Fuel saving and lower pollutants emissions using an ethanol-fueled engine in a hydraulic hybrid passengers vehicle

Abstract This paper aims to compare the behavior of ethanol-fueled vehicles when operating exclusively with an internal combustion engine (ICE) and when using a small series hydraulic drivetrain in simulated standardized and real-world driving cycles. The computational models use fuel consumption and emissions maps acquired experimentally in stationary conditions from a multi-cylinder engine in previous work. The hydraulic hybrid powertrain uses the power generated by a pump driven by the ICE or stored in a hydro-pneumatic accumulator to accelerate the vehicle through a hydraulic motor connected to the differential box. Furthermore, a multi-objective optimization tool was used to size the hydraulic components and to calculate the values of the control variables for activating the motor-pump system, in order to achieve the compromise solution of minimum fuel consumption and emissions. The series hydraulic hybrid architecture implemented showed the possibility of reducing fuel consumption mainly in urban routes. The hybrid model optimized for reducing engine-out emissions pointed out the potential of reducing up to 47.2% and 20.7% the CO2 and NOx emissions levels in the real-world driving cycles, respectively. Furthermore, the optimized solution of lower engine-out emissions also showed potential between 30.17% and 44.14% of fuel-saving in urban routes with frequent stop-and-go events.