Abstract

Diesel engine emissions of oxides of nitrogen and particulate matter can be reduced simultaneously through the use of high levels of exhaust gas recirculation (EGR) to achieve low temperature combustion (LTC). Although the potential benefits of diesel LTC are clear, the main challenges to its practical implementation are the requirement of EGR levels that can exceed 60%, high fuel consumption, and high unburned hydrocarbon and carbon monoxide emissions. These limit the application of LTC to medium loads. In order to implement the LTC strategy in an on-road vehicle application, a transition to conventional diesel operation is required to satisfy the expected high load demands on the engine. The investigation was therefore aimed at improving the viability of the high-EGR LTC strategy for steady-state and transient operation and this would be core of the presentation.

In this presentation, the research work carried out on a single cylinder high-speed direct injection diesel engine will be presented and discussed in terms of engine in-cylinder performance and engine-out gaseous and particulate emissions at operating conditions (i.e. EGR rate, intake pressure, fuel quantity, injection pressure) likely to be encountered by an engine during transient and steady-state operation. At selected operating points, further investigation in terms of in-cylinder spray and combustion visualization, flame temperature and soot concentration measurements will be provided in order to get deeper insight into the combustion and emissions phenomena.

Increased intake pressure at single injection and split fuel injection will be presented as strategies to reduce the emissions of partial combustion by-products and to improve fuel economy in the high-EGR LTC operation. The higher intake pressure, although effective in reducing partial combustion by-products emissions and improving fuel economy, increased the EGR requirement to achieve LTC. A split fuel injection strategy with advanced injection timing on the other hand was effective in reducing the EGR requirement for LTC from 62% with single injection to 52% with split injections. The difficulties associated with drivability, emissions and fuel economy during a load transient necessitating a combustion mode transition at a constant speed will also be presented. A future outlook outlining research proposals in low temperature combustion will be discussed.

Bio-sketch

Dr Asish Sarangi is currently working as a Senior Engine Development Engineer in JCB Power Systems, UK. JCB is a leading firm that develops many of their engine systems for off-road equipment: his current role covers all aspects of engine development from engine modelling to combustion and exhaust after-treatment system development. Dr Sarangi completed PhD in Mechanical Engineering from Loughborough University, UK where he worked on his PhD thesis entitled “Diesel Low Temperature Combustion – An Experimental Study” under the supervision of Professor Colin Garner and Dr Gordon McTaggart-Cowan. For pursuing his PhD, Asish has been the recipient of Loughborough University Departmental Scholarship with support from the UK Engineering and Physical Sciences Research Council. Dr Sarangi did his postdoctoral work at the Future Engines and Fuels Lab in The University of Birmingham, working on gasoline direct injection combustion and the effects of fuel additive, bio-fuel contents and fuel quality on injector deposit formation.

Prior to joining PhD, Asish worked in Honeywell, Bangalore on the thermodynamic simulation of turbochargers, and in National Aerospace Laboratories Bangalore on the mechanical aspects of turbo-machineries, rotor dynamics and the development of high-speed foil air bearings. He completed his undergraduate degree in Mechanical Engineering from Utkal University Odisha and subsequently his MS (by Research) degree in Mechanical Engineering with specialisation in IC Engines from IIT Madras Chennai. For his MS thesis, Asish worked under the guidance of Professor Pramod Mehta and Professor A. Ramesh on the evaluation of performance, combustion and emission characteristics of a mini IC engine used in unmanned air vehicles. He received the Junior and Senior Research Fellowships of CSIR India to pursue his MS degree. Asish has authored and co-authored over 10 journal and conference papers.

High EGR diesel low temperature combustion - advantages, challenges and way forward by Dr. Asish Sarangi

Abstract

Bio-sketch