Effect of relative humidity on water injection technique in downsized spark ignition engines

2020 ◽  
pp. 146808742094085
Author(s):  
Jayesh Khatri ◽  
Nikhil Sharma ◽  
Petter Dahlander ◽  
Lucien Koopmans
Keyword(s):  
Relative Humidity ◽  
Water Injection ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Injection Technique ◽  
Injection Timing ◽  
Particulate Emissions ◽  
Spark Ignition Engines ◽  
General Applicability ◽  
Major Barrier

Combustion knock is a major barrier to achieving high thermal efficiency in spark ignition engines. Water injection was recently identified as a potential way of overcoming this barrier. To evaluate its general applicability, experiments were performed on a downsized three-cylinder spark ignition engine, varying the humidity of the intake air, the water injection timing, and the engine speed. The minimum quantity of injected water required to maintain a given load (and thus level of engine performance) was determined under each set of tested conditions. The knock-suppressing effects of water injection were found to be related to changes in the fuel–air mixture’s specific heat ratio (kappa) rather than evaporative cooling, and to therefore depend on the total quantity of water in the cylinder rather than the relative humidity per se. The total quantity of water in the cylinder was also shown to be a key determinant of advancement in combustion phasing and particulate emissions under various conditions.

Thermal efficiency improvement of super-lean burn spark ignition engine by stratified water insulation on piston top surface

2020 ◽  
pp. 146808742090816 ◽  
Author(s):  
Tsuyoshi Nagasawa ◽  
Yuichi Okura ◽  
Ryota Yamada ◽  
Susumu Sato ◽  
Hidenori Kosaka ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Thermal Stratification ◽  
Water Injection ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Injection Timing ◽  
Engine Test ◽  
Ignition Timing ◽  
Lean Burn ◽  
Compression Stroke

In order to improve thermal efficiency of spark ignition engine under super-lean burn conditions (excess air ratio [Formula: see text]), thermal stratification technique by in-cylinder water injection toward piston surface (stratified water insulated combustion architecture), in which low temperature water vapor layer is formed on the surface, is proposed. From the water spray visualization using the optically accessible engine, injected water is distributed near the piston top surface at ignition timing and thermal stratification can be achieved in the case that water injection timing (SOIw) is set at earlier stage of a compression stroke. In addition, heat flux on the piston surface measured at the same time is reduced by water injection. The 0.5-L single-cylinder engine test at λ = 2.0 at a constant ignition timing also shows that water injection at earlier stage of a compression stroke makes it possible to mitigate knock without significant increase in combustion instability. On the other hand, part of water is distributed near the spark plug at ignition timing with the water injection at SOIw = −60 °ATDC, resulting in unstable combustion. In addition, the engine test at λ = 2.0 and water/fuel ratio(W/F) = 18% shows that knock mitigation by water injection enables spark advance and following combustion enhancement. As a result, combustion period becomes short and cooling loss decreases, followed by the 1.0-pt improvement of gross indicated thermal efficiency. Moreover, the engine can be operated at minimum spark advance for best torque by increasing W/F up to 35%. Finally, stratified water insulated combustion architecture concept is applied at λ = 1.9 with a higher compression ratio of 17, showing that water injection at SOIw = −120 °ATDC and W/F = 50% enables minimum spark advance for best torque operation, and remarkably high gross indicated that thermal efficiency of 52.63% can be achieved with a sufficiently low knock level and coefficient of variation of indicated mean effective pressure.

scholarly journals Emission Experiment of Intake air Humidification of a Port Fuel Injected Spark Ignition engine

2019 ◽  
Vol 8 (6S4) ◽  
pp. 61-65
Keyword(s):  
Relative Humidity ◽  
Experimental Analysis ◽  
Fuel Injection ◽  
Water Injection ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Air Humidity ◽  
Port Fuel Injection ◽  
Test Engine ◽  
Humidified Air

In this study, experimental analysis was carried out to investigate the effect of humidified air induction on emissions of a single cylinder, four stroke, air cooled, Royal Enfield Bullet engine 350cc, with modifications made to assist port fuel injection. Tests have been performed on test engine fuelled with gasoline over a range of engine loads and at rated speed for 75 % and 95 % relative humidity with water injection. The outcomes of the experimental analysis reveal that increasing the intake air humidity from 75 % to 95 % decreased the exhaust emissions of NOx, CO, HC and CO2 at 95% rated load of the engine without much or less impact on the thermal brake efficiency.

