Helical Condensing Heat Exchanger With Controlled Inter-Tube Gaps
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Solution Overview
Problem
Condensation heat exchangers with single or multiple concentric round tube windings suffer from inefficient heat exchange due to hot gases only interacting with limited tube surface areas between turns, leading to poor thermal efficiency and increased radial bulk, pressure irregularities, and manufacturing complexities.
Innovation Solution
A condensation heat exchanger design featuring multiple helically wound tubes with specific gap configurations and calibration means, such as bosses, to maintain constant gas passage speed and interstice values, ensuring efficient heat transfer across the tubes despite temperature changes, and using thermally conductive metals like stainless steel or copper alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple concentric tubular windings with significantly different diameters are used, then the overall heat exchange efficiency is improved, but the radial bulk increases significantly
Solution Approach 1:
The patent implements multiple concentric tubular windings nested within each other, with each winding having a slightly larger diameter than the previous one. This nesting arrangement allows the heat exchanger to achieve high heat exchange efficiency through multiple sequential cooling stages while minimizing the radial bulk by tightly packing the windings together with controlled spacing
2Ease of manufacture
If round tubes are used instead of flattened tubes, then the manufacture is simpler and less expensive, but the heat exchange efficiency deteriorates
Solution Approach 1:
The patent uses round tubes with locally created interstices or gaps between adjacent tubes. These localized openings in specific areas allow hot gases to access and heat the tube surfaces, compensating for the reduced heat exchange efficiency of round tubes compared to flattened tubes while maintaining manufacturing simplicity
3Shape
If the pitch of intermediate winding is opposite to internal and external windings, then the winding is formed, but the pressure distribution becomes irregular and heat exchange quality deteriorates
Solution Approach 1:
The patent deliberately inverts the pitch direction of the intermediate winding relative to the internal and external windings. This inversion creates a specific three-dimensional flow pattern where hot gases are forced to follow a more complex path, increasing their contact time and interaction with tube surfaces, thereby improving heat exchange quality despite the apparent irregularity
4Loss of time
If hot gases bypass the inner and outer zones of the tube, then the flow path is shorter, but the heat exchange efficiency deteriorates
Solution Approach 1:
The patent segments the tube surfaces by creating interstices or gaps between adjacent round tubes. These segmented openings act as access points that force hot gases to interact with specific zones of the tubes, effectively dividing the heat exchange process into multiple localized interactions that compensate for the shorter overall flow path
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 enhances heat transfer efficiency by maintaining constant gas speed and interstice values, improving thermal performance and reducing manufacturing complexities, while utilizing cost-effective materials for efficient energy transfer.
Implementation Method 1
a tube made of a metal that is thermally good conductor
Implementation Method 2
hot gases... pass through the inter-turn gaps... so as to heat the fluid circulating in the tube
Implementation Method 3
condensation heat exchanger... cooled gases... are evacuated
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The exchanger has inner and outer tubes (1, 2), each with turns separated with respect to each other by an interstice of specific width. A burner (8) generates hot gas inside the tubes such that the gas traverses the interstice so as to reheat water circulating in the tubes, where the tubes are made of heat conductive material. The tubes have a configuration such that a minimal spacing between the tubes is lesser than or equal to half of the width of the interstice, and the width of the interstice separating the turns of the tube (2) is lesser than or equal to double the spacing.