Nested Helical Fin Tube Coil for Combustion Gas Bypass Control
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Solution Overview
Problem
Helically coiled fin/tube heat exchanger coils suffer from reduced heat transfer efficiency due to hot combustion gases bypassing the tubing coils, and existing solutions to direct gases over the tubing increase weight, complexity, and cost, while still allowing significant gas bypass.
Innovation Solution
A helical fin/tube heat exchanger coil design with integrally formed fins that are laterally inwardly bent and circumferentially folded to form triangular configurations, creating baffle outlets to concentrate gas flow across the tubing, and nested fin edges to seal between adjacent coil pairs, enhancing heat transfer efficiency without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If separate baffle structures are secured to the fin/tube assembly to direct combustion gases over the tubing, then heat transfer efficiency is improved, but weight, complexity, and cost increase
Solution Approach 1:
The patent merges the baffle function with the existing fin structure by integrating laterally inwardly bent fin portions that extend between adjacent tubing coils. This combines two previously separate functions (heat transfer fins and gas directing baffles) into a single integrated structure, eliminating the need for separate baffle components while maintaining both heat transfer efficiency and gas flow direction.
Solution Approach 2:
The fin structure is designed to perform multiple functions simultaneously: it serves as both a heat transfer surface and a gas directing baffle. The laterally inwardly bent portions of the fins create channels that guide combustion gases over the tubing while the fin surfaces continue to facilitate heat transfer, making the structure multi-functional and eliminating the need for dedicated baffle components.
2Loss of energy
If separate baffle structures are added to channel combustion gases, then heat transfer efficiency increases, but manufacturing cost and weight increase
Solution Approach 1:
The baffle function is merged into the existing fin structure, eliminating the need for additional heavy baffle components. The same fin material and structure that provides heat transfer surface area also creates the gas directing channels, reducing overall weight while maintaining heat transfer efficiency.
3Loss of energy
If separate baffle structures are used to direct gases, then heat transfer efficiency is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent combines the baffle function with the fin structure, eliminating the need for separate manufacturing and assembly steps for baffles. The integrated structure can be manufactured as a single unit or pre-assembled component, simplifying the manufacturing process while achieving improved heat transfer efficiency.
4Loss of energy
If fins are configured to seal between adjacent coil pairs, then gas bypass is reduced and heat transfer efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The fin edges are pre-formed with laterally inwardly bent portions that create sealing surfaces before the coils are assembled. This preliminary formation of the sealing geometry allows for easier alignment during assembly, as the sealing surfaces are already prepared and positioned correctly, reducing the precision requirements during the final assembly process.
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 improves heat transfer efficiency by directing hot gases over the tubing and sealing gaps between coil pairs, reducing gas bypass and manufacturing costs, while maintaining structural integrity.
Implementation Method 1
helically coiled heat conductive tubing having secured thereto a longitudinally spaced series of heat conductive fins
Implementation Method 2
hot combustion gases that are forced laterally outwardly through the coil and function to heat the liquid flowing through the tubing
Data Source
AI summary
A heat exchanger, illustratively utilized in a fuel-fired pool heater, circumscribes a burner operative to discharge hot combustion gases outwardly through the heat exchanger. The heat exchanger has a tube portion helically coiled about an axis, with a series of heat transfer fins circumscribing the tube portion and spaced apart along it length. The fins on longitudinally adjacent pairs of coils of the tubing have nested facing edge portions which collectively form a seal area that coils between the tubing portion adjacent coil pairs in axially spaced relationships therewith, the seal area substantially impeding combustion gas flow therethrough in a direction generally transverse to the axis of the heat exchanger. Additionally, the fins have deformed laterally outer portions that define a coiled, circumferentially spaced series of restricted combustion gas outlets in substantial axial alignment with the helically coiled tube portion.