Low-Pressure EGR Cooling Split Control for Condensate Management
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Solution Overview
Problem
Low-pressure EGR systems in natural gas-powered internal combustion engines face significant condensation issues in the intake manifold, leading to misfires and reduced fuel efficiency due to condensate buildup, particularly when used with turbochargers.
Innovation Solution
Incorporating a liquid separator and linked operation of an intercooler and EGR cooler, controlled relative to their respective dewpoints, to avoid condensation formation in the intercooler and intentionally form condensate in the EGR cooler for collection and ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If low-pressure EGR system is used to reduce NOx emissions, then emission reduction efficiency is improved, but condensation forms in the intake manifold causing misfires and reduced fuel efficiency
Solution Approach 1:
The system segments the cooling function into two separate components: the intercooler that cools the air-EGR mixture, and the EGR cooler that specifically cools the recirculated exhaust gas. This segmentation allows the EGR cooler to manage condensation separately, preventing it from entering the intake manifold and causing misfires, while maintaining the emission reduction benefits of low-pressure EGR.
Solution Approach 2:
The EGR cooler acts as an intermediary device between the exhaust gas source and the intake manifold. It intentionally forms condensate in a controlled environment and provides it to the intake manifold, preventing uncontrolled condensation formation there. This intermediary function resolves the contradiction by managing the harmful condensation effect separately from the beneficial EGR recirculation.
2Temperature
If EGR cooler is used to cool recirculated exhaust gas, then NOx reduction efficiency is improved, but condensate buildup occurs in the intake manifold
Solution Approach 1:
The system converts the harmful effect of condensation into a beneficial one by intentionally forming condensate in the EGR cooler and providing it to the intake manifold. This controlled condensation prevents uncontrolled condensation formation in the intake manifold, thereby preventing misfires and fuel efficiency loss while maintaining the temperature reduction needed for NOx emission control.
Solution Approach 2:
The EGR cooler serves as an intermediary that manages condensation formation separately from the intake manifold. By controlling where and how condensation forms, it eliminates the harmful buildup in the intake manifold while maintaining the necessary cooling function for NOx reduction.
3Productivity
If intercooler cools the air-EGR mixture, then combustion efficiency is improved, but condensation forms below dewpoint causing misfires
Solution Approach 1:
The cooling function is segmented between the intercooler and EGR cooler. The intercooler cools the air-EGR mixture to improve combustion efficiency, while the EGR cooler handles the condensation management by intentionally forming condensate and providing it to the intake manifold, preventing harmful condensation there.
Solution Approach 2:
The EGR cooler acts as an intermediary that manages the condensation issue separately from the intercooler's cooling function. This allows the intercooler to focus on improving combustion efficiency through cooling, while the EGR cooler prevents the harmful side effect of uncontrolled condensation in the intake manifold.
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
Minimizes condensate buildup in the intake manifold by collecting and draining condensate before recirculation, improving engine efficiency and preventing misfires.
Implementation Method 1
the EGR cooler is configured to cool the recirculated exhaust gas below a dewpoint of the recirculated exhaust gas to intentionally form condensate
Implementation Method 2
a liquid separator is in fluid communication with the EGR cooler and is configured to separate any condensate from the recirculated exhaust gas
Data Source
AI summary
An exhaust gas recirculation (EGR) system for an internal combustion (IC) engine. The EGR system has a first cooler configured to cool exhaust from an exhaust system of the IC and to drain exhaust liquid formed by the cooling. The EGR system has a mixture chamber configured to mix exhaust cooled by the first cooler with intake air to form an exhaust-air mixture. The EGR system has a second cooler configured to cool the exhaust-air mixture. The EGR system has a heat exchange system for circulating and cooling coolant fluid used by the first and second coolers, and includes a split valve configured to divide coolant fluid flow between the first and second coolers. The EGR system has an engine control module configured to adjust the split valve based on comparing a temperature of the exhaust-air mixture to a determined dewpoint temperature of the exhaust-air mixture.