Challenges for turbulent combustion (2022)

Turbulent combustion will remain central to the next generation of combustion devices that are likely to employ blends of renewable and fossil fuels, transitioning eventually to electrofuels (also referred to as e-fuels, powerfuels, power-to-x, or synthetics). This paper starts by projecting that the decarbonization process is likely to be very slow as guided by history and by the sheer extent of the current network for fossil fuels, and the cost of its replacement. This transition to renewables will be moderated by the advent of cleaner engines that operate on increasingly cleaner fuel blends. A brief outline of recent developments in combustion modes, such as gasoline compression ignition for reciprocating engines and sequential combustion for gas turbines, is presented. The next two sections of the paper identify two essential areas of development for advancing knowledge of turbulent combustion, namely multi-mode or mixed-mode combustion and soot formation. Multi-mode combustion is common in practical devices and spans the entire range of processes from transient ignition to stable combustion and the formation of pollutants. A range of burners developed to study highly turbulent premixed flames and mixed-mode flames, is presented along with samples of data and an outline of outstanding research issues. Soot formation relevant to electrofuels, such as blends of diesel-oxymethylene ethers, hydrogen-methane or ethylene-ammonia, is also discussed. Mechanisms of soot formation, while significantly improved, remain lacking particularly for heavy fuels and their blends. Other important areas of research, such as spray atomization, turbulent dense spray flames, turbulent fires, and the effects of high pressure, are briefly mentioned. The paper concludes by highlighting the continued need for research in these areas of turbulent combustion to bring predictive capabilities to a level of comprehensive fidelity that enables them to become standard reliable tools for the design and monitoring of future combustors.

Original languageEnglish (US)
Title of host publicationProceedings of the Combustion Institute
PublisherElsevier BV
Pages121-155
Number of pages35
DOIs
StatePublished - Apr 10 2021
Externally publishedYes
  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry
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Masri, A. R. (2021). Challenges for turbulent combustion. In Proceedings of the Combustion Institute (pp. 121-155). Elsevier BV. https://doi.org/10.1016/j.proci.2020.07.144

Masri, Assaad R. / Challenges for turbulent combustion. Proceedings of the Combustion Institute. Elsevier BV, 2021. pp. 121-155

@inproceedings{f2089903e9e547d7b25a20932d825d85,

title = "Challenges for turbulent combustion",

abstract = "Turbulent combustion will remain central to the next generation of combustion devices that are likely to employ blends of renewable and fossil fuels, transitioning eventually to electrofuels (also referred to as e-fuels, powerfuels, power-to-x, or synthetics). This paper starts by projecting that the decarbonization process is likely to be very slow as guided by history and by the sheer extent of the current network for fossil fuels, and the cost of its replacement. This transition to renewables will be moderated by the advent of cleaner engines that operate on increasingly cleaner fuel blends. A brief outline of recent developments in combustion modes, such as gasoline compression ignition for reciprocating engines and sequential combustion for gas turbines, is presented. The next two sections of the paper identify two essential areas of development for advancing knowledge of turbulent combustion, namely multi-mode or mixed-mode combustion and soot formation. Multi-mode combustion is common in practical devices and spans the entire range of processes from transient ignition to stable combustion and the formation of pollutants. A range of burners developed to study highly turbulent premixed flames and mixed-mode flames, is presented along with samples of data and an outline of outstanding research issues. Soot formation relevant to electrofuels, such as blends of diesel-oxymethylene ethers, hydrogen-methane or ethylene-ammonia, is also discussed. Mechanisms of soot formation, while significantly improved, remain lacking particularly for heavy fuels and their blends. Other important areas of research, such as spray atomization, turbulent dense spray flames, turbulent fires, and the effects of high pressure, are briefly mentioned. The paper concludes by highlighting the continued need for research in these areas of turbulent combustion to bring predictive capabilities to a level of comprehensive fidelity that enables them to become standard reliable tools for the design and monitoring of future combustors.",

author = "Masri, {Assaad R.}",

(Video) Jacqueline Chen: "DNS of Turbulent Combustion in Complex Flows"

