Compact Heat Exchanger Alternating Channels Primary Surface Area
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Solution Overview
Problem
Conventional compact heat exchangers with alternating layers limit the direct surface area for heat transfer, leading to inefficiencies in heat exchange and increased pressure drops, as fluids flow through secondary surface areas rather than primary areas.
Innovation Solution
The design of compact heat exchangers with alternating channels within the same layer, where hot and cold fluids flow in direct contact, increases the primary surface area for heat transfer, enhancing efficiency and reducing pressure drops by converting secondary surface areas to primary areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional alternating layer design is used, then structural simplicity is maintained, but heat transfer efficiency deteriorates due to limited primary surface area
Solution Approach 1:
The patent transitions from alternating layers (vertical arrangement) to alternating channels within the same layer (horizontal arrangement). This dimensional shift allows hot and cold fluids to flow in adjacent channels separated only by thin walls, maximizing primary surface area contact and heat transfer efficiency while maintaining structural simplicity through planar etching patterns.
Solution Approach 2:
The patent segments the single layer into multiple alternating channels for hot and cold fluids. By creating discrete adjacent channels within one layer rather than stacking layers, the design increases the proportion of primary surface area where heat transfer occurs directly between hot and cold fluids, resolving the contradiction between heat transfer efficiency and structural complexity.
2Ease of operation
If alternating layers design is used, then manufacturing simplicity is maintained, but pressure drop increases due to fluid flow through secondary surface areas
Solution Approach 1:
By reconfiguring from vertical layer stacking to horizontal channel arrangement within a single layer, the patent enables fluid to flow through adjacent channels separated by thin walls. This reduces the path length and resistance, minimizing pressure drop while the planar etching and diffusion bonding processes maintain manufacturing simplicity.
Solution Approach 2:
The patent applies local quality by creating thin wall separations specifically at the interfaces between adjacent hot and cold channels. This localized thin-walled structure minimizes flow resistance and pressure drop in the critical heat transfer zones while maintaining overall structural integrity through standard manufacturing processes.
3Area of stationary object
If fully etched multiple sheets are used, then heat transfer surface area increases, but device weight and volume increase
Solution Approach 1:
The patent merges multiple channel functions into a single layer through alternating channel design. Instead of stacking multiple fully etched sheets that would increase weight and volume, the design creates adjacent hot and cold channels within one layer, achieving high heat transfer surface area through planar expansion rather than vertical stacking, thus reducing overall device weight.
Solution Approach 2:
The patent uses photochemical etching to create precise channel patterns in thin sheets, then stacks and diffusion bonds multiple sheets to form the alternating channel structure. This copying approach allows replication of channel patterns across sheets while maintaining thin wall separations, maximizing heat transfer surface area without proportionally increasing weight.
4Productivity
If partial etching is used, then manufacturing flexibility is improved, but heat transfer efficiency deteriorates due to reduced primary surface area
Solution Approach 1:
The patent uses partial etching to create channels that extend through only portions of the sheet thickness, then stacks etched sheets with unetched portions to form alternating channels. This approach maintains manufacturing flexibility of partial etching while creating adjacent hot and cold channels that maximize primary surface area for heat transfer, resolving the contradiction between heat transfer rate and manufacturing flexibility.
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 results in higher heat transfer efficiency, potentially smaller and lighter exchangers, with improved heat transfer rates and reduced fluid pressure drops, maximizing heat transfer efficiency to 100% by utilizing more primary surface area.
Implementation Method 1
hot and cold fluids flow in direct contact, increases the primary surface area for heat transfer
Implementation Method 2
fluids flow through the exchanger to transfer heat
Implementation Method 3
The sheets are stacked and diffusion bonded to produce a strong structure for heat exchange
Data Source
AI summary
A compact heat exchanger is provided, in which multiple streams can flow within the same layer or layers, and different fluids may flow in alternating channels within the same layer as well as flowing in alternating layers. Having fluids in alternating channels—as compared to only alternating layers within the same layer—increases the direct surface area between the fluids (the primary surface area) for heat transfer, thereby increasing the rate and efficiency of heat transfer. Methods of making and using the heat exchanger are also provided.