EGR Cooler Heat Recovery via Exhaust Pressure Waves
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Solution Overview
Problem
Existing exhaust gas recirculation (EGR) systems in internal combustion engines are inefficient during periods of inactivity, as the EGR cooler remains unused, leading to unutilized exhaust gas energy and reduced system efficiency, particularly during cold starts when high emissions and friction losses occur.
Innovation Solution
A method that involves closing the EGR valve and adjusting the volume of a variable volume vessel downstream of the EGR cooler to leverage pressure waves in the exhaust system, allowing the EGR cooler to extract heat from exhaust gas even when the EGR system is inactive, and using this heat to warm engine coolant and oil, thereby increasing combustion efficiency and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the EGR valve is closed during periods of EGR inactivity (e.g., cold start), then emissions are reduced and combustion efficiency is improved, but the EGR cooler remains unused and exhaust gas energy is wasted
Solution Approach 1:
The system uses periodic pressure waves in the exhaust system to periodically drive exhaust gas through the EGR cooler during EGR inactivity periods. The variable volume vessel oscillates to create pressure differentials that pulse gas flow through the cooler, enabling continuous heat extraction even when the EGR valve is closed.
Solution Approach 2:
The exhaust gas pressure waves themselves are utilized to drive the cooling process. The natural pressure oscillations in the exhaust system are harnessed to move gas through the EGR cooler without requiring additional energy input or active control mechanisms, allowing the system to self-cool during idle periods.
2Use of energy by moving object
If the EGR cooler is operated continuously to maximize heat extraction, then energy efficiency is improved, but the system complexity and control requirements increase
Solution Approach 1:
The system utilizes the naturally occurring pressure waves in the exhaust system to drive cooling during EGR inactivity. No additional actuators, sensors, or control systems are required - the existing exhaust pressure oscillations automatically perform the work of moving gas through the cooler when needed.
Solution Approach 2:
The EGR cooler serves dual functions: it cools exhaust gas during active EGR operation and extracts heat during EGR inactivity periods. The variable volume vessel also serves multiple purposes by adjusting exhaust system acoustics to enhance pressure wave propagation through the cooler during idle periods.
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 engine efficiency by utilizing exhaust gas energy during EGR inactivity, reducing emissions, and minimizing friction losses, especially during cold starts, by effectively operating the EGR cooler and warming critical engine components.
Implementation Method 1
the EGR cooler can extract heat from exhaust gas while the EGR valve is closed
Implementation Method 2
adjusting a volume of variable volume vessel based on the profile of the exhaust pressure waves... the volume of the variable volume vessel may be adjusted to reinforce pressure wave propagation through the EGR cooler
Data Source
AI summary
A method for operating an internal combustion engine is provided. The method includes closing an EGR valve positioned in an exhaust gas recirculation (EGR) conduit downstream of an EGR cooler, the EGR conduit coupled to an intake system and an exhaust system and determining a profile of exhaust pressure waves in the exhaust system. The method also includes adjusting a volume of variable volume vessel based on the profile of the exhaust pressure waves, the variable volume vessel positioned downstream of the EGR cooler and upstream of the EGR valve.