Combustion of Liquid and Gaseous Fuels

Combustion of Liquid and Gaseous Fuels

  • Andrew P. Wandel added an answer:
    What's the difference between flame blow off and flame blow out?

    what's difference between flame blow off and flame blow out???? plz help

    Andrew P. Wandel · University of Southern Queensland

    Hello Mohamed,

    "Blow off" is when the flow speed is so high, the flame cannot be stabilised (kept at a fixed location), and so you can watch the flame propagate downstream and eventually extinguish.

    I haven't used "blow out" in a technical sense, but colloquially you "blow out a candle".  I would describe this phenomenon as a very high flow speed that quenches the flame, so that it extinguishes at that location.

    For "blow off", there is some flow to sustain the flame and the cause of the blow off is additional (but not excessive) speed in the same direction so that the flame can continue to burn as it moves because there is a combustible mixture.  For "blow out", there is an enormous speed of flow, coming from any direction, which quenches the flame immediately because the temperature is quickly reduced and the mixture becomes excessively lean (normally) or excessively rich, so that there is no longer a combustible mixture.

    Regards,
    Andrew

  • Paul Gateau added an answer:
    Can any one suggest how to couple CSTR , WSTR and PFR for simulation of gas turbine combustion chamber?

    I am planning to simulate gas turbine combustion chamber as a reactor. But reactor modelling is suggesting various theories for different thermodynamic conditions such as constant volume reactor, constant pressure reactor, well stirred reactor and plugged flow reactor. how to couple them to simulate gas turbine combustion chamber?

    Paul Gateau · SYNGAS

    To complete Manish Shah's answer.

    It's true that CFD simulation is a good method (may be the more appropriate) but it can be complicate.

    Chemkin is also complicate if you don't have the software. If you have the software Chemkin or another like Comsol you can simulate with the GRIMECH data for gaz combustion.

    The Borghi diagram is interesting to see the theorical situation in combustion for a perfectly stirred reactor.

    There are many papers dealing with combustion and perfectly stirred reactors.

    CFD : the kinetics are rather simple but you can obtain the temperature and velocity repartition in 3D

    Perfectly stirred : you can simulate very complex kinetics.

  • Amitav Chakraborty added an answer:
    Can we blend LPG and diesel fuel inside the cylinder?
    Through intake manifold can we inject LPG and mixing with diesel particle during the compression stroke?
    Amitav Chakraborty · National Institute of Technology, Agartala

    I agree to Mr Ekenechukwu C Okafor partially if we go for increasing the cetane number of LPG in diesel platform with some additives it may reduce the HC emissions,but on other hand the PM emission will try to shoot up due to rise in temperature in the cylinder

  • Alexandria Marie Noble added an answer:
    Does anyone know which type of ethanol blend is most effective in motorcycles?
    Different percentage mixes of ethanol and petrol used to drive motorcycles, have a significant impact on emissions and fuel consumption.
    Alexandria Marie Noble · Virginia Polytechnic Institute and State University

    According to the US Department of Energy, E15 is prohibited for use in motorcycles and other small engines.The Renewable Fuels Association (RFA) has recognized concerns
    of the small engine community (ethanol degrades engine parts and hoses and essentially gums up the works). The RFA outlined possibilities to allow for the use of E15 for on-road applications to the EPA, specifically passenger vehicles. According to the EPA there is insufficient evidence to determine whether E15 emissions will cause or contribute to non-road vehicles and non-road engines failing to meet emission standards, but it was suggested that the EPA grant a waiver for E15 limited to passenger vehicles/vehicles with large on road engines.

    Some of these publications below, they may be of use to you, good luck. 

  • Alliche Mounir added an answer:
    How to model a simple 1D flame propagation in a SI engine?
    I want to model the propagation of a flame front using MATLAB. What model can be used? Any references from where I can get information?
    Alliche Mounir · Dr. Yahia Fares University of Médéa

    I think you can use the book of Turns "An Introduction to Combustion”, McGraw-Hill, 2000, it is Very appropriate for this case and for your Library. You must use a multi scale method for detecting the flame region (corresponging to Tmax), for example the multigrid method.

