Solid-Core Heat Exchanger Separating Combustible Exhaust and Oxidant
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Solution Overview
Problem
Existing heat exchanger systems face challenges in efficiently recovering waste heat from combustion exhaust gases, particularly when the combustion gases contain combustible substances and high oxygen content, leading to potential ignition risks, and existing solutions either require high material constraints or are prohibitively expensive.
Innovation Solution
A heat exchanger design featuring a solid inner core with multiple circuitous flow paths surrounded by a core material that acts as a heat storage medium, separating and transferring heat effectively between hot and cold fluids, enhancing heat recovery while preventing direct contact between combustible substances and oxidant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative heat recovery is used with high temperature furnaces, then heat recovery efficiency is improved and fuel consumption is reduced, but the risk of ignition of combustible substances in exhaust gases increases due to direct contact with high oxygen content oxidant
Solution Approach 1:
The heat exchanger is divided into multiple flow paths (first flow path for oxidant, second flow path for exhaust gas) that are spatially separated within the same device. This segmentation allows heat recovery while preventing direct contact between combustible exhaust gases and high oxygen oxidant, eliminating the ignition risk while maintaining high heat recovery efficiency.
2Stability of the object's composition
If recuperative heat recovery systems are used to provide stable oxidant temperatures, then temperature stability is improved, but material constraints increase and costs become prohibitively expensive at high temperatures
Solution Approach 1:
The system uses periodic switching between two combustion units, where one unit is firing while the other is being preheated, and vice versa. This periodic operation allows the oxidant temperature to remain stable while using simpler, more cost-effective materials that can withstand the alternating thermal conditions, avoiding the need for expensive high-temperature resistant materials required in continuous high-temperature recuperative systems.
3Stability of the object's composition
If the duration of firing phases is shortened and switching frequency is increased to maintain stable oxidant temperature in regenerative systems, then temperature stability is improved, but system complexity and switching requirements increase
Solution Approach 1:
The heat exchanger is divided into multiple flow paths (first flow path for oxidant, second flow path for exhaust gas) that are spatially separated within the same device. This segmentation allows heat recovery while preventing direct contact between combustible exhaust gases and high oxygen oxidant, eliminating the ignition risk while maintaining high heat recovery efficiency.
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 design increases heat transfer surface area and maintains stable temperature ranges for preheating combustion oxidants, reducing fuel consumption and emissions, and allows for efficient heat recovery with reduced material constraints and costs.
Implementation Method 1
the combustion exhaust gas generated by the firing first combustion unit passes, from the hot-side opening to the cold-side opening, through the heat reservoir of the non-firing second combustion unit so that said heat reservoir accumulates thermal energy from the exhaust gas and is thereby heated
Implementation Method 2
the combustion oxidant passes from the cold-side opening to the hot-side opening through the heated heat reservoir of said firing second combustion unit and absorbs the thermal energy recovered by said heat reservoir during the previous phase
Implementation Method 3
said heat reservoir accumulates thermal energy from the exhaust gas and is thereby heated
Data Source
AI summary
A heat exchanger including a shell extending in a longitudinal direction D from a first end to a second end and including a mantle extending from the first end to the second end, and a solid inner core made of a core material and located inside the shell, the core extending in direction D from a first extremity towards the first end to a second extremity towards the second end. Whereby, at least one first flow path is provided inside the core, each first flow path extending from the first extremity to the second extremity of the core, n circuitous second flow paths extend through the core and/or between the core and the mantle, so that the at least one first flow path is surrounded by the n second flow paths over a non-zero rectilinear distance ΔL in direction D, n being an integer greater than 1.