A Simulation Study of the Effects of Turbo-Expansion Concept Implementation on Combustion and Gas-Exchange Processes of a 1.4 L Spark-Ignition Engine

Abstract

Internal combustion engines account for approximately a quarter of global energy demand. The primary reason is the very high reliance of the transportation sector on fossil fuels. Reducing IC Engines' environmental impact and fuel consumption is one of the directions taken by vast research efforts aimed at increasing the sustainability of the transportation sector. One of the possibilities is the use of a charge-air cooling process - turbo-expansion, to raise efficiency by harnessing more exhaust energy and raising the intake charge density. It allows intake-air temperature to be lowered to around, or even below, ambient levels and exempts the turbocharger system from using a wastegate. A co-simulation in WAVE and MATLAB/Simulink environments was conducted to investigate the effects of the turbo-expansion concept on gas-exchange and combustion processes of a small, 1,4 L spark-ignition turbocharged engine. An empirical, operating conditions-correlated, Wiebe-based spark-ignition combustion model was used to predict the influence of intake and exhaust conditions on combustion duration and heat release dynamics. The implications on the engine gas-exchange processes are quantified. Despite significant intake charge cooling effect not being conveyed inside the cylinders, the brake specific fuel consumption is predicted to be reduced by 1,8 % at 4500 RPM.