scholarly journals Ethanol/Gasoline Blends as Alternative Fuel in Last Generation Spark-Ignition Engines: A Review on CO and HC Engine Out Emissions

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4034
Author(s):  
Paolo Iodice ◽  
Massimo Cardone
Keyword(s):  
Physicochemical Properties ◽  
Alternative Fuels ◽  
Experimental Studies ◽  
Alternative Fuel ◽  
Exhaust Emissions ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Spark Ignition Engines ◽  
The Impact

Among the alternative fuels existing for spark-ignition engines, ethanol is considered worldwide as an important renewable fuel when mixed with pure gasoline because of its favorable physicochemical properties. An in-depth and updated investigation on the issue of CO and HC engine out emissions related to use of ethanol/gasoline fuels in spark-ignition engines is therefore necessary. Starting from our experimental studies on engine out emissions of a last generation spark-ignition engine fueled with ethanol/gasoline fuels, the aim of this new investigation is to offer a complete literature review on the present state of ethanol combustion in last generation spark-ignition engines under real working conditions to clarify the possible change in CO and HC emissions. In the first section of this paper, a comparison between physicochemical properties of ethanol and gasoline is examined to assess the practicability of using ethanol as an alternative fuel for spark-ignition engines and to investigate the effect on engine out emissions and combustion efficiency. In the next section, this article focuses on the impact of ethanol/gasoline fuels on CO and HC formation. Many studies related to combustion characteristics and exhaust emissions in spark-ignition engines fueled with ethanol/gasoline fuels are thus discussed in detail. Most of these experimental investigations conclude that the addition of ethanol with gasoline fuel mixtures can really decrease the CO and HC exhaust emissions of last generation spark-ignition engines in several operating conditions.

Model of water injection process during closed phase of spark ignition engine

Energy ◽  
2019 ◽  
Vol 174 ◽  
pp. 1121-1132 ◽  
Author(s):  
Jair Leopoldo Loaiza Bernal ◽  
Janito Vaqueiro Ferreira
Keyword(s):  
Water Injection ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Injection Process

Laminar flame speed correlations for methane, ethane, propane and their mixtures, and natural gas and gasoline for spark-ignition engine simulations

2017 ◽  
Vol 18 (9) ◽  
pp. 951-970 ◽  
Author(s):  
Riccardo Amirante ◽  
Elia Distaso ◽  
Paolo Tamburrano ◽  
Rolf D Reitz
Keyword(s):  
Natural Gas ◽  
Laminar Flame ◽  
Spark Ignition ◽  
Flame Speed ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Computational Time ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Empirical Correlations

The laminar flame speed plays an important role in spark-ignition engines, as well as in many other combustion applications, such as in designing burners and predicting explosions. For this reason, it has been object of extensive research. Analytical correlations that allow it to be calculated have been developed and are used in engine simulations. They are usually preferred to detailed chemical kinetic models for saving computational time. Therefore, an accurate as possible formulation for such expressions is needed for successful simulations. However, many previous empirical correlations have been based on a limited set of experimental measurements, which have been often carried out over a limited range of operating conditions. Thus, it can result in low accuracy and usability. In this study, measurements of laminar flame speeds obtained by several workers are collected, compared and critically analyzed with the aim to develop more accurate empirical correlations for laminar flame speeds as a function of equivalence ratio and unburned mixture temperature and pressure over a wide range of operating conditions, namely [Formula: see text], [Formula: see text] and [Formula: see text]. The purpose is to provide simple and workable expressions for modeling the laminar flame speed of practical fuels used in spark-ignition engines. Pure compounds, such as methane and propane and binary mixtures of methane/ethane and methane/propane, as well as more complex fuels including natural gas and gasoline, are considered. A comparison with available empirical correlations in the literature is also provided.

scholarly journals Numerical Study of Engine Performance and Emissions for Port Injection of Ammonia into a Gasoline\Ethanol Dual-Fuel Spark Ignition Engine

2021 ◽  
Vol 11 (4) ◽  
pp. 1441
Author(s):  
Farhad Salek ◽  
Meisam Babaie ◽  
Amin Shakeri ◽  
Seyed Vahid Hosseini ◽  
Timothy Bodisco ◽  
...  
Keyword(s):  
Numerical Study ◽  
Combustion Process ◽  
Engine Performance ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Model ◽  
Dual Fuel ◽  
Spark Ignition Engines ◽  
Performance And Emissions ◽  
Hc Emissions

