Phenomenological Analysis of the Combustion of Gaseous Fuels to Measure the Fuel's Energy Quality and Availability to Produce Work in Si Engines, Part 2

2021 ◽  
Author(s):  
Juan Pablo Gomez Montoya ◽  
Andres Amell
Keyword(s):  
Compression Ratio ◽  
Laminar Flame ◽  
Flame Temperature ◽  
Electrical Energy ◽  
Gaseous Fuels ◽  
Diesel Fuels ◽  
Fuel Blends ◽  
Si Engines ◽  
High Turbulence ◽  
Methane Number

Abstract A novel methodology is proposed to evaluate fuel´s performance in spark ignition (SI) engines based on the fuel´s energy quality and availability to produce work. Experiments used a diesel engine with a high compression ratio (CR), modified by SI operation, and using interchangeable pistons. The interchangeable pistons allowed for the generation of varying degrees of turbulence during combustion, ranging from middle to high turbulence. The generating efficiency (ηq), and the maximum electrical energy (EEmax) were measured at the knocking threshold (KT). A cooperative fuel research (CFR) engine operating at the KT was also used to measure the methane number (MN), and critical compression ratio (CCR) for gaseous fuels. Fuels with MNs ranging from 37 to 140 were used: two biogases, methane, propane, and five fuel blends of biogas with methane/propane and hydrogen. Results from both engines are linked at the KT to determine correlations between fuel´s physicochemical properties and the knocking phenomenon. Certain correlations between knocking and fuel properties were experimentally determined: energy density (ED), laminar flame speed (SL), adiabatic flame temperature (Tad), heat capacity ratio (γ), and hydrogen/carbon (H/C) ratio. Based on the results, a mathematical methodology for estimating EEmax and ηq in terms of ED, SL, Tad, γ, H/C, and MN is presented. These equations were derived from the classical maximum thermal efficiency for SI engines given by the Otto cycle efficiency (ηOtto). Fuels with MN > 97 got higher EEmax, and ηq than propane, and diesel fuels.

Phenomenological Analysis of Combustion of Gaseous Fuels to Measure the Energy Quality and the Capacity to Produce Work in Spark Ignition Engines.

2020 ◽  
Author(s):  
Juan Pablo GOMEZ MONTOYA ◽  
Andres Amell
Keyword(s):  
Energy Density ◽  
Compression Ratio ◽  
Laminar Flame ◽  
Flame Temperature ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Adiabatic Flame Temperature ◽  
Gaseous Fuels ◽  
Combustion Properties ◽  
Si Engines

Abstract Combustion at the knocking threshold was tested using fuels with different methane numbers (MN) in a modified SI engine, with high compression ratio (CR) and high turbulence intensity to the combustion process; fuels were tested in a CFR engine to measure MN and critical compression ratio (CCR); in both engines test were performed just into the knocking threshold. Is proposed that MN to gaseous fuels will be considered in similar way than octane number (ON) to liquid fuels to indicate the energy quality and the capacity to produce work. According to the tests biogas has better combustion properties than the others fuels; biogas is the fuel with the highest knocking resistance; biogas is the fuel with the best energy quality measured with the energy density and combustion temperature; biogas has the highest capacity to produce work in SI engines, because its high MN, low energy density, low laminar flame speed and low adiabatic flame temperature. Fuel combustion phenomenological characteristics were compared using CCR versus: output power, generating efficiency, energy density, laminar flame speed and adiabatic flame temperature. It is suggested that the strategies to suppress knocking are the key to improve the performance of SI engines; knocking is the engine limit to power generation in SI engines and quantum thermal efficiency is defined at this condition.

