Exhaust Gas Heat Exchanger Inlay Coolant Flow Steering
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Solution Overview
Problem
Conventional exhaust gas heat exchangers experience local boiling due to undefined coolant distribution, leading to reduced lifespan and increased risk of thermal fatigue.
Innovation Solution
A tube bundle with a stepped outer circumference and a housing with a round cross section, featuring coolant bypass passages and an inlay that guides the coolant flow to prevent local boiling, ensuring optimal cooling and improved heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coolant flows directly into the housing without guidance, then the structure is simple, but local boiling occurs in regions with poor coolant distribution
Solution Approach 1:
A coolant distribution element is introduced as an intermediary component between the coolant inlet and the tube bundle. This element actively guides and distributes the coolant flow to ensure all regions are adequately cooled, thereby resolving the contradiction by adding a mediating structure that prevents local boiling without significantly complicating the overall system
Solution Approach 2:
The housing internal space is segmented into multiple flow channels or zones using guide elements or baffle structures. This segmentation ensures that coolant is distributed to different regions systematically, preventing concentration in specific areas and eliminating the conditions for local boiling while maintaining manufacturing feasibility
2Reliability
If coolant flow is increased to prevent boiling, then local boiling risk is reduced, but pump performance and fuel consumption increase
Solution Approach 1:
The coolant distribution system is designed to provide locally optimized flow distribution, directing higher coolant flow rates to specific high-heat-flux regions (such as near the exhaust gas inlet) while maintaining adequate but lower flow in other areas. This local quality approach ensures effective cooling where needed most without requiring a uniform increase in overall coolant flow, thereby reducing pump energy consumption and fuel usage
3Speed
If coolant bypass passages are provided between tube bundle and housing, then coolant flow path is shortened, but coolant distribution becomes more undefined
Solution Approach 1:
The coolant distribution element acts as a mediator between the shortened bypass passages and the tube bundle, receiving coolant from the bypass passages and redistributing it uniformly across the tube bundle surface. This intermediary function maintains the speed advantage of bypass passages while achieving the uniformity required for effective cooling
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 solution effectively reduces the risk of local boiling, increases thermal fatigue strength, and lowers coolant pump performance and fuel consumption by directing coolant flow to critical areas, enhancing overall heat exchanger performance.
Implementation Method 1
exhaust gas heat exchanger, which transfers the heat discharged by the combustion exhaust gas from the combustion chamber to a cooling medium
Implementation Method 2
the coolant bypass passages are at least partly blocked by an inlay, which steers a coolant flow specifically in the direction of the first tube base
Implementation Method 3
the coolant inlet is situated in the region of the second tube base while the coolant inlet is arranged in the region of the first tube base so that the coolant in the housing flows in counter-flow to the exhaust gas in the tubes
Data Source
AI summary
An exhaust gas heat exchanger may include a tube bundle and a housing through which a coolant is flowable. The tube bundle may include a plurality of exhaust gas-conducting tubes held in a first tube base and a second tube base. The housing may enclose the tube bundle and may have face ends delimited by the first tube base and the second tube base. The housing may include a coolant inlet arranged in a region of the second tube base and a coolant outlet arranged in a region of the first tube base such that the coolant flows in counter flow relative to the exhaust gas. A plurality of coolant bypass passages may be arranged between the tube bundle and the housing. At least a subset of the plurality of coolant bypass passages may be at least partly blocked by an inlay structured and arranged to steer a coolant flow.