note = "KAUST Repository Item: Exported on 2022-07-01 Acknowledgements: The author would like to thank Professors Timothy Lieuwen and Fei Qi as Program Co-Chairs of the 38th International Combustion Symposium for inviting me to present this Plenary Lecture. I am eternally grateful to the Australian Research Council for the continued and generous support it has provided for my research through a series of grants, the most recent being: DP200103609, DP180104190, LE180100203, DP160105023, DP130104904, DP110105535, DP1097125, and DP0772408. I am also funded by Qatar National Research Fund Project NPRP-7-036-2-018. Support and encouragement within the University of Sydney and in particular, my School of Aerospace, Mechanical and Mechatronic Engineering has provided me with a continued incentive to advance my research and grow my team and network of collaborators who are largely responsible for the work presented here. I am blessed to have colleagues of the calibre of Prof. John Kent, A/Prof. Matthew Cleary, Dr Matthew Dunn and Dr Agisilaos Kourmatzis who, together with our students and Postdoctoral Fellows, provide a stimulating, enjoyable and productive environment for research. Advances in many projects discussed here would not have been possible without the help of my long term collaborators, namely Dr Robert Barlow, then at Sandia National Laboratories, Livermore, USA, Professor William Roberts at King Abdullah University of Science and Technology, KAUST in Saudi Arabia, Professor Andrea D'Anna and Dr Mariano Sirignano at the University of Naples Federico II, Italy, Professor Epaminondas Mastorakos at the University of Cambridge, UK, Professor Steve Pope at Cornell University, USA, Professor Mohy Mansour at the American University of Cairo, Dr Salah Ibrahim at Loughborough University, UK and Professor Fei Qi from Shanghai Jiao Tong University in China. I am indebted to the following colleagues (listed in alphabetical order) who have provided thoughtful comments on the manuscript and subsequent stimulating discussions which have helped bring the manuscript to its current stage: Dr Robert Barlow, A/Prof. Matthew Cleary, Dr Matthew Dunn, Prof. Evatt Hawkes, Dr Gautam Kalghatgi, Dr Agisilaos Kourmatzis, Professor Prof. Heinz Pitsch and Professor Epaminondas Mastorakos . I am grateful to Dr Wesley Boyette, Dr Thibault Guiberti, Dr Mrinal Juddoo for helping with various figures. The able assistance of Dr Gajendra Singh in various tasks of editing and refining the figures is very much appreciated. Last, but not least, the constructive feedback of the anonymous reviewers is also acknowledged. This paper is dedicated to my family, who continue to put up with my erratic hours, to the souls of my parents and, my mentor, the late Professor R.W. Bilger who introduced me to this wonderful field of combustion. This publication acknowledges KAUST support, but has no KAUST affiliated authors.",

year = "2021",

month = apr,

day = "10",

doi = "10.1016/j.proci.2020.07.144",

language = "English (US)",

pages = "121--155",

booktitle = "Proceedings of the Combustion Institute",

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Masri, AR 2021, Challenges for turbulent combustion. in Proceedings of the Combustion Institute. Elsevier BV, pp. 121-155. https://doi.org/10.1016/j.proci.2020.07.144

(Video) Turbulent Combustion: Experiments and Fundamental Models, Driscoll, Day 1, Part 1

Challenges for turbulent combustion. / Masri, Assaad R.

Proceedings of the Combustion Institute. Elsevier BV, 2021. p. 121-155.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

TY - GEN

T1 - Challenges for turbulent combustion

AU - Masri, Assaad R.