This study aims to investigate the effect of the port injection of ammonia on performance, knock and NOx emission across a range of engine speeds in a gasoline/ethanol dual-fuel engine. An experimentally validated numerical model of a naturally aspirated spark-ignition (SI) engine was developed in AVL BOOST for the purpose of this investigation. The vibe two zone combustion model, which is widely used for the mathematical modeling of spark-ignition engines is employed for the numerical analysis of the combustion process. A significant reduction of ~50% in NOx emissions was observed across the engine speed range. However, the port injection of ammonia imposed some negative impacts on engine equivalent BSFC, CO and HC emissions, increasing these parameters by 3%, 30% and 21%, respectively, at the 10% ammonia injection ratio. Additionally, the minimum octane number of primary fuel required to prevent knock was reduced by up to 3.6% by adding ammonia between 5 and 10%. All in all, the injection of ammonia inside a bio-fueled engine could make it robust and produce less NOx, while having some undesirable effects on BSFC, CO and HC emissions.

Experimental research on pumping losses and combustion performance in an unthrottled spark ignition engine

2018 ◽  
Vol 232 (7) ◽  
pp. 888-897 ◽  
Author(s):  
Tingting Sun ◽  
Yingjie Chang ◽  
Zongfa Xie ◽  
Kaiyu Zhang ◽  
Fei Chen ◽  
...  
Keyword(s):  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Lift ◽  
Combustion Characteristic ◽  
Spark Ignition Engines ◽  
Intake Valve ◽  
Valve System ◽  
Combustion Performance ◽  
Intake Swirl ◽  
Variable Valve

A novel fully hydraulic variable valve system is described in this paper, which achieves continuous variations in maximum valve lift, valve opening duration, and the timing of valve closing. The load of the unthrottled spark ignition engine with fully hydraulic variable valve system is controlled by using an early intake valve closing rather than the conventional throttle valve. The experiments were carried out on BJ486EQ spark ignition engine with fully hydraulic variable valve system. Pumping losses of the throttled and unthrottled spark ignition engines at low-to-medium loads are compared and the reason of it decreasing significantly in the unthrottled spark igntion engine is analyzed. The combustion characteristic parameters, such as cyclic variation, CA50, and heat release rate, were analyzed. The primary reasons for the lower combustion rate in the unthrottled spark ignition engines are discussed. In order to improve the evaporation of fuel and mix with air in an unthrottled spark ignition engine, the in-cylinder swirl is organized with a helical intake valve, which can generate a strong intake swirl at low intake valve lifts. The effects of the intake swirl on combustion performance are investigated. Compared with the throttled spark ignition engine, the brake specific fuel consumption of the improved unthrottled spark ignition engine is reduced by 4.1% to 11.2%.

A Laminar Burning Velocity Correlation for Hydrogen/Air Mixtures Valid at Spark-Ignition Engine Conditions

2003 ◽  
Author(s):  
Sebastian Verhelst ◽  
Roger Sierens
Keyword(s):  
Chemical Kinetics ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Spark Ignition ◽  
Flame Speed ◽  
Spark Ignition Engine ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Laminar Burning Velocity ◽  
Velocity Correlation

During the development of a quasi-dimensional simulation programme for the combustion of hydrogen in spark-ignition engines, the lack of a suitable laminar flame speed formula for hydrogen/air mixtures became apparent. A literature survey shows that none of the existing correlations covers the entire temperature, pressure and mixture composition range as encountered in spark-ignition engines. Moreover, there is ambiguity concerning the pressure dependence of the laminar burning velocity of hydrogen/air mixtures. Finally, no data exists on the influence of residual gases. This paper looks at several reaction mechanisms found in the literature for the kinetics of hydrogen/oxygen mixtures, after which one is selected that corresponds best with available experimental data. An extensive set of simulations with a one-dimensional chemical kinetics code is performed to calculate the laminar flame speed of hydrogen/air mixtures, in a wide range of mixture compositions and initial pressures and temperatures. The use of a chemical kinetics code permits the calculation of any desired set of conditions and enables the estimation of interactions, e.g. between pressure and temperature effects. Finally, a laminar burning velocity correlation is presented, valid for air-to-fuel equivalence ratios λ between 1 and 3 (fuel-to-air equivalence ratio 0.33 < φ < 1), initial pressures between 1 bar and 16 bar, initial temperatures between 300 K and 800 K and residual gas fractions up to 30 vol%. These conditions are sufficient to cover the entire operating range of hydrogen fuelled spark-ignition engines.

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