An Alternative Calculation for Methane Number for Lean Burn Spark Ignited Engines Operating on Low Energy Content Gaseous Fuels

2017 ◽  
Author(s):  
Hui Xu ◽  
Axel O. zur Loye ◽  
Robin J. Bremmer
Keyword(s):  
Laminar Flame ◽  
Energy Content ◽  
Flame Temperature ◽  
Relative Difference ◽  
Low Energy ◽  
Si Engine ◽  
Lean Burn ◽  
Combustion Properties ◽  
Si Engines ◽  
Methane Number

Low energy content fuels such as landfill gas can contain a significant amount of diluents like CO2. Critical fuel properties including the lower heating value (LHV) and an anti-knock property, in particular the methane number (MN), should be considered to optimize operation of a spark ignited (SI) engine. The MN has been shown to be a good indicator of knock propensity in stoichiometric SI engines. However, this approach is not always as effective for lean burn SI engines. Two fuels with the same methane number, but with different compositions, may exhibit a different propensity to knocking in an advanced lean burn SI engine. This effect is particularly pronounced when comparing fuels that have different amounts of diluents. In this paper we propose an alternative calculation of the MN, which compensates for the effect of diluents. More specifically, we define a lean burn methane index (LBMI), which is calculated without the diluents. This approach was validated using chemical kinetics modeling. The analysis considered fundamental combustion properties, including laminar flame speed (LFS), adiabatic flame temperature (AFT) and the autoignition interval (AI). For this study, a baseline fuel was selected based on a typical US pipeline natural gas composition. CO2 was then added as a diluent to the baseline fuel to simulate low energy density fuel compositions. Lambda values were selected to provide the same AFT or engine-out NOx. Low energy content fuel were found to have very similar AI values (less than 2% relative difference) to the baseline fuel at the target lambda values. A key result of this study is that the LBMI is a much better predictor of knock propensity than the traditional MN, when comparing fuels with widely varying levels of dilution for advanced lean burn SI engines.

Knock Rating of Gaseous Fuels

2003 ◽  
Vol 125 (2) ◽  
pp. 500-504 ◽  
Author(s):  
A. A. Attar ◽  
G. A. Karim
Keyword(s):  
Binary Mixtures ◽  
Compression Ratio ◽  
Equivalence Ratio ◽  
Spark Ignition ◽  
The Other ◽  
Mixture Composition ◽  
Spark Ignition Engines ◽  
Gaseous Fuels ◽  
Spark Timing ◽  
Methane Number

The knock tendency in spark ignition engines of binary mixtures of hydrogen, ethane, propane and n-butane is examined in a CFR engine for a range of mixture composition, compression ratio, spark timing, and equivalence ratio. It is shown that changes in the knock characteristics of binary mixtures of hydrogen with methane are sufficiently different from those of the binary mixtures of the other gaseous fuels with methane that renders the use of the methane number of limited utility. However, binary mixtures of n-butane with methane may offer a better alternative. Small changes in the concentration of butane produce almost linearly significant changes in both the values of the knock limited compression ratio for fixed spark timing and the knock limited spark timing for a fixed compression ratio.

scholarly journals The possibilities of using DME (BioDME), as an additive to conventional gaseous fuels in SI engine

2017 ◽  
Vol 171 (4) ◽  
pp. 150-155
Author(s):  
Marek FLEKIEWICZ ◽  
Grzegorz KUBICA ◽  
Paweł MARZEC
Keyword(s):  
Mass Fraction ◽  
Negative Impact ◽  
Chassis Dynamometer ◽  
Si Engine ◽  
Engine Load ◽  
Gaseous Fuels ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Si Engines ◽  
And Storage

The results of SI engine fueled with blends of LPG and DME are presented in the paper. The range studies submitted includes measurements at varying engine loads, at selected values of speed. The research was conducted on a chassis dynamometer, specifying the engine load by the degree of throttle opening. Value of the mass fraction of DME in the blend with LPG was determined based on previous analyzes. The selected fuel blends containing from 7 to 17% DME (mass fraction). During the study was also performed a series of comparative measurements with pure LPG. Analyses show that of DME can be used as a partial substitute for LPG in SI engines. Its presence does not a negative impact on performance and emissions of the engine. The obtained results indicate that the amount of addition of DME should be varied depending on the engine load. Moreover, the use of this fuel does not require changes to the design fueling system and storage of LPG.

