A Dual Fuel Hydrogen - Diesel Compression Ignition Engine and Its Potential Application in Road Transport 2019-01-0564
In this paper investigations of hydrogen use as a main fuel for a compression ignition engine with pilot injection of diesel fuel will be presented. The experiments were performed in steady state conditions on a single cylinder research compression ignition engine with a bore of 85 mm and piston stroke of 90 mm, coupled with an electric dynamometer. The diesel engine with optimized compression ratio was equipped with a diesel fuel direct injection common rail system. A homogeneous mixture of air and hydrogen was formed using a port fuel injection. The influence of hydrogen share on total fuel energy was systematically investigated between limits given by the pure diesel operation and up to a maximum hydrogen share, reaching 98% by energy. The tested hydrogen share was constrained by practical limits at various loads between 4 and 16 bar of IMEP with simulation of the real turbocharger performance and at three engine speeds. It was observed that increase in the hydrogen share reduces emissions of CO2 and CO proportionally with decrease in carbon content in the fuel. Simultaneously, PM emissions in raw exhaust gas dropped continuously with increase in hydrogen share. NOx emissions for the highest H2 share dropped only slightly from the level of the diesel engine. The engine efficiency was slightly reduced, when operated with a highest share of hydrogen compared to the pure diesel operation. Based on experimental results a steady state performance and emissions maps of a turbocharged four cylinder hydrogen - diesel dual fueled engine were compiled. A particular implementation of a dual fuel H2 - diesel engine in a passenger van in a WLTP driving cycle was simulated. Two fueling strategies were compared. The simulations showed a potential of almost 70 percent reduction of the driving cycle CO2 emissions for the strategy using the highest hydrogen share, compared to the pure diesel operation. Vehicle range with a reasonable hydrogen storage exceeds 460 km.