Heat Exchanger Passages with Variable Length for Uniform Flow
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Solution Overview
Problem
In conventional heat exchangers, the uneven flow velocity of the first fluid across the cross-section leads to inefficient heat exchange, as the fluid flows faster near the central axis and slower near the side walls, resulting in inadequate heat transfer and lower efficiency.
Innovation Solution
The heat exchanger design features first and second passages that extend parallel to the central axis, with increasing length towards the center, and wider passage widths on the upstream side, allowing the fluids to flow evenly and efficiently, ensuring parallel flow with minimal resistance and optimal heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first fluid flows through the case in conventional heat exchangers, then heat exchange occurs between the first fluid and the second fluid, but the flow velocity varies across the cross-section with faster flow near the central axis and slower flow near the side walls, resulting in insufficient heat exchange in the outside portion
Solution Approach 1:
The patent applies local quality by creating different passage lengths for different radial positions. Passages near the central axis are made longer while passages near the side walls are made shorter, allowing each region to have optimized flow characteristics. This resolves the contradiction by ensuring that fluid in all regions spends appropriate time for heat exchange, preventing both insufficient exchange at side walls and excessive resistance at the center.
Solution Approach 2:
The heat exchanger is segmented into multiple parallel passages arranged radially, with each passage independently optimized for its specific location. This segmentation allows the system to address the non-uniform flow velocity distribution by providing location-specific passage lengths, thereby improving overall heat exchange efficiency while managing flow resistance variations.
2Ease of operation
If the first fluid flows parallel to the central axis with minimal resistance, then flow efficiency improves, but the fluid may not spread evenly from the center toward the side walls, potentially causing stagnation in certain regions
Solution Approach 1:
The patent implements local quality by varying passage lengths according to radial position. Passages at the center are longer to accommodate the naturally faster flow, while passages at the periphery are shorter to compensate for slower flow velocity. This localized optimization ensures uniform fluid distribution across all regions while maintaining smooth parallel flow along the central axis.
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 configuration ensures even fluid flow and efficient heat exchange between the first and second fluids, preventing stagnation and enhancing the overall heat transfer efficiency.
Implementation Method 1
a heat exchanger main body having a plurality of first passages 34 through which the exhaust gas flows, and second passages 35 which house the cooling water inside the heat exchanger main body and through which the cooling water flows
Data Source
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AI summary
It is an object to provide a heat exchanger which allows efficient heat exchange between a first fluid and a second fluid which flows inside the heat exchanger. A heat exchanger 11 includes a heat exchanger main body 31 which is housed inside a case 12 where a first fluid flows and which houses a second fluid therein. The heat exchanger main body 31 has a plurality of first passages 34 which are disposed such that the first fluid flows across the inside of the heat exchanger main body 31. In a side view from one direction, the heat exchanger main body 31 has a shape which is left-right symmetric about the central axis of the case 12 and of which the upstream side protrudes farther in the upstream direction toward the center. The first passages 34 extend parallel to the central axis of the case 12, and are formed to be longer as they are disposed closer to the center of the heat exchanger main body 31.