EGR Cooler Fluidic Diode for Backflow Prevention
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Solution Overview
Problem
Internal combustion engines face limitations in increasing exhaust gas recirculation (EGR) flow at peak torque conditions due to low pressure differences between the exhaust and intake manifolds, which restricts brake thermal efficiency (BTE).
Innovation Solution
The implementation of an EGR intercooler that functions as a fluidic diode, utilizing a thermally conductive material and a Tesla valve design with partial loops and annuli, to allow forward flow of EGR gases while resisting reverse flow, thereby maintaining efficient EGR operation without mechanical parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional EGR cooler design is used, then structural simplicity is maintained, but EGR flow efficiency is limited due to low pressure differences
Solution Approach 1:
The EGR cooler conduit is segmented into multiple sub-conduits (first sub-conduit, second sub-conduit, third sub-conduit) that are arranged in series. This segmentation creates multiple heat exchange surfaces and extends the fluid flow path, improving heat transfer efficiency and EGR cooling performance without requiring a proportionally larger overall device volume.
Solution Approach 2:
The patent implements a nested configuration where the second sub-conduit is positioned within or adjacent to the first sub-conduit, and the third sub-conduit is positioned within or adjacent to the second sub-conduit. This nesting arrangement maximizes the use of available space, allowing multiple heat exchange surfaces to be packed into a compact volume, thereby improving heat transfer efficiency without significantly increasing device volume.
2Productivity
If pressure difference is increased to improve EGR flow, then EGR efficiency improves, but engine operating conditions become compromised
Solution Approach 1:
The patent replaces mechanical pressure increase mechanisms (such as compressors or high-pressure pumps) with a passive heat exchange system that relies on the natural pressure difference between exhaust and intake manifolds. The enhanced heat transfer efficiency achieved through the multi-subconduit nested design allows sufficient EGR cooling to be obtained without actively increasing the pressure difference, thereby maintaining engine operating flexibility.
Solution Approach 2:
The patent changes the thermal exchange parameters by extending the heat transfer path and increasing the heat exchange surface area through the nested sub-conduit arrangement. This allows more effective heat transfer at the existing pressure difference, improving EGR flow efficiency without requiring changes to the engine's pressure operating parameters.
3Temperature
If heat transfer efficiency is increased through larger heat exchange surfaces, then cooling performance improves, but device volume increases
Solution Approach 1:
The nested arrangement of sub-conduits allows multiple heat exchange surfaces to be positioned within or adjacent to each other in a compact configuration. The first sub-conduit, second sub-conduit, and third sub-conduit are arranged such that they utilize the same spatial envelope, maximizing heat transfer surface area within a minimal volume.
Solution Approach 2:
The patent transitions from a two-dimensional planar heat exchange surface to a three-dimensional nested conduit structure. By arranging sub-conduits in multiple spatial dimensions and orientations, the design achieves extensive heat transfer surface area within a compact volume, effectively utilizing volumetric space rather than just surface area.
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 solution enhances EGR efficiency by preventing backflow, reducing engine fuel usage, emissions, and exhaust back pressure, while improving spark timing, reducing exhaust after-treatment costs, and smoothing transient engine operation.
Implementation Method 1
a first fluid conduit defining a first fluid flow path for a first fluid and comprising a fluid diode that is at least partly fluidically diodic and formed of a thermally conductive material
Implementation Method 2
a fluid diode having a first fluid inlet, a first fluid outlet, a first sub-conduit extending from the fluid inlet to the fluid outlet, and a second sub-conduit extending from the first sub-conduit proximal the fluid inlet to the first sub-conduit proximal the fluid outlet as a partial loop defining a cavity extending through the partial loop
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, a heat exchanger apparatus that includes a first fluid conduit defining a first fluid flow path for a first fluid and comprising a fluid diode that is at least partly fluidically diodic and formed of a thermally conductive material, the fluid diode having a first fluid inlet, a first fluid outlet, a first sub-conduit extending from the fluid inlet to the fluid outlet, and a second sub-conduit extending from the first sub-conduit proximal the fluid inlet to the first sub-conduit proximal the fluid outlet as a partial loop defining a cavity extending through the partial loop, and a second fluid conduit in thermal communication with the first fluid conduit and defining a second fluid flow path through the partial loop, fluidically isolated from the first fluid flow path, for a second fluid.