Embossed Thermal Interface Membrane for Aerosol Heating
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Solution Overview
Problem
Existing aerosol generating systems face inefficiencies in heat transfer between the heating surface and the liquid aerosol substrate, leading to suboptimal heating performance and user experience due to limited heat transfer coefficients and unstable boiling processes.
Innovation Solution
The introduction of a thermal interface membrane with embossed nucleation-enhancing micro- and/or nanostructures on the heating surface, creating a biphilic surface that combines hydrophobic and hydrophilic regions to increase nucleation sites and improve heat transfer efficiency, while minimizing superheat temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional smooth heating surface is used, then the device structure is simple, but the heat transfer coefficient is limited and boiling is unstable
Solution Approach 1:
The heating surface is embossed with nucleation-enhancing micro- and/or nanostructures to create localized regions with different surface properties. These microstructures provide specific nucleation sites that enhance bubble formation and detachment, improving heat transfer efficiency at critical locations without requiring the entire surface to be complex.
Solution Approach 2:
The embossed micro- and/or nanostructures on the heating surface create a porous-like architecture that facilitates nucleation and vapor bubble formation. This porous structure at the micro-scale increases the effective surface area for heat transfer and promotes stable boiling, analogous to how porous materials enhance heat transfer in conventional applications.
2Reliability
If the heating surface temperature is increased to improve heat transfer, then the heat transfer coefficient increases, but the superheat temperature increases and boiling becomes unstable
Solution Approach 1:
The embossed micro- and/or nanostructures change the surface geometry parameters of the heating surface. These structural modifications create preferential nucleation sites that lower the energy barrier for bubble formation, allowing efficient heat transfer at lower superheat temperatures. The surface geometry parameters are optimized to enhance nucleation without requiring excessive temperature increases.
3Reliability
If the heating surface is made hydrophobic to reduce wetting, then bubble detachment is improved, but liquid supply to the heating surface is reduced
Solution Approach 1:
The heating surface incorporates both hydrophobic regions (for bubble detachment) and hydrophilic regions (for liquid supply) through the embossed micro- and/or nanostructure pattern. The microstructures create localized hydrophobic peaks that promote bubble formation and detachment, while the valleys between peaks maintain hydrophilic characteristics to ensure adequate liquid supply to the heating surface.
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 solution enhances the heat transfer coefficient and critical heat flux, allowing for efficient heating at lower temperatures and increased vapor production, resulting in improved user experience and system performance.
Implementation Method 1
a thermal interface membrane comprising a heating surface, said thermal interface membrane being configured to transfer heat from the heating element in the base part to said aerosol-forming substrate in the cartridge to generate an aerosol
Implementation Method 2
the heating surface is embossed to comprise a plurality of nucleation-enhancing micro- and/or nanostructures
Implementation Method 3
The CHF represents the maximum useful heat flux, as above this temperature boiling becomes unstable and difficult to control. The superheat temperature is defined as ΔT = Tw - Tsat
Data Source
Figure 1~2
Figure 3(a)~3(d)
Figure 4~5
AI summary
A cartridge for an aerosol generating system, the cartridge being disposable and configured to connect to a base part comprising a heating element, the cartridge comprising: a liquid storage reservoir (24) configured for containing therein a liquid aerosol-forming substrate (20), and a thermal interface membrane comprising a heating surface (12), said thermal interface membrane being configured to transfer heat from the heating element in the base part to said aerosol-forming substrate in the cartridge to generate an aerosol that may be inhaled by a user, wherein the heating surface is embossed to comprise a plurality of nucleation-enhancing micro- and/or nanostructures.