N1 - KAUST Repository Item: Exported on 2022-07-01Acknowledgements: The author would like to thank Professors Timothy Lieuwen and Fei Qi as Program Co-Chairs of the 38th International Combustion Symposium for inviting me to present this Plenary Lecture. I am eternally grateful to the Australian Research Council for the continued and generous support it has provided for my research through a series of grants, the most recent being: DP200103609, DP180104190, LE180100203, DP160105023, DP130104904, DP110105535, DP1097125, and DP0772408. I am also funded by Qatar National Research Fund Project NPRP-7-036-2-018. Support and encouragement within the University of Sydney and in particular, my School of Aerospace, Mechanical and Mechatronic Engineering has provided me with a continued incentive to advance my research and grow my team and network of collaborators who are largely responsible for the work presented here. I am blessed to have colleagues of the calibre of Prof. John Kent, A/Prof. Matthew Cleary, Dr Matthew Dunn and Dr Agisilaos Kourmatzis who, together with our students and Postdoctoral Fellows, provide a stimulating, enjoyable and productive environment for research. Advances in many projects discussed here would not have been possible without the help of my long term collaborators, namely Dr Robert Barlow, then at Sandia National Laboratories, Livermore, USA, Professor William Roberts at King Abdullah University of Science and Technology, KAUST in Saudi Arabia, Professor Andrea D'Anna and Dr Mariano Sirignano at the University of Naples Federico II, Italy, Professor Epaminondas Mastorakos at the University of Cambridge, UK, Professor Steve Pope at Cornell University, USA, Professor Mohy Mansour at the American University of Cairo, Dr Salah Ibrahim at Loughborough University, UK and Professor Fei Qi from Shanghai Jiao Tong University in China. I am indebted to the following colleagues (listed in alphabetical order) who have provided thoughtful comments on the manuscript and subsequent stimulating discussions which have helped bring the manuscript to its current stage: Dr Robert Barlow, A/Prof. Matthew Cleary, Dr Matthew Dunn, Prof. Evatt Hawkes, Dr Gautam Kalghatgi, Dr Agisilaos Kourmatzis, Professor Prof. Heinz Pitsch and Professor Epaminondas Mastorakos . I am grateful to Dr Wesley Boyette, Dr Thibault Guiberti, Dr Mrinal Juddoo for helping with various figures. The able assistance of Dr Gajendra Singh in various tasks of editing and refining the figures is very much appreciated. Last, but not least, the constructive feedback of the anonymous reviewers is also acknowledged. This paper is dedicated to my family, who continue to put up with my erratic hours, to the souls of my parents and, my mentor, the late Professor R.W. Bilger who introduced me to this wonderful field of combustion.This publication acknowledges KAUST support, but has no KAUST affiliated authors.

PY - 2021/4/10

Y1 - 2021/4/10

(Video) Can Turbulent Combustion Models be Both Computationally Efficient and Generally Applicable?

N2 - Turbulent combustion will remain central to the next generation of combustion devices that are likely to employ blends of renewable and fossil fuels, transitioning eventually to electrofuels (also referred to as e-fuels, powerfuels, power-to-x, or synthetics). This paper starts by projecting that the decarbonization process is likely to be very slow as guided by history and by the sheer extent of the current network for fossil fuels, and the cost of its replacement. This transition to renewables will be moderated by the advent of cleaner engines that operate on increasingly cleaner fuel blends. A brief outline of recent developments in combustion modes, such as gasoline compression ignition for reciprocating engines and sequential combustion for gas turbines, is presented. The next two sections of the paper identify two essential areas of development for advancing knowledge of turbulent combustion, namely multi-mode or mixed-mode combustion and soot formation. Multi-mode combustion is common in practical devices and spans the entire range of processes from transient ignition to stable combustion and the formation of pollutants. A range of burners developed to study highly turbulent premixed flames and mixed-mode flames, is presented along with samples of data and an outline of outstanding research issues. Soot formation relevant to electrofuels, such as blends of diesel-oxymethylene ethers, hydrogen-methane or ethylene-ammonia, is also discussed. Mechanisms of soot formation, while significantly improved, remain lacking particularly for heavy fuels and their blends. Other important areas of research, such as spray atomization, turbulent dense spray flames, turbulent fires, and the effects of high pressure, are briefly mentioned. The paper concludes by highlighting the continued need for research in these areas of turbulent combustion to bring predictive capabilities to a level of comprehensive fidelity that enables them to become standard reliable tools for the design and monitoring of future combustors.

