Variable Density Heat Exchanger Flow Channel
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Solution Overview
Problem
Existing heat exchangers face a challenge in achieving an optimal balance between power density and pressure drop, particularly in exhaust gas heat exchangers, where increased heat transfer elements lead to higher pressure drops that are undesirable due to increased exhaust gas backpressure.
Innovation Solution
The heat exchanger features structural elements with a variable density along the flow direction, increasing heat transfer in areas with higher temperature differences and thinner boundary layers while minimizing elements in areas with lower demands, thereby reducing pressure drop and maintaining high power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If structural elements are distributed evenly over the entire length of flow channels to increase heat transfer, then heat transfer coefficient is improved, but pressure drop increases
Solution Approach 1:
The patent applies local quality by varying the density of structural elements along the flow channel length. The entry area has a lower density of structural elements to minimize pressure drop, while the downstream area has a higher density to maximize heat transfer coefficient where the temperature difference and boundary layer conditions justify it.
Solution Approach 2:
The flow channel is segmented into different zones along its length: an entry area with lower structural element density and a downstream area with higher density. This segmentation allows each zone to be optimized for its specific thermal and flow conditions rather than applying a uniform design throughout.
2Power
If increased power density is required for exhaust gas heat exchangers, then heat transfer performance is improved, but exhaust gas back pressure increases
Solution Approach 1:
The patent resolves this contradiction by applying local quality to the distribution of structural elements. The entry area uses fewer structural elements to maintain low back pressure, while the downstream area uses more structural elements to achieve high power density where the thermal driving force and boundary layer conditions permit it.
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 approach effectively reduces pressure drop while maintaining high power density by adapting structural element density to local conditions, optimizing heat transfer and minimizing pressure losses, particularly beneficial in exhaust gas heat exchangers and intercoolers.
Implementation Method 1
structural elements... which generate vortices and a turbulent flow
Implementation Method 2
generate vortices and a turbulent flow
Implementation Method 3
heat dissipation in the inlet area of the flow channel... is greater than in the downstream area
Implementation Method 4
heat transfer increases in the direction of flow
Data Source
Figure 1~2
Figure 3a~4
Figure 5~8
AI summary
The invention relates to a heat exchanger with at least one flow channel through which a fluid flows from an inlet to an outlet cross-section, the channel having an inner and an outer surface, and which has structural elements on its inner surface to increase heat transfer. It is proposed that the structural elements (11) be arranged and/or designed variably in the flow direction (P) such that the flow channel (10) has a variable heat transfer on its inner surface, in particular a heat transfer that increases in the flow direction (P).