  • Tianlai Gu asked a question:
    How can one get product reaction rate of each species from output files when using the "FlameMaster"?

    The process needs some information such as mass fraction and product reaction rate of each species at a given point. Steady laminar flamelet model and a certain PDF is applied. But in the FlameMaster outputfile(e.g. FlameMaster\FlameManRun\Diff\Steady\H2\OutMixFrac\H2_p01_0chi1.73414tf0300to0300), I cannot find reaction rate of required species, except for Z, T, massfraction- , W, chi, et al.

  • Awajiogak Anthony Ujile added an answer:
    Standard temperature-rise curves for jet fuels, where can I find them?

    Hi everyone, 

    I'm new in the jet fuel world, I would like to have some info about temperature-rise curves of jet fuels (kerosine...) as a function of pressure and air temperature.

    Thank you.

    Awajiogak Anthony Ujile · Rivers State University of Science and Technology

    Please consider the combustion reaction equation of kerosene (jet fuel). Check the thermodynamics of the process with respect to enthalpy and entropy charts. With these correlations, you should be able to obtain the temperature rise curve of jet fuel. I hope your objective is to evaluate the cost effectiveness of the jet fuel?

  • Mohammed Saber Gad added an answer:
    What are the properties of glass used for combustion diagnostics application and how to measure the properties of the glass?
    Glass used for optical engines
    Mohammed Saber Gad · National Research Center, Egypt

    i think this glass resists the thermal and mechanical stresses. Quartz glass resists high pressures in internal combustion engines. 

  • Mitja Kožuh added an answer:
    What are the hazards and risks from an offshore LNG production and storage facility?

    I am researching on the harzards and risk from FLNG and how they compare with other more familiar related technologies. Relevant literatures as well as your thoughts would be appreciated.

    Mitja Kožuh · University of Ljubljana, Faculty of Chemistry and Chemicla Technology, Ljubljana, Slovenia
    Regarding explosion there was explosion in production facility in Skikda in Algiers (2004.01.19). The other problems are pool and jet fire and possibly late ignition of the cloud after leaking into the water (reference Sandia documents). Rapid Phase Transition explosion in the tank.
  • Gabriel Negreanu added an answer:
    How are gas turbine cycles affected by oxygen enrichment in the air?
    see above
    Gabriel Negreanu · Polytechnic University of Bucharest

    Usualy, the air excess coefficient in the combustion chamber of gas turbines is quite high (2,5-4) in comparison with regular furnaces (1,2-1,5 with 6% oxygen in the flue gasses).  It's a lot of oxygen in the flue gasses, so it's possible to make also a post combustion without supplementary air injection. In conclusion, the air enrichment with oxygen should not affect the cycle parameters too much.

  • Joseph F McDonald added an answer:
    How can I measure the higher lambda value above 1.8 from a lambda sensor?
    1.Typical Lambda sensor range is between 0.2 to 1.8. How to measure higher lambda value more than 1.8 in experiments. i.e to measure very lean equivalence ratio? Can Brett schneider equation be used for low temperature combustion when the lambda value is more than 1.8. or brett schneider equation is valid only for lambda value closer to 1?
    2. whether lambda sensor is available for different ranges with digital display and connection to ECU for control?
    3. Fuel to be used diesel and gasoline.
    Joseph F McDonald · United States Environmental Protection Agency

    In my experience, UEGO sensors can be calibrated out to the O2 concentration in air if necessary. If you are on a tight budget, you can use OE Bosch or NGK automotive sensors and a either a UEGO controller or DIY kit from:

    http://www.wbo2.com/

    We used the Horiba MEXA units (Bosch sensors if memory serves me) and also one-off instrumentation with NGK sensors.  We typically calibrated UEGO sensors using a capillary gas divider and a mixture of 2.6% H2 - 6.6% CO - 10 % CO2 - balance N2 for calibrating rich and then chose an oxygen concentration for lean calibration based on the application.  The rich calibration mixture gave us a rich-span value equivalent to approximately 0.81 lambda.  For lean calibration, 4.7% O2 spanned at about 1.27 lambda (fine for most stoichiometric gasoline applications) and 9.7% O2 spanned at about 1.91 lambda (fine for many lean-burn applications) - just choose the oxygen concentration to span to the lean lambda value that you are looking for. 

