Syngas Laminar Flame Speed Computation and its Application to Gaseous Fueled Spark Ignited Engines Performance Prediction

2016 ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe ◽  
Robin J. Bremmer
Keyword(s):  
Natural Gas ◽  
Chemical Kinetics ◽  
Laminar Flame ◽  
Combustion Process ◽  
Engine Performance ◽  
Ambient Conditions ◽  
Piston Engine ◽  
Natural Gas Engines ◽  
Gaseous Fuels ◽  
Engine Combustion

Gaseous fueled spark ignited (SI) engines are often developed using pipeline quality natural gas as the fuel. However, natural gas engines are occasionally expected by customers to accommodate different fuel compositions when deployed in the field. Depending on the source or production processing of the fuel and the ambient conditions, gaseous fuels can have different levels of heavy hydrocarbons and/or significant levels of diluents when compared to natural gas. In recent years, there are increasing interests in using synthesis gas (syngas) from renewable sources in gaseous fueled spark ignition engines. This work investigated syngas compositions from different production processes and describes a methodology to predict engine performance using syngas. Syngas composition variations can provide different laminar flame speeds (LFS), which can result in changes in combustion burn rate, heat release rate and knock likelihood, if the engine combustion process is not optimized appropriately. It is challenging to obtain LFS data at the high pressure and temperature conditions that are characteristic of the piston engine combustion process. It has proven to be effective to employ a chemical kinetics solver using an appropriate chemical kinetics mechanism to obtain LFS values under piston engine combustion conditions. Alternative chemical kinetics mechanisms were investigated to identify one which best characterized combustion performance relative to detailed rig and engine measurements. With this appropriate chemical kinetics mechanism, LFS results are now used to guide natural gas engine combustion tuning when using syngas as a fuel. Engine performance is predicted in terms of NOx emissions and knock likelihood using the in-house developed methodology.

Effects of Natural Gas Compositions on Engine In-Cylinder Process

2015 ◽  
Vol 1092-1093 ◽  
pp. 498-503
Author(s):  
La Xiang ◽  
Yu Ding
Keyword(s):  
Natural Gas ◽  
Alternative Fuels ◽  
Combustion Process ◽  
Engine Performance ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Test Bed ◽  
Promising Alternative ◽  
Natural Gas Engines ◽  
Lower Maximum

Natural gas (NG) is one of the most promising alternative fuels of diesel and petrol because of its economics and environmental protection. Generally the NG engine share the similar structure profile with diesel or petrol engine but the combustion characteristics of NG is varied from the fuels, so the investigation of NG engine combustion process receive more attentions from the researchers. In this paper, a zero-dimensional model on the basis of Vibe function is built in the MATLAB/SIMULINK environment. The model provides the prediction of combustion process in natural gas engines, which has been verified by the experimental data in the NG test bed. Furthermore, the influence of NG composition on engine performance is investigated, in which the in-cylinder maximum pressure and temperature and mean indicated pressure are compared using different type NG. It is shown in the results that NG with higher composition of methane results in lower maximum temperature and mean indicated pressure as well as higher maximum pressure.

Research of Micro Free-Piston Engine Generator Performance

2011 ◽  
Vol 199-200 ◽  
pp. 198-202
Author(s):  
Qian Wang ◽  
Jin Hua Yang ◽  
Jin Bai ◽  
Jun Jie Chen ◽  
Ze Chen
Keyword(s):  
Dynamic Model ◽  
Combustion Process ◽  
Engine Performance ◽  
Combustion Efficiency ◽  
Operating Characteristics ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Engine Combustion ◽  
Ignition And Combustion

Based on the operating characteristics of a micro HCCI (Homogeneous Charge Compress Ignition) free-piston engine, a multidimensional model which coupled CFD code, chemical dynamic model and piston dynamic model has been established. Using this model, an ignition and combustion process of the micro engine is simulated, the cylinder pressure and temperature profiles are obtained, and the influence of leakage and heat lost on micro engine combustion process is analyzed. Meanwhile, working characteristics of micro engine generator are evaluated by employing the simulation result. Power, combustion efficiency, etc of the micro engine are obtained. Lastly, the micro engine working characteristics with different load, fuel and piston mass are compared and effects of those varying conditions on engine performance are investigated. Simulation result provides essential requirements for micro free-piston engine control and design.

