The Use of Hydrogen in the Automotive Diesel Engine—An Efficient Solution to Control Its Operation with Reduced Carbon Emissions

The use of hydrogen in the diesel engine automotive can be a viable and sustainable solution through which to reduce carbon-based emissions for the same operating regimens, without major constructive modifications of the engine. The use of hydrogen in the automotive diesel engine constitutes an efficient solution for controlling its operation with low carbon-based emissions and with reduced energetic specific consumption. This way, the requirements of the EC’s Green Deal policy can be met without major costs. Substitution of fossils fuels with hydrogen ensures the reduction of the carbon content of the air–fuel mixture in the engine cylinder, with favourable influences on the processes of the air–fuel mixture formation and combustion, making it possible to reduce carbon-based emissions. The improvement of the combustion process due to hydrogen use leads to the reduction in carbon-based emissions. For the experimental investigations carried on an automotive diesel engine with 1.5 L by displacement, the authors highlighted the following results: a reduction in smoke emissions by over 22%, a reduction in unburned hydrocarbon emissions by over 25%, and a reduction in carbon dioxide by about 20%, even from the use of relatively low cyclic doses of hydrogen at a usual engine load compared with a standard engine. The authors also obtained an 18.5% increase in the level of nitrogen oxides in the partial load engine, even with the use of small amounts of hydrogen added to the intake air; this is a disadvantage, but by applying specific measures, this emission can be reduced. The increase in the homogeneous air–fuel mixture with the use of hydrogen and the combustion processes’ duration time were reduced due to the high combustion flame speed of hydrogen comparative to diesel fuel; this ensures a reduction in energetic specific consumption and an increase in thermal efficiency.