Performance Analysis of Hydrogen Combustion under Ultra Lean Conditions in a Spark Ignition Research Engine Using a Barrier Discharge Igniter

Abstract

<div class="section abstract"><div class="htmlview paragraph">The global push to minimize carbon emissions and the imposition of more rigorous regulations on emissions are driving an increased exploration of cleaner powertrains for transportation. Hydrogen fuel applications in internal combustion engines are gaining prominence due to their zero carbon emissions and favorable combustion characteristics, particularly in terms of thermal efficiency. However, conventional Spark-Ignition (SI) engines are facing challenges in meeting performance expectations while complying with strict pollutant-emission regulations. These challenges arise from the engine's difficulty in handling advanced combustion strategies, such as lean mixtures, attributed to factors like low ignition energy and abnormal combustion events.</div><div class="htmlview paragraph">To address these issues, the Barrier Discharge Igniter (BDI) stands out for its capability to generate non-equilibrium Low-Temperature Plasma (LTP), a strong promoter of ignition through kinetic, thermal, and transport effects. Its surface discharge also facilitates combustion promotion across a wide area, overcoming the limitations of conventional spark systems. The research outlined in this study involves conducting experiments that integrate hydrogen (H<sub>2</sub>) with LTP discharge. Tests were carried out using a single-cylinder research engine by varying the air-fuel mixture and maintaining the same load condition and the same engine speed. Results from the application of BDI, revealed an acceleration in the evolution of the flame front when compared to conventional spark methods. This effect extended the lean stable limit of the engine, leading to reduction in the fuel consumption and emissions and improvements in the delivered power close to the engine lean stable limit. Additionally, adjustment of BDI control parameters played a crucial role in enhancing igniter performance, contributing significantly to a more comprehensive understanding of the innovative approach presented in this study.</div></div>