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.

scholarly journals Effects of oil and water contamination on natural gas engine combustion processes

2017 ◽  
Author(s):  
Shyam Menon ◽  
Himakar Ganti ◽  
Kyle Evan Niemeyer ◽  
Christopher Hagen
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Combustion Process ◽  
Flame Speed ◽  
Slight Reduction ◽  
Laminar Flame Speed ◽  
Autoignition Temperature ◽  
Engine Combustion ◽  
Combustion Processes

Abundant availability and potential for lower emissions are drivers for increased utilization of natural gas in automotive engines for transportation applications. A novel bimodal engine has been developed that allows on-board refueling of natural gas by utilizing the engine as a compressor. Engine compression however, results in altering the initial state of the natural gas. Increase in temperature and addition of oil are two key effects attributed to the onboard refueling process. A secondary effect is the presence of water in the natural gas supply line. This study investigates the effect of upstream conditions of natural gas on three parameters: autoignition temperature, ignition delay, and laminar flame speed. These parameters play key roles in the engine combustion process. Parametric studies are conducted by varying the initial mixture temperature, water, and oil content in the fuel. The studies utilize numerical simulations conducted with detailed chemistry for natural gas with n-heptane used as a surrogate for oil. Water addition to natural gas at 1–5% by volume did not result in any major changes in the combustion processes, other than a slight reduction in laminar flame speeds. Oil addition of 1–5% by volume reduced autoignition temperature by 5–10% and ignition delay by 27–95% depending on the initial temperature. Sensitivity analysis showed that this was likely due to decrease in the sensitivity of two recombination reactions with oil addition. Evolution profiles of key radical species also showed increasing mole fraction of the hydroperoxy radical at lower temperature that likely aids in reducing the ignition delay. Oil addition resulted in a relatively small increase in the laminar flame speed of 1.7% along with an increase in the adiabatic flame temperature. These results help inform the combustion process and performance to be expected from the bimodal engine.

CO and H2O Time-Histories in Shock-Heated Blends of Methane and Ethane for Assessment of a Chemical Kinetics Model

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
O. Mathieu ◽  
C. R. Mulvihill ◽  
E. L. Petersen ◽  
Y. Zhang ◽  
H. J. Curran
Keyword(s):  
Chemical Kinetics ◽  
Laminar Flame ◽  
Combustion Process ◽  
Time History ◽  
Good Marker ◽  
Ignition Delay Times ◽  
Depletion Rate ◽  
Time Histories ◽  
Main Components ◽  
Detailed Kinetics

Methane and ethane are the two main components of natural gas and typically constitute more than 95% of it. In this study, a mixture of 90% CH4/10% C2H6 diluted in 99% Ar was studied at fuel lean (equiv. ratio = 0.5) conditions, for pressures around 1, 4, and 10 atm. Using laser absorption diagnostics, the time histories of CO and H2O were recorded between 1400 and 1800 K. Water is a final product from combustion, and its formation is a good marker of the completion of the combustion process. Carbon monoxide is an intermediate combustion species, a good marker of incomplete/inefficient combustion, as well as a regulated pollutant for the gas turbine industry. Measurements such as these species time histories are important for validating and assessing chemical kinetics models beyond just ignition delay times and laminar flame speeds. Time-history profiles for these two molecules were compared to a state-of-the-art detailed kinetics mechanism as well as to the well-established GRI 3.0 mechanism. Results show that the H2O profile is accurately reproduced by both models. However, discrepancies are observed for the CO profiles. Under the conditions of this study, the CO profiles typically increase rapidly after an induction time, reach a maximum, and then decrease. This maximum CO mole fraction is often largely over-predicted by the models, whereas the depletion rate of CO past this peak is often over-estimated for pressures above 1 atm.

CO and H2O Time-Histories in Shock-Heated Blends of Methane and Ethane for Assessment of a Chemical Kinetics Model

2017 ◽  
Author(s):  
O. Mathieu ◽  
C. Mulvihill ◽  
E. L. Petersen ◽  
Y. Zhang ◽  
H. J. Curran
Keyword(s):  
Gas Turbine ◽  
Chemical Kinetics ◽  
Laminar Flame ◽  
Combustion Process ◽  
Practical Interest ◽  
Time History ◽  
Good Marker ◽  
Ignition Delay Times ◽  
Time Histories ◽  
Detailed Kinetics

