Methods for Specific Emission Evaluation in Spark Ignition Engines Based on Calculation Procedures of Air-Fuel Ratio: Development, Assessment, and Critical Comparison

2005 ◽  
Vol 127 (4) ◽  
pp. 869-882 ◽  
Author(s):  
Stefano d’Ambrosio ◽  
Ezio Spessa ◽  
Alberto Vassallo
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Specific Mass ◽  
Exhaust Gases ◽  
Fuel Ratio ◽  
Wide Range ◽  
Specific Emissions ◽  
Ic Engines ◽  
New Procedures

New computational procedures are proposed for evaluating the exhaust brake specific mass emissions of each pollutant species in internal combustion (IC) engines. The procedures start from the chemical reaction of fuel with combustion air and, based on the measured exhaust raw emissions THC, CH4,NOx, CO, O2,CO2, calculate the volume fractions of the compounds in the exhaust gases, including those that are not usually measured, such as water, nitrogen and hydrogen. The molecular mass of the exhaust gases is then evaluated and the brake specific emissions can be obtained if the exhaust flow rate and the engine power output are measured. The algorithm can also be applied to the evaluation of air-fuel ratio from measured raw volume emissions of IC engines. The new procedures take the effects of various fuel and combustion air compositions into account, with particular reference to different natural gas blends as well as to the presence of water vapor, CO2, Ar and He in the combustion air. In the paper, the algorithms are applied to the evaluation of air-fuel ratio and brake specific mass emissions in an automotive bi-fuel Spark Ignition (SI) engine with multipoint sequential port-fuel injection. The experimental tests were carried out in a wide range of steady-state operating conditions under both gasoline and compressed natural gas operations. The specific emissions calculated from the new procedures are compared to those evaluated by applying Society of Automotive Engineers (SAE) and International Standards Organization (ISO) recommended practices and the air-fuel ratio results are compared to those obtained either from directly measured air and fuel mass flow rates or from Universal Exhaust Gas Oxygen (UEGO) sensor data. The sensitivity of the procedure results to the main engine working parameters, the influence of environmental conditions (in particular the effect of air humidity on NOx formation) and the experimental uncertainties are also determined.

Methods for Specific Emission Evaluation in SI Engines Based on Calculation Procedures of Air-Fuel Ratio: Development, Assessment and Critical Comparison

2003 ◽  
Author(s):  
Stefano d’Ambrosio ◽  
Ezio Spessa ◽  
Alberto Vassallo
Keyword(s):  
Operating Conditions ◽  
Sensor Data ◽  
Injection System ◽  
Specific Mass ◽  
Nox Formation ◽  
Exhaust Gases ◽  
Wide Range ◽  
Specific Emissions ◽  
Ic Engines ◽  
Working Parameters

New computational procedures are proposed for evaluating the exhaust brake specific mass emissions of each pollutant species in IC engines. The procedures start from the chemical reaction of fuel with combustion air and, basing on the measured exhaust raw emissions THC, CH4, NOx, CO, O2, CO2, calculate the volume fractions of the compounds in the exhaust gases, including those that are not usually measured, such as water, nitrogen and hydrogen. The method also takes the effects of various fuel and combustion air compositions into account, with particular reference to different natural gas blends as well as to the presence of water vapor, CO2, Ar and He in the combustion air. The molecular mass of the exhaust gases is then evaluated and the brake specific emissions can be obtained if the exhaust flow rate and the engine power output are measured. The methods stem from the extension of the different procedures that are used in the literature to evaluate α from measured raw volume emissions of IC engines running on conventional fuels. In the present study, a new algorithm is developed so as to generalize and refine all the mentioned α evaluation procedures, keeping conventional and alternative fuel compositions into account. First, the algorithm is applied to the evaluation of α in an automotive bi-fuel SI engine running on gasoline and CNG under a wide range of operating conditions. The α evaluation tests were carried out with a carefully controlled multipoint sequential injection system for both gasoline and CNG fueling. The results are compared to those obtained from the directly measured air and fuel mass flow rates as well as from more conventional UEGO sensor data. The algorithm is then applied to the evaluation of the brake specific mass emission of each pollutant species under gasoline and CNG engine operations for different steady-state working conditions. The sensitivity of results to the main engine working parameters, the influence of environmental conditions (in particular the effect of air humidity on NOx formation) and the experimental uncertainties are determined. The specific emissions calculated from the proposed algorithm are finally compared to those obtained by applying SAE and ISO recommended practices.