AB - Turbulent combustion will remain central to the next generation of combustion devices that are likely to employ blends of renewable and fossil fuels, transitioning eventually to electrofuels (also referred to as e-fuels, powerfuels, power-to-x, or synthetics). This paper starts by projecting that the decarbonization process is likely to be very slow as guided by history and by the sheer extent of the current network for fossil fuels, and the cost of its replacement. This transition to renewables will be moderated by the advent of cleaner engines that operate on increasingly cleaner fuel blends. A brief outline of recent developments in combustion modes, such as gasoline compression ignition for reciprocating engines and sequential combustion for gas turbines, is presented. The next two sections of the paper identify two essential areas of development for advancing knowledge of turbulent combustion, namely multi-mode or mixed-mode combustion and soot formation. Multi-mode combustion is common in practical devices and spans the entire range of processes from transient ignition to stable combustion and the formation of pollutants. A range of burners developed to study highly turbulent premixed flames and mixed-mode flames, is presented along with samples of data and an outline of outstanding research issues. Soot formation relevant to electrofuels, such as blends of diesel-oxymethylene ethers, hydrogen-methane or ethylene-ammonia, is also discussed. Mechanisms of soot formation, while significantly improved, remain lacking particularly for heavy fuels and their blends. Other important areas of research, such as spray atomization, turbulent dense spray flames, turbulent fires, and the effects of high pressure, are briefly mentioned. The paper concludes by highlighting the continued need for research in these areas of turbulent combustion to bring predictive capabilities to a level of comprehensive fidelity that enables them to become standard reliable tools for the design and monitoring of future combustors.

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(Video) Solving Complex Combustion Challenges

Masri AR. Challenges for turbulent combustion. In Proceedings of the Combustion Institute. Elsevier BV. 2021. p. 121-155 https://doi.org/10.1016/j.proci.2020.07.144

(Video) Challenges for Turbulent Combustion, Assaad Masri

FAQs

How does turbulence affect combustion? ›

This turbulence causes an increase in the burning velocity of the gases present, accelerating the production of heat and causing increased rates of pressure rise. Thus a knowledge of both the turbulence present and its effect on the combustion is required to understand the phenomena of these gas explosions.

What I found challenging combustion and flame? ›

Answer. It is more difficult to burn some combustible substances than others because different substances catch fire at different temperatures. Some substances have a low ignition temperature; therefore, they can catch fire more easily than others.

What causes fuel turbulence? ›

This pressure rise is caused by heating due to turbulent (frictional) mixing. With increasing pressure, the flame accelerates, which leads to higher energy release, in turn resulting in further compression and acceleration, and so on—a feedback loop that causes a catastrophic runaway to detonation.

What is a turbulent combustion chamber? ›

Inside a combustion chamber, an unsteady three-dimensional flow occurs, known as turbulent flow. This turbulence, plus the chemistry of various fuels combusting, makes for very complex phenomena.

How turbulence affect flame propagation speed? ›

The maximum velocity and duration of flame propagation increased with the increase in turbulence intensity. Under the same turbulence intensity, the flame propagation velocity generally augmented first and then lessened.

How does the flame speed affect the performance of combustion chamber? ›

The higher the flame speed is, the closer is the overall combustion process to the TDC, resulting in higher average temperature and pressure. As a result, auto-ignition in the end-gas region is prone to occur.

What are the three essential requirements for combustion? ›

What are the three essential requirements for combustion? Fuel, air (to supply oxygen) and heat (to raise the temperature of the fuel beyond the ignition temperature).

What precautions should we take to prevent incomplete combustion of fuel? ›

Explanation:
  • Leave proper gaps between logs of wood so that sufficient air reaches them for their complete combustion.
  • Use the grate for holding the burning solid fuels. ...
  • Use wick stove for gaseous fuel combustion. ...
  • In gaseous fuel like CNG and LPG, the stove has holes for constant supply of air.
10 Sept 2020

What are the conditions under which combustion takes place? ›

The conditions under which combustion can take place : Presence of combustible substance. Presence of a supporter of combustion i.e., oxygen. Attainment of ignition temperature
  • Presence of combustible substance.
  • Presence of a supporter of combustion i.e., oxygen.
  • Attainment of ignition temperature.

