Abstract
Under transient conditions, the emission of turbocharged diesel engine will deteriorate to a certain extent, and the adoption of EGR is also a factor leading to the increase of some pollutants. For this reason, a high pressure common rail turbocharged and inter-cooled heavy duty diesel engine was used to study the influence of EGR closed-loop control method on the emission performance under typical transient conditions with constant speed and torque increasing in 5s. The results show: The NOx emission can not be effectively reduced when the air input is used as feedback parameter; When the intake oxygen concentration is used as feedback parameter, smoke emission will increase sharply; When exhaust oxygen concentration is used as feedback parameter, the smoke deterioration is less, the peak smoke is 15.8%. It has a better compromise relationship with NOx and fuel consumption, and can be used as closed-loop control parameter for diesel engine transient performance optimization.
Highlights
In order to obtain the smoke and NOx compromise emissions in the transient process as the main objective, the author intends to use the closed-loop control strategy of EGR valve opening to explore the influence of typical constant speed and increased torque transient process performance on a high-pressure common rail, turbocharged and inter-cooled heavy-duty diesel engine, and provide research ideas and data support for the development of the transient performance of heavy-duty diesel engine
The exhaust gas is extracted before the high-pressure stage turbine, and it passes through the EGR inter-cooler and EGR valve in turn
Because the EGR valve is almost fully opened in the early stage of the transient process, the poor oil-gas mixing results in delayed combustion phase, lower combustion rate and peak extinction smoke emission, but the NOx emission is effectively limited
Summary
The research object is a high-pressure common rail electronic-controlled diesel engine with two-stage turbocharging system. The exhaust gas is extracted before the high-pressure stage turbine, and it passes through the EGR inter-cooler (exhaust gas cooling) and EGR valve (control exhaust gas flow) in turn. It is introduced into the high-pressure stage compressor. A real-time parameter acquisition system (10ms) is constructed with high-speed sensors and millisecond A/D acquisition card, which can realize the real-time acquisition of diesel engine parameters such as speed, torque, intake and exhaust temperature and pressure, extinction smoke, intake flow rate and exhaust emissions. In the above formula: (O2)int is intake oxygen concentration, (O2)exh is exhaust oxygen concentration, (O2)atm is air ambient oxygen concentration
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