  • What is the environmental impact of fuel consumption in air pollution?
    What is the amount of Co produced for one liter of fuel combustion?

    CO and CO2 - a little dangerous components of pollutions. The least dangerous component, of course, is CO2, if you ignore the thermal pollution.

    The most dangerous components (ascending danger): hydrogen - carbon,

    nitrogen oxides NOx and benzoalfapiren.

    In diesel engines, of course, very dangerous nitrogen oxides NOx and soot (smoke).

  • Tamilalagan Natarajan added an answer:
    Can anyone help with power transformer dataset (DGA test results)?

    I am in urgent need of data from transformer DGA test results. I have some transformer dga test results with only key gases and hydrocarbon gases. 

    I need some DGA results with additional features such as moisture, oil breakdown values , acidity etc. All data will be kept confidential and will be used for research only. Please help.

    Tamilalagan Natarajan · Curtin University Australia

    Hi, I am not sure if I was clear. I am in need of a dataset from transformer DGA for testing. I am planning to use a combination of IEEE/IEC methods for fault diagnosis. If you happen to have any DGA results that contain more features, please share it with me. The more features, the better.

  • Petra Roosen added an answer:
    How much actual (practically) air is required for 1kg/hr coal combustion?

    How much actual (practically) air is required for 1kg/hr coal gasification?

    Petra Roosen · Fachhochschule Aachen

    @Rasool: You are right, but I was trading oxygen against ashes - at least for the 1st order approximation. :-)

