PPT: Introduction to Heat Transfer | Heat Transfer - Mechanical Engineering

 Page 2


INTRODUCTION
Heat transfer is a physical process
involving the transfer of heat from hot area
to cold area.
? Heat transfer occurs due to temperature
difference i.e. driving force between the points
where heat is received and where heat is
originating.
? Heat always tend to flow from point of high
temperature to point of low temperature.
Page 3


INTRODUCTION
Heat transfer is a physical process
involving the transfer of heat from hot area
to cold area.
? Heat transfer occurs due to temperature
difference i.e. driving force between the points
where heat is received and where heat is
originating.
? Heat always tend to flow from point of high
temperature to point of low temperature.
INTRODUCTION
? It is a unit operation.
? It is always accompanied by another unit 
operation in practice such as…
Heating & cooling of liquid/solid/air
Refrigeration
Evaporation
Drying
Distillation
Page 4


INTRODUCTION
Heat transfer is a physical process
involving the transfer of heat from hot area
to cold area.
? Heat transfer occurs due to temperature
difference i.e. driving force between the points
where heat is received and where heat is
originating.
? Heat always tend to flow from point of high
temperature to point of low temperature.
INTRODUCTION
? It is a unit operation.
? It is always accompanied by another unit 
operation in practice such as…
Heating & cooling of liquid/solid/air
Refrigeration
Evaporation
Drying
Distillation
MECHANISM OF HEAT TRANSFER
There are 3 basic mechanisms of heat 
transfer.
? Conduction
? Convection
? Radiation
Page 5


INTRODUCTION
Heat transfer is a physical process
involving the transfer of heat from hot area
to cold area.
? Heat transfer occurs due to temperature
difference i.e. driving force between the points
where heat is received and where heat is
originating.
? Heat always tend to flow from point of high
temperature to point of low temperature.
INTRODUCTION
? It is a unit operation.
? It is always accompanied by another unit 
operation in practice such as…
Heating & cooling of liquid/solid/air
Refrigeration
Evaporation
Drying
Distillation
MECHANISM OF HEAT TRANSFER
There are 3 basic mechanisms of heat 
transfer.
? Conduction
? Convection
? Radiation
CONDUCTION
“When heat flow in a body is achieved by
the transfer of the momentum of individual
atoms or molecules without mixing, such
process is known as conduction.”
? It takes place in solids and fluids whose
movement is restricted.
? e.g. - iron rod such as metal wall of an
evaporator.