Smoking Article Combustible Heat Source Isolation Barrier
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Solution Overview
Problem
Existing heated smoking articles face challenges in preventing spikes in temperature of the aerosol-forming substrate during intense puffing, leading to potential combustion or pyrolysis, and the entry of combustion and decomposition products into the mainstream aerosol, as well as migration of aerosol-formers from the substrate to the heat source.
Innovation Solution
A smoking article design featuring a combustible heat source with opposed front and rear faces, isolated from airflow pathways by a non-combustible, air-impermeable barrier coating on the rear face, and an aerosol-forming substrate downstream, which prevents direct contact between the heat source and airflow, thereby minimizing temperature spikes and product entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If air is drawn through the combustible heat source to enable convection heating, then heat transfer efficiency is improved, but temperature spikes and combustion activation occur during intense puffing
Solution Approach 1:
The heat source is divided into two functional zones: a front combustion zone for heating and a rear convective zone for controlled air flow. This segmentation allows the patent to achieve both efficient heat transfer and stable temperature control by preventing direct air contact with the combustion zone while enabling convection in the rear zone.
Solution Approach 2:
A porous barrier layer is introduced as an intermediary between the air flow pathway and the combustible heat source. This barrier allows controlled heat and mass transfer while preventing direct air contact with the combustion zone, thereby eliminating temperature spikes and combustion activation during intense puffing.
2Use of energy by moving object
If the aerosol-forming substrate is placed in direct contact with the combustible heat source, then heat transfer efficiency is improved, but pyrolysis and combustion of the substrate occur
Solution Approach 1:
The porous barrier layer serves as an intermediary between the combustible heat source and the aerosol-forming substrate. It allows efficient heat and mass transfer to maintain substrate heating while preventing direct contact that would cause pyrolysis and combustion during intense puffing.
Solution Approach 2:
The barrier layer is positioned specifically at the interface between the heat source and substrate, providing localized protection against harmful effects while maintaining overall heat transfer efficiency. This localized application ensures the substrate receives sufficient heat without undergoing pyrolysis or combustion.
3Reliability
If combustion additives are included in the heat source to improve ignition properties, then ignition reliability is improved, but decomposition and reaction products enter the mainstream aerosol
Solution Approach 1:
The porous barrier layer acts as an intermediary that filters out decomposition and reaction products generated by combustion additives in the heat source. It allows heat and vapor transfer while blocking harmful substances from entering the mainstream aerosol, thus maintaining ignition reliability without compromising aerosol quality.
4Use of energy by moving object
If convective heat transfer is used to heat the aerosol-forming substrate, then energy efficiency is improved, but aerosol composition becomes highly sensitive to user puffing regime
Solution Approach 1:
The heat source is segmented into combustion and convection zones, with the porous barrier controlling the interface. This segmentation allows efficient energy use through convection while maintaining stable aerosol composition by preventing temperature spikes that would occur with direct air contact during varying puffing regimes.
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 design effectively prevents combustion and pyrolysis of the aerosol-forming substrate, reduces the impact of puffing regimes on aerosol composition, and inhibits the migration of aerosol-formers, resulting in a more stable and cleaner aerosol inhalation experience.
Implementation Method 1
a non-combustible, air-impermeable barrier coating on the rear face, which prevents direct contact between the heat source and airflow, thereby minimizing temperature spikes
Implementation Method 2
heat transfer from the combustible heat source to the aerosol-forming substrate occurs by convection and conduction
Implementation Method 3
heat transfer from the combustible heat source to the aerosol-forming substrate occurs by convection and conduction
Implementation Method 4
As the released compounds cool, they condense to form an aerosol that is inhaled by the user
Data Source
AI summary
A smoking article is provided, including: a combustible heat source having front and rear ends; an aerosol-forming substrate downstream of the rear end; an outer wrapper circumscribing the substrate and at least a rear portion of the heat source; one or more airflow pathways along which air may be drawn through the article for inhalation; one or more third air inlets downstream of the substrate for drawing air into the airflow pathways; and an airflow directing element downstream of the substrate, the third air inlets being provided between a downstream end of the substrate and a downstream end of the airflow directing element, the airflow pathways include an airflow pathway extending between the third air inlets and a mouth end of the article, and the heat source being isolated from the pathways such that air drawn through the article along the pathways does not directly contact the heat source.