  • Arun Kishore Eswara added an answer:
    What is the optimum acidity level of a bio-diesel for IC engine operation?
    Which components of the IC engine are affected?
    Arun Kishore Eswara · Indian Maritime University - Visakhapatnam
    Every engine manufacturer sets his own specification on the type of fuels and lubes that can be used. There are rules framed like in Maritime applications (by IMO) that the fuels should be free of inorganic acids. This is something to do with the health of the crew. Further if you refer some international standards like the EN 14214:2003 standard for bio-diesels, the maximum acidity specified is 0.5 mg KOH/g. While that of crude liquid bio fuels is 15mg KOH/g. The acidity is more important as to the suitability for the engine considering the type of materials used in the fuel systems, combustion and exhaust components and exhaust heat recovery units.
    The conclusion is TAN is mere acceptance to the engine hence quoted as maximum mg KOH/g.
  • Luis Le Moyne added an answer:
    Why is cycle to cycle fluctuation in HCCI /PCCI engine very high, how can it be controlled?
    This is for gasoline PCCi engine running with gasoline alone without diesel injection at TDC.
    Luis Le Moyne · Institut Supérieur de l'Automobile et des Transports, U. Bourgogne
    Hello,
    normally, when PCCI/CAI/HCCI combustion is achieved one observes rather a high stability of cycle to cycle fluctuatution. Specially when compared to standard SI, petrol engines in auto-or controlled auto ignition modes present a high stability as the igntion process does no longer rely on spark and flame propagation (both very sensitive to cycle variations and not self regulating) but depends on the right distribution of radicals and respect of thermo-chemical conditions which tend to be self regulating. Nevertheless, as the conditions in which residual or recirculated exhaust gases are capital on ignition, variations even slight in temperature, pressure, injection timing, etc. can cause large variations in combustion behaviour. All this parameters must be monitored to eliminate variations in order to better control combustion efficiency and regularity
    hope it is of use for you
  • Mohammad Faisal added an answer:
    What is a good way to validate CFD results (i.e. exhaust velocity, temperature, pressure etc) for Rocket combustion for propulsion system?
    For aerodynamic design (aircraft or aerofoil or any body), we have wind tunnel tests which validate the CFD simulated results for aerodynamic design. Similarly for automotive combustion chamber, we can carry out experimentation of fuel combustion inside the chamber upto certain extent for the cfd simulated results.
    But for the cfd simulation like combustion chamber design or combustion modelling in rocket propulsion system, how the simulated results are validated as experimentation of propulsion is not possible or it gives a huge cost. What is the method of validation and comparison of simulated data as we do in external aerodynamics?
    Mohammad Faisal · University of Petroleum & Energy Studies
    Thanks a lot. It was really helpful.
  • Harjeet Nath added an answer:
    How can I measure the fluoride amount of a gas sample? Which is the best equipment and why?
    How can I measure gaseous Fluoride?
    Harjeet Nath · Indian Institute of Technology Guwahati
    Thank You, GC can be used??
  • Aimen Zeiny added an answer:
    Why is Naphtha not used as a fuel for Spark Ignition Engines?
    Can anyone tell me the main reasons that prevent the use of Naphtha as a fuel in SI engines?
    Aimen Zeiny · University Of Kufa
    Thank you Gautam. But I did a piece of research on using Naphtha in SI engine. I found that adding 7 vol.% of methanol to Naphtha enhances the engine performance and reducing emissions even better than using gasoline as fuel. Also, I measured the noise of the engine and I found that at this percentage the noise is lower than the noise generated when using Gasoline.
    What do you think?
    I would be grateful if I can hear your comment.
  • Marek Flekiewicz added an answer:
    Is there any study on the rate of natural gas loss in natural gas engines through piston rings? To what extend does this affect the performance?
    When gasoline or diesel engines are converted to natural gas, one obvious result is the reduction in power due to volumetric loss and slower flame speed. In addition, the charge heating value is reduced from the sipping out of natural gas through the piston rings during compression stroke. All these lead to power loss.
    Marek Flekiewicz · Silesian University of Technology
    I think the best way is to ask M.A.N directly. The report explains among other why the rings and piston have a different design. I do not know any other publications on this subject.
  • Tongchit Suthisripok added an answer:
    Why does self ignition temperature of a mixture decrease as we increase the equivalence ratio?
    .
    Tongchit Suthisripok · Rangsit University
    Thank you, Mr. Francois. I should have mentioned less fuel or comparatively more air. Typically fuel used in the combustion will be rich or lean (not lean air or rich air).
  • Giuma Fellah added an answer:
    How do we explain why low temperature combustion engines achieve higher thermal efficiency?
    It seems to violate the Carnot efficiency for heat engines. Low temperature combustion engines have gained significant interest in engine research due to lower average burning temperature, lowering heat loss that contributes to the reduction of thermal efficiency. However, according to the Carnot heat engine thermal efficiency definition, increasing source temperature increases thermal efficiency.
    Giuma Fellah · University of Tripoli
    In this case we should reduce the amount of heat rejected to surroundings, i.e. we should reduce the ratio of heat rejected to heat supplied to the engine. This can be done be reducing the average temperature of the exhaust gases. However, the exhaust temperature must be always greater than the dew point. We may need larger surface areas to insure the desired rate of the heat transfer for closed systems.
  • Ge Yan added an answer:
    Do fossil fuels contain residues from bacterial biomass?
    Is it possible to identify the bacterial signatures in fossil fuels and their combustion exhaust?
    Ge Yan · Seoul National University
    Thank you very much for your reply. Could you give an estimate on the bacterially derived content in these fossil fuel?
  • Xuebin Wang added an answer:
    What is the amino acid content of fossil fuels, such as coal, crude oil, and gasoline?
    Is it significant? If so, will these amino acids be emitted during combustion processes and thus present in the exhaust fume?
    Xuebin Wang · Xi'an Jiaotong University
    In coal, N (~1%) is mainly as heterocyclic ring forms and the content of amino acid is low. In biomass, N (~0.x-1%) is as the form of amino acid.
  • László Kótai added an answer:
    What is the component in biodiesel that will plug the fuel filter in a diesel engine?
    When biodiesel is used as a fuel-mix with diesel oil (B20), in a road test for 2,500 km.
    László Kótai · Hungarian Academy of Sciences
    It depends on many factors. Agreeing with the previous answers, I can tell you, if copper is present in the fuel system, the polyunsaturated components of biodiesel can be polymerized and form resin-like materials. This is a frequent reason for appearing resins and plugging.
  • Per Tunestal added an answer:
    How do you find percentage of oxygen required during combustion of c i engine?
    During suction stroke how much oxygen or air is required to calculate a single cylinder (5 HP) C I engine?
    Per Tunestal · Lund University
    The work output per cycle divided by the engine efficiency gives you the amount of fuel energy required per combustion event. Divide by the fuel heating value (about 42 MJ/kg for diesel) to get the fuel mass per combustion event. A CI (diesel) engine operates with an air/fuel ratio of about 20. Multiply the fuel mass by this factor and you get the air mass per cycle. The power (5 hp) is given, but you need the rated engine speed (number of cycles per second) to determine the work output per cycle.
  • Ekenechukwu C Okafor added an answer:
    Can we see different flame propagation of component gases when a premixed multi component gaseous fuel is ignited with a spark in a combustion chamber?
    Example of a multi-component fuel is a gas that contains H2, CO, CH4, CO2 and N2 etc.
    Ekenechukwu C Okafor · Kyushu University
    I have examined both turbulent and laminar premixed flames of H2 + CH4 + O2 + N2 in a constant volume chamber ignited with a spark. The flames propagated like those of homogenous mixtures. Different flame propagation of the component gases was not evident. The effect of the different component is seen in the global flame properties in the form or increase or decrease of the properties due to the concentrations of the components. For instance, increasing H2 content to some extent in that mixture would increase the burning velocity and decrease the markstein number. Although CH4 does not react with H2, they are not oxidized independently. increase in H2 concentration increases the rate of consumption of CH4 by by increasing the pool of OH and H radicals in the flame. Hence, one would not see different flame propagations due to the different components because they "burn together".
  • Santhosh Palanisamy asked a question:
    Can someone help to identify the Gas critical Velocity, while predicting liquid loading in gas well according to Nossier's equations?
    Nossier's equation which is an improvement of turner and Coleman's model of calculating critical velocity has the formula as below:

