R ADIATION AND C OMBUSTION P HENOMENA P ROF. S EUNG W OOK B AEK D EPARTMENT OF A EROSPACE E NGINEERING, KAIST, IN KOREA R OOM : Building N7-2 #3304 T ELEPHONE : 3714 Cellphone: 010 – T A : Bonchan Gu R OOM : Building N7-2 # 3315 T ELEPHONE : 3754 Cellphone: 010 – P ROF. S EUNG W OOK B AEK D EPARTMENT OF A EROSPACE E NGINEERING, KAIST, IN KOREA R OOM : Building N7-2 #3304 T ELEPHONE : 3714 Cellphone: 010 – T A : Bonchan Gu R OOM : Building N7-2 # 3315 T ELEPHONE : 3754 Cellphone: 010 –

E XAMPLE R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM T WO C LOSELY L OCATED P ARALLEL P LATES. T EMPERATURES A RE &. R ADIOSITIES

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM V IEW F ACTORS R EFER TO (REF.1 S&H) P.197 Ex 6-2 AND P.297 Ex 7-21

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM A LSO, BY R ECIPROCITY THEN I NTEGRAL EQUATION REF) F.B. Hildebrand Methods of Application Mathematics

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM EX) P.289 Ex 7-18, P.297 Ex 7-21 (REF.1) FROM M ETHODS FOR S OLVING I NTEGRAL E QUATIONS P.299 HW#2 [REF.1] P.317 #7-16(a), P.325 #7-40

7-16. (a) What is the effect of a single thin radiation shield on the transfer of energy between two concentric cylinders? Assume the cylinder and shield surfaces are diffuse-gray with emissivities independent of temperature. Both sides of the shield have emissivity, and the inner and outer cylinders have respective emissivities and A cavity having a gray interior surface is uniformly heated electrically and achieves a surface temperature distribution while being exposed to a zero absolute temperature environment,. If the environment is raised to and the heating kept the same, what will the surface temperature distribution be?

C OMBINED H EAT T RANSFER R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM E NERGY B ALANCE E XAMPLE 1

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM C ASE I) SMALL I NTRODUCE, P LANCK N UMBER R EARRANGE AS

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM C ASE II)

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM 1. C ONSERVATION OF M ASS E XAMPLE 2 C OUETTE F LOW 2. C ONSERVATION OF M OMENTUM

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM 2 (a). C ONSERVATION OF M ECHANICAL E NERGY 3. C ONSERVATION OF T OTAL (THERMAL + MECHANICAL) E NERGY 4. B ALANCE OF T HERMAL E NERGY

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM 5. C ONSTITUTION G OVERNING E QUATION B OUNDARY C ONDITIONS

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM S OLUTION N OTE M OMENTUM S OLUTION A DIABATIC W ALL T EMPERATURE

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM E FFECT OF R ADIATION ON THE A DIABATIC W ALL T EMPERATURE

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE N ON -E QUILIBRIUM L INEARIZE, HW#3 [REF.1] P.447 #10-2, P.449 #10-12

10-2. A thin two-dimensional fin in vacuum is radiating to outer space, which is assumed at. The base of the fin is at, and the heat loss from the end edge of the fin is negligible. The fin surface is gray with emissivity. Write the differential equation and boundary conditions in dimensionless form for determining the temperature distribution of the fin. (Neglect any radiant interaction with the fin base.) Can you separate variables and indicate the integration necessary to obtain the temperature distribution? A copper-constantan thermocouple ( ) is in an inert gas stream at 350K adjacent to a large blackbody surface at 900K. The heat transfer coefficient from the gas to the thermocouple is. Estimate the thermocouple temperature if it is (a) bare (b) surrounded by a single polished aluminum radiation shield in the form of a cylinder open at both ends. The heat transfer coefficient from the gas to both sides of the shield is.

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY G AS R ADIATION R EADING A SSIGNMENTS CARBON DIOXIDE AND WATER VAPOR FORMED AS PRODUCTS OF COMBUSTION WERE FOUND TO BE THE SIGNIFICANT EMITTERS AND ABSORBERS OF RADIANT ENERGY (P.514 Fig 12-1, eg : FURNACE, ENGINE, ETC.) THE ENERGY EMITTED FROM FLAME ; DEPENDS NOT ONLY ON THE GASEOUS EMISSION BUT ALSO ARISES FROM THE HEATED CARBON (SOOT) PARTICLES FORMED WITHIN THE FLAME TWO DIFFICULTIES Absorption, emission and scattering occur not only at system boundaries, but also at some locations within the medium. Spectral effects are much more pronounced in gases than for solid surfaces – non-gray. (p.539, Fig.12-10)

A TTENUATION BY E ARTH’S A TMOSPHERE OF I NCIDENT S OLAR S PECTRAL E NERGY F LUX R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY G AS R ADIATION

L OW- R ESOLUTION S PECTRUM OF A BSORPTION B ANDS FOR V ARIOUS G ASES R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY C ARBON D IOXIDE G AS AT 830 K, 10 atm, AND FOR P ATH L ENGTH THROUGH G AS OF m. G AS R ADIATION

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY C ARBON D IOXIDE, W ATER V APOR, AND M ETHANE G AS R ADIATION

P HYSICAL M ECHANISMS OF A BSORPTION, E MISSION AND S CATTERING R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY A BSORPTION AND E MISSION (P.540, FIG 12-11, P.553, FIG12-16) (REF.1) B OUND- B OUND A BSORPTION OR E MISSION A photon is absorbed or emitted by an atom or molecule without ionization or recombination of ions and electrons. Since bound-bound energy changes are associated with specific energy levels, the absorption and emission coefficients will be sharply peaked functions of frequency in the form of a series of spectral lines – do have a finite width resulting from various broadening effects. The rotational spectral lines superimposed on the vibrational line give a band of closely spaced spectral lines (p.553 Fig.12-16). At industrial temps the radiation is principally from vibrational and rotational transitions ; at high temps, it is electronic transitions that are important. G AS R ADIATION

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY Bound-free absorption coefficient is a continuous function of photon energy frequency. Resulting ion and electron take on any kinetic energy. Free bound emission produces a continuous spectrum, as the combining particles have any initial kinetic energy. G AS R ADIATION B OUND F REE A BSORPTION ( P HOTOIONIZATION) OR F REE B OUND E MISSION ( P HOTORECOMBINATION) F REE F REE T RANSITION Since the initial and final free energies can have any values, a continuous absorption or emission spectrum is produced.

E NERGY S TATES AND T RANSITIONS FOR A TOM OR I ON R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY G AS R ADIATION

P OTENTIAL E NERGY D IAGRAM AND T RANSITIONS FOR A D IATOMIC M OLECULE R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY G AS R ADIATION

R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY Scattering – Any encounter between a photon and one or more other particles during which the photon does not lose its entire energy. Scattering coefficient : The inverse of the mean free path that a photon of wave length will travel before undergoing scattering. Elastic scattering – photon energy (frequency) unchanged Inelastic scattering - changed G AS R ADIATION S CATTERING