Methane and ethane are the two main components of natural gas and typically constitute more than 95% of it. In this study, a mixture of 90% CH4 /10% C2H6 diluted in 99% Ar was studied at fuel lean (ϕ = 0.5) conditions, for pressures around 1, 4, and 10 atm. Using laser absorption diagnostics, the time histories of CO and H2O were recorded between 1400 and 1800 K. Water is a final product from hydrocarbon combustion, and following its formation is a good marker of the completion of the combustion process. Carbon monoxide is an intermediate combustion species, a good marker of incomplete/inefficient combustion, as well as a regulated pollutant for the gas turbine industry. Measurements such as these species time histories are important for validating and assessing chemical kinetics models beyond just ignition delay times and laminar flame speeds. Time-history profiles for these two molecules measured herein were compared to a modern, state-of-the-art detailed kinetics mechanism as well as to the well-established GRI 3.0 mechanism. Results show that the H2O profile is accurately reproduced by both models. However, discrepancies are observed for the CO profiles. Under the conditions of this study, the measured CO profiles typically increase rapidly after an induction time, reach a maximum and then decrease. This maximum CO mole fraction is often largely over-predicted by the models, whereas the depletion rate of CO past this peak is often over-estimated by the models for pressures above 1 atm. This study demonstrates the need to improve on the accuracy of the HCCO reactions involved in CO formation for pressures of practical interest for the gas turbine industry.

Evaluation of Spark Plug and Timing Configurations on the Fuel Consumption, Combustion Stability, and Emissions of a Large-Bore, Two-Stroke, Natural Gas Engine

2016 ◽  
Author(s):  
Derek Johnson ◽  
Marc Besch ◽  
Nathaniel Fowler ◽  
Robert Heltzel ◽  
April Covington
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Combustion Engine ◽  
Engine Performance ◽  
Combustion Stability ◽  
Oxides Of Nitrogen ◽  
Natural Gas Engines ◽  
Fuel Delivery ◽  
Spark Plug ◽  
Trade Offs

Emissions compliance is a driving factor for internal combustion engine research pertaining to both new and old technologies. New standards and compliance requirements for off-road spark ignited engines are currently under review and include greenhouse gases. To continue operation of legacy natural gas engines, research is required to increase or maintain engine efficiency, while reducing emissions of carbon monoxide, oxides of nitrogen, and volatile organic compounds such as formaldehyde. A variety of technologies can be found on legacy, large-bore natural gas engines that allow them to meet current emissions standards — these include exhaust after-treatment, advanced ignition technologies, and fuel delivery methods. The natural gas industry uses a variety of spark plugs and tuning methods to improve engine performance or decrease emissions of existing engines. The focus of this study was to examine the effects of various spark plug configurations along with spark timing to examine any potential benefits. Spark plugs with varied electrode diameter, number of ground electrodes, and heat ranges were evaluated against efficiency and exhaust emissions. Combustion analyses were also conducted to examine peak firing pressure, location of peak firing pressure, and indicated mean effective pressure. The test platform was an AJAX-E42 engine. The engine has a bore and stroke of 0.216 × 0.254 meters (m), respectively. The engine displacement was 9.29 liters (L) with a compression ratio of 6:1. The engine was modified to include electronic spark plug timing capabilities along with a mass flow controller to ensure accurate fuel delivery. Each spark plug configuration was examined at ignition timings of 17, 14, 11, 8, and 5 crank angle degrees before top dead center. The various configurations were examined to identify optimal conditions for each plug comparing trade-offs among brake specific fuel consumption, oxides of nitrogen, methane, formaldehyde, and combustion stability.

Optical and Numerical Investigations of Flame Propagation in a Heavy Duty Spark Ignited Natural Gas Engine

2021 ◽  
Author(s):  
Jinlong Liu ◽  
Christopher Ulishney ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Flame Propagation ◽  
Turbulence Intensity ◽  
Laminar Flame ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Heavy Duty ◽  
Piston Chamber