A Real-Time Method for Determining the Composition and Heating Value of Opportunity Fuel Blends

2012 ◽  
Author(s):  
Vilas Jangale ◽  
Alexei Saveliev ◽  
Serguei Zelepouga ◽  
Vitaly Gnatenko ◽  
John Pratapas
Keyword(s):  
Real Time ◽  
Laminar Flame ◽  
Energy Content ◽  
The United States ◽  
Least Squares Regression ◽  
Heating Value ◽  
Regression Methods ◽  
Fuel Blends ◽  
Pyrolysis Of Biomass ◽  
Methane Number

Engine manufacturers and researchers in the United States are finding growing interest among customers in the use of opportunity fuels such as syngas from the gasification and pyrolysis of biomass and biogas from anaerobic digestion of biomass. Once adequately cleaned, the most challenging issue in utilizing these opportunity fuels in engines is that their compositions can vary from site to site and with time depending on feedstock and process parameters. At present, there are no identified methods that can measure the composition and heating value in real-time. Key fuel properties of interest to the engine designer/researcher such as heating value, laminar flame speed, stoichiometric air to fuel ratio and Methane Number can then be determined. This paper reports on research aimed at developing a real-time method for determining the composition of a variety of opportunity fuels and blends with natural gas. Interfering signals from multiple measurement sources are processed collectively using multivariate regression methods, such as, the principal components regression and partial least squares regression to predict the composition and energy content of the fuel blends. The accuracy of the method is comparable to gas chromatography.

Engine Capability Prediction for SI Engine Fueled With Syngas

2015 ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Solid Waste ◽  
Laminar Flame ◽  
Combustion Engine ◽  
Flame Temperature ◽  
Engine Performance ◽  
Nox Emissions ◽  
Lean Burn ◽  
Gaseous Fuels ◽  
Combustion Duration

There are increasing interests in converting solid waste or lignocellulosic biomass into gaseous fuels and using reciprocating internal combustion engine to generate electricity. A widely used technique is gasification. Gasification is a process where the solid fuel and air are introduced to a partial oxidation environment, and generate combustible gaseous called synthesis gas or syngas. Converting solid waste into gaseous fuel can reduce landfill and create income for process owners. However it can be very challenging to use syngas on a gaseous fueled spark ignited engine, such as a natural gas (NG) engine. NG engines are typically developed with pipeline quality natural gas (PQNG). NG engines can operate at lean burn spark ignited (LBSI), or stoichiometric with EGR spark ignited (SESI) conditions. This work discusses the LBSI engine condition. NG engines can perform very differently when fueled with nonstandard gaseous fuels such as syngas without appropriate tuning. It is necessary to evaluate engine performance in terms of combustion duration, relative knock propensity and NOx emissions for such applications. Due to constraints in time and resources it is often not feasible to test such fuel blends in the laboratory. An analytical method is needed to predict engine performance in a timely manner. This study investigated the possibility of using syngas on a spark ignited engine developed with PQNG. Engine performance was predicted using in house developed models and PQNG as the reference fuel. Laminar flame speed (LFS), adiabatic flame temperature (AFT) and Autoignition interval (AI) are used to predict combustion duration, engine out NOx and engine knock propensity relative to NG at the target Lambda values. Single cylinder research engine data obtained under lean burn conditions fueled with PQNG was selected as the baseline. LFS, AFT and AI of syngas were computed at reference conditions. Lambda of operation was predicted for syngas to provide the same burn rate as NG at the reference Lambda value for NG. Analysis shows that, using syngas at the selected Lambda, the engine can have less engine out NOx emissions and less knock propensity relative to NG at the same speed and load. Modifications to fuel system components may be required to avoid engine derate.