Using Multi-Dimensional Combustion Simulations of a Natural Gas/Diesel Dual Fuel Engine to Investigate NOx Trends With Air-Fuel Ratio

2017 ◽  
Author(s):  
Andrew Hockett ◽  
Michael Flory ◽  
Joel Hiltner ◽  
Scott Fiveland
Keyword(s):  
Natural Gas ◽  
Oil And Gas ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Nox Emissions ◽  
Nox Formation ◽  
Jet Flame ◽  
Gas Drilling ◽  
Fuel Ratio ◽  
Wide Range

Natural gas/diesel dual fuel engines used in oil and gas drilling operations must be able to meet NOx emissions limits across a wide range of substitution percentage, which affects the air to natural gas ratio or gas lambda. In a dual fuel engine operating at high substitution, premixed, propagating natural gas flames occur and the NOx formed in such premixed flames is known to be a strong function of gas lambda. Consequently there is interest in understanding how NOx formation in a dual fuel engine is affected by gas lambda. However, NOx formation in a dual fuel engine is complicated by the interaction with the non-premixed diesel jet flame. As a result, previous studies have shown that enriching the air-fuel ratio can either increase or decrease NOx emissions depending on the operating conditions investigated. This study presents multi-dimensional combustion simulations of an air-fuel ratio sweep from gas lambda 2.0 to 1.5 at 80% substitution, which exhibited a minimum in NOx emissions at a natural gas lambda of 1.75. Images from the simulations are used to provide detailed explanations of the physical processes responsible for the minimum NOx trend with natural gas lambda.

Development of a natural gas spark ignition engine for optimum performance

1997 ◽  
Vol 211 (5) ◽  
pp. 361-378 ◽  
Author(s):  
A Das ◽  
H C Watson
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Limited Range ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Petrol Engine ◽  
Shape Modification ◽  
Will Emit ◽  
Brake Thermal Efficiency ◽  
Wide Range

A 4 litre displacement, six cylinder, fuel injected petrol engine was modified to natural gas (NG) fuelling. Experimental investigation was carried out with various mixture controls and compression ratios over a wide range of operating conditions. As a strategy for combustion chamber shape modification, the compression ratio was raised with simultaneous enhancement of in-cylinder turbulence through squish motion. A fast burning chamber for the combustion of lean mixtures of natural gas and air was developed. Brake thermal efficiency in excess of 40 per cent and brake torque in excess of the peak base torque with petrol were achieved. The research provides the foundation for the implementation of NG cars that will emit only about 65 per cent of the carbon dioxide (CO2) of their petrol engine counterparts, with the prospect of extending the limited range of NG cars by up to one-third and producing low hydrocarbon (HC) and nitrogen oxide (NOx) emissions.

A comparative study of the performance and exhaust emissions of a spark ignition engine fuelled by natural gas and gasoline

1997 ◽  
Vol 211 (1) ◽  
pp. 39-47 ◽  
Author(s):  
R. L. Evans ◽  
J Blaszczyk
Keyword(s):  
Natural Gas ◽  
Engine Performance ◽  
Detailed Comparison ◽  
Exhaust Emissions ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Spark Ignition Engines ◽  
Wide Range ◽  
Lean Limit

The purpose of this study was to obtain a detailed comparison of engine performance and exhaust emissions from natural gas and gasoline fuelled spark ignition engines. Each fuel was tested at both wide-open throttle and two part-load operating conditions over a wide range of air—fuel ratios. The results show that the power output of the engine at a given throttle position was reduced by about 12 per cent when fuelled by natural gas due to displacement of air by the gas. The emission levels for natural gas were lower by from 5 to 50 per cent, depending on the pollutant, compared to gasoline. On an energy basis, both fuels exhibited nearly equal thermal efficiency, except that at very lean air—fuel ratios natural gas showed increased efficiency due to an extension of the lean limit of combustion.

