Analysis of a series hybrid vehicle concept that combines low temperature combustion and biofuels as power source

Abstract

This work evaluates the potential of a series hybrid vehicle concept that combines low temperature combustion (LTC) and biofuels as power source. To do this, experimental data from a previous work obtained in a single-cylinder engine running under ethanol-diesel dual-fuel combustion is used. Then, vehicle systems simulations are used to estimate performance and emissions of the LTC hybrid vehicle and compare them versus conventional diesel combustion (CDC). The vehicle selected to perform the simulations is the Opel Vectra, which equips the compression ignition engine used in the experimental tests.The results from the simulations used for the analysis are firstly optimized by combining design of experiments and the Kriging fitting method. The multi-objective optimization allows to determine some characteristics and controls of the hybrid vehicle. The comparison of the estimated performance and emissions of the LTC-hybrid concept versus CDC over the worldwide harmonized light vehicles test cycle (WLTC) and real driving cycle (RDE) revealed clear benefits in terms of energy consumption, CO2 and NOx and soot emissions. In this sense, the hybrid concept enabled a reduction of the final energy consumed of 3% in the RDE cycle and 6.5% in the WLTC as compared to CDC. In terms of engine-out emissions, the CO2 was reduced around 16% versus CDC, and engine-out NOx and soot were reduced below the levels imposed by the Euro 6 regulation. As a penalty, the engine-out HC and CO emissions increased to more than double than CDC. However, based on previous experimental results, it is expected that a conventional diesel oxidation catalyst can reduce the tail-pipe HC and CO levels below the Euro 6 limits. Keywords: Low temperature combustion, Series hybrid vehicle, Dual-fuel combustion, Alternative fuels, Driving cycles