Abstract
A three-phase sequential turbocharging system with two unequal-size turbochargers is developed to improve the fuel economy performance and reduce the smoke emission of the automotive diesel engine, and it has wider range of application than the current two-phase sequential turbocharging system. The steady matching method of the turbochargers and engine and the steady switching boundary are presented. The experimental results show that this system is effective to improve the engine performance especially at the low speed and high load. The maximum reductions of BSFC and smoke opacity are 7.1% and 70.9%. The optimized switching strategies of the valves are investigated, and the surge of the compressor in the switching process is avoided. The switching strategies in the accelerating process are optimized, and the acceleration time from 900 r/min and 2100 r/min at constant torque is reduced by approximately 20%.
Highlights
With the continuous development of high power density and wide speed range diesel engines, the requirements of the turbocharging systems matching with the diesel engines are increasing
The equivalent turbine flow area is capable of more than 50% variation in the Sequential turbocharging (ST) system, so it significantly improves the performance of the engine with high brake mean effective pressure (BMEP) at low speed
This research was based on a two-phase sequential turbocharging with two unequal-size turbochargers which was equipped with Volvo TD121FD six-cylinder diesel engine
Summary
With the continuous development of high power density and wide speed range diesel engines, the requirements of the turbocharging systems matching with the diesel engines are increasing. Compared to other twin turbo system such as two-stage serial turbocharging system, the parallel sequential system has advantages of packaging and costs due to smaller turbocharger size It gets a wide range of applications in ships, locomotives, and military armored vehicles, and it is applied in sports car gasoline engine, diesel trucks, and cars. This research was based on a two-phase sequential turbocharging with two unequal-size turbochargers which was equipped with Volvo TD121FD six-cylinder diesel engine. A novel 3-phase ST system with two parallel unequal-size turbochargers has been presented and studied by experiments It has wider regulating capacity than the current 2-phase ST system, and it is simpler and more economic than the existing 3-phase ST system
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