Lean-Burn Engine Reformer Air-Fuel Temperature Control
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Solution Overview
Problem
Lean-burn combustion conditions in internal combustion engines reduce nitrogen oxide emissions but decrease combustion rate and heat efficiency, making stable operation challenging, especially when using three-way catalysts, and require additional measures like hydrogen addition to improve ignitability.
Innovation Solution
An internal combustion engine system that includes a turbocharger, a reformer generating a hydrogen-rich air-fuel mixture through an exothermic reaction, and a flow ratio adjusting mechanism to control the temperature of the air-fuel mixture, ensuring ideal lean-burn conditions by adjusting the flow rates of compressed air and hydrogen, thereby stabilizing combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If lean-burn combustion is used to reduce nitrogen oxide emissions, then NOx emission decreases, but combustion rate and heat efficiency decrease
Solution Approach 1:
Hydrogen is introduced as an intermediary substance to mediate between the lean air-fuel mixture and the combustion process. The hydrogen, generated by the reformer from exhaust gas, acts as a catalyst and energy carrier that enhances combustion rate without increasing NOx emissions, effectively bridging the gap between emission reduction and combustion efficiency
Solution Approach 2:
The air-fuel ratio parameter is changed to achieve lean-burn conditions (excess air), and simultaneously the hydrogen concentration parameter is adjusted by controlling the reformer operation. This dual parameter adjustment allows the system to maintain low NOx emissions while compensating for the reduced combustion rate through hydrogen addition
2Object-generated harmful factors
If lean-burn combustion is used to reduce nitrogen oxide emissions, then NOx emission decreases, but heat efficiency decreases
Solution Approach 1:
The excess air in the lean-burn mixture, which normally leads to heat loss and reduced efficiency, is converted into a benefit by using it as the oxidizing medium for the reformer reaction. The reformer utilizes this excess oxygen to generate hydrogen from exhaust gas components, transforming what would be wasted oxygen into valuable hydrogen fuel that improves combustion efficiency
Solution Approach 2:
Exhaust gas components (CO, H2, hydrocarbons) that would normally be discarded are recovered through the reformer process. These components are converted into hydrogen-rich gas that is recirculated to the combustion chamber, recovering energy that would otherwise be lost and improving overall heat efficiency
3Productivity
If hydrogen is added to increase combustion rate, then ignitability improves, but device complexity increases
Solution Approach 1:
The reformer is designed to perform multiple functions: it generates hydrogen from exhaust gas, preheats the incoming air through heat exchange, and conditions the gas composition for optimal combustion. This multi-functionality reduces the need for separate devices and minimizes overall system complexity while achieving improved combustion rate
Solution Approach 2:
The system uses its own exhaust gas as the feedstock for hydrogen generation, and uses its own combustion heat to preheat the incoming air through the reformer heat exchanger. This self-service approach eliminates the need for external hydrogen sources and additional heating devices, reducing system complexity
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
The system achieves stable and continuous lean-burn combustion by controlling the air-fuel mixture temperature, enhancing combustion efficiency and reducing nitrogen oxide emissions without the need for additional thermal control elements.
Implementation Method 1
a reformer discharging a first compressed air-fuel mixture obtained by an exothermic reaction between the compressed air and fuel
Implementation Method 2
a turbocharger discharging compressed air using exhaust gas supplied from the internal combustion engine
Data Source
AI summary
An internal combustion engine system includes an internal combustion engine, a turbocharger, and a flow ratio adjustment device including a branch configured to divide the compressed into first compressed air and second compressed air and a valve device configured to adjust a flow rate of the first compressed air and a flow rate of the second compressed air. The system additional includes a reformer configured to discharge first generated as a result of a reaction between the first compressed air and the fuel gas, a junction configured to generate second gas including the first gas and the second compressed air, an air-fuel mixture generator configured to generate an air-fuel mixture including the second gas and the fuel gas, and a controller configured to determining a ratio of the flow rate of the first compressed air based on the temperature of the air-fuel mixture.