Recuperative Burner Cellular Metal Inserts Heat Transfer
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Solution Overview
Problem
Conventional recuperative burners have complex structures and low efficiency due to the large number of heat exchanger tubes, and existing heat exchangers are not suitable for high-temperature applications or do not meet noise level requirements.
Innovation Solution
A recuperative burner design featuring a recuperator with cellular metal inserts that improve heat transfer and reduce noise, using an FeCrAl or CrNi-Al alloy to enhance thermal resistance and corrosion resistance, and a configuration that allows for efficient heat exchange between exhaust gas and combustion air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional heat exchanger tubes are used in recuperative burners, then heat exchange function is provided, but the structure becomes complicated and efficiency remains low due to the large number of tubes required
Solution Approach 1:
The patent applies porous ceramic materials as the recuperator core, replacing conventional heat exchanger tubes. The porous structure provides extensive internal surface area for heat exchange within a compact volume, eliminating the need for numerous external tubes while maintaining high heat transfer efficiency. The porous walls allow exhaust gas to permeate through them, creating intimate contact between hot and cold gas streams.
Solution Approach 2:
The patent uses composite construction combining ceramic porous material with metallic end caps and support structures. The ceramic portion provides high-temperature heat exchange functionality, while the metallic components provide structural support and sealing, creating a unified recuperator assembly that is both structurally sound and thermally efficient.
2Temperature
If standard heat exchangers are used, then heat transfer is achieved, but they cannot withstand high-temperature operation above 1000°C
Solution Approach 1:
The patent changes the material parameter from conventional metals to high-temperature-resistant ceramic materials. This parameter change enables the recuperator to operate reliably at temperatures exceeding 1000°C, as ceramics maintain their structural integrity and thermal performance in high-temperature environments where metals would fail or deform.
Solution Approach 2:
The patent accounts for thermal expansion by selecting ceramic materials with appropriate thermal expansion coefficients and designing the recuperator structure to accommodate expansion at high temperatures. The ceramic material's thermal properties are optimized to handle the extreme temperature differential between the exhaust gas side and combustion air side without cracking or deforming.
3Productivity
If conventional recuperator designs are used, then heat exchange occurs, but noise levels exceed acceptable limits of 70-80 dB(A)
Solution Approach 1:
The porous ceramic structure acts as an acoustic absorber, dampening turbulence and reducing noise generated by the high-velocity gas flows through the recuperator. The porous walls create friction and dissipate acoustic energy, lowering the sound pressure level to within acceptable limits while maintaining effective heat exchange.
4Strength
If metallic heat exchanger materials are used, then thermal conductivity is high, but corrosion resistance at high temperatures is insufficient
Solution Approach 1:
The patent changes the material composition from conventional metals to ceramic materials with superior high-temperature corrosion resistance. While ceramics generally have lower thermal conductivity than metals, the patent optimizes the ceramic composition and porosity to achieve adequate thermal performance while gaining exceptional resistance to thermal degradation and chemical corrosion in the harsh exhaust gas environment.
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 achieves a significant increase in efficiency and reduces noise emissions, with improved heat transfer and thermal resistance, allowing for quiet operation and high-temperature performance.
Implementation Method 1
Porous metallic inserts with high thermal conductivity made of a nickel alloy are placed in the spaces between the ridges and depressions. This is intended to improve heat transfer.
Implementation Method 2
recuperative burners feature a recuperator, along which exhaust gas flows on one side and combustion air flows in a counterflow pattern on the other, thus preheating the combustion air
Implementation Method 3
the cellular metal acts as a silencer for the flowing gases. This type of recuperator results in extremely quiet operation of the recuperator burner
Implementation Method 4
The alloy provided according to the invention, in the form of an FeCrAl or CrNi-Al alloy, forms Al2O3 on its surface, resulting in high corrosion resistance.
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
A recuperator for a recuperator burner (10) for preheating combustion air using exhaust gas heat is described, wherein the recuperator (30, 30a, 30b, 30c) is tubular with an inner surface (56) and an outer surface (54), and wherein at least one insert (64) made of a cellular metal is accommodated on the inner surface (56) or on the outer surface (54), which preferably allows flow through the recuperator (30, 30a, 30b, 30c) in the longitudinal direction. The supply air is preferably preheated twice in the burner head (12), namely in a first supply air duct section (24) by an exhaust gas duct (18) coaxially enclosed therein in co-current flow, and additionally by a second supply air duct section (26), which is coaxially enclosed by the exhaust gas duct (18), in counter-current flow.