Expanded Graphite Aerosol-Forming Substrate for Uniform Heat Distribution
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Solution Overview
Problem
Existing aerosol-forming substrates have low thermal conductivity, leading to uneven temperature distribution and reduced efficiency in releasing volatile compounds, and often require a susceptor element for induction heating, increasing costs.
Innovation Solution
Incorporating expanded graphite particles with a thermal conductivity greater than 0.12 W/mK into the aerosol-forming substrate, which enhances thermal conductivity, ensures even temperature distribution, and allows for lower power consumption and faster heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a susceptor element is added to enable induction heating, then the substrate can be heated to operating temperatures, but the device complexity and cost increase
Solution Approach 1:
The patent combines the susceptor functionality with the aerosol-forming substrate itself by incorporating conductive particles (silver, gold, copper, or graphite) directly into the substrate matrix. This merging eliminates the need for a separate susceptor element while enabling direct induction heating of the substrate to operating temperatures.
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: it serves as both the aerosol-forming material carrier and the inductively heated susceptor. The conductive particles embedded in the substrate enable it to absorb electromagnetic energy and convert it to heat, making the substrate universally functional for both aerosol generation and heating purposes.
2Stability of the object's composition
If the thermal conductivity of the substrate is increased, then the temperature distribution becomes more uniform, but the manufacturing complexity increases
Solution Approach 1:
The patent achieves uniform temperature distribution by strategically distributing conductive particles throughout the substrate matrix. These particles are not uniformly mixed but are positioned to create localized thermal conduction pathways that efficiently distribute heat from the induction heating zone throughout the entire substrate, ensuring uniform temperature without requiring the entire substrate material to have high thermal conductivity.
Solution Approach 2:
The substrate is formulated as a composite material combining an aerosol-forming matrix with embedded conductive particles. This composite structure leverages the thermal conductivity of the conductive particles (especially graphite with its anisotropic thermal properties) to enhance heat distribution while maintaining the functional properties of the base aerosol-forming material.
3Power
If a central susceptor element is used for induction heating, then heating is enabled, but portions of the substrate furthest from the susceptor do not reach high temperatures
Solution Approach 1:
The patent segments the heating function by distributing multiple conductive particles throughout the substrate rather than using a single central susceptor element. This segmentation creates multiple localized heating zones and thermal conduction pathways throughout the substrate, ensuring that heat is generated and distributed uniformly across the entire substrate volume, eliminating the temperature gradients that would exist with a central susceptor configuration.
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 use of expanded graphite particles results in a more efficient aerosol-forming substrate with uniform temperature distribution, higher usage efficiency, and reduced heating time, while potentially lowering the weight and shipping costs of aerosol-generating articles.
Implementation Method 1
the expanded graphite particles may act as thermal conduits to conduct heat through the aerosol-forming substrate
Implementation Method 2
heat the aerosol-forming substrate and cause the aerosol-forming substrate to release volatile compounds
Data Source
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AI summary
An aerosol-forming substrate for use in a heated aerosol-generating article comprises expanded graphite particles. Expanded graphite particles have high thermal conductivity and low density and may improve efficiency of aerosol delivery from the substrate.