EGR Intake Stratification via Angled Annular Slot
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Solution Overview
Problem
Existing engine systems face inefficiencies due to non-uniform mixing of recirculated exhaust gas (EGR) and fresh air, leading to varying densities and temperatures that affect compressor operation and efficiency, and the lack of space for mixers upstream of the compressor results in pressure losses and reduced robustness.
Innovation Solution
The method involves flowing EGR along the periphery and fresh air through the center of the intake compressor inlet, with EGR introduced through an angled annular slot that maintains a stratified flow, ensuring consistent fluid properties as they enter the compressor, which improves compressor efficiency and reduces wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EGR is introduced upstream of the intake compressor to mix with fresh air, then emissions are reduced and fuel economy is improved, but the EGR and fresh air are not uniformly mixed due to density differences, causing varying conditions through compressor blades that adversely affect compressor efficiency
Solution Approach 1:
The intake passage is segmented into distinct flow regions: a central region for fresh air and a peripheral region for EGR. This spatial segmentation allows different fluid streams to be maintained separately through the compressor, preventing the adverse mixing effects that would otherwise reduce compressor efficiency while still achieving the desired EGR dilution for combustion stability.
Solution Approach 2:
Different regions of the intake passage are assigned different fluid qualities: the center region carries fresh air while the periphery carries EGR. This local differentiation ensures that compressor blades experience more uniform conditions as each blade passes through consistent fluid regions, thereby maintaining compressor efficiency while achieving emissions reduction.
2Stability of the object's composition
If a mixer is added to the intake passage to improve EGR and fresh air mixing, then uniformity of fluid flow is improved, but packaging constraints prevent sufficient space upstream of the compressor and addition of mixers causes pressure losses
Solution Approach 1:
The mixing function is extracted from the traditional location upstream of the compressor and relocated to occur downstream through the compressor and charge air cooler. This eliminates the need for separate mixer components in the constrained upstream space, avoids associated pressure losses, and achieves uniform mixing as a natural result of the flow path design rather than forced mixing.
3Ease of operation
If EGR is introduced at an angle to the intake passage upstream of the compressor, then mixing is facilitated, but the difference in density causes non-uniform mixing and the EGR may not be uniformly distributed
Solution Approach 1:
Instead of introducing EGR at an angle in the traditional upstream direction, the EGR is introduced through an annular slot that distributes it along the peripheral dimension of the intake passage. This dimensional change from linear angular injection to circumferential annular distribution achieves uniform EGR placement around the periphery without the mixing non-uniformity caused by density differences in angled injection.
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 enhances compressor efficiency by maintaining consistent fluid properties and reducing wear, without the need for additional mixers, thereby improving engine performance and emissions control.
Implementation Method 1
The EGR passage is configured with an asymmetric wall to introduce EGR to the intake passage via an annular slot. The angular slot may be configured to form a non-zero angle with a horizontal plane and may deliver the EGR proximal to a wall (periphery) of the intake passage. The EGR may enter the intake passage and flow along the periphery (along the wall) of the passage while the fresh air flowing through the intake passage may flow through the central portion of the intake passage.
Implementation Method 2
As the EGR and fresh air (combination of fluids) passes through the blades of the compressor, fluid of different densities and temperatures may pass through different regions of the blades. Due to the un-uniform mixing, the densities and temperatures of fluids passing through each region of the blades may change constantly. As the blades are subjected to continually varying conditions (such as density and temperature), the operation of the compressor may be adversely affected causing reduction in compressor efficiency.
Implementation Method 3
The EGR may be thoroughly mixed with the fresh air as the fluids exit the compressor and flow through a charge air cooler and an intake throttle.
Data Source
AI summary
Methods and systems are provided for merging recirculated exhaust gas (EGR) with fresh intake air in an intake passage. In one example, a method may include introducing EGR to the intake passage via an angled annular slot and flowing unmixed EGR and ambient air through an intake compressor inlet. Ambient air may flow to a center of the intake compressor while the EGR may flow along a periphery of the intake compressor inlet.