Radiation Advanced Transport Phenomena Peter Hamersma, Faculty of - - PowerPoint PPT Presentation

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Oct 21, 2023 346 likes •513 views

Radiation Advanced Transport Phenomena Peter Hamersma, Faculty of Applied Sciences Energy loss Energy loss Radiation Convection Conduction Cooking Radiator Stefan-Boltzmann Black body: Absorbs all incoming radiation black = AT 4

SLIDE 1

Radiation

Advanced Transport Phenomena

Peter Hamersma, Faculty of Applied Sciences

SLIDE 2

Energy loss

SLIDE 3

Energy loss

Convection Conduction Radiation

SLIDE 4

Cooking

SLIDE 5

Radiator

SLIDE 6

Stefan-Boltzmann

Black body: Absorbs all incoming radiation

φblack =σAT 4withσ = 5.6710−8W /(m2 ⋅K 4)

SLIDE 7

Black body radiation: Parallel plates

T1 T2

SLIDE 8

Grey body radiation: Parallel plates

T1 T2

4 4 1 2 , ,12 ,21 1 2

( ) 1 1 1

grey net grey grey

A T T e e σ φ φ φ − = − = ⎛ ⎞ + − ⎜ ⎟ ⎝ ⎠

4 4 1 2

( ) 1 1 1 1 1 A T T σ − = ⎛ ⎞ + − ⎜ ⎟ ⎝ ⎠

4 4 1 2

( ) A T T σ = −

SLIDE 9

Radiation: Free form

T2 T1

SLIDE 10

Radiation: Free form

T2 T1

4 4 1 2 1 2

( ) ( )

radiation effective

T T h e T T σ − = −

SLIDE 11

Radiation: Free form

T2 T1

4 4 1 2 1 2

( ) ( )

radiation effective

T T h e T T σ − = −

1 2

( ) T T −

SLIDE 12

Example: Thermometer

Twall<Tthermo Twall Tair Tthermo Tthermo=Tair?

( )

radiation radiation thermo wall

h A T T φ = − ( )

convection convection air thermo

h A T T φ = −

SLIDE 13

Example: Thermometer

Twall<Ttherm

Twall

Tair Tthermo Tthermo=Tair ?

( )

radiation radiation thermo wall

h A T T φ = − ( )

convection convection air thermo

h A T T φ = − ( ) ( )

radiation thermo wall convection air thermo

h A T T h A T T − = −

4 ( ) ( )

air thermo thermo wall convection

e T T T T T h σ − ≈ − = T 300K

− =

thermo wall

(T T ) 10K = e 0.05 = ⋅

2 convection

h 6W /(m K) − =

air thermo

(T T ) 0.5K

SLIDE 14

Free convection & radiation

SLIDE 15

Thanks for your attention

Advanced Transport Phenomena Peter Hamersma, Faculty of Applied Sciences