Material and Its Thermal Property
Transcript of Material and Its Thermal Property
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MATERIAL & ITS THERMAL
PROPERTIES
to be presented by-
PURNENDU KARTIKAY
Energy Engineering (4th Sem.)
Roll no:26
CUJ/I/2011/IEE/25 Under the guidance of –
Dr. Basudev Pradhan
Mr. Partha Das
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IN THIS PRESENTATION
What is Material Science ?
Why we study Material Science?
Thermal Properties of Materials..
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MATERIAL SCIENCE
Material Science
The discipline of investigating the relationshipsthat exist between the structures and
properties of materials.Material Engineering
The discipline of designing or engineering thestructure of a material to produce a
predetermined set of properties based onestablished structure-property correlation.
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WHY MATERIAL SCIENCE
The knowledge of Material Science serves
as a basic for the development of new
materials for the generation, storage, an
use of energy and for mitigation of the
environmental impacts of energy use..
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M a t e r i a l s
Metals
Ceramics
Polymers
Composites
AdvancedMaterials
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Metals
Iron
Aluminum
Copper
Titanium
Ceramics
Glass
Concrete
Brick
Alumina
Polymers
Plastics
Wood
Cotton(rayon,nylon)
Glue
Composites
Glass fibre
EngineeredWoods
CarbonFibre
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THERMAL PROPERTIES
The characteristic of material that determine how it
reacts when it is subjected to excessive heat, or heat
fluctuation over time
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HEAT CAPACITY
A property that is indicative of a material’s
ability to absorb heat from the external
surroundings.
The energy required to increase thetemperature of the material.
dT
dQ
C
C=heat capacity
(J/mol-K)
energy input (J/mol)
temperature change
(K)
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COMPARISON OF HEAT CAPACITY
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PLOT OF HEAT CAPACITY VS. TEMPERATURE
GRAPH
• Heat capacity... increases with temperature
reaches a limiting value of 3R
The temperature dependence of the heat capacity at constant volume; D is the
Debye temperature
*Debye temperature is the highest temperature that
can be achieved due to a single normal vibration.
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THERMAL EXPANSION
It is the tendency of matter to change in volume
in response to a change in temperature.
)( initial finalinitial
initial finalT T
L
L L
α
α= Coefficient of Thermal Expansion
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COMPARISON OF THERMAL EXPANSION
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CONSEQUENCE OF THERMAL EXPANSION
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THERMAL CONDUCTIVITY
The ability of a material to transfer heat.
q=heat flux (J/m2-s)
k=thermal conductivity (J/m-K-s)
= temperature gradient
q kdT
dx
dx
dT
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COMPARISON OF THERMAL CONDUCTIVITY
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WIEDEMANN–FRANZ LAW (1953)
It is the ratio of the electronic contribution of
the thermal conductivity (κ) to the electrical
conductivity (σ) of a metal, and is proportional
to the temperature (T).σ=electrical conductivity
k=thermal conductivity
T=absolute temperature
L=constant {2.44*10^8 Ω-W/(K)^2}
T
k
σ
L
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THERMAL STRESS
Stresses that are induced in a body as a result
of changes in temperature.
= (∆ )
=Thermal StressE=Modulus of Elasticity
=linear coefficient of thermal expansion
∆ =change in temperature
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THERMAL SHOCK
It occurs when a thermal gradient causes
different parts of an object to expand by
different amounts.
In a layman words it occurs due to unevenheating/cooling.
Thermal shock is a primary contributor to head
gasket failure in internal combustion engines.
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CONCLUSIONS
by the study of thermal properties of materials-
We can design the buildings with well insulated
walls by using materials like mineral wool and
polystyrene..
During the construction of bridges the thermal joints should be provided which allows the
metals to expand due to thermal expansion..
Thermal sock can be prevented by reducing the
thermal gradient seen by the object, by
Changing its temperature more slowly
Increasing the material's thermal conductivity
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