Multi-Layer Susceptor Tube for Inductive Aerosol Heating
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Solution Overview
Problem
Inductively heated aerosol-generating systems have a poor load factor for converting energy from the alternating magnetic field into heat, resulting in significant energy wastage as most of the magnetic field spreads beyond the susceptor element.
Innovation Solution
A multi-layer susceptor tube assembly with an inner tubular layer of higher resistivity and an outer tubular layer of lower resistivity, encasing the induction coil to enhance magnetic field coupling and heat conversion, along with a fluid-permeable design to facilitate aerosol release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional susceptor element is used with an induction coil, then the system can generate an alternating magnetic field for heating, but the majority of the magnetic field spreads beyond the susceptor element resulting in poor energy conversion efficiency
Solution Approach 1:
The susceptor element is segmented into multiple concentric layers with different electrical resistivities. The inner layer has higher resistivity for heat generation, while the outer layer has lower resistivity for magnetic field confinement. This segmentation allows the susceptor to simultaneously perform multiple functions: generating heat through Joule heating in the inner layer and confining the magnetic field through eddy currents in the outer layer, thereby improving energy conversion efficiency without requiring additional external components.
Solution Approach 2:
The susceptor element is constructed as a composite structure with at least two concentric layers of different electrically conductive materials. The inner layer comprises a material with higher electrical resistivity (e.g., stainless steel) optimized for heat generation, while the outer layer comprises a material with lower electrical resistivity (e.g., aluminum or copper) optimized for magnetic field confinement. This composite structure enables efficient energy conversion by assigning different functional properties to different layers.
2Loss of energy
If the susceptor element is made highly conductive to confine the magnetic field, then magnetic field coupling is improved, but heat generation capability decreases due to lower resistivity
Solution Approach 1:
Different regions of the susceptor element are assigned different electrical resistivity properties to perform different functions. The inner layer has higher resistivity specifically for heat generation through Joule heating, while the outer layer has lower resistivity specifically for magnetic field confinement through eddy currents. This local differentiation of material properties allows the susceptor to simultaneously optimize both magnetic field coupling and heat generation capability without compromise.
Solution Approach 2:
The susceptor is divided into functional segments: an inner heat-generating layer with higher resistivity and an outer field-confining layer with lower resistivity. This segmentation resolves the contradiction by separating the heat generation function from the magnetic field confinement function into different layers, each optimized for its specific purpose through appropriate material selection.
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
Significantly increases the effective coupling of the alternating magnetic field to the susceptor tube, improving energy conversion into heat and enabling a more efficient aerosol generation process while maintaining a compact system design.
Implementation Method 1
an induction source including an induction coil to generate an alternating magnetic field for inducing heat generating eddy currents and/or hysteresis losses in a susceptor element
Implementation Method 2
inducing heat generating eddy currents and/or hysteresis losses in a susceptor element
Implementation Method 3
An electrical resistivity of the first electrically conductive material is larger than an electrical resistivity of the second electrically conductive material
Data Source
AI summary
A susceptor assembly for inductively heating an aerosol-forming substrate is provided, the susceptor assembly including a multi-layer susceptor tube defining a cavity configured to receive an induction coil inside the multi-layer susceptor tube, the multi-layer susceptor tube includes an inner tubular layer, which includes a first electrically conductive material, and an outer tubular layer surrounding the inner tubular layer, which includes a second electrically conductive material, and an electrical resistivity of the first electrically conductive material is greater than an electrical resistivity of the second electrically conductive material. An inductive heating assembly for inductively heating an aerosol-forming substrate, an aerosol-generating article for an aerosol-generating device, and an aerosol-generating system are also provided.