The impact of air-fuel mixture composition on SI engine performance during natural gas and producer gas combustion

Abstract This paper addresses the impact of natural gas composition on both the operability and emissions of lean premixed gas turbine combustion system. This is an issue of growing interest due to the challenge for gas turbine manufacturers in developing fuel-flexible combustors capable of operating with variable fuel gases while producing very low emissions at the same time. Natural gas contains primarily methane (CH4) but also notable quantities of higher order hydrocarbons such as ethane (C2H6) can also be present. A deep understanding of natural gas combustion is important to obtain the highest combustion efficiency with minimal environmental impact. For this purpose, Large Eddy Simulations of an annular combustor sector equipped with a partially premixed burner are carried out for two different natural gas compositions with and without including the effect of flame strain rate and heat loss resulting in a more adequate description of flame shape, thermal field, and extinction phenomena. Promising results, in terms of NOx, compared against available experimental data, are obtained including these effects on the flame brush modeling, enhancing the fuel-dependency under nonadiabatic condition.

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Experimental Investigation of the Performance of a Micro Gas Turbine Fueled With Mixtures of Natural Gas and Biogas

Volume 6A: Energy ◽

10.1115/imece2013-64299 ◽

2013 ◽

Cited By ~ 4

Author(s):

Homam Nikpey ◽

Mohsen Assadi ◽

Peter Breuhaus

Keyword(s):

Natural Gas ◽

Gas Turbine ◽

Co2 Emissions ◽

Fuel Mixture ◽

Combined Heat And Power ◽

Test Rig ◽

Heating Value ◽

Micro Gas Turbine ◽

Fuel Mixtures ◽

The Impact

Previously published studies have addressed modifications to the engines when operating with biogas, i.e. a low heating value (LHV) fuel. This study focuses on mapping out the possible biogas share in a fuel mixture of biogas and natural gas in micro combined heat and power (CHP) installations without any engine modifications. This contributes to a reduction in CO2 emissions from existing CHP installations and makes it possible to avoid a costly upgrade of biogas to the natural gas quality as well as engine modifications. Moreover, this approach allows the use of natural gas as a “fallback” solution in the case of eventual variations of the biogas composition and or shortage of biogas, providing improved availability. In this study, the performance of a commercial 100kW micro gas turbine (MGT) is experimentally evaluated when fed by varying mixtures of natural gas and biogas. The MGT is equipped with additional instrumentation, and a gas mixing station is used to supply the demanded fuel mixtures from zero biogas to maximum possible level by diluting natural gas with CO2. A typical biogas composition with 0.6 CH4 and 0.4 CO2 (in mole fraction) was used as reference, and corresponding biogas content in the supplied mixtures was computed. The performance changes due to increased biogas share were studied and compared with the purely natural gas fired engine. This paper presents the test rig setup used for the experimental activities and reports results, demonstrating the impact of burning a mixture of biogas and natural gas on the performance of the MGT. Comparing with when only natural gas was fired in the engine, the electrical efficiency was almost unchanged and no significant changes in operating parameters were observed. It was also shown that burning a mixture of natural gas and biogas contributes to a significant reduction in CO2 emissions from the plant.

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HCCI Gas Engine: Evaluation of Engine Performance, Efficiency and Emissions - Comparing Producer Gas and Natural Gas

10.4271/2011-01-1196 ◽

2011 ◽

Cited By ~ 5

Author(s):

Matthias Achilles ◽

Jonas Ulfvik ◽

Martin Tuner ◽

Bengt Johansson ◽

Jesper Ahrenfeldt ◽

...

Keyword(s):

Natural Gas ◽

Engine Performance ◽

Producer Gas ◽

Gas Engine

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Homogeneous Charge Compression Ignition Operation With Natural Gas: Fuel Composition Implications

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1581895 ◽

2003 ◽

Vol 125 (3) ◽

pp. 837-844 ◽

Cited By ~ 13

Author(s):

J. Hiltner ◽

R. Agama ◽

F. Mauss ◽

B. Johansson ◽

M. Christensen

Keyword(s):

