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Approximation Error RACKETT EQUATION RADAR RADIAL COMPRESSOR RADIAL ENERGY FLOWS RADIAL FANS RADIAL GAP SIZE RADIATION RADIATION ABSORPTION METHOD RADIATION BETWEEN PARALLEL PLATES RADIATION DIFFUSION APPROXIMATION, FOR COMBINED RADIATION AND CONDUCTION RADIATION DOSIMETRY RADIATION DRYING Radiation from semi-transparent oxide particles in thermal spraying Radiation heat transfer in a supersonic nozzle of a solid-propellant rocket engine Radiation heat transfer in solid-propellant rocket engines RADIATION IN ENCLOSURES Radiation in nanomanufacturing Radiation in production of carbon fibers Radiation of an isothermal plane-parallel layer Radiation of isothermal volumes of scattering medium: An error of the diffusion model Radiation of nonisothermal layer of scattering medium RADIATION SHIELDS RADIATION TO FURNACE TUBES Radiation transfer between the surfaces through a non-participating medium Radiation transfer in emitting, absorbing and scattering media Radiation transfer in combustion chambers Radiation transfer problems in nature and engineering Radiation transfer theory and the computational methods Radiation-turbulence interaction Radiative boundary layer Radiative cooling and solidification of core melt droplets Radiative cooling of particle flow in vacuum RADIATIVE DIFFUSION Radiative effects in semi-transparent liquid containing gas bubbles Radiative equilibrium in plane-parallel layer RADIATIVE EXCHANGE Radiative exchange between an isothermal gas and surrounding walls RADIATIVE HEAT FLUX Radiative heat transfer Radiative heat transfer in moving media RADIATIVE HEAT TRANSFER, IN POROUS MEDIA Radiative properties of gas bubbles in semi-transparent medium Radiative properties of metal particles in infrared and microwave spectral ranges Radiative properties of micro- and nanostructures Radiative properties of particles and fibers (theoretical analysis) Radiative properties of polydisperse systems of independent particles Radiative properties of semi-transparent fibers at arbitrary illumination Radiative properties of semi-transparent particles Radiative properties of single particles and fibers: the hypothesis of independent scattering and the Mie theory Radiative properties of soot particles Radiative properties of water droplets in near infrared RADIATIVE SPECTRAL INTENSITY Radiative transfer equation Radiative transfer equation: a general formulation Radiative transfer for coupled atmosphere and ocean systems Radiative transfer in combustion phenomena affected by radiation Radiative transfer in combustion systems Radiative Transfer in Coupled Atmosphere and Ocean Systems: Impact of Surface Roughness on Remotely Sensed Radiances Radiative transfer in coupled atmosphere and ocean systems: the adding and doubling method Radiative Transfer in Coupled Atmosphere and Ocean Systems: the Discrete Ordinate Method RADIATIVE TRANSFER IN COUPLED ATMOSPHERE AND OCEAN SYSTEMS: THE SUCCESSIVE ORDER OF SCATTERING METHOD Radiative transfer in glass production Radiative transfer in laminar flames Radiative transfer in laser processing Radiative transfer in medical laser treatment RADIATIVE TRANSFER IN MULTIDIMENSIONAL PROBLEMS: A COMBINED COMPUTATIONAL MODEL Radiative transfer in space applications Radiative transfer in the atmosphere Radiative transfer in turbulent flames Radiative transfer in two-phase combustion Radiative-conductive heat transfer in dispersed materials Radiative-conductive heat transfer in foam insulations RADIO FREQUENCY HEATING RADIO FREQUENCY, RF, DRYING RADIO WAVES RADIOACTIVE DECAY RADIUM RADIUS, HYDRAULIC RADON RAE RAFFINATE PHASE RAINBOW VOLUMIC VELOCIMETRY RAINFALL RAMAN SPECTROSCOPY RAMJET ENGINES RANDOM PROCESSES RANKINE CYCLE RANKINE DEGREE RANKINE VORTEX RANKINE, WJM RAOULT'S AND DALTON'S LAW RAOULT'S LAW RAREFACTION RAREFACTION WAVE RAREFIED