Search results for "spark ignition engine"
showing 10 items of 21 documents
The Experimental Validation of a New Thermodynamic Method for TDC Determination
2007
In-cylinder pressure analysis is becoming more and more important both for research and development purpose and for control and diagnosis of internal combustion engines; directly measured by means of a combustion chamber pressure transducers or evaluated by analysing instantaneous engine speed [1,2,3,4], incylinder pressure allows the evaluation of indicated mean effective pressure (IMEP), combustion heat release, combustion phase, friction pressure, etc...It is well known to internal combustion engine researchers that for a right evaluation of these quantities the exact determination of Top Dead Centre (TDC) is of vital importance: a 1° error on TDC determination can lead to evaluation err…
A Comprehensive Model for the Auto-Ignition Prediction in Spark Ignition Engines Fueled With Mixtures of Gasoline and Methane-Based Fuel
2018
The introduction of natural gas (NG) in the road transport market is proceeding through bifuel vehicles, which, endowed of a double-injection system, can run either with gasoline or with NG. A third possibility is the simultaneous combustion of NG and gasoline, called double-fuel (DF) combustion: the addition of methane to gasoline allows to run the engine with stoichiometric air even at full load, without knocking phenomena, increasing engine efficiency of about 26% and cutting pollutant emissions by 90%. The introduction of DF combustion into series production vehicles requires, however, proper engine calibration (i.e., determination of DF injection and spark timing maps), a process which…
Development of a low-cost piezo film-based knock sensor
2003
It is well known that spark advance is a key parameter in spark ignition engine management. Increasing fuel cost and emission regulation strictness require a higher engine efficiency, which can be improved by an accurate regulation of the spark advance. Under high load conditions, an optimal spark advance choice leads the engine to run next to the knock limit, so the management and control system needs to be equipped with a knock sensor in order to preserve the engine from damage. The authors developed a low-cost knock sensor whose sensing element is a thin washer of polyvinylidine fluoride (PVDF), a fluoropolymer characterized by a great piezoelectric e ect if polarized. The sensor has be…
A New Simple Friction Model for S. I. Engine
2009
Internal combustion engine modeling is nowadays a widely employed tool for modern engine development. Zero and mono dimensional models of the intake and exhaust systems, combined with multi-zone combustion models, proved to be reliable enough for the accurate evaluation of in-cylinder pressure, which in turn allow the estimation of the engine performance in terms of indicated mean effective pressure (IMEP). In order to evaluate the net engine output, both the torque dissipation due to friction and the energy drawn by accessories must be taken into consideration, hence a model for the friction mean effective pressure (FMEP) evaluation is needed. One of the most used models accounts for engin…
Knock Resistance Increase through the Addition of Natural Gas or LPG to Gasoline: An Experimental Study
2013
Bi-fuel spark ignition engines, nowadays widely spread, are usually equipped with two independent injection systems, in order run the engine either with gasoline or with gaseous fuel, which can be Natural Gas (NG) or Liquefied Petroleum Gas (LPG). These gases, besides lower cost and environmental impact, are also characterized by a higher knock resistance with respect to gasoline that allows to adopt a stoichiometric proportion with air also at full load. Gasoline, on the other hand, being injected as liquid, maintains higher volumetric efficiency and hence higher power output. As a compromise solution, it could be desired to exploit the advantages of both gasoline and gas (NG or LPG), thus…
Performance Prevision of a Turbocharged Natural Gas Fuelled S.I. Engine
2008
Natural gas represents today maybe the most valid alternative to conventional fuels for road vehicles propulsion. The main constituent of natural gas, methane, is characterized by a high autoignition temperature, which makes the fuel highly resistant to knocking: this allows a considerable downsizing of the engine by means of supercharging even under high compression ratio. Starting from these considerations, the authors realized a thermodynamic model of a 4-cilynder s.i. engine for the prevision of in-cylinder pressure, employing a two-zone approach for the combustion and adding sub-models to account for gas properties change and knocking occurrence. An extensive experimental campaign has …
Detailed Combustion Analysis of a Supercharged Double-Fueled Spark Ignition Engine
2021
The 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 …
Performances and Emissions Improvement of an S.I. Engine Fuelled by LPG/Gasoline Mixtures
2010
As 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, …
Experimental model-based linearization of a S.I. engine gas injector flow chart:
2014
Experimental tests previously executed by the authors on the simultaneous combustion of gasoline and gaseous fuel in a spark ignition engine revealed the presence of strong nonlinearities in the lower part of the gas injector flow chart. These nonlinearities arise via the injector outflow area variation caused by the needle impacts and bounces during the transient phenomena that take place in the opening and closing phases of the injector and may seriously compromise the air-fuel mixture quality control for the lower injection times, thus increasing both fuel consumption and pollutant emissions. Despite the extensive literature about the operation and modelling of fuel injectors, there are …
Performance and combustion analysis of a supercharged double-fuel spark ignition engine
2019
In 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 effici…