Electrified Powertrain with Multiple Planetary Gears and Corresponding Energy Management Strategy

Modern hybrid electric vehicles (HEVs) like the fourth generation of Toyota Prius incorporate multiple planetary gears (PG) to interconnect various power components. Previous studies reported that increasing the number of planetary gears from one to two reduces energy consumption. However, these studies did not compare one PG and two PGs topologies at their optimal operation. Moreover, the size of the powertrain components are not the same and hence the source of reduction in energy consumption is not clear. This paper investigates the effect of the number of planetary gears on energy consumption under optimal operation of the powertrain components. The powertrains with one and two PGs are considered and an optimal simultaneous torque distribution and mode selection strategy is proposed. The proposed energy management strategy (EMS) optimally distributes torque demands amongst the power components whilst also controlling clutches (i.e., mode selection). Results show that increasing from one to two PGs reduces energy consumption by 4%

Tribological Performance of Biomass-Derived Bio-Alcohol and Bio-Ketone Fuels

This study relates to developing future alternative fuels and focuses on the effects of a fuel’s molecular structure on its properties and performance in advanced propulsion systems. The tribological performance of various biomass-derived oxygenated alternative fuels, including butanol, pentanol, cyclopentanol, cyclopentanone, and gasoline and their blends with diesel, was investigated. Lubricity tests were conducted using a high-frequency reciprocating rig (HFRR). Cyclopentanone-diesel and cyclopentanol-diesel blends result in smaller wear scar sizes compared to using their neat forms. A lower steel disc contaminated with the alternative fuels during the HFRR tests resulted in worn surface roughness values lower than those of the neat diesel by up to 20%. It is believed that these reductions are mainly due to the presence of the hydroxyl group and the carbonyl group in alcohols and ketones, respectively, which make them more polar and consequently helps the formation of the protective lubrication film on the worn moving surfaces during the sliding process. Overall, the results from this study indicate that environmentally friendly cyclopentanol and cyclopentanone are practical and efficient fuel candidates for future advanced propulsion systems

The significance of low carbon bio-alcohols and bio-ketones fuels for clean propulsion systems

This experimental work investigates oxygenated bio-fuel component blends of butanol, pentanol and cyclopentanone with diesel on the combustion characteristics, gaseous emissions and particulate matter (PM). Furthermore, PM characteristics, including size distributions, morphology and nanostructure are investigated.The oxygen content on the sustainable fuel blend components (bio-alcohols and bio-ketone) and the lower cetane number leading to a longer ignition delay, larger premixed combustion phase and high mean peak combustion temperature reduced the total number of particle concentration by up to 91%. Characterisation of particles demonstrated morphological and nanostructural alterations, such as the reduction in primary particle size that would lead to greater particle oxidation reactivity. Furthermore, the combustion of oxygenated blends showed a reduction in the total hydrocarbon emissions and an increase in NO2 concentration. This research provides new knowledge to understand the effects of fuel properties on gaseous and particle emissions formation and characteristics. Overall this work demonstrates bio-alcohols and bio-ketones as low carbon fuels in unveiling strategies for vehicular emissions abatement