GAS DYNAMICS RATE-CONTROLLED CONSTRAINED EQUILIBRIUM Ray effects and false scattering Ray optics and wave effects in radiation propagation Rayleigh equation, for bubble growth Rayleigh equation, for droplet formation Rayleigh formula Rayleigh law of scattering Rayleigh number Rayleigh scattering Rayleigh, Lord (1842-1919) Rayleigh-Gans scattering Rayleigh-Taylor instability REACTING GAS FLOW REACTION TURBINES REACTIVE CONTAMINANT TRANSPORT REACTOR PHYSICS Real gaseous spectra REATTACHMENT REATTACHMENT, OF BOUNDARY LAYER Reaumur Degree REBOILERS RECIPROCATING COMPRESSOR RECIRCULATION RECIRCULATION BOILERS RECONSTRUCTED WAVEFRONTS RECOVERY COEFFICIENT RECOVERY TEMPERATURE RECTANGULAR CHANNEL RECTANGULAR CYLINDERS RECTANGULAR DUCTS RECTANGULAR STENOTIC MODELS RECUPERATIVE HEAT EXCHANGERS REDLICH-KWONG EQUATION REDOX REACTIONS REDUCED GRAVITY CONDITIONS REDUCED INSTRUCTION SET COMPUTER, RISC REDUCED PROPERTIES REFINING REFLECTANCE REFLECTION COEFFICIENT (REFLECTANCE) REFLECTION COEFFICIENTS FOR EARTH'S SURFACE REFLECTIVITY REFLOOD REFLUX CONDENSATION REFLUX CONDENSER REFLUX RATIOS REFORMING REFRACTION REFRACTIVE INDEX REFRACTIVE INDICES FOR GASES AND LIQUIDS REFRACTORY MATERIALS, FOR ELECTRIC FURNACES REFRIGERANTS REFRIGERATION REGENERATIVE BURNER REGENERATIVE FEED HEATING REGENERATIVE GAS TURBINE REGENERATIVE HEAT EXCHANGERS REGULAR REGIME OF DRYING REHEATING REICHARDT'S FORMULA, FOR VELOCITY DISTRIBUTION IN TUBES REIMANN'S INTEGRAL REINER-RIVLIN FLUID RELATIVE HUMIDITY RELATIVE MOLAR MASS RELATIVE PERMEABILITY RELATIVE POWER DEMAND, RPD RELATIVE ROUGHNESS RELAXATION TIME RENEWABLE ENERGY RENEWABLE ENERGY SOURCES RESIDUAL ENTHALPY RESIDUAL GIBBS ENERGY RESINS RESISTANCE HEATING RESISTANCE THERMOMETERS RESISTANCE THERMOMETRY RESISTANCE, ELECTRICAL RESISTIVITY, ELECTRICAL RESONANCE FLUORESCENCE RETENTATE RETENTION INDEX RETROGRADE CONDENSATION RETURN TO NUCLEATE BOILING REVERSE OSMOSIS REVERSED HEAT ENGINE CYCLES REVERSIBILITY PRINCIPLE REVERSIBLE PROCESSES REWETTING REWETTING OF HOT SURFACES REYNOLDS ANALOGY Reynolds Number REYNOLDS NUMBER, CRITICAL, IN TUBES REYNOLDS STRESS REYNOLDS STRESS TRANSPORT MODELS REYNOLDS' AVERAGING REYNOLDS' EQUATIONS REYNOLDS, OSBORNE (1842-1912) RHEOLOGY RHEOMETERS RHEOPEPTIC FLUIDS RHODAMINE RICCATTY-BESSEL FUNCTIONS RICHARDSON NUMBER RIDEAL-ELEY MODEL, FOR HETEROGENEOUS CATALYSIS RIEDEL-PLANK-MILLER EQUATION RIEMAN WAVES RIGHT-ANGLE TRIANGULAR ENCLOSURE RIGID-WALLED CHANNEL RISC. REDUCED INSTRUCTION SET COMPUTER RISK ANALYSIS TECHNIQUES RISK ASSESSMENT ROASTING ROCKET PROPELLANTS ROCKETS ROD BAFFLES ROD BUNDLE TESTS ROD BUNDLES, FLOW IN ROD BUNDLES, HEAT TRANSFER IN ROD BUNDLES, PARALLEL FLOW IN ROD CLIMBING ROD-STABILIZED LAMINAR PREMIXED FLAME RODRIGUES FORMULA ROHRSCHNEIDER CONSTANT ROLL MOMENT ROLL WAVES ROOTS TYPE COMPRESSOR ROSIN-RAMMLER ROSIN-RAMMLER SIZE DISTRIBUTION ROSSBY NUMBER ROSSELAND COEFFICIENT ROTAMETERS ROTARY ATOMIZERS ROTARY DRYERS ROTARY KILNS ROTARY REGENERATORS ROTATED TUBE BANKS ROTATING CHANNEL WITH RIBS ROTATING CYLINDERS, CRITICAL SPEED ROTATING CYLINDERS, FLOW BETWEEN ROTATING CYLINDERS, FLOW OVER ROTATING DISC CONTACTOR ROTATING DISC SYSTEMS, APPLICATIONS ROTATING DISC SYSTEMS, BASIC PHENOMENA ROTATING DUCT SYSTEMS, ORTHOGONAL, HEAT TRANSFER IN ROTATING DUCT SYSTEMS, PARALLEL, HEAT TRANSFER IN ROTATING FLOW IN A POROUS LAYER ROTATING FLOW PASSAGE ROTATING PIPE FLOW ROTATING SURFACES ROTATIONAL DISCONTINUITIES Rotational Rayleigh number ROTATIONAL REYNOLDS NUMBERS ROUGH CHANNELS, FRICTION FACTOR IN ROUGH SURFACE FRICTION FACTORS ROUGH SURFACES ROUGH TUBES ROUGH TUBES, FLOW IN ROUGH TUBES, HEAT TRANSFER IN ROUGHNESS FACTORS ROYAL ACADEMY OF ENGINEERING, RAE ROYAL SOCIETY OF CHEMISTRY ROYAL SOCIETY, RS RS RSC RUBBER RUMFORD, COUNT, BENJAMIN THOMPSON RUSHTON TURBINE
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Radiative transfer in combustion systems

