Computational Studies of Glow Plug Ignition of Injected High Pressure Gas Jets

2015 ◽  
Author(s):  
Kang Pan ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Ignition Delay ◽  
Numerical Study ◽  
Pressure Rise ◽  
Air Gap ◽  
Time Difference ◽  
Glow Plug ◽  
Gas Ignition ◽  
Ignition And Combustion

A numerical study of ignition and combustion in a glow plug (GP) assisted direct-injection natural gas (DING) engine is presented in this paper. The glow plug is shielded and the shield design is an important part of the combustion system development. The results simulated by KIVA-3V indicated that the ignition delay (ID) predicted by an in-cylinder pressure rise was different from that based on a temperature rise, attributed to the additional time required to burn more fuel to obtain a detectable pressure rise in the combustion chamber. This time difference for the ignition delay estimation can be 0.5 ms, which is significant relative to an ignition delay value of less than 2 ms. To further evaluate the time difference between the two different methods of ignition delay determination, sensitivity studies were conducted by changing the glow plug temperature, and rotating the glow plug shield opening angle towards the fuel jets. The results indicated that the ID method time difference varied from 0.3 to 0.8 ms for different combustion chamber configurations. In addition, this study also investigated the influences of different glow plug shield parameters on the natural gas ignition and combustion characteristics, by modifying the air gap between the glow plug and its shield, and by changing the shield opening size. The computational results indicated that a bigger air gap inside the shield can delay gas ignition, and a smaller shield opening can block the flame propagation for some specific fuel injection angles.

Numerical Studies of Glow Plug Shield on Natural Gas Ignition Characteristics in a CI Engine

2016 ◽  
Author(s):  
Kang Pan ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Fuel Injection ◽  
Numerical Study ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Injection Angle ◽  
Glow Plug ◽  
Gas Ignition ◽  
Ignition And Combustion

This paper presents a numerical study on fuel injection, ignition and combustion in a direct-injection natural gas (DING) engine with ignition assisted by a shielded glow plug (GP). The shield geometry is investigated by employing different sizes of elliptical shield opening and changing the position of the shield opening. The results simulated by KIVA-3V indicated that fuel ignition and combustion is very sensitive to the relative angle between the fuel injection and the shield opening, and the use of an elliptical opening for the glow plug shield can reduce ignition delay by 0.1∼0.2ms for several specific combinations of the injection angle and shield opening size, compared to a circular shield opening. In addition, the numerical results also revealed that the natural gas ignition and flame propagation will be delayed by lowering a circular shield opening from the fuel jet center plane, due to the blocking effect of the shield to the fuel mixture, and hence it will reduce the DING performance by causing a longer ignition delay.

Numerical Studies of Glow Plug Shield on Natural Gas Ignition Characteristics in a Compression-Ignition Engine

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Kang Pan ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Fuel Injection ◽  
Numerical Study ◽  
Fuel Mixture ◽  
Compression Ignition Engine ◽  
Injection Angle ◽  
Glow Plug ◽  
Gas Ignition ◽  
Ignition And Combustion

This paper presents a numerical study on fuel injection, ignition, and combustion in a direct-injection natural gas (DING) engine with ignition assisted by a shielded glow plug (GP). The shield geometry is investigated by employing different sizes of elliptical shield opening and changing the position of the shield opening. The results simulated by KIVA-3V indicated that fuel ignition and combustion is very sensitive to the relative angle between the fuel injection and the shield opening, and the use of an elliptical opening for the glow plug shield can reduce ignition delay by 0.1–0.2 ms for several specific combinations of the injection angle and shield opening size, compared to a circular shield opening. In addition, the numerical results also revealed that the natural gas ignition and flame propagation will be delayed by lowering a circular shield opening from the fuel jet center plane, due to the blocking effect of the shield to the fuel mixture, and hence, it will reduce the DING engine performance by causing a longer ignition delay.

Modeling of Ignition and Combustion for Glow Plug Assisted Direct Injection Natural Gas Engines

2012 ◽  
Author(s):  
Stewart Xu Cheng ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Heated Surface ◽  
Direct Injection ◽  
Cfd Modeling ◽  
Spontaneous Ignition ◽  
Layer Model ◽  
Glow Plug ◽  
Natural Gas Engines ◽  
Gas Ignition ◽  
Ignition And Combustion

