material and its thermal property

8/18/2019 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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material and its thermal property

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