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Electric vehicle technology
Published in Tom Denton, Electric and Hybrid Vehicles, 2020
The result of the hybridization of a motor and an engine is that it can always be operated (with suitable electronic control) at its optimum speed for reducing emissions and consumption while still producing good torque. A smaller capacity engine can also be used (downsizing) in conjunction with a higher geared transmission so the engine runs at lower speed (downspeeding) but performance is maintained.
Atom probe tomography characterisation of powder forged connecting rods alloyed with vanadium and copper
Published in Philosophical Magazine, 2022
Kristina Lindgren, Karin Frisk, Maheswaran Vattur Sundaram, Mattias Thuvander
There is a constant drive towards increasing the performances of the internal combustion engines to meet the regulations and emission norms, by increasing the specific power output and lowering the engine displacement. Also, the trend towards hybridisation pushes for engine downsizing by moving towards increased efficiency and performance. To meet such demands of the high-performance engines, the engine components must have excellent properties to withstand such requirements [1]. Connecting rods (conrods) are high-performance components that experience high thermo-mechanical loadings. Manufacturing is performed either by drop forging of wrought steels or by powder forging. The main advantage when it comes to the powder forged conrods is the high precision from powder forging, reduced machining costs (better machinability) and the possibility to use fracture splitting [2].
Progress in alcohol-gasoline blends and their effects on the performance and emissions in SI engines under different operating conditions
Published in International Journal of Ambient Energy, 2021
Abdulfatah Abdu Yusuf, Freddie L. Inambao
Wang et al. (2018) showed the breakdown of thermal efficiency gains for ethanol-gasoline blends in TC DISI engines. Results showed that the engine thermal efficiency gains were affected mainly due to a cooling effect and chemical effect, both of which increased with the ethanol ratio. These results pointed out that the chemical effect is the most dominant, especially for the blend with a low research octane number (RON) base fuel. Also, the cooling effect shows a significant effect for the blend with a low RON94.5 (ΔEOI/ΔCR = 4) base fuel. However, the improvement of engine downsizing, flame speed effect, and octane sensitivity were comparable and were less than those of chemical and cooling effects. With a little amount of ethanol addition, the engine thermal efficiency increased faster than the reduction of lower heating value (LHV). When the ethanol content was high the thermal efficiency decreased. This trend was reported by other researchers as well (Jo, Bromberg, and Heywood 2016; Leone et al. 2015; Liu et al. 2015; Wang, Janssen, et al. 2017; Wang, Zeraati-Rezaei, et al. 2017), who suggested that for compression ratios from 8:1 to 14:1, the thermal efficiency gain with compression ratio is almost linear (Δη/ΔCR = 1.8%). The contribution of the high flame speed of ethanol to thermal efficiency is 0.20% for every 10% by volume of ethanol content in fuel blends. They emphasised that engine downsizing is a technology that increases engine thermal efficiency by allowing an engine to operate at more efficient high load regimes, instead of at low load regimes where pumping losses significantly reduce engine thermal efficiencies. The researchers suggested that a thermal efficiency increment multiplier from additional engine downsizing for TC DISI engines.
Contemporary challenges of soot build-up in IC engine and their tribological implications
Published in Tribology - Materials, Surfaces & Interfaces, 2018
L. B. Abdulqadir, N. F. Mohd Nor, R. Lewis, T. Slatter
Tackling the issue of fuel consumption through downsizing implies an increase in specific power output, accompanied by higher cylinder pressures (increased dynamic load) and oil temperatures (increased thermal load) [12]. Controlling the formation and emission of NOx by reducing combustion chamber temperatures and retarding the fuel injection timing during the combustion cycle, however, traps more soot in the chamber. EGR also assists in controlling the combustion process but also results in soot build-up.