1,721,015 research outputs found
On the Use of a Hydrogen-Fueled Engine in a Hybrid Electric Vehicle
Full text linkHybrid electric vehicles are currently one of the most effective ways to increase the efficiency and reduce the pollutant emissions of internal combustion engines. Green hydrogen, produced with renewable energies, is an excellent alternative to fossil fuels in order to drastically reduce engine pollutant emissions. In this work, the author proposes the implementation of a hydrogen-fueled engine in a hybrid vehicle; the investigated hybrid powertrain is the power-split type in which the engine, two electric motor/generators and the drive shaft are coupled together by a planetary gear set; this arrangement allows the engine to operate independently from the wheels and, thus, to exploit the best efficiency operating points. A set of numeric simulations were performed in order to compare the gasoline-fueled engine with the hydrogen-fueled one in terms of the thermal efficiency and total energy consumed during a driving cycle. The simulation results show a mean engine efficiency increase of around 17% when fueled with hydrogen with respect to gasoline and an energy consumption reduction of around 15% in a driving cycle
Detailed Combustion Analysis of a Supercharged Double-Fueled Spark Ignition Engine
Full text linkThe main goal of researches in the field of automotive engineering is to obtain a large-scale implementation
of low- or zero-emissions vehicles in order to substantially reduce air pollution in urban
areas. A fundamental step toward this green transition is represented by the improvement of current
internal combustion (IC) engines in terms of fuel economy and pollutant emissions. The spark ignition
(SI) engines of modern light-duty vehicles are supercharged, down-sized, and equipped with direct
injection. Gaseous fuels, such as liquefied petroleum gas (LPG) or natural gas (NG), proved to be a
valid alternative to gasoline in order to reduce pollutant emissions and increase fuel economy. In
previous works the authors investigated the simultaneous combustion, in an SI engine, of gasoline
and a gaseous fuel (referred to as Double-Fuel operation, DF) both in the naturally aspirated and
supercharged version; a significant increment of engine efficiency and a great reduction of pollutant
emissions were obtained with respect to pure gasoline operation, with almost unchanged performance.
This article is a development of the previous work and shows the results of a detailed heat
release analysis, performed on the DF supercharged engine fueled with mixtures of gasoline and
NG in order to highlight the effects of engine speed, charging pressure, and fuel mixture composition
(the proportion between gasoline and NG) on the combustion speed.
It was found that both gasoline content in the DF mixture and supercharging pressure contribute
to increase the combustion speed, which, in some cases, produced engine-indicated efficiency
increments up to 5%. The wide set of experimental data presented in this article allows us to better
understand the combustion behavior of gasoline-NG fuel mixtures and can be also used to calibrate
combustion submodels integrated into engine numerical simulations
Performance and combustion analysis of a supercharged double-fuel spark ignition engine
No full textIn order to increase fuel economy and reduce pollutant emissions in the last decades light duty spark ignition (SI) engines have become smaller, supercharged and equipped with direct injection. A suitable alternative to oil derived fuel is represented by gaseous fuels, such as Natural Gas (NG) and Liquefied Petroleum Gas (LPG), whose higher knock resistance and better mixing capabilities substantially improve vehicle fuel economy and pollutant emissions. The simultaneous combustion of gasoline and gaseous fuel (Double-Fuel operation, DF) in a naturally aspirated SI engine has already been investigated in the past also by the same authors, proving remarkable results in terms of engine efficiency increment and exhaust emissions reduction. In this paper the authors present the results of a new methodical experimental study aimed to investigate engine performance, efficiency and pollutant emissions obtained on a supercharged SI engine operated in double fuel mode, with comparison to the use of "reference" pure fuels (i.e. gasoline and NG). A detailed heat release analysis is also performed with the aim to highlight the effect of fuel mixture composition (i.e. the proportion between gasoline and NG) and of charging pressure on the combustion speed
Heat Transfer Modeling of Hydrogen-Fueled Spark Ignition Engine
Full text linkCurrently, green hydrogen, generated through renewable energy sources, stands out as one of the best substitutes for fossil fuels in mitigating pollutant emissions and consequent global warming. Particularly, the utilization of hydrogen in spark ignition engines has undergone extensive study in recent years. Many aspects have been analyzed: the conversion of gasoline engines to hydrogen operation, the combustion duration, the heat transfer, and, in general, the engine thermal efficiency. Hydrogen combustion is characterized by a smaller quenching distance compared to traditional hydrocarbon fuels such as gasoline or natural gas and this produces a smaller thermal boundary layer and consequently higher heat transfer. This paper presents findings from experimental trials and numerical simulations conducted on a hydrogen-powered CFR (cooperative fuel research) engine, focusing specifically on heat transfer with combustion chamber walls. The engine has also been fueled with methane and isooctane (two reference fuels); both the engine compression ratio and the air/fuel ratio have been changed in a wide range in order to compare the three fuels in terms of heat transfer, combustion duration, and engine thermal efficiency in different operating conditions. A numerical model has been calibrated with experimental data in order to predict the amount of heat transfer under the best thermal efficiency operating conditions. The results show that, when operated with hydrogen, the best engine efficiency is obtained with a compression ratio of 11.9 and an excess air ratio (lambda) of 2
Festsitzende kleferorthopädische Behändlung mit dem Herbst-Gerät und dem Jasper Jumper
No full text
Performances and Emissions Improvement of an S.I. Engine Fuelled by LPG/Gasoline Mixtures
No full textAs is known gaseous fuels, such as Liquefied Petroleum Gas (LPG) and Natural Gas (NG), thanks to their good mixing capabilities, allow complete and cleaner combustion than normal gasoline, resulting in lower pollutant emissions and particulate matter. Some of the automobile producers already put on the market “bi-fuel” engines, which may be fed either with standard gasoline or with LPG. These engines, endowed of two separate injection systems, are originally designed for gasoline operation; hence they do not fully exploit the good qualities of LPG, such as its better knocking resistance, which would allow higher compression ratios. Moreover, when running with gasoline at medium high loads, the engine is often operated with rich mixture and low spark advance (with respect to the maximum brake torque value) in order to prevent from dangerous knocking phenomena: this produces both high hydrocarbon and carbon monoxide emissions and high fuel consumption. Starting from these observations, the authors experimentally investigated on the simultaneous combustion of LPG- gasoline mixtures in stoichiometric proportion with air (with different LPG/gasoline mass ratios), so as to exploit the good qualities of both fuels to obtain cleaner and more efficient combustions: the addition of LPG to the gasoline-air mixture in fact raises knocking resistance, allowing thus to run the engine with both “overall stoichiometric” mixture and more efficient spark advance even at full load, while the stoichiometric A/F ratio allows to minimize pollutant emissions. In this paper the authors present the results of an extensive experimental study in terms of engine efficiency increments and reduction of pollutant emissions with respect to the pure gasoline operation
- …
