Presentation related to thermofluids.

1. University of Engineering &
Technology Lahore
DEPARTMENT OF INDUSTRIAL AND MANUFACTURING
ENGINEERING

2. Presented by: Group No.6
Sr No. Name Registration No.
1 IBRAHIM
SALEEM
2017-IM-8
2 IBRAR AHMAD 2017-IM-37
3 HASSAN ALI
BUTT
2017-IM-39
4 HAMZA
WAHEED
2017-IM-42

3. THERMO-FLUIDS PRESENTATION
TOPIC :
HEAT TRANSFER BY ROOM HEATERS

4. INTRODUCTION TO HEAT TRANSFER
Heat transfer: In terms of the thermodynamic system,
heat transfer is the movement of heat across the boundary
of the system due to temperature difference between the
system and the surroundings.
 The heat transfer can also take place within the system
due to temperature difference at various points inside
the system.

5.  Heat transfer is the process of transfer of heat from
high temperature reservoir to low temperature
reservoir.
 The difference in temperature is considered to be
‘potential’ that causes the flow of heat and the heat
itself is called as flux.

6. Heat Transfer as Per Second Law of
Thermodynamics
As per the second law of thermodynamics the transfer
of heat takes place from the body of high temperature
to the body of low temperature. There won’t be
spontaneous transfer of heat from the body at low
temperature to the body at high temperature. For heat
transfer from low temperature body to high
temperature body, external work has to be done.

7. MODES OF HEAT TRANSFER
There are three modes of heat transfer between the
two bodies:
 Conduction
 Convection
 Radiation

8. CONDUCTION:
“ The transfer of heat between two solid
bodies is called as conduction. It depends on the difference
in temperature of the hot and cold body.’’
 Example of conduction heat transfer is two bodies at
different temperature kept in contact with each other.
 Another example is heating one end of the metal like
copper; due to conduction heat transfer the other end of
the metal also gets heated.
Another example is heating one end of the metal like copper; due to conduction heat transfer the other end of the metal also gets heated.

9. CONVECTION:
The transfer of heat between the solid
surface and the liquid is called as convection heat transfer.
 For example, a vessel of water being heated, in this case
heating of water due to transfer of heat from the vessel is
convection heat transfer.

10. RADIATION:
When two bodies are at different
temperatures and separated by distance, the heat transfer
between them is called as radiation heat transfer.
 In case of the radiation heat transfer there is no media.

11. PRINCIPLE OF HEAT TRANSFER IN
HEATERS
 Electric heating is a process in which electrical energy is converted
to heat energy. Common applications include space
heating, cooking, water heating and industrial processes. An electric
heater is an electrical device that converts an electric current into heat.
 The heating element inside every electric heater is an electrical resistor,
and works on the principle of Joule heating an electric current passing
through a resistor will convert that electrical energy into heat energy.
 Most modern electric heating devices use nichrome wire as the active
element.

12. Electric heater

13. Several types
 Radiant heaters: Electric radiant heating uses heating elements that
reach a high temperature. The element is usually packaged inside a glass
envelope resembling a light bulb and with a reflector to direct the energy
output away from the body of the heater. The element emits infrared
radiation that travels through air or space until it hits an absorbing surface,
where it is partially converted to heat and partially reflected. This heat
directly warms people and objects in the room, rather than warming the air.
 Convection heaters: In a convection heater, the heating element heats the air in
contact with it by thermal conduction. Hot air is less dense than cool air, so it rises due
to buoyancy, allowing more cool air to flow in to take its place. This sets up
a convection current of hot air that rises from the heater, heats up the surrounding
space, cools and then repeats the cycle

14. Radiant heater Convection heater

15. The End