Laminated Header Branch Geometry for Uniform Heat Exchanger Flow
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Solution Overview
Problem
Conventional laminated headers in heat exchangers suffer from non-uniform fluid distribution due to gravitational forces, leading to uneven flow and reduced heat exchange performance.
Innovation Solution
A laminated header design featuring stacked flat-plate passages with progressively decreasing cross-sectional areas in branch passages, maintaining a flow speed of at least 0.3 m/s to prevent liquid film accumulation and ensure uniform distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distributors with uniform branch passages are used, then the structure is simple and easy to manufacture, but the fluid distribution becomes non-uniform due to gravitational forces
Solution Approach 1:
The patent applies local quality by varying the cross-sectional area of branch passages according to their position in the stacking direction. Specifically, the cross-sectional area decreases as the distance from the reference surface increases, creating locally optimized flow characteristics that compensate for gravitational effects and achieve uniform fluid distribution across all exit passages.
Solution Approach 2:
The patent changes the geometric parameter of the branch passages by making the cross-sectional area a function of position. The cross-sectional area is systematically reduced in downstream branches compared to upstream branches, which alters the flow resistance distribution and compensates for the uneven fluid distribution caused by gravity.
2Ease of manufacture
If branch passages have equal cross-sectional areas, then the manufacturing is easier, but liquid film accumulates due to gravitational force affecting flow speed
Solution Approach 1:
The patent implements local quality by differentiating the cross-sectional areas of branch passages based on their vertical position. Branch passages closer to the reference surface have larger cross-sectional areas, while those farther away have smaller areas. This local differentiation maintains adequate flow speed in all passages to prevent liquid film accumulation.
Solution Approach 2:
The patent systematically changes the cross-sectional area parameter along the stacking direction to maintain minimum flow velocity. By reducing the cross-sectional area in downstream passages, the flow speed is maintained above the threshold required to prevent liquid film formation, ensuring reliable operation.
3Speed
If the cross-sectional area of downstream branch passages is reduced, then the flow speed increases to prevent liquid film accumulation, but the passage becomes more complex to manufacture
Solution Approach 1:
The patent applies parameter changes by establishing a systematic relationship between cross-sectional area and vertical position. The cross-sectional area is reduced in a controlled manner from upstream to downstream passages, which increases flow speed in downstream passages to prevent liquid film accumulation while maintaining manufacturability through a regular gradient pattern.
Solution Approach 2:
The patent incorporates preliminary action by pre-calculating and pre-designing the cross-sectional area distribution before manufacturing. The gradient of cross-sectional areas is built into the passage plates during fabrication, ensuring that the flow speed distribution is optimized from the outset to prevent liquid film accumulation without requiring complex post-manufacturing adjustments.
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 the uniformity of fluid distribution, reducing the impact of gravitational forces and improving heat exchange performance by maintaining a minimum flow speed and preventing liquid film accumulation in branch passages.
Implementation Method 1
When the conventional distributor is used in such a state that the gravitational force applies in the branching direction of branch passages, a larger amount of liquid fluid flows to one of the branch passages.
Implementation Method 2
the flow speed of the fluid is increased by further reducing the passage cross-sectional area of a branch passage positioned further downstream
Data Source
Figure 1~2
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Figure 5~6
AI summary
A laminated header according to the present invention includes: a first passage plate having a flat-plate shape in which a first passage is formed; a second passage plate having a flat-plate shape in which a plurality of second passages are formed; a third passage plate having a flat-plate shape in which a plurality of third passages are formed; a first branch passage plate having a flat-plate shape in which an upstream side branch passage is formed, the upstream side branch passage branching the first passage into the plurality of second passages; and a second branch passage plate having a flat-plate shape in which a downstream side branch passage is formed, the downstream side branch passage branching one of the plurality of second passages into the plurality of third passages. The first passage plate, the first branch passage plate, the second passage plate, the second branch passage plate, and the third passage plate are stacked in this order. A first cross-sectional area as a maximum value of a passage cross-sectional area of the upstream side branch passage is larger than a second cross-sectional area as a maximum value of a passage cross-sectional area of the downstream side branch passage.