Impact of varying the injection angle on compression ignition (CI) engines fueled with hydrogen-enriched microalgae biodiesel

Injection parameters such as fuel opening injection pressure have a significant impact on engine combustion, performance, and emissions. The experiment was performed on a single four-stroke cylinder CRDi engine powered using a fixed hydrogen flow rate of 7 lpm and 10 lpm for micro algae biodiesel blends of 10% (MA10H2), 20% (MA20H2), and 30% (MA30H2). This study seeks to enhance the performance and minimize emissions of single-cylinder diesel engines across different loading conditions, specifically at 30%, 60%, 80%, 90%, and 100% loads. It focuses on exploring hydrogen and biodiesel as alternative fuels, which have the potential to reduce energy consumption and meet stringent emission standards. The investigation is carried out for three distinct injection advance angle 15°, 20° and 25°. The experimental results indicated that changing injection angles did not have a significant impact on brake-specific fuel consumption (BSFC). However, brake thermal efficiency (BTE) increased by up to 16% at a 15° injection angle. At this angle, exhaust emissions including CO, CO2, unburned hydrocarbons (UHC), and smoke opacity were mostly enhanced. Conversely, NOx emissions were reduced, and increases in cylinder peak pressure were observed only at a 15° injection angle. Hydrogen enrichment is beneficial for engine performance and emissions. It improves both brake thermal efficiency (BTE) and reduces brake-specific energy consumption (BSEC) due to hydrogen’s high calorific value and absence of carbon, resulting in decreased emissions of hydrocarbons (HC), carbon monoxide (CO), and carbon dioxide (CO2). However, this enrichment may lead to an increase in exhaust gas temperature (EGT), consequently raising nitrogen oxide (NOx) emissions. Furthermore, hydrogen enrichment enhances combustion properties such as in-cylinder pressure (ICP), heat release rate (HRR), and ignition delay (ID), indicating more efficient combustion. Additionally, it reduces combustion duration (CD), implying faster combustion processes.