Influence of Hydrogen Co-Combustion with HVO on Performance, Emissions and Combustion in the Compression Ignition Engine

This study presents results from analysis of the combustion in the single cylinder compression ignition (CI) engine with the common rail injection system fueled with Hydrotreated Vegetable Oil (HVO) and hydrogen. The objective of the research, was to examine the impact of HES on combustion properties and combustion duration in the CI engine working at the constant speed of 965 rpm and with IMEP (Indicated Mean Effective Pressure) of low (345 - 380 kPa), medium (495 - 545 kPa) and nominal (652 - 692 kPa) loads. Hydrogen was used at amounts up to 40% hydrogen energy share (HES). Hydrogen was injected into the intake manifold, where it created homogeneous mixture with air. Tests were performed at both fixed and optimal injection timings Results from experiments show that with increase of amounts of hydrogen into the engine, ignition delay time gets shorter that also affects main combustion phase and increases the in-cylinder peak pressure (p(max)). The increase of BTE (brake thermal efficiency) was noticed, and decrease of BSFC (Brake specific fuel consumption) was registered with increase of hydrogen fraction. The supply of H2 decreases engine emissions: smokiness, carbon dioxide and carbon monoxide. However, unburnt hydrocarbons increased with increase of HES to 10 - 15% and next decreased with further increase of HES. The hydrogen induction up to 10% HES decreased the NO levels. However with HES of more than 10%, NO level increased. The effect of hydrogen fraction on the combustion characteristics of the diesel - hydrogen mixture was validated by applying the AVL BOOST software.