Heat Exchanger Bypass Flow Path for Coolant Boiling Prevention
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Solution Overview
Problem
Existing heat exchangers for motor vehicle exhaust systems often experience coolant boiling on the inflow side due to overheating, leading to damage and reduced thermodynamic efficiency, and existing solutions to mitigate this issue increase complexity and require additional fluid connections, resulting in a larger installation space.
Innovation Solution
A heat exchanger design with a housing divided into a first flow path and a second flow path, where the tubes are arranged within the second path, and a bypass is created to direct the coolant to the exhaust gas inflow side, allowing countercurrent flow with a cross-sectional area ratio between 15% and 65% for the bypass to the total area, minimizing heat absorption and pressure loss, and featuring rectangular tubes with specific dimensions and spacing for optimal cooling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the housing is divided into a first flow path and a second flow path with a bypass, then coolant boiling is prevented and cooling capacity is improved, but device complexity increases
Solution Approach 1:
The housing is divided into a first flow path and a second flow path, creating separate coolant flow channels. The first flow path serves as a bypass that directs coolant to the exhaust gas inlet side, preventing coolant boiling in the high-temperature zone while the second flow path handles the main heat exchange function.
Solution Approach 2:
The first flow path acts as an intermediary bypass channel that mediates between the coolant inlet and the exhaust gas inlet side. It provides a thermal buffer by directing coolant through a path that avoids direct exposure to the highest temperatures, thereby preventing boiling while maintaining cooling effectiveness.
2Loss of energy
If the bypass cross-sectional area is optimized between 15% and 65% of the total area, then pressure loss is minimized and thermodynamic efficiency is improved, but design precision requirements increase
Solution Approach 1:
The cross-sectional area of the first flow path is optimized to be between 15% and 65% of the total cross-sectional area through which the coolant flows. This parameter optimization balances the coolant flow distribution between the bypass and the main heat exchange path, minimizing pressure loss and maximizing thermodynamic efficiency.
3Reliability
If additional fluid connections are added to improve coolant distribution, then coolant boiling is prevented, but installation space and system complexity increase
Solution Approach 1:
The first flow path and second flow path are merged within a single housing structure, with both flow paths sharing the same inlet and outlet connections. This integration improves coolant distribution to prevent boiling without requiring additional external fluid connections or increasing installation space.
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 effectively prevents coolant boiling, achieves maximum cooling capacity with minimal pressure loss, and reduces the coolant requirement, resulting in a compact and efficient heat exchanger with improved thermodynamic performance.
Implementation Method 1
This is achieved by creating a heat transfer between the exhaust gas flowing in an exhaust system and a coolant, in order to transfer heat from the exhaust gas to the coolant.
Implementation Method 2
the exhaust gas and the coolant can flow counter-currently through the heat exchanger
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a heat exchanger (20) for an exhaust tract of a motor vehicle, having a housing (2) and having a multiplicity of tubes (3) through which exhaust gas can flow and around which a coolant can flow, wherein the tubes (3) are arranged within the housing (2), and the housing (2) has a coolant inlet (5, 9) and a coolant outlet (6), wherein the exhaust gas and the coolant can flow in a countercurrent configuration with respect to one another through the heat exchanger (20), wherein the internal volume of the housing (2) is divided into a first flow path (22) and a second flow path (21) and the tubes (3) are arranged within the second flow path (21), wherein the first flow path (22) forms a bypass with respect to the second flow path (21), wherein the cross-sectional area (AB) of the first flow path (22) amounts to between 15% and 65%, preferably between 30% and 50%, of the total cross-sectional area (AT), through which the coolant flows, of the housing (2), wherein the total cross-sectional area (AT), through which the coolant flows, of the housing (2) is formed by the cross-sectional area (AB) of the first flow path (22) and the cross-sectional area of the second flow path (21) minus the cross-sectional area occupied by the tubes (3).