Biogenous Ethanol: CO ₂ Savings and Operation in a Dual-Fuel Designed Diesel Engine 2019-24-0040

The usage of ethanol and two different mixtures of ethanol and gasoline (E85 and E65) wаs investigated on a modified diesel engine designed to work in a dual-fuel combustion mode with intake manifold alcohol injection. The maximum ratio of alcohol to diesel fuel was limited by irregular combustion phenomena like degrading combustion quality and poor process controllability at low load and knock as well as auto-ignition at high load. With rising alcohol amount, a significant reduction of soot mass and particle number was observed. At some testing points, substituting diesel with ethanol, E65 or E85 led to a reduction of NO_x emissions; however, the real benefit concerning the nitrogen oxides was introduced by the mitigation of the soot-NO_x trade-off. The indicated engine efficiency in dual-fuel mode showed an extended tolerance against high EGR rates. It was significantly improved with enhanced substitution ratios at high loads, whereas it dropped at low loads. A simulation model was built for the test engine and selected operation points of the engine test bed measurements were implemented into the model in order to generate an efficiency loss analysis. The discussion of the simulation results allowed a better understanding of the findings of the engine test stand experiments. Substituting diesel with intake manifold injected alcoholic fuels impressively lowered the engine CO₂ emissions at medium and high loads. A case study of the bioethanol production by the Austrian bioethanol producer AGRANA demonstrated the high ability of bioethanol to reduce the holistic well-to-wheel CO₂ emissions of the dual-fuel powered diesel engine.