Characteristics of Auto-Ignition in Internal Combustion Engines Operated With Gaseous Fuels of Variable Methane Number

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
German Amador ◽  
Jorge Duarte Forero ◽  
Adriana Rincon ◽  
Armando Fontalvo ◽  
Antonio Bula ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Internal Combustion Engines ◽  
Coal Gasification ◽  
Error Function ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Combustion Engines ◽  
Gaseous Fuels ◽  
Auto Ignition ◽  
Methane Number

This paper explores the feasibility of using Syngas with low methane number as fuel for commercial turbocharged internal combustion engines. The effect of methane number (MN), compression ratio (CR), and intake pressure on auto-ignition tendency in spark ignition internal combustion engines was determined. A nondimensional model of the engine was performed by using kinetics mechanisms of 98 chemical species in order to simulate the combustion of the gaseous fuels produced from different thermochemical processes. An error function, which combines the Livengood–Wu with ignition delay time correlation, to estimate the knock occurrence crank angle (KOCA) was proposed. The results showed that the KOCA decreases significantly as the MN increases. Results also showed that Syngas obtained from coal gasification is not a suitable fuel for engines because auto-ignition takes place near the beginning of the combustion phase, but it could be used in internal combustion engines with reactivity controlled compression ignition (RCCI) technology. For the case of high compression ratio and a high inlet pressure at the engine's manifold, fuels with high MN are suitable for the operating conditions proposed.

Measurements of Laminar Flame Speeds of Gas-to-Liquid-Diesel Fuel Blends

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Samahat Samim ◽  
Abdellatif M. Sadeq ◽  
Samer F. Ahmed
Keyword(s):  
Initial Temperature ◽  
Laminar Flame ◽  
Ambient Pressure ◽  
Direct Visualization ◽  
Diesel Fuels ◽  
Rich Mixture ◽  
Fuel Blends ◽  
Blended Fuel ◽  
Gas To Liquid ◽  
Rich Mixtures

This work investigates the laminar flame speed, SN, of gas-to-liquid (GTL) fuel and its 50–50% by volume blends with conventional diesel, in a cylindrical bomb capable of measuring SN at different initial temperatures and equivalence ratios at ambient pressure. SN was measured by analysing the pressure signals after combustion detected by a pressure transducer mounted on the bomb. Direct visualization has also been conducted to observe the ignition and flame propagation. It was found that pure GTL fuel has the highest SN near stoichiometric conditions, which is about 88.3 cm/s. However, at lean and rich mixtures, SN of GTL is slightly lower than that of the conventional diesel. The blended fuel has the lowest SN at lean and rich mixture conditions comparing with those of GTL and diesel fuels. Studying the effect of increasing the initial temperature on SN revealed that SN of the three tested fuels increases with the increase in the initial temperature almost linearly. However, the blended fuel has the lowest SN at the highest temperature, about 89.7 cm/s at 250 °C.

A Numerical Study on the Reactivity of Biogas/Reformed-Gas/Air and Methane/Reformed-Gas/Air Mixtures at Gas Turbine Relevant Conditions

2016 ◽  
Author(s):  
Pablo Diaz Gomez Maqueo ◽  
Philippe Versailles ◽  
Gilles Bourque ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Gas Turbine ◽  
Laminar Flame ◽  
Numerical Study ◽  
Flame Temperature ◽  
Flame Speed ◽  
Flame Stability ◽  
Laminar Flame Speed ◽  
Fuel Reforming ◽  
Numerical Work ◽  
Chemical Effects

This study investigates the increase in methane and biogas flame reactivity enabled by the addition of syngas produced through fuel reforming. To isolate thermodynamic and chemical effects on the reactivity of the mixture, the burner simulations are performed with a constant adiabatic flame temperature of 1800 K. Compositions and temperatures are calculated with the chemical equilibrium solver of CANTERA® and the reactivity of the mixture is quantified using the adiabatic, freely-propagating premixed flame, and perfectly-stirred reactors of the CHEMKIN-Pro® software package. The results show that the produced syngas has a content of up to 30 % H2 with a temperature up to 950 K. When added to the fuel, it increases the laminar flame speed while maintaining a burning temperature of 1800 K. Even when cooled to 300 K, the laminar flame speed increases up to 30 % from the baseline of pure biogas. Hence, a system can be developed that controls and improves biogas flame stability under low reactivity conditions by varying the fraction of added syngas to the mixture. This motivates future experimental work on reforming technologies coupled with gas turbine exhausts to validate this numerical work.

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