What are two main causes of turbulent flow? ›

Turbulence is a fluid flow in which layers mix together via eddies and swirls. It has two main causes. First, any obstruction or sharp corner, such as in a faucet, creates turbulence by imparting velocities perpendicular to the flow. Second, high speeds cause turbulence.

Which factors can cause turbulent flow? ›

Also, turbulent flow is affected by surface roughness, so that increasing roughness increases the drag. Transition to turbulence can occur over a range of Reynolds numbers, depending on many factors, including the level surface roughness, heat transfer, vibration, noise, and other disturbances.

How do you stop turbulence? ›

The best seat on the plane to avoid turbulence is either over the wings or towards the front of the aircraft. The wings of the plane keep it balanced and smooth, whereas the tail of the aircraft can bounce up and down more. The closer a passenger is to the front of the plane the less turbulence they would usually feel.

What causes turbulence in an IC engine? ›

Turbulence is caused by modified piston. Turbulence enhances mixing and probably produces a leaning effect. The turbulence in the combustion chamber makes the charge into homogeneous and increases the combustibility of fuel. So brake thermal efficiency of modified piston is 2% more than the normal piston.

What are the basic requirement of a good combustion chamber? ›

1 Basic Requirements of a Good Combustion Chamber. The three main requirements of a SI engine combustion chamber are high power output with minimum octane requirement, high thermal efficiency, and smooth engine operation.

What is turbulence in an engine? ›

The turbulent field in an engine is produced by high shear flows that occur during the intake process and/or near top dead center (TDC) of the compression stroke for engines that have large squish regions (i.e. a region of small clearance between the cylinder head and the piston crown).

What are the factors affecting the flame propagation? ›

Factors affecting flame propagation

Engine speed: Flame propagation speed increases almost linearly with engine speed. Fuel-air ratio: Velocity of flame diminishes if fuel is too lean or too rich. Turbulence: Turbulent motion of mixture increases the heat-mass transfer, and hence the flame propagation.

What are the types of turbulent flame? ›

6.1. 2 Turbulent flames. Turbulent flames, including jet flames (turbulent conical), bluff-body flames, and swirling premixed flames, are now reviewed with respect to static and dynamic stability. Turbulent conical jet flames in premixed cases have been significantly documented.

What are the different factors which influence the knocking? ›

Factors Affecting Knock

These are the temperature, pressure, density of the unburned charge and the time factors. Temperature factor includes inlet temperature of the mixture and temperature of the combustion chamber walls.

Why is flame speed important? ›

In a flow system, the flame speed depends on whether the flow is laminar or turbulent. It is important to consider flame speed for determining the rate that a fire can move through the flammable mixture and subsequently distribute the fire throughout the system.

What is ignition lag in combustion stage? ›

a noticeable rise in pressure due to combustion. This time lag is called IGNITION LAG. Ignition lag is the time interval in the process of chemical reaction during which. molecules get heated up to self ignition temperature , get ignited and produce a self. propagating nucleus of flame.

Which hydrocarbon has the highest burning velocity? ›

3.1.2.

Contrary to methane, ethane is the hydrocarbon corresponding to the highest laminar flame velocity with a maximum of 42 cm/s for an equivalence ratio of 1.1.

How many types of combustion are there? ›

There are five different forms of combustion- complete combustion, incomplete combustion, rapid combustion, spontaneous combustion, and explosion.

What is combustion efficiency? ›

Combustion efficiency is a measure of how effectively the heat content of a fuel is transferred into usable heat. The stack temperature and flue gas oxygen (or carbon dioxide) concentrations are primary indicators of combustion efficiency.

What type of process is combustion? ›

Combustion is a high-temperature exothermic chemical reaction. Hence, combustion is a chemical process. Because, here the substance is rapidly reacting with oxygen and there is a formation of heat. And this reaction is taking place between the fuel and an oxidant.

