Modelling the effect of variable valve timing on exhaust thermal management of a diesel engine

Nowadays, one of the solution for reduced-emission diesel engines is to utilize exhaust thermal management systems.However; these systemswork efficiently mostly at temperatures above 250°Cand for diesel engines, especially at low speed and low load conditions, exhaust gas temperatures are not generally higher than 250°C. Variable valve timing (VVT) can be used to achieve those high exhaust gas temperatures. Therefore, the aim of this study is to try to increase the turbine exit temperature of a diesel engine above 250°C for various engine loadings at a particular engine speed by combining advanced intake valve closing with earlier opening of the exhaust valve. Diesel engine system is simulated by using Lotus Engine Simulation (LES) program. It is then validated with experimental results. It is seen that exhaust gas temperatures can be raised higher than 250°C for most of the loading cases when VVT is applied.