Thermodynamic Analysis Of Turbochargers For High Power Density Diesel Engine. 2019-26-0051
The objective of this work is to optimize a low displacement, high power density diesel engine to meet best low end torque without much compromising on max power. This study also includes valve dynamics optimization to achieve best low end torque for the given architecture. After multiple simulations / iterations, it was concluded that, for a lower capacity 4 cylinder engine, residual gas impact on low end performance was very high and due to this, a completely optimized variable geometry turbocharger can actually match the performance of regulated two stage turbo. Thus, different variable geometry turbochargers with variation in constructional parameters like compressor trims along with ported shroud were tried. An in-depth thermodynamic analysis was done for the selection of the proper specification. The impact of each parameter on engine performance was studied and specification was finalized. Along with the specification selection, intake duct modification was done for proper uniformity index at the compressor inlet. D section intake duct helped in reduction of eddy currents at the compressor inlet. The final selected compressor trim improved compressor efficiency at high end. This enabled higher boost pressures, which resulted in higher rated power. Compressor efficiency improvement at the higher end, helped in reducing the compressor speeds for the same boost pressure. Along with that, valve timing was optimized to reduce the impact of the residual gas.