Comparative analysis of H2-diesel co-combustion in a single cylinder engine and a chassis dynamometer vehicle

Midhat Talibi,Paul Hellier,Martin Watkinson,Nicos Ladommatos

doi:10.1016/j.ijhydene.2018.11.092

Abstract

Concerns as to the adverse effects of diesel engine exhaust on urban air quality have resulted in increasingly stringent emissions legislation, with the prospect of many major global cities potentially banning diesel vehicles. Emissions of nitrogen oxides (NOx) and particulate matter (PM) are linked to increases in premature mortality, and the simultaneous control of both pollutants through modified combustion strategies presents a significant challenge. In this work, the effects of displacing diesel fuel with hydrogen on exhaust emissions were investigated in both a single cylinder research engine and in a demonstration vehicle. In the initial stage, tests were undertaken on a supercharged, direct injection, single cylinder diesel research engine at different engine loads, intake air pressures and EGR levels. Hydrogen was aspirated with the intake air, and EGR was simulated by supplying the intake pipe with compressed nitrogen gas. The results showed a reduction in CO2 and particulate emissions with increasing H2 addition, and an increase in NOx emissions at H2 levels greater than 10% of the total input energy to the engine. The next stage involved tests on a chassis dynamometer with a small van equipped with the multi-cylinder version of the single cylinder research engine. The van was fitted with a programmable H2 augmentation system, with H2 addition levels specified by accelerator pedal position. During full drive cycle tests conducted with and without H2 augmentation up to 10%, an average rate of 1 kW of H2 was supplied to the engine. With H2 augmentation, over the total drive-cycle, reductions in CO, NOx and particle number were observed, but a higher total PM mass was recorded.

Highlights

Concurrent to increasingly stringent legislation restricting levels of toxic pollutants permitted in exhaust gases from internal combustion engines utilised for road transport [1], there has been growing public awareness and concern as to the detrimental impact of such emissions on human health, especially in urban areas
In the UK, 29,000 premature deaths per year have been attributed to anthropogenic emissions of particulate matter (PM) [2], with 3000 of these in London alone
Throughout this work, the ignition delay has been defined as the time in crank angle degrees (CAD) between the start of the injection signal supplied to the diesel fuel injector (SOI) and the start of combustion (SOC) as indicated by the first incidence of positive heat release

Summary

Introduction

Concurrent to increasingly stringent legislation restricting levels of toxic pollutants permitted in exhaust gases from internal combustion engines utilised for road transport [1], there has been growing public awareness and concern as to the detrimental impact of such emissions on human health, especially in urban areas. Levels of atmospheric nitrogen dioxide (NO2) as measured in 2010 are estimated to be responsible for approximately 5800 premature deaths per year in London [3]. While emissions of both PM and nitrogen oxides (NOx) arise from a range of anthropogenic combustion activities, it is diesel engine powered vehicles that both policy makers and the mainstream media have focused on in recent years as a significant contributor to emissions of both [4].

Methods

Results

Conclusion