    Nosseir's Equation-I (Transition flow regime):
    vgc = 14.6[σ ^ 0.35(ρl - ρg)^ 0.21] /[(μg)^ 0.134(ρg)^0.426];

    Nosseir's Equation-II (Highly turbulent flow regime):
    vgc = 21.3[σ^1/4(ρl - ρg)^1/4] /[(ρg)^1/2];


    The above equation comes from a SPE paper. Also there are other equations on online calculators which has a different equation as below:
    Nosseir's Equation-I (Transition flow regime):
    vgc = 0.5092[σ ^ 0.35(ρl - ρg)^ 0.21] /[(μg)^ 0.134(ρg)^0.426];

    Nosseir's Equation-II (Highly turbulent flow regime):
    vgc = 1.938[σ^1/4(ρl - ρg)^1/4] /[(ρg)^1/2];

    The only difference is the constant values at the start but not sure how they arrived at the constant values. Had checked all the unit conversions and both uses the same units. The SPE paper equation seem to not give the correct answer for us. But the one from on line calculators gives me the expected answer and predicts minimum gas flow properly.

    I am not a oil and gas person to understand the difference between these equations. Any help will be greatly appreciated. Thanks.
  • Svaetopluk Zeman added an answer:
    If Natural Gas is 97% methane, is this equation (CNG= Compressed Methane) a correct equation?
    CNG has been used to fuel buses and large marine vessels for sometime now. So what's stopping compressed methane from doing the same thing?
    Svaetopluk Zeman · Euronex
    I prepared a simple graphics in excel to display relation between the concentration of methane in biogas to its calorific value. English version is to follow ... when? As soon as I find some free time again ...

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