Dual Exhaust Recirculation for Combustion Temperature Control
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Solution Overview
Problem
Existing exhaust gas recirculation devices struggle to effectively control nitrogen oxide production in engine combustion chambers, as the temperature in local regions of the combustion chamber can remain high despite averaging to a lower cylinder temperature, leading to incomplete nitrogen oxide reduction.
Innovation Solution
The exhaust gas recirculation device controls the ratio of exhaust gases introduced through two separate recirculation passages to adjust the oxygen concentration in the combustion chamber, with increased recirculation through the second passage when the flame temperature exceeds an allowable limit, to quickly decrease the flame temperature and reduce nitrogen oxide production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the cylinder temperature is controlled to be lower than the reference cylinder temperature, then the nitrogen oxide production is restricted, but the local temperature in parts of the combustion chamber may remain extremely high
Solution Approach 1:
The exhaust gas recirculation system is divided into two separate passages: a first passage that introduces exhaust gas from upstream of the turbine, and a second passage that introduces exhaust gas from downstream of the turbine. This segmentation allows independent control of exhaust gas flow from different locations, enabling precise temperature management in different combustion chamber regions.
Solution Approach 2:
The system applies different exhaust gas recirculation strategies to different parts of the combustion chamber by controlling the ratio of exhaust gas introduced through the first versus second passages. The second passage, which provides cooler exhaust gas, is specifically utilized when local flame temperature exceeds the allowable upper limit, thereby针对性地 addressing local overheating issues.
2Use of energy by moving object
If the ratio of exhaust gases from the first and second passages is controlled based on cylinder temperature, then fuel consumption is improved, but nitrogen oxide production cannot be sufficiently restricted when local temperatures are high
Solution Approach 1:
The control system continuously monitors the flame temperature in the combustion chamber and dynamically adjusts the ratio of exhaust gas recirculation through the first and second passages. When the flame temperature exceeds the allowable upper limit, the system increases the proportion of exhaust gas from the second passage to cool the combustion chamber, ensuring nitrogen oxide production remains within acceptable limits while maintaining fuel efficiency.
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 ensures that the nitrogen oxide production is restricted to an allowable amount by effectively decreasing the oxygen concentration and temperature in the combustion chamber, even when local temperatures are high, thereby improving combustion efficiency and reducing emissions.
Implementation Method 1
Much inert gas such as carbon dioxide is included in the exhaust gas, and therefore a temperature of combustion of fuel in the combustion chamber is decreased by recirculating the exhaust gas into the combustion chamber
Data Source
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AI summary
An exhaust gas recirculation device of an engine (10) of the invention comprises a first exhaust gas recirculation passage (50) for connecting an exhaust passage (40) and an intake passage (30) to each other and introducing into the intake passage an exhaust gas discharged from a combustion chamber (21) to the exhaust passage, and a second exhaust gas recirculation passage (55) for connecting the exhaust passage upstream of a part of the exhaust passage connected to the first exhaust gas recirculation passage and the intake passage downstream of a part of the intake passage connected to the first exhaust gas recirculation passage to each other and introducing into the intake passage the exhaust gas discharged from the combustion chamber to the exhaust passage. The amount of the exhaust gas introduced into the intake passage via the first exhaust gas recirculation passage is controlled to a first target exhaust gas recirculation amount and the amount of the exhaust gas introduced into the intake passage via the second exhaust gas recirculation passage is controlled to a second target exhaust gas recirculation amount. When a temperature of the flame on the combustion of a fuel is lower than or equal to an allowable upper limit flame temperature, a first reference exhaust gas recirculation amount set depending on the operation condition of the engine, is set as the first target exhaust gas recirculation amount and a second reference exhaust gas recirculation amount set depending on the operation condition of the engine, is set as the second target exhaust gas recirculation amount. When the temperature of the flame on the combustion of the fuel is higher than the allowable upper limit flame temperature, one of the first reference exhaust gas recirculation gas amount and an amount smaller than the first reference exhaust gas recirculation gas amount is set as the first target exhaust gas recirculation amount and an amount larger than the reference second exhaust gas recirculation amount is set as the second target exhaust gas recirculation amount.