Multi-Channel Secondary Heat Exchanger for Compact Heat Transfer
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Solution Overview
Problem
Existing heat exchangers in furnaces face inefficiencies in heat transfer between combustion gases and the heat exchanger surfaces, particularly in secondary heat exchangers, which can increase the size and cost of the furnace when trying to enhance heat transfer efficiency.
Innovation Solution
A multi-channel heat exchanger design with elongate passageways and integrally formed channel walls that increase the heat transfer surface area without expanding the external size, allowing for efficient heat transfer from combustion gases to the walls of the heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If turbulent flow design is employed to increase heat transfer efficiency, then heat transfer efficiency is improved, but the size of the heat exchanger increases
Solution Approach 1:
The heat exchanger is divided into multiple parallel channels separated by longitudinal walls, creating a segmented structure that increases internal surface area without increasing external volume. This segmentation allows combustion gases to flow through multiple pathways simultaneously, enhancing heat transfer efficiency while maintaining a compact overall size.
Solution Approach 2:
The patent transitions from a single-channel design to a multi-channel configuration by adding the dimension of parallel pathways. The longitudinal walls create additional spatial dimensions for heat transfer surfaces, allowing the heat exchanger to pack more heat transfer area into the same external footprint, thus improving efficiency without increasing size.
2Productivity
If heat transfer surface area is increased, then heat transfer efficiency is improved, but the cost of the furnace increases
Solution Approach 1:
Multiple channels are merged into a single integrated heat exchanger structure with shared longitudinal walls. This merging approach allows the heat exchanger to achieve the surface area of multiple separate units while using common structural elements (the longitudinal walls serve as boundaries for adjacent channels), thereby reducing material requirements and manufacturing costs compared to using multiple independent heat exchangers.
Solution Approach 2:
The longitudinal walls serving as separators between channels also function as heat transfer surfaces themselves. This multi-functionality means the same structural elements perform dual roles: defining channel boundaries and providing additional heat transfer area, thereby increasing efficiency without proportionally increasing material costs or manufacturing complexity.
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
This design enhances heat transfer efficiency by maintaining a compact size while increasing the number of walls in contact with the gases, leading to improved heat transfer and reduced pressure drop loss, thus optimizing energy extraction from combustion gases.
Implementation Method 1
The walls are positioned for heat conductive transfer with the combustion gases flowing through the passageways
Data Source
AI summary
A combustion gas furnace includes a plurality of primary heat exchangers for passage of combustion gases therethrough. A plurality of secondary heat exchangers receive the combustion gases from the primary heat exchanger. Each of the secondary heat exchangers includes a heat conductive element defining a plurality of elongate passageways for the flow of combustion gas therethrough. The passageways include aligned ports at either end thereof. The passageways are generally aligned and separated by longitudinal walls extending between the ends. The walls are positioned for heat conductive contact with the combustion gases flowing through passageways.