation Method 3
The present invention combines modulation of chemical reactions, thereby allowing tuning of substrate temperature profiles through sequestering of several exothermic reactions
Implementation Method 4
regulation of reaction, heat and mass transfer rates
Data Source
AI summary
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.