Chimney Closure Device for Soot Fire Resistance and Gas Tightness
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Solution Overview
Problem
Modern wood fireplaces and similar systems require an exhaust system that is resistant to soot fire and meets higher gas-tightness requirements, which existing technologies fail to achieve effectively, especially in overpressure conditions.
Innovation Solution
A closure device comprising an inner lid, an insulating element, and an outer lid, where the inner lid forms a seal with the shaft wall, the insulating element provides thermal and sound insulation, and the outer lid seals with intermediate insulation elements, ensuring a leak rate of no more than 0.006 l/(s m²) and resistance to soot fire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple metal or ceramic door is used for closing the nozzle, then the device complexity is low, but the gas-tightness is insufficient for overpressure exhaust systems
Solution Approach 1:
The closure device is divided into three distinct parts: an inner lid made of heat-resistant material, an insulating element, and an outer lid. This segmentation allows each component to perform its specific function - the inner lid withstands high temperatures, the insulating element reduces thermal load, and the outer lid provides sealing. This resolves the contradiction by achieving high gas-tightness through a multi-component structure rather than a simple single-piece door.
Solution Approach 2:
The closure device combines different materials with complementary properties: heat-resistant ceramic or metal for the inner lid, thermal insulation materials (such as ceramic fiber or mineral wool) for the insulating element, and sealing materials for the outer lid. This composite construction enables the overall device to meet both high gas-tightness requirements and thermal resistance, resolving the contradiction between reliability and simplicity.
2Reliability
If a thick insulating layer is added to the closure device, then the gas-tightness and thermal resistance improve, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
By segmenting the closure device into separate components (inner lid, insulating element, outer lid), the manufacturing complexity is distributed across multiple simple parts rather than requiring one complex thick-walled component. Each part can be manufactured independently using standard processes, then assembled together to achieve the required thermal resistance and gas-tightness.
Solution Approach 2:
The insulating element is nested between the inner lid and outer lid, with the outer lid containing the insulating element which in turn contains the inner lid. This nested arrangement achieves thick insulation without requiring a single complex monolithic structure, simplifying manufacturing while maintaining thermal resistance.
3Reliability
If the outer lid is placed close to the hot exhaust shaft, then the sealing effectiveness improves, but the thermal load on the outer lid increases making sealing difficult
Solution Approach 1:
The insulating element acts as an intermediary between the hot exhaust shaft and the outer lid. It thermally insulates the outer lid from the high temperatures in the exhaust shaft, reducing the thermal load on the sealing surfaces. This allows the outer lid to maintain its sealing effectiveness without being subjected to excessive temperatures that would compromise the sealing materials.
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 solution effectively seals the chimney system under overpressure conditions, preventing gas leakage and withstanding soot fire temperatures, thus meeting the thermal load tests and ensuring safe operation.
Implementation Method 1
The insulation element primarily serves for thermal insulation
Implementation Method 2
In the case of negative pressure exhaust systems, i.e. exhaust systems in which the pressure in the exhaust shaft is lower than outside
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The chimney is provided with an exhaust duct (2) with a duct wall (21) surrounding the exhaust duct. A closure device (1) is provided with an inner cover (11), which is engaged in the duct wall opening (22) and is arranged with a section inside a connection (3). An outer cover (12) is arranged outside the duct wall opening and with a section inside the port. An insulating element (13) is arranged inside the connection between the inner cover and the outer cover.