Microchannel Heat Exchanger Layout for Hot-Spot Cooling
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Solution Overview
Problem
Conventional microchannel heat exchangers are ineffective in cooling heat-producing devices with spatially-varying heat loads, as they fail to efficiently deliver fluid to hot spots, leading to temperature non-uniformity and increased pressure drop, which exacerbates heat transfer inefficiencies and instability.
Innovation Solution
A microchannel heat exchanger system with a manifold region for fluid delivery and a microscaled region comprising microchannels, micropillars, or a microporous structure, coupled with a thermoelectric device and a pump, which directs fluid specifically to hot spots, maintaining a small pressure drop and achieving temperature uniformity across the heat source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional parallel microchannel arrangements are used, then the heat exchanger can cool the heat source, but the fluid flows uniformly along the entire bottom surface and does not supply more fluid to hot spot areas, resulting in temperature non-uniformity
Solution Approach 1:
The patent implements local quality by creating regions with different flow resistance characteristics. Specifically, it uses variable channel widths, selective blocking of certain channels, or incorporation of expansion chambers in areas corresponding to hot spots, allowing these regions to receive proportionally more cooling fluid than uniform channels would provide
Solution Approach 2:
The patent applies dynamics by making the fluid flow distribution adaptive rather than static. As hot spots develop, the system dynamically redirects fluid flow to those areas through mechanisms such as thermally-responsive materials that expand/contract or channels that open/close based on temperature conditions, ensuring continuous optimization of cooling distribution
2Temperature
If fluid flows from inlet to outlet along the entire length of parallel microchannels, then heat transfer occurs along the flow path, but the fluid temperature increases along the flow direction, causing downstream regions to receive warmer fluid that is less effective for cooling
Solution Approach 1:
The patent segments the fluid flow path into multiple independent parallel channels with different lengths. Shorter channels are positioned downstream where cooler fluid is needed, while longer channels are positioned upstream. This segmentation allows each channel to have optimized residence time, preventing the cumulative heating effect that occurs in single long-channel configurations
Solution Approach 2:
The patent inverts the conventional arrangement by placing shorter channels downstream and longer channels upstream, opposite to the natural flow progression. This inversion ensures that fluid takes shorter paths when it has already been heated, delivering it quickly to exit, while cooler fluid takes longer paths upstream where more cooling is needed
3Device complexity
If the heat exchanger has only one inlet and one outlet forcing fluid to travel along long parallel microchannels, then the structure is simple, but a large pressure drop is created due to the length the fluid must travel, making pumping difficult and augmenting instabilities
Solution Approach 1:
The patent segments the single long flow path into multiple shorter parallel channels. While this increases the number of channels, each individual channel has reduced length and thus reduced pressure drop. The overall structure remains relatively simple as it uses the same basic parallel channel geometry, just with more channels of shorter length rather than fewer long channels
Solution Approach 2:
The patent transitions from a one-dimensional flow path (single long channel) to a two-dimensional array of parallel channels. This dimensional change allows fluid to be distributed across multiple pathways simultaneously, reducing the effective travel distance in each channel while maintaining a planar, manufacturable 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 system effectively cools heat sources by delivering fluid directly to hot spots, reducing pressure drop and enhancing heat transfer efficiency, thereby maintaining temperature uniformity and improving cooling performance.
Implementation Method 1
a thermoelectric device having a cooling portion and a heating portion and configured so that at least a portion of the cooling portion is in thermal contact with the fluid heat exchanger to cool the fluid heat exchanger
Data Source
AI summary
A system for cooling a heat source includes a fluid heat exchanger, a pump, a thermoelectric device and a heat rejector. The thermoelectric device includes a cooling portion and a heating portion. The heat rejector is configured to be in thermal contact with at least a portion of the heating portion of the thermoelectric device. The pump is coupled with the fluid heat exchanger and configured to pass a fluid therethrough. The thermoelectric device is configured along with the heat exchanger in the cooling system.