Direct injection natural gas (DING) engines offer the advantages of high thermal efficiency and high power output compared to spark ignition natural gas engines. Injected natural gas requires some form of ignition assist in order to ignite in the time available in a diesel engine combustion chamber. A glow plug — a heated surface — is one form of ignition assist. Simple experiments show that the thickness of the heat penetration layer of a glow plug is very small (≈10−5 m) within the time scale of the ignition preparation period (1–2 ms). Meanwhile, the theoretical analyses reveal that only a very thin layer of the surrounding gases (in micrometer scale) can be heated to high temperature to achieve spontaneous ignition. A discretized glow plug model and virtual gas sub-layer model have been developed for CFD modeling of glow plug ignition and combustion for DING diesel engines. In this paper, CFD modeling results are presented. The results were obtained using a KIVA3 code modified to include the above mentioned new developed models. Natural gas ignition over a bare glow plug was simulated. The results were validated against experiments. Simulation of natural gas ignition over a shielded glow plug was also carried out and the results illustrate the necessity of using a shield. This paper shows the success of the discretized glow plug model working together with the virtual gas sub-layer model for modeling glow plug assisted natural gas direct injection engines. The modeling can aid in the design of injection and ignition systems for glow plug assisted DING engines.

scholarly journals Laminar Burning Velocities of Hydrogen-Blended Methane–Air and Natural Gas–Air Mixtures, Calculated from the Early Stage of p(t) Records in a Spherical Vessel

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7556
Author(s):  
Maria Mitu ◽  
Domnina Razus ◽  
Volkmar Schroeder
Keyword(s):  
Natural Gas ◽  
Initial Conditions ◽  
Numerical Study ◽  
Early Stage ◽  
Linear Trend ◽  
Burning Velocity ◽  
Pressure Rise ◽  
Spherical Vessel ◽  
Practical Applications ◽  
Hydrogen Addition

The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determined in accordance with EN 15967, by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen, rH, follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV, as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures, the rate of heat release, and the concentration of active radical species in the flame front and contribute, thus, to LBV variation.

scholarly journals Mathematical modeling of a swirling jet in applications to low-emission combustion of low-grade fuels

2021 ◽  
Vol 23 (3) ◽  
pp. 308-317
Author(s):  
Usama J. Mizher ◽  
Peter A. Velmisov
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Negative Impact ◽  
Numerical Study ◽  
Combustion Process ◽  
Theoretical Data ◽  
Modern Society ◽  
Low Grade ◽  
Similar Solutions

Abstract. The search for new solutions in the field of energy, preventing negative impact on the environment, is one of the priority tasks for modern society. Natural gas occupies a stable position in the demand of the UES of Russia for fossil fuel. Biogas is a possible alternative fuel from organic waste. Biogas has an increased content of carbon dioxide, which affects the speed of flame propagation, and a lower content of methane, which reduces its heat of combustion. However, the combined combustion of natural gas and biogas, provided that the mixture of fuel and oxidizer is well mixed, can, on the one hand, reduce the maximum adiabatic temperature in the combustion chamber of power boilers at TPPs, and, on the other, increase the stability of biogas combustion. For the combined combustion of natural gas and biogas in operating power boilers, it is necessary to reconstruct the existing burners. For a high-quality reconstruction of burners capable of providing stable and low-toxic combustion of fuel, it is important to have theoretical data on the combustion effect of combustion of combinations of organic fuels on the temperature distribution in the combustion zone and on its maximum value. In this paper, self-similar solutions of the energy equation for axisymmetric motion of a liquid (gas) in a model of a viscous incompressible medium are obtained. Basing on them, a stationary temperature field in swirling jets is constructed. A set of programs based on the ANSYS Fluent software solver has been developed for modeling and researching of thermal and gas-dynamic processes in the combustion chamber. On the basis of the k - ϵ (realizable) turbulence model, the combustion process of a swirling fuel-air mixture is simulated. The results of an analytical and numerical study of the temperature and carbon dioxide distribution in the jet are presented.

Probing the Effects of NOx and SOx Impurities on Oxy-Fuel Combustion in Supercritical CO2: Shock Tube Experiments and Chemical Kinetic Modeling

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Ramees K. Rahman ◽  
Samuel Barak ◽  
K.R.V. (Raghu) Manikantachari ◽  
Erik Ninnemann ◽  
Ashvin Hosangadi ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Shock Tube ◽  
Combustion Chamber ◽  
Ignition Delay ◽  
Methane Combustion ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Effect Of Impurities ◽  
Base Mechanism

