Heat Exchanger Step Geometry for Non-Communicating Gas Vents
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Solution Overview
Problem
In conventional heat exchangers with stacked heat exchange units, the non-communicating gas vents lead to a flange portion that increases flow resistance and reduces the efficiency of heat transfer from combustion exhaust gas to the fluid flowing through the internal space, as the fluid tends to flow away from the heated peripheral region.
Innovation Solution
The heat exchanger incorporates an inwardly directed step portion that reduces the height of the internal space between adjacent gas vents, facilitating fluid flow near the heated flange portions and enhancing turbulence, thereby improving heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas vents penetrate the internal space in a non-communicating state, then structural integrity and sealing are improved, but flow resistance increases and heat transfer efficiency deteriorates
Solution Approach 1:
The internal space is segmented into multiple regions by the flange portions of the gas vents, creating distinct flow zones. The step portions further divide the space, guiding fluid flow through specific paths that maximize contact with heated surfaces while maintaining the non-communicating seal between gas vent regions.
Solution Approach 2:
The step portions create local variations in internal space height, forming low-height regions between adjacent gas vents and high-height regions at other areas. This local quality differentiation directs fluid flow to specific zones, ensuring optimal heat transfer near gas vents while maintaining overall sealing integrity.
2Reliability
If flange portions are formed at gas vent peripheral portions, then sealing and structural stability are improved, but flow resistance near the gas vent increases
Solution Approach 1:
The step portions are pre-formed in the heat exchange plate to create predetermined flow paths before fluid enters the internal space. This preliminary structuring guides the fluid to flow through low-height regions between gas vents, preventing random flow patterns and reducing overall flow resistance despite the presence of flange portions.
3Loss of energy
If the internal space height is reduced between adjacent gas vents, then heat transfer efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of uniformly reducing internal space height across the entire plate, the invention creates localized low-height regions only between adjacent gas vents while maintaining normal height elsewhere. This selective dimensional modification achieves enhanced heat transfer in critical areas without imposing stringent precision requirements across the whole component.
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 inwardly directed step portion increases the contact time between the combustion exhaust gas and the heat exchange plates, leading to improved thermal efficiency, with the heat exchanger achieving approximately 88% efficiency compared to 86% without this feature.
Implementation Method 1
enhancing turbulence, thereby improving heat transfer efficiency
Implementation Method 2
heat of the combustion exhaust gas is not efficiently transferred to the fluid to be heated
Implementation Method 3
heat transfer efficiency
Data Source
AI summary
The heat exchanger (1) has a plurality of heat exchange units (10) stacked in a direction of a gas flow passage of combustion exhaust gas, each of the heat exchange units (10) includes an internal space (14) through which a fluid to be heated flows, a plurality of gas vents (13) penetrating the internal space (14) in a non-communicating state and through which the combustion exhaust gas passes, and an inwardly directed step portion (17) reducing a height of the internal space (14) between adjacent gas vents (13).