Abstract
PurposeUse of fossil fuels in automotive sector is one of the primary causes of greenhouse emissions. The automotive engines need to perform at their best efficiency point to limit these emissions. Most of the quality indicators in this regard are based on near steady state global operational characteristics for engines without considering local performance. In the present study, extensive numerical simulations have been carried out covering a wide range of steady state and transient operating conditions to quantify interaction of turbocharger with engines through turbo lag phenomena which may cause increased emissions during the load change conditions. Furthermore possible innovations have been explored to minimize turbo lag phenomena. The paper aims to discuss these issues.Design/methodology/approachIn this paper quality indicators have been developed to quantify the performance of turbocharged diesel engine under the transient event of rapid change in fueling rate which has been rarely investigated. The rate of fueling is changed from 40 mm3/injection to 52 mm3/injection at 1,000 rpm engine speed which corresponds to normal operating condition. To improve quality of transient response, torque assistance method and reduction of inertia of compressor wheel have been used. Parametric study has been undertaken to analyze the quality indicators such as outlet pressure of the compressor and the compressor speed. The turbo lag is quantified to obtain the close to optimal transient response of turbocharged diesel engine.FindingsIt has been shown that, with torque assist the transient response of the internal combustion engine is significantly improved. On the other hand, marginal improvement in transient response is observed by the reduction in inertia of the compressor wheel.Research limitations/implicationsThe findings indicate that turbo lag can be minimized by providing torque assistance by active and passive means.Practical implicationsThe developed methods can be used in practice for efficient operation of vehicles.Social implicationsThe work carried out in the paper provides a way to minimize harmful emissions.Originality/valueThe quality indicators developed provide a quantitative measure of turbo lag phenomena and address the above mentioned problems.
Highlights
Diesel engines are extensively used in passenger cars as well as in long distance haulage sector vehicles to impart motive force
Turbochargers are extensively used in diesel engines for the recovery of heat lost in the exhaust gases and boosting the power output of the engine with the same displacement volume of the engine by providing intake air with increased density and increased mass
The plots show the variation in BSFC (Brake specific fuel consumption), brake torque, brake power and brake mean effective pressure (BMEP)
Summary
Diesel engines are extensively used in passenger cars as well as in long distance haulage sector vehicles to impart motive force These are internal combustion (IC) engines in which fuel is burnt through compression ignition (CI) process. The compressor outlet is connected to the inlet manifold through an intercooler to increase the air density flowing into the intake manifold In this way the volumetric efficiency of the diesel engine is enhanced by the use of turbocharger. As a result the air-fuel ratio quickly changes to undesired value, deteriorating combustion and leading to slower engine response and increased emissions. This condition is known as turbo-lag which needs to be minimized for efficient operation of turbo-charged diesel engines
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