Development of a 2-Stage Supercharging System for a HSDI Diesel Engine 2009-01-2757
2-stage supercharging applied to HSDI Diesel engines is a promising solution for enhancing rated power, low end torque, transient response and hence the launch characteristics of a vehicle. However, a trade-off is required to match some conflicting issues, i.e. overall dimensions, cost, emissions control and performance. The outcome strongly depends on the specific constraints and goals of the project.
In the paper, reference is made to 2.8L, 4 cylinder in-line unit produced by VM Motori (Cento, Italy), equipped by a standard variable geometry turbocharger. A 1D thermo-fluid-dynamic model of the Euro V version of the engine was built and calibrated against experiments at the dynamometer bench, at both full and partial load.
Two types of 2-stage supercharging systems have been analyzed and optimized through CFD-1D simulation: a conventional configuration made up of two turbochargers of different size, serially connected, and another set-up where a single turbocharger is coupled to a positive displacement compressor.
The study demonstrates that, on the VM Motori engine, the use of a supercharging system made up by a positive displacement compressor and a VGT turbocharger is able to noticeably enhance engine performance at full load, with further advantages, in comparison to the other analyzed system, in terms of fuel consumption and emissions control.