H E A T SKMM 3443 T R A N S HEAT TRANSFER F E Rmazlan/?download=HT Cengel - Chapter 4 -...
Transcript of H E A T SKMM 3443 T R A N S HEAT TRANSFER F E Rmazlan/?download=HT Cengel - Chapter 4 -...
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HEAT
TRANSFER
SKMM 3443
HEAT TRANSFERHEAT TRANSFER
CCHH
AA
PP
TT
EE
RR
44DrDr Mazlan 2016Mazlan 2016
LECTURER: ASSOC PROF. DR. MAZLAN ABDUL WAHIDhttp://www.fkm.utm.my/~mazlan
TEXT: Heat and Mass TransferFundamental and Applications, 5th Edition by Cengel & GhajarMc Graw Hill
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HEAT
TRANSFER
ASSOC. PROF. DR. MAZLAN ABDUL WAHID
Transient Heat Conduction
CCHH
AA
PP
TT
EE
RR
44DrDr Mazlan 2016Mazlan 2016
2
2
ASSOC. PROF. DR. MAZLAN ABDUL WAHIDC24-333
Towards an Entrepreneurial University
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Recap
• Generalized Heat Conduction Equation
• Steady-one dimensional
• Including heat generation• Including heat generation
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Transient Heat Conduction
Lumped capacitance
methodSpatial effects
method
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Lumped capacitance Spatial effects
Lumped Capacitance Method
“Analysis tool for solids with negligible
temperature gradients”
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Lumped capacitance Spatial effects
Lump?
Synonym of lump: combine, put, group, bunch,
aggregate, unite, pool, mix, blend, merge, mass,
join, fuse, conglomerate, coalesce, consolidate,
collect, throw, collect, throw,
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Lumped capacitance Spatial effects
Capacitance analogy
Capacitors store
electric charge
Solids store
heat
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Lumped capacitance Spatial effects
Energy balance
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Lumped capacitance Spatial effects
Energy balance
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Lumped capacitance Spatial effects
Thermal time constant
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Lumped capacitance Spatial effects
Thermal time constant
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Lumped capacitance Spatial effects
Thermal time constant
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Lumped capacitance Spatial effects
Heat transfer rate
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Lumped capacitance Spatial effects
Validity of Lumped Capacitance
Method
Relate the temperature change in the solid to
the temperature change between surface and
fluid
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Lumped capacitance Spatial effects
Biot Number
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Lumped capacitance Spatial effects
Non-Conservative Characteristic
Length
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Lumped capacitance Spatial effects
Conservative Characteristic Length
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Lumped capacitance Spatial effects
Biot Number
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Lumped capacitance Spatial effects
Biot Number
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Lumped capacitance Spatial effects
Biot Number
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Lumped capacitance Spatial effects
Biot number
Which one can we apply LCM ?
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Lumped capacitance Spatial effects
Biot number
Which one can we apply LCM ?
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Lumped capacitance Spatial effects
Example (Problem 4-21)
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Lumped capacitance Spatial effects
Spatial Effects: One dimensional
Large plane
wallLong cylinder Sphere
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Lumped capacitance Spatial effects
Fourier Number (Revisit)
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Lumped capacitance Spatial effects
Transient, one dimensional conduction
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Lumped capacitance Spatial effects
Plane wall : Transient, one dimensional
conduction
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Lumped capacitance Spatial effects
Plane wall : Transient, one dimensional
conduction
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Lumped capacitance Spatial effects
Plane wall : Transient, one dimensional
conduction
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Lumped capacitance Spatial effects
Plane wall : Transient, one dimensional
conduction
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Lumped capacitance Spatial effects
Plane wall : Transient, one dimensional
conduction
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Lumped capacitance Spatial effects
Approximate analytical solution
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Lumped capacitance Spatial effects
One term approximation
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Lumped capacitance Spatial effects
One term approximation
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Lumped capacitance Spatial effects
One term approximation
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Lumped capacitance Spatial effects
One term approximation
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Lumped capacitance Spatial effects
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Lumped capacitance Spatial effects
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Lumped capacitance Spatial effects
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Lumped capacitance Spatial effects
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Lumped capacitance Spatial effects
Example (Problem 4-39)