Abstract The direct-fired supercritical carbon dioxide cycles are one of the most promising power generation methods in terms of their efficiency and environmental friendliness. Two important challenges in implementing these cycles are the high pressure (300 bar) and high CO2 dilution (>80%) in the combustor. The design and development of supercritical oxy-combustors for natural gas require accurate reaction kinetic models to predict the combustion outcomes. The presence of a small amount of impurities in natural gas and other feed streams to oxy-combustors makes these predictions even more complex. During oxy-combustion, trace amounts of nitrogen present in the oxidizer is converted to NOx and gets into the combustion chamber along with the recirculated CO2. Similarly, natural gas can contain a trace amount of ammonia and sulfurous impurities that get converted to NOx and SOx and get back into the combustion chamber with recirculated CO2. In this work, a reaction model is developed for predicting the effect of impurities such as NOx and SOx on supercritical methane combustion. The base mechanism used in this work is GRI Mech 3.0. H2S combustion chemistry is obtained from Bongartz et al. while NOx chemistry is from Konnov. The reaction model is then optimized for a pressure range of 30–300 bar using high-pressure shock tube data from the literature. It is then validated with data obtained from the literature for methane combustion, H2S oxidation, and NOx effects on ignition delay. The effect of impurities on CH4 combustion up to 16 atm is validated using NOx-doped methane studies obtained from the literature. In order to validate the model for high-pressure conditions, experiments are conducted at the UCF shock tube facility using natural gas identical mixtures with N2O as an impurity at ∼100 bar. Current results show that there is a significant change in ignition delay with the presence of impurities. A comparison is made with experimental data using the developed model and predictions are found to be in good agreement. The model developed was used to study the effect of impurities on CO formation from sCO2 combustors. It was found that NOx helps in reducing CO formation while the presence of H2S results in the formation of more CO. The reaction mechanism developed herein can also be used as a base mechanism to develop reduced mechanisms for use in CFD simulations.

Numerical Study on High Temperature Air Combustion in U-Type Tube

2008 ◽  
Author(s):  
Xing Li ◽  
Li Jia ◽  
Tiantian Zhang ◽  
Lixin Yang
Keyword(s):  
High Temperature ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Numerical Study ◽  
Maximum Temperature ◽  
No Emission ◽  
High Temperature Air Combustion ◽  
Average Temperature ◽  
Combustion Technology ◽  
Type Tube

In this paper, the combustion characteristics of natural gas with high-temperature air combustion technology in a U-type combustion chamber were investigated by the numerical method. The results of the CFD-based mathematical modeling of rated condition were compared with experimental data including the maximum temperature, average temperature and NO emission. The research indicates that the combustion can be well simulated using the suggested numerical model. The temperature distribution, velocity distribution in the combustion chamber and NO emission were attained. In addition, the effects of some parameters such as oxygen concentration, excessive air ratio and combustion air temperature were discussed in detail. It provided primarily theoretic basis for further study of natural gas high temperature air combustion.

Modeling HPDI Natural Gas Heavy Duty Engine Combustion

2005 ◽  
Author(s):  
Guowei Li ◽  
Tim Lennox ◽  
Dale Goudie ◽  
Mark Dunn
Keyword(s):  
Natural Gas ◽  
Test Data ◽  
Direct Injection ◽  
Cfd Modeling ◽  
Combustion Model ◽  
Model Parameters ◽  
Prediction Errors ◽  
Engine Test ◽  
Gas Ignition ◽  
Ignition And Combustion

CFD Modeling of the injection, the mixing, the combustion and the emission formation processes in a high pressure direct injection (HPDI) natural gas engine is presented in this paper. KIVA3V was used together with an injector model. Two sub-models had been developed that the concurrent injection, ignition and combustion of natural gas and diesel could be simulated. The gas injection was simulated with the injector model. In the injector model, the electromagnetism, the hydraulics and the mechanics were computed by solving a set of ordinary differential equations. Based on the engine experimental data, a combustion model was built in which premixed combustion of natural gas was excluded and the natural gas ignition was initiated by the pilot diesel combustion rather than a spontaneous process. The model calibration and validation are discussed. The model parameters were tuned against one set of engine test data. For the model validation, 30 engine test data were applied. The data were from HPDI engine tests at varied engine speeds, loads and injection timings with and without EGR. The model gave good agreement with the engine tests having no EGR. However, the model, in general, under-predicted the burning rate. With EGR, the model prediction errors were large and the NOx were under-predicted, though the trends were still captured.

Study of Turbulent Spray Combustion of N-Dodecane Fuel

2015 ◽  
Author(s):  
O. Samimi Abianeh
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Pressure Rise ◽  
Chamber Pressure ◽  
Spray Combustion ◽  
Turbulent Spray Combustion ◽  
Temperature Combustion ◽  
Time Histories ◽  
Turbulent Spray ◽  
Lift Off

Turbulent spray combustion of n-dodecane fuel was studied numerically in current paper. The ignition delay, lift-off length, combustion chamber pressure rise, fuel penetration and vapor mass fraction were compared with experimental data. n-Dodecane kinetic model was studied by using a recently developed mechanism. The combustion chamber pressure rise was modeled and compared with experiments; the result was corrected for speed-of-sound to find the ignition delay timing in comparison with pressure-based ignition delay measurement. Species time histories and reaction paths at low and high temperature combustion are modeled and studied at two conditions, 900 K and 1200 K combustion chamber temperatures. The modeled species mass histories were discussed to define the first-stage and total ignition delay timings. Among all of the studied species in this work, including OH, Hydroperoxyalkyl mass history can be utilized to determine the exact timing of luminosity-based ignition delay. Moreover, n-dodecane vapor penetration can be used to determine the luminosity-based ignition delay.

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