Multi-flue heat exchanger assembly with baffle insert
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Solution Overview
Problem
Traditional fuel-fired fluid heating devices with a single central flue pipe suffer from inefficient heat transfer to fluid farthest from the flue pipe due to short residence time of hot combustion gases, and existing baffles can be costly and cause pressure drops, leading to carbon dioxide buildup.
Innovation Solution
A baffle design with a body having a hanging portion and progressively increasing angled fins is inserted into heat exchanger tubes, increasing the residence time of hot combustion gases and enhancing heat transfer while minimizing pressure drop and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If baffles are inserted into flue pipe to interrupt natural laminar flow, then residence time of hot combustion gases increases and heat transfer improves, but pressure drop increases causing carbon dioxide buildup
Solution Approach 1:
The baffle design changes the flow parameters by introducing angled fins that progressively increase in angle from the first end to the second end. This gradual parameter change allows the baffle to extend residence time while controlling pressure drop by optimizing the flow disruption pattern through varying fin angles.
Solution Approach 2:
Different portions of the baffle have different local characteristics - the fins have varying angles at different locations along the baffle length. This local quality variation allows optimal flow disruption at each position, improving heat transfer efficiency while managing overall pressure drop to prevent harmful CO2 buildup.
2Duration of action of moving object
If traditional baffles are used to increase residence time, then heat transfer improves, but manufacturing cost increases due to welding requirements
Solution Approach 1:
The baffle integrates multiple functions into a single component - the body provides structural support and flow interruption, while the fins are formed as an integral part of the body through bending. This merging eliminates the need for separate welding operations to attach fins, significantly reducing manufacturing cost while maintaining the residence time extension function.
Solution Approach 2:
The baffle design incorporates dynamic fin angles that vary along the length of the baffle, with fins progressively increasing in angle from the first end to the second end. This dynamic configuration optimizes flow disruption and heat transfer efficiency while the entire structure remains a single-piece component that can be manufactured and installed without welding.
3Device complexity
If single central flue pipe is used, then device complexity is reduced, but heat transfer efficiency to fluid farthest from flue pipe becomes minimal
Solution Approach 1:
The single central flue pipe is segmented into multiple sections along its length, with baffles installed at different positions. Each baffle segment independently disrupts the laminar flow in its local region, creating multiple zones of enhanced heat transfer. This segmentation allows efficient heat transfer to fluid throughout the tank, including areas far from the flue pipe, while maintaining the simplicity of a single flue pipe structure.
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 baffle design improves heat transfer efficiency by prolonging the residence time of hot gases within the heat exchanger tubes, reducing manufacturing costs, and minimizing pressure drop, thus enhancing the heating process without undesirable emissions.
Implementation Method 1
the hot combustion gases can flow upwardly through the flue pipe in a natural laminar flow path
Implementation Method 2
the residence time of the hot combustion gases within the flue pipe can be relatively short. Accordingly, baffles and/or baffle arrangements can be inserted into a flue pipe to interrupt the natural laminar flow of the hot combustion gases, thereby providing an increase in residence time, and thus, improved heat transfer to fluid within the tank
Implementation Method 3
Combustion of fuel and air within the combustion chamber can provide a primary source of heat for the fluid within the tank
Data Source
AI summary
The disclosed technology includes a heat exchanger assembly having a plurality of heat exchanger tubes. Each heat exchanger tube can include a baffle. The baffle can include a first end and a second end, a length of the baffle being defined as a distance between the first end and the second end, a body having a first side and a second side, a hanging portion located proximate the second end, and a plurality of fins disposed along the body. The plurality of fins can extend outwardly from the body and upwardly towards the second end at an angle relative to a central axis of the body. The plurality of fins can include a first fin positioned proximate the first end and having a first angle and a second fin positioned proximate the second end and having a second angle, the first angle being less than the second angle.