Abstract Increasing the natural gas (NG) use in heavy-duty engines is beneficial for reducing greenhouse-gas emissions from power generation and transportation. However, converting compression ignition (CI) engines to NG spark ignition operation can increase methane emissions without expensive aftertreatment, thereby defeating the purpose of utilizing a low carbon fuel. The widely accepted explanation for the low combustion efficiency in such retrofitted engines is the lower laminar flame speed of natural gas. In addition, diesel engine’s larger bowl size compared to the traditional gasoline engines increases the flame travel length inside the chamber and extends the combustion duration. However, optical measurements performed in this study suggested that a fast-propagating flame was developed inside the cylinder even at extremely lean operation. This was supported by a three-dimensional numerical simulation, which indicated that the squish region of the bowl-in-piston chamber generated a high turbulence intensity inside the bowl. However, the flame propagation experienced a sudden 2.25x reduction in speed when transiting from the bowl to the squish region. Such a phenomenon was caused by the large decrease in the turbulence intensity inside the squish region during the combustion process. Moreover, the squish volume trapped an important fuel fraction, and it is this fraction that experienced a slow and inefficient burning process during the expansion stroke. This resulted in increased methane emissions and reduced combustion efficiency. Overall, it was the specifics of the combustion process inside a bowl-in-piston chamber not the methane’s slow laminar flame speed that contributed to the low methane combustion efficiency for the retrofitted engine. The results suggest that optimizing the chamber shape is paramount to boost engine efficiency and decrease its emissions.

scholarly journals Simulation Research of Aircraft Piston Engine Rotax 912

2019 ◽  
Vol 252 ◽  
pp. 05007 ◽  
Author(s):  
Łukasz Grabowski ◽  
Ksenia Siadkowska ◽  
Krzysztof Skiba
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Basic Unit ◽  
Piston Engine ◽  
Engine Operation ◽  
Simulation Research ◽  
One Dimensional ◽  
Operation Process ◽  
Model Aircraft

This paper reports the results of simulation works of Rotax 912 aircraft piston engine, which is a basic unit in most ultra-light aircrafts. The method for preparing the model aircraft engine operation process was presented. Simulation tests were carried out in the AVL Boost programme. The programme allows a full use of zero-dimensional and one-dimensional modelling. It also allows a comparison of other engine models. The developed model has enabled us to simulate the flow of air through the inlet pipes, carburettors, valves and combustion process. The preparation of the model required us to enter parameters that are not available in the manufacturer's catalogue, therefore, necessary measurements and analysis of the engine parts were carried out on a laboratory bench. The calculations in the AVL Boost programme were carried out in the conditions determined for the selected BMEP values with the objective of characterising the engine performance by determining its power, torque and fuel consumption.

scholarly journals Parametric Knocking Performance Investigation of Spark Ignition Natural Gas Engines and Dual Fuel Engines

2020 ◽  
Vol 8 (6) ◽  
pp. 459 ◽  
Author(s):  
La Xiang ◽  
Gerasimos Theotokatos ◽  
Haining Cui ◽  
Keda Xu ◽  
Hongkai Ben ◽  
...  
Keyword(s):  
Natural Gas ◽  
Compression Ratio ◽  
Engine Performance ◽  
Spark Ignition ◽  
Combustion Model ◽  
Dual Fuel ◽  
Ignition Timing ◽  
Natural Gas Engines ◽  
Study Results ◽  
Pilot Fuel

Both spark ignition (SI) natural gas engines and compression ignition (CI) dual fuel (DF) engines suffer from knocking when the unburnt mixture ignites spontaneously prior to the flame front arrival. In this study, a parametric investigation is performed on the knocking performance of these two engine types by using the GT-Power software. An SI natural gas engine and a DF engine are modelled by employing a two-zone zero-dimensional combustion model, which uses Wiebe function to determine the combustion rate and provides adequate prediction of the unburnt zone temperature, which is crucial for the knocking prediction. The developed models are validated against experimentally measured parameters and are subsequently used for performing parametric investigations. The derived results are analysed to quantify the effect of the compression ratio, air-fuel equivalence ratio and ignition timing on both engines as well as the effect of pilot fuel energy proportion on the DF engine. The results demonstrate that the compression ratio of the investigated SI and DF engines must be limited to 11 and 16.5, respectively, for avoiding knocking occurrence. The ignition timing for the SI and the DF engines must be controlled after −38°CA and 3°CA, respectively. A higher pilot fuel energy proportion between 5% and 15% results in increasing the knocking tendency and intensity for the DF Engine at high loads. This study results in better insights on the impacts of the investigated engine design and operating settings for natural gas (NG)-fuelled engines, thus it can provide useful support for obtaining the optimal settings targeting a desired combustion behaviour and engine performance while attenuating the knocking tendency.

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