What are the causes of incomplete combustion? ›

Incomplete combustion is generally due to poor mixing of the air and fuel, insufficient residence time, insufficient temperature and low total excess air.

What is necessary for complete combustion of fuels? ›

Necessary Conditions for Combustion are-

Presence of a combustible substance, a fuel and a supporter of combustion. Heating the combustible substance to its ignition temperature and maintaining it. The presence of air or oxygen.

Why is incomplete combustion of fuels harmful to human beings? ›

During incomplete combustion part of the carbon is not completely oxidized producing soot or carbon monoxide (CO). Incomplete combustion uses fuel inefficiently and the carbon monoxide produced is a health hazard.

What are the required constituents and conditions required for combustion to take place? ›

Fire can be controlled by removing any or some factors of combustion, i.e. fuel, oxygen (air) and ignition temperature.

Which conditions are fulfilled in case of combustion A oxygen is reduced? ›

Complete combustion requires that the following conditions be satisfied: An adequate air (oxygen) supply. Adequate fuel/air mixture. Appropriate combustor temperature for fuel ignition.

What are the conditions required for computation? ›

Three things are required in proper combination before ignition and combustion can take place . They are heat ,oxygen and fuel......

Why is turbulence so important? ›

Some nearly 90 years later, the effort to understand and predict turbulence remains of immense practical importance. Turbulence factors into the design of much of our technology, from airplanes to pipelines, and it factors into predicting important natural phenomena such as the weather.

Why is turbulent flow important? ›

The mixing action of the turbulent flow enhances the temperature averaging effect in addition to the transfer of energy from the hot water to the surrounding fluid. When a hot object is cooled, the mixing action of turbulent flows in the fluid surrounding the object plays an important role in cooling it (Figure 2.3).

What are the characteristics of turbulent flow? ›

turbulent flow, type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, or mixing, in contrast to laminar flow, in which the fluid moves in smooth paths or layers. In turbulent flow the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction.

What are the four factors that affect flow rate? ›

Fluid flow in pipes is affected by many different factors: The viscosity, density, and velocity of the fluid. Changes in the fluid temperature will change the viscosity & density of the fluid. The length, inner diameter, and in the case of turbulent flow, the internal roughness of the pipe.

How does turbulence affect the flow properties? ›

In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, exchanging energy, as a result drag increases due to friction effects. The level of turbulence has significant impact on the stability of boundary and shear layers.

How does turbulent flow Increase heat? ›

The swirling and diffusive characteristics of turbulent flow enhances heat transfer. Mixing induced by turbulent flow can also disrupt the growth of boundary layer on heat exchanger core surfaces. However, turbulent flow is often associated with higher pressure drop.

What happens during turbulence? ›

Severe turbulence causes large and abrupt changes in altitude and/or attitude and, usually, large variations in indicated airspeed. The airplane may momentarily be out of control. Occupants of the airplane will be forced violently against their seat belts.

How do planes handle turbulence? ›

Planes are built to withstand most turbulence. And in the case of more extreme turbulence, which would ideally be navigated around, your pilot is able to bring down the plane's speed to a safe velocity, so your plane won't be damaged it passes through the disturbances.

What are the different types of turbulence? ›

Here are the 7 most common types of turbulence:
  • 1) Clear Air Turbulence. ...
  • 2) Thermal Turbulence. ...
  • 3) Temperature Inversion Turbulence. ...
  • 4) Mechanical Turbulence. ...
  • 5) Frontal Turbulence. ...
  • 6) Mountain Wave Turbulence. ...
  • 7) Thunderstorm Turbulence.
4 Mar 2016

How does turbulence affect the mass transfer coefficient? ›

The main effect of the clustering is to decrease the overall mass transfer rate. The second way turbulence influences the mass transfer rate is by increasing the mean velocity difference between the particle and the gas. This effect will increase the mass transfer rate.

What is equivalence ratio in combustion? ›

The equivalence ratio (ER) is the ratio between the oxygen content in the oxidant supply and that required for complete stoichiometric combustion. It is likely the most important operating parameter for allothermal processes, since it strongly affects the gas composition (including tar content) and its heating value.

