Applicability of Variable-Geometry Turbocharger for Diesel Generators under High Exhaust Back Pressure

Abstract

The exhaust back pressure of diesel engines is becoming increasingly higher nowadays. In order to keep discharging exhaust unhindered and operating smoothly under high exhaust back pressure, a large reduction in engine maximum brake output is often observed, as well as increased fuel consumption and lower combustion efficiency with heavy exhaust smokes. In our previous study, Applicability of Reducing Valve Timing Overlap for Diesel Engines under High Exhaust Back Pressure a reduced valve timing overlap of 12 degrees CA partially improves the brake output and BSFC for a fixed-geometry turbocharged diesel engine under high exhaust back pressures. A potential solution for restoring the brake output under high exhaust back pressures could be the use of variable-geometry turbochargers. In this study a variable-geometry turbocharger is applied to a diesel engine to study the engine performance characteristics and applicability especially the further improvement of brake output and the brake-specific fuel consumption of the engine. Continuing with the results of our previous research a basic setting of 12 degrees CA for the valve timing overlap is set up for the subsequent engine performance simulations in this study (using GT-Power SW). Via simulation exhaust back pressures of 25 kPa45 kPa and 65 kPa gauge are studied for a turbocharged diesel engine. The results for the engine parameters