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RADIATIVE TRANSFER IN COMBUSTION SYSTEMS

R. Viskanta

Leading to: Combustion phenomena affected by radiation; Radiative transfer in laminar flames; Radiative transfer in turbulent flames; Radiative transfer in combustion chambers; Radiative transfer in two-phase combustion; Thermal radiation in unwanted fires

Fossil fuel utilization, primarily in the form of combustion transformations, has been the backbone of worldwide development for about two centuries. The reliance on fossil fuel is not likely to change in the foreseeable future because gas and remaining supplies of coal, oil, shale oil, and tar sands appear to be adequate for decades. Some of these sources are to be gradually replaced by renewable fuels, and alternate technologies such as direct conversion of solar radiation to electricity, wind power, etc., are expected to replace fossil fuels. In spite of these trends and the anticipated continuing cost advantage of fossil fuel–based combustion technologies, there are and will continue to be research, development, and design requirements for advanced as well as sustainable combustion technologies in the decades to come.

Combustion is the oldest technology of mankind and has furnished man with a major source of energy for more than one million years, and at present about 90% of our worldwide energy needs (e.g., in electrical power generation, transportation, heating) is provided by combustion of hydrocarbon fuels. More recently, nuclear energy has provided a significant fraction of energy for electric power. However, many years will elapse before combustion loses its predominance, and for the foreseeable future it will continue to be an energy source for power, industrial processes, human comfort, etc.

Combustion is a rapid oxidation generating heat or both heat and radiation. This definition emphasizes the intrinsic importance of chemical reactions to combustion and why combustion is so useful. Combustion transforms energy stored in chemical bonds of a fuel to heat that can be utilized in a variety of ways.

The purpose of combustion is to retrieve energy from the burning of fuels in the most efficient way possible. Combustion can occur in either a flame or a nonflame mode. A flame is considered to be a combustion reaction that can propagate subsonically through space. It is usually accompanied by the emission of radiation (ultraviolet, visible, and infrared). The property of spatial propagation is the important one that distinguishes flames from other combustion reactions. The spatial propagation of flames is a result of strong coupling between chemical reaction kinetics, the transport processes of mass and heat diffusion, and fluid flow. Heat transfer, thermal radiation, and active species can all accelerate a chemical reaction. Qualitatively, this can be considered as a positive feedback. If the feedback exceeds some threshold, the system will be self-sustaining. The existence of flame motion implies that the reaction is confined to a small zone. This reaction zone is called the flame front, combustion wave, or combustion zone.