Natural Gas ◽

Compression Ratio ◽

Homogeneous Charge Compression Ignition ◽

Engine Performance ◽

Fuel Composition ◽

Primary Concern ◽

Compression Ignition ◽

Engine Operation ◽

The Impact ◽

Homogeneous Charge

Homogeneous charge compression ignition (HCCI) is a potentially attractive operating mode for stationary natural gas engines. Increasing demand for efficient, clean burning engines for electrical power generation provides an opportunity to utilize HCCI combustion if several inherent difficulties can be overcome. Fuel composition, particularly the higher hydrocarbon content (ethane, propane, and butane) of the fuel is of primary concern. Fuel composition influences HCCI operation both in terms of design, via compression ratio and initial charge temperature, and in terms of engine control. It has been demonstrated that greater concentrations of higher hydrocarbons tend to lower the ignition temperature of the mixture significantly. The purpose of this paper is to demonstrate, through simulation, the effect of fuel composition on combustion in HCCI engines. Engine performance over a range of fuels from pure methane to more typical natural gas blends is investigated. This includes both the impact of various fuels and the sensitivity of engine operation for any given fuel. Results are presented at a fixed equivalence ratio, compression ratio, and engine speed to isolate the effect of fuel composition. Conclusions are drawn as to how the difficulties arising from gas composition variations may affect the future marketability of these engines.

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Producer gas combustion in the internal combustion engine

Combustion Engines ◽

10.19206/ce-117143 ◽

2010 ◽

Vol 141 (2) ◽

pp. 27-32

Author(s):

Karol CUPIAŁ ◽

Stanisław SZWAJA

Keyword(s):

Combustion Engine ◽

Dual Fuel ◽

Producer Gas ◽

Compression Ignition ◽

Combustion Instabilities ◽

Si Engine ◽

Gas Combustion ◽

Ci Engine ◽

Combustion Knock ◽

High Work

The investigation presented in the paper concerns producer gas combustion in both the spark ignited (SI) and the dual-fuel compression ignition (CI) engine with a diesel pilot of 15% with respect to its nominal dose, at compression ratio (CR) of 8, 12 (for the SI engine) and 17 (for the CI engine). The research tasks were mainly focused on combustion instabilities such as engine work cycles unrepeatability and combustion knock onset. The investigation included also combustion of such gases as methane, biogas and hydrogen, which were taken for making comparison between them and the producer gas. The conducted analysis shows that producer gas is resistant to generate knock even if it contains significant hydrogen content of 16%. However, high work cycles unrepeatability is observed when producer gas is combusted in the SI engine. Obtained results led to conclusion that producer gas can be burnt more efficiently in the dual-fuel CI engine than the SI one. Neither misfiring nor knocking have occurred during its combustion in that engine.

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Effect of Octane Number on Performance and Exhaust Emissions of an SI Engine

Engineering and Technology Journal ◽

10.30684/etj.v38i4a.263 ◽

2020 ◽

Vol 38 (4A) ◽

pp. 574-585

Author(s):

Noor H. Athafah ◽

Adei M. Salih

Keyword(s):

Octane Number ◽

Engine Performance ◽

Exhaust Emissions ◽

Brake Specific Fuel Consumption ◽

Spark Ignition Engines ◽

Si Engine ◽

Brake Thermal Efficiency ◽

The World ◽

The Impact ◽

Stroke Engine

Spark ignition engines are very popular engines that they are running millions of vehicles all over the world. This engine emits many harmful pollutants, such as CO, UHC, and NOX. In this paper, the impact of gasoline octane number on the engine performance and exhaust emissions was studied. In the tests, four-cylinder, four-stroke engine, and two variable octane numbers (RON83 and 94.5) were used. The engine was run at different engine speeds and loads. The results from the experimental study indicated that the brake specific fuel consumption (bsfc) of RON94.5 was higher than RON83 by 13.93%, while the brake thermal efficiency (ƞbth) was higher for RON83 compared to RON94.5 by 12.31%. The emitted emissions for the tested fuels were high when RON83 was used compared to RON94.5 by 65.52%, 49.11%, and 57.33% for CO, UHC, and NOX, respectively.

