Biogenous Ethanol: CO2 Savings and Operation in a Dual-Fuel Designed Diesel Engine
The usage of ethanol and two different mixtures of ethanol and gasoline (E85 and E65) was 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 NOx emissions; however, the real benefit concerning the nitrogen oxides was introduced by the mitigation of the soot-NOx trade-off. With regard to the engine efficiency aspect, the results show bidirectional behaviour: at low load points engine efficiency degrades, whereas the process becomes by up to 6 % (rel.) more effective at higher engine loads.