EGR Catalyst Heating to Prevent Ice in Hydrogen Exhaust Recirculation
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Solution Overview
Problem
Existing exhaust gas recirculation systems in internal combustion engines, particularly in hydrogen engines, face issues with ice formation due to high water content in exhaust gases, leading to blockages and operational failures at low temperatures, and existing solutions like expensive valves or complex heating systems are inefficient or costly.
Innovation Solution
An exhaust gas recirculation system with a catalyst containing platinum metals arranged after the cooler, which catalytically oxidizes hydrogen to generate heat and prevent ice formation, allowing conventional valves with leakage and eliminating the need for electrical heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional exhaust gas recirculation valve with leakage is used, then the system can operate at different temperatures and conditions, but ice forms in the recirculation line at cold temperatures due to high water content
Solution Approach 1:
The patent converts the harmful effect of unburned hydrogen (which causes knocking) into a beneficial heating source by directing it through a catalyst in the exhaust gas recirculation line. The catalytic combustion of hydrogen generates heat that prevents ice formation in the recirculation line and intake system, transforming a detrimental factor into a solution for the freezing problem.
2Object-affected harmful factors
If a sealed exhaust gas recirculation valve is used to prevent leakage, then ice formation is avoided, but the valve is expensive and prone to breakdown
Solution Approach 1:
The system accepts controlled leakage through conventional valves and instead uses the leaked unburned hydrogen as a fuel source for catalytic combustion. This approach avoids the need for expensive sealed valves while preventing ice formation through heat generation, thereby improving valve reliability and reducing costs.
Solution Approach 2:
The system uses the engine's own unburned hydrogen exhaust gas as the fuel source for heating the recirculation line. This self-service approach eliminates the need for external heating systems, sealed valves, or additional fuel supplies, reducing complexity and improving reliability.
3Object-affected harmful factors
If electric heating or coolant heating systems are used to prevent ice formation, then freezing is avoided, but the system becomes complex and energy intensive
Solution Approach 1:
Instead of adding complex external heating systems, the patent utilizes the harmful unburned hydrogen in the exhaust gas as a fuel source. The catalytic combustion of this hydrogen generates the necessary heat to prevent ice formation, eliminating the need for electric heaters, coolant heating systems, and associated control mechanisms.
Solution Approach 2:
The system uses its own waste hydrogen as the heating source, eliminating dependency on external energy sources or complex heating infrastructure. This self-service approach significantly reduces system complexity and energy consumption.
4Object-generated harmful factors
If the catalyst is arranged before the exhaust gas recirculation cooler, then nitrogen oxides are reduced, but the catalyst does not provide sufficient heat to prevent ice formation
Solution Approach 1:
The patent segments the catalyst function into two distinct stages: first, a NOx reduction catalyst upstream cools the exhaust gas and reduces nitrogen oxides; second, a hydrogen combustion catalyst downstream in the recirculation line generates heat to prevent ice formation. This segmentation allows each catalyst to perform its specialized function effectively.
Solution Approach 2:
The patent moves the hydrogen combustion catalyst from the upstream position (before the cooler) to the downstream position (after the cooler, in the recirculation line). This dimensional repositioning in the flow path allows the catalyst to access unburned hydrogen that would otherwise be lost, converting it into a heat source for ice prevention while maintaining NOx reduction capabilities upstream.
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
Effectively prevents ice formation in the exhaust gas recirculation line and intake system using catalytic conversion of hydrogen, ensuring system efficiency and reliability without additional components.
Implementation Method 1
A catalyst having a platinum metal (so-called Platinoids, Platinum Group Metal (PGM), Pt, Ir, Os, Pd, Rh, Ru) or a combination of several platinum metals is arranged after the exhaust gas recirculation cooler in the flow direction. Fuel, and here in particular only hydrogen, which reaches the catalyst, is able to be catalytically oxidized in this catalyst
Implementation Method 2
In this manner, a sufficient amount of heat can be supplied to the exhaust gas recirculation line and then subsequently the intake system of the internal combustion engine, in order to reliably prevent icing at low ambient temperatures
Data Source
AI summary
An apparatus recirculates exhaust gas for an internal combustion engine. The apparatus includes an exhaust gas recirculation line, which has an exhaust gas recirculation cooler, an exhaust gas recirculation valve, and a catalyst. The is arranged after the exhaust gas recirculation cooler in the flow direction of the recirculated exhaust gas. A defined fuel concentration in the exhaust gas can be set via special control of combustion and/or ignition, which is then converted in the catalyst producing heat.