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Numerical Simulation of a Naturally Aspirated Natural Gas/Diesel RCCI Engine for Investigating the Effects of Injection Timing on the Combustion and Emissions

Journal of Energy Resources Technology ◽

10.1115/1.4046470 ◽

2020 ◽

Vol 142 (7) ◽

Author(s):

Amir Hossein Fakhari ◽

Rouzbeh Shafaghat ◽

Omid Jahanian

Keyword(s):

Natural Gas ◽

Fuel Mixture ◽

Injection Timing ◽

Reactivity Controlled Compression Ignition ◽

Piston Bowl ◽

Start Of Injection ◽

Performance And Emissions ◽

The Difference ◽

The Impact ◽

Co Emission

Abstract The start of injection (SOI) timing has a significant effect on increasing the homogeneity of the air–fuel mixture in an reactivity controlled compression ignition (RCCI) engine. In this paper, the impact of the SOI timing from 14 deg to 74 deg before top dead center (bTDC) and different inlet valve closing (IVC) temperatures on natural gas/diesel RCCI performance and emissions have been studied. Also, the simulations carried out by avl fire which is coupled with chemical kinetics. The results showed that in the SOIs of 14 deg, 24 deg, and 34 deg bTDC, the fuel is sprayed into the piston bowl; however, in the SOI of 44 deg bTDC, the fuel collides the bowl rim edge, because of the downward movement of the piston. With the advancement of diesel SOI timing from 14 deg to 74 deg bTDC, two different combustion trends can be observed. However, this advancement leads to a lower CO emission, but it raises the CO2 emission level. Although the pressure is a primary parameter for NOx emission, the difference between the trends of NOx and pressure plots indicates that different factors affect the NOx production and also increase the IVC temperature, and raises the in-cylinder pressure, heat release rate, NOx and CO2 emissions, while it reduces the CO emission.

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Ignition in Pilot-Ignited Natural Gas Low Temperature Combustion: Multi-Zone Modeling and Experimental Results

ASME 2009 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2009-76145 ◽

2009 ◽

Cited By ~ 4

Author(s):

Sundar Rajan Krishnan ◽

Kalyan Kumar Srinivasan ◽

Kenneth Clark Midkiff

Keyword(s):

Natural Gas ◽

Shell Model ◽

Ignition Delay ◽

Combustion Engine ◽

Engine Performance ◽

Intake Manifold ◽

Model Parameters ◽

Injection Timing ◽

Oxides Of Nitrogen ◽

Gas Combustion

In previous research conducted by the authors, the Advanced Low Pilot-Ignited Natural Gas (ALPING) combustion employing early injection of small (pilot) diesel sprays to ignite premixed natural gas-air mixtures was demonstrated to yield very low oxides of nitrogen (NOx) emissions and fuel conversion efficiencies comparable to conventional diesel and dual fuel engines. In addition, it was observed that ignition of the diesel-air mixture in ALPING combustion had a profound influence on the ensuing natural gas combustion, engine performance and emissions. This paper discusses experimental and predicted ignition behavior for ALPING combustion in a single-cylinder engine at a medium load (BMEP = 6 bar), engine speed of 1700 rpm, and intake manifold temperature (Tin) of 75°C. Two ignition models were used to simulate diesel ignition under ALPING conditions: (a) Arrhenius-type ignition models, and (b) the Shell autoignition model. To the authors’ knowledge, the Shell model has previously not been implemented in a multi-zone phenomenological combustion simulation to simulate diesel ignition. The effects of pilot injection timing and Tin on ignition processes were analyzed from measured and predicted ignition delay trends. Experimental ignition delays showed a nonlinear trend (increasing from 11 to 51.5 degrees) in the 20°–60° BTDC injection timing range. Arrhenius-type ignition models were found to be inadequate and only yielded linear trends over the injection timing range. Even the inclusion of an equivalence ratio term in Arrhenius-type models did not render them satisfactory for the purpose of modeling ALPING ignition. The Shell model, on the other hand, predicted ignition better over the entire range of injection timings compared to the Arrhenius-type ignition delay models and also captured ignition delay trends at Tin = 95°C and Tin = 105°C. Parametric studies of the Shell model showed that the parameter Ap3, which affects chain propagation reactions, was important under medium load ALPING conditions. With all other model parameters remaining at their original values and only Ap3 modified to 8 × 1011 (from its original value of 1 × 1013), the Shell model predictions closely matched experimental ignition delay trends at different injection timings and Tin.

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