What is mean by BSFC? ›

Brake-specific fuel consumption (BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft power. It is typically used for comparing the efficiency of internal combustion engines with a shaft output. It is the rate of fuel consumption divided by the power produced.

How do you calculate brake specific fuel consumption? ›

The formula of the brake specific fuel consumption is given by, BSFC = Fuel consumption rate(. m)Brake power (B.P.) Fuel consumption rate ( m . )

What factors affect mass transfer rate? ›

Some important factors affecting the mass transfer rate, such as surfactant and its content, stirring speed, ratio of reagents, treating ratio and volume ratio of membrane phase to internal phase, have been studied. The breakage and the swelling of the emulsion have also been investigated.

What affects mass transfer coefficient? ›

The mass transfer coefficients depend on the diffusivity of the solute and the hydrodynamics of the phases. They can be calculated using expressions derived from fundamentals of mass transfer, in the case of laminar flow, or from empirical correlations.

How do you increase mass transfer rate? ›

In that case you can increase mass transfer by increasing flow rate of the liquid (leads to elevated mass transfer coefficients), using more liquid (keeps the difference in chemical potential of the solute in the solid and the liquid at a higher level -> increased driving force) or exchange the liquid completely from ...

Why excess air is required for complete combustion? ›

To ensure complete combustion of the fuel used combustion chambers are supplied with excess air. Excess air increase the amount of oxygen to the combustion and the combustion of fuel.

What are the causes of incomplete combustion? ›

Incomplete combustion is generally due to poor mixing of the air and fuel, insufficient residence time, insufficient temperature and low total excess air.

Which is better lean or rich mixture? ›

The key difference between lean and rich fuel mixture is that we use a lean mixture for maximum efficiency while we use a rich mixture for maximum power in an engine. We use the terms lean and rich fuel mixtures to describe combustion processes in engines and industrial furnaces.

What is the limitation of EGR? ›

Abstract: Exhaust gas recirculation (EGR) is an effective strategy to control NOx emissions from diesel engines. NOx emissions may be further reduced by cooling of the EGR stream. Drawbacks of EGR include increased PM emissions and increased fuel consumption.

Is higher BSFC better? ›

A lower BSFC value is MORE efficient. Higher BSFC numbers are LESS efficient.

How can I improve my BSFC? ›

Retarding intake opening will also benefit BSFC due to improved effective compression ratio, i.e. larger effective expansion to compression ratio. Advancing the exhaust valve opening will always result a higher BSFC and is not beneficial. Advancing the intake valve opening also improves BSFC.

What's the most efficient engine? ›

The steam turbine is the most efficient steam engine and for this reason is universally used for electrical generation. Steam expansion in a turbine is nearly continuous, which makes a turbine comparable to a very large number of expansion stages.

Why does volumetric efficiency decrease with RPM? ›

Once chocked occurs, further increase of speed does not increase the flow rate significantly, thus, the volumetric efficiency decreases sharply. This sharp decrease happens due to the charge heating in the manifold and higher friction flow losses.

What is brake power formula? ›

The power developed by an engine at the output shaft is called brake power and is given by Power = NT/60,000 in kW where T= torque in Nm = WR W = 9.81 * Net mass applied in kg.

Videos

1. Canonical NH3H2N2 air turbulent flames state of the art and future challenges
(Clean Combustion Research Center, KAUST)
2. Multi-resolution Analysis for Assessment of Turbulent Combustion Models for LES
(Combustion Webinar)
3. Towards Exascale Simulation of Turbulent Combustion, Jacqueline Chen (Sandia National Lab, USA)
(cscsch)
4. Turbulent Combustion: Experiments and Fundamental Models, Driscoll, Day 5, Part 1
(CEFRC)
5. Turbulent Combustion: Experiments and Fundamental Models, Driscoll, Day 1, Part 3
(CEFRC)
6. Turbulent Combustion: Experiments and Fundamental Models, Driscoll, Day 3, Part 1
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