In view of the preceding discussion, it is certain that in the future scientists and engineers engaged in development of combustion technologies will be confronted with complex phenomena that depend on interrelated processes of thermodynamics, chemical kinetics, fluid flow, heat and mass transfer, turbulence, and radiative transfer. Thermal radiation in combustion systems at high temperatures is an important energy transport process that needs to be considered for both fundamental understanding of the process and for its implementation in practical combustion systems. In this contribution to THERMOPEDIA, we apply the fundamental concepts and methodologies of radiative transfer theory to combustion situations arising in ignition of solids, laminar and turbulent flames, combustion chambers, furnaces for materials processing, and unwanted fires.

This article focuses on recent interest of incorporating radiative transfer in fundamental combustion analysis and practical combustion systems. Radiation does not directly affect the physicochemical reaction processes and major species, but the transfer of radiation indirectly alters the flame temperature distribution and, consequently, the local rate of elementary chemical reactions and minor species through, for instance, chemoluminesence and other de-excitation processes. Combustion textbooks (Williams, 1985; Kuo, 1986; Turns, 2000) have decoupled combustion and radiation. In the past, flame radiation was considered a posteriori based on the adiabatic temperature, which is determined from combustion analysis without considering the effects of radiative transfer. More recent works that have accounted for radiative transfer in fundamental combustion studies have revealed that radiation can significantly affect the flame temperature, minor species, the NOx emissions, soot formation, flame extinction, and other phenomena (Chan, 2005; Viskanta, 2005). In the articles to follow, knowledge of radiative transfer is used to account for radiation in combustion phenomena and in combustion systems. Reference is made to textbooks on radiation in participating media (Brewster, 1992; Siegel and Howell, 2002; Modest, 2003) for fundamentals of the theory and for practical results that can be applied to combustion.

REFERENCES

Brewster, M. Q., Thermal Radiative Transfer and Properties, Wiley, Hoboken, NJ, 1992.

Chan, S. H., Combined Radiation and Combustion, In C.L. Tien, Ed., Annual Review of Heat Transfer, Vol. 14, Begell House, New York and Redding, CT, pp. 49–64, 2005.

Kuo, K. K., Principles of Combustion, Wiley, Hoboken, NJ, 1986.

Modest, M. F., Radiative Heat Transfer, 2nd ed., Academic Press, Amsterdam, 2003.

Siegel, R. and Howell, J. R., Thermal Radiation Heat Transfer, 4th ed., Taylor and Francis, New York, 2002.

Turns, S. R., An Introduction to Combustion, 2nd ed., McGraw-Hill, New York, 2000.

Viskanta, R., Radiative Transfer in Combustion Systems: Fundamental and Applications, Begell House, New York and Redding, CT, 2005.

Williams, F. A., Combustion Theory: The Fundamental Theory of Chemically Reacting Flow Systems, 2nd ed., Benjamin/Cummings Publishing, Menlo Park, CA, 1985.

References

  1. Brewster, M. Q., Thermal Radiative Transfer and Properties, Wiley, Hoboken, NJ, 1992.
  2. Chan, S. H., Combined Radiation and Combustion, In C.L. Tien, Ed., Annual Review of Heat Transfer, Vol. 14, Begell House, New York and Redding, CT, pp. 49–64, 2005.
  3. Kuo, K. K., Principles of Combustion, Wiley, Hoboken, NJ, 1986.
  4. Modest, M. F., Radiative Heat Transfer, 2nd ed., Academic Press, Amsterdam, 2003.
  5. Siegel, R. and Howell, J. R., Thermal Radiation Heat Transfer, 4th ed., Taylor and Francis, New York, 2002.
  6. Turns, S. R., An Introduction to Combustion, 2nd ed., McGraw-Hill, New York, 2000.
  7. Viskanta, R., Radiative Transfer in Combustion Systems: Fundamental and Applications, Begell House, New York and Redding, CT, 2005.
  8. Williams, F. A., Combustion Theory: The Fundamental Theory of Chemically Reacting Flow Systems, 2nd ed., Benjamin/Cummings Publishing, Menlo Park, CA, 1985.

Leading to:

Thermal radiation in unwanted fires
Radiative transfer in two-phase combustion
Radiative transfer in turbulent flames
Radiative transfer in laminar flames
Radiative transfer in combustion phenomena affected by radiation
Radiation transfer in combustion chambers

This article belongs to the following areas:

Rocket Engines and Aerospace Applications in Applications
Industrial Thermal Engineering in Applications
Combustion Systems in Applications
Radiation transfer problems in nature and engineering in Fundamentals
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