IR-Absorbing Foil Coating for Faster Oven Heat Transfer
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Solution Overview
Problem
Conventional aluminum foils used in food packaging are inefficient in absorbing infrared radiation, leading to prolonged cooking times and increased energy consumption, as they only utilize about 7% of radiant heat transfer at oven temperatures of 200°C, whereas black surfaces can achieve 66% efficient heat transfer.
Innovation Solution
A duplex coating system is applied to the aluminum foil, comprising a radiation-absorbing layer with a wavelength spectrum matching that of the oven cavity, typically within the range of 8,000-10,000 nanometers, and a top layer that enhances internal reflection, allowing for improved absorption and reflection of IR radiation, utilizing materials like TiO2 and 'carbon black' with SiO2, to achieve higher temperature and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional aluminum foil is used, then the reflective properties of aluminum material are maintained, but the contribution from radiant heat is only about 7%, leading to prolonged cooking times
Solution Approach 1:
The patent applies a composite coating structure consisting of multiple layers with different functions: a bottom layer (e.g., carbon black or dark minerals) for absorbing IR radiation, and a top layer (e.g., TiO2 or light-colored minerals) for aesthetic appearance and internal reflection enhancement. This composite structure transforms the foil from purely reflective to a combination of absorption and reflection, achieving over 66% radiant heat contribution while maintaining visual appeal.
2Use of energy by moving object
If black coating is applied to aluminum foil to improve IR absorption, then radiant heat absorption increases to 66%, but the visual appearance becomes dark and less aesthetically pleasing
Solution Approach 1:
The patent applies different properties to different layers of the coating: the bottom layer has high IR absorption capability (dark color) while the top layer has aesthetic appearance properties (light color). Each layer performs its specific function locally, and the combination achieves both high radiant heat absorption and visual appeal.
Solution Approach 2:
The patent transitions from a single-layer coating to a multi-layer coating structure, adding a vertical dimension to the coating system. This allows the bottom layer to handle IR absorption while the top layer handles aesthetics, resolving the contradiction between function and appearance.
3Productivity
If single-layer coating is applied, then the structure is simple, but the heat transmission efficiency does not surpass black surfaces
Solution Approach 1:
The patent uses a composite multi-layer coating structure where each layer contributes different properties: the bottom layer absorbs IR radiation while the top layer enhances internal reflection and provides aesthetic appearance. This composite approach achieves heat transmission efficiency surpassing black surfaces while maintaining reasonable structural complexity.
Solution Approach 2:
The top layer acts as an intermediary between the absorbed IR radiation and the external environment, reflecting heat back toward the heated element while allowing the bottom layer to perform absorption. This intermediary layer enhances the overall heat transmission efficiency beyond what a single black layer can achieve.
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
The duplex coating system significantly enhances heat transmission efficiency, allowing for shorter cooking times and energy savings by increasing the contribution of radiant heat transfer to over 66%, surpassing the efficiency of traditional black surfaces and single-layer coatings.
Implementation Method 1
a radiation-absorbing layer, wherein the wavelength spectrum of the electromagnetic radiation of the radiation-absorbing layer and the wavelength spectrum of the electromagnetic radiation of the oven cavity are attuned to each other
Implementation Method 2
a second layer is configured for reflecting the radiation of heat emitted from a heated element wrapped in the foil, wherein the heat from the element is thus reflected back to the element
Implementation Method 3
the wavelength spectrum of the electromagnetic radiation of the oven cavity
Data Source
AI summary
The invention relates to a heat transmission system based on electromagnetic radiation, which heat transmission system comprises an oven cavity and a foil with at least two layers, said at least two layers of the foil comprising a radiation-absorbing layer, wherein the wavelength spectre of the electromagnetic radiation of the radiation-absorbing layer and wavelength spectre of the electromagnetic radiation of the oven cavity are attuned to each other. The invention also relates to a foil for use in a heat transmission system, said foil comprising at least two layers, and wherein the wavelength spectre of the electromagnetic radiation of the foil is attuned to that of a heat source, eg the wavelength spectre of the electromagnetic radiation of an oven. The foil may be provided with a radiation-absorbing surface that may be configured both as a flexible foil and as an inflexible foil that may be of either metal or of a polymer, paper, cardboard or other materials that are based on wood.