Prediction of gaseous pollutant emissions from a spark-ignition direct-injection engine with gas-exchange simulation

2021 ◽  
pp. 146808742110050
Author(s):  
Stefania Esposito ◽  
Lutz Diekhoff ◽  
Stefan Pischinger
Keyword(s):  
Gas Exchange ◽  
Combustion Chamber ◽  
Direct Injection ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Operating Parameters ◽  
Gaseous Pollutant ◽  
Fuel Ratio ◽  
No Emissions

With the further tightening of emission regulations and the introduction of real driving emission tests (RDE), the simulative prediction of emissions is becoming increasingly important for the development of future low-emission internal combustion engines. In this context, gas-exchange simulation can be used as a powerful tool for the evaluation of new design concepts. However, the simplified description of the combustion chamber can make the prediction of complex in-cylinder phenomena like emission formation quite challenging. The present work focuses on the prediction of gaseous pollutants from a spark-ignition (SI) direct injection (DI) engine with 1D–0D gas-exchange simulations. The accuracy of the simulative prediction regarding gaseous pollutant emissions is assessed based on the comparison with measurement data obtained with a research single cylinder engine (SCE). Multiple variations of engine operating parameters – for example, load, speed, air-to-fuel ratio, valve timing – are taken into account to verify the predictivity of the simulation toward changing engine operating conditions. Regarding the unburned hydrocarbon (HC) emissions, phenomenological models are used to estimate the contribution of the piston top-land crevice as well as flame wall-quenching and oil-film fuel adsorption-desorption mechanisms. Regarding CO and NO emissions, multiple approaches to describe the burned zone kinetics in combination with a two-zone 0D combustion chamber model are evaluated. In particular, calculations with reduced reaction kinetics are compared with simplified kinetic descriptions. At engine warm operation, the HC models show an accuracy mainly within 20%. The predictions for the NO emissions follow the trend of the measurements with changing engine operating parameters and all modeled results are mainly within ±20%. Regarding CO emissions, the simplified kinetic models are not capable to predict CO at stoichiometric conditions with errors below 30%. With the usage of a reduced kinetic mechanism, a better prediction capability of CO at stoichiometric air-to-fuel ratio could be achieved.

Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jinlong Liu ◽  
Hemanth Kumar Bommisetty ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Cycle Variation ◽  
Spark Timing ◽  
Ci Engines

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

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.

The effect of air/fuel ratio on the CO and NOx emissions for a twin-spark motorcycle gasoline engine under wide range of operating conditions

Energy ◽  
2019 ◽  
Vol 169 ◽  
pp. 1202-1213 ◽  
Author(s):  
Banglin Deng ◽  
Qing Li ◽  
Yangyang Chen ◽  
Meng Li ◽  
Aodong Liu ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Ratio ◽  
Wide Range

Lean-Burn Characteristics of a Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition

2018 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Fuel Injector ◽  
Heavy Duty ◽  
Lean Burn ◽  
Spark Timing ◽  
Heavy Duty Diesel

Increased utilization of natural-gas (NG) in the transportation sector can decrease the use of petroleum-based fuels and reduce greenhouse-gas emissions. Heavy-duty diesel engines retrofitted to NG spark ignition (SI) can achieve higher efficiencies and low NOx, CO, and HC emissions when operated under lean-burn conditions. To investigate the SI lean-burn combustion phenomena in a bowl-in-piston combustion chamber, a conventional heavy-duty direct-injection CI engine was converted to SI operation by replacing the fuel injector with a spark plug and by fumigating NG in the intake manifold. Steady-state engine experiments and numerical simulations were performed at several operating conditions that changed spark timing, engine speed, and mixture equivalence ratio. Results suggested a two-zone NG combustion inside the diesel-like combustion chamber. More frequent and significant late burn (including double-peak heat release rate) was observed for advanced spark timing. This was due to the chamber geometry affecting the local flame speed, which resulted in a faster and thicker flame in the bowl but a slower and thinner flame in the squish volume. Good combustion stability (COVIMEP < 3 %), moderate rate of pressure rise, and lack of knocking showed promise for heavy-duty CI engines converted to NG SI operation.

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