Lect No 01

1. Unit No:01
Thermodynamics
Prof. Yash B. Parikh
M.Tech (Computer Integrated Manufacturing)
B.E.(Mechanical Engineering)
Assistant Professor
Department of Mechanical Engineering

2. Contents
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3. Definition
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 Thermodynamics is a science of energy.
 Everybody has a feeling of what energy is, but it’s
hard to define.
 We can loosely say that energy is the ability to cause
change.
 The name Thermodynamics came from the Greek
words,
therme (heat) and dynamis (power)
 The study of this science is based on experimental
results & observations of common experiences of a
man.

4. Introduction
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 There exist different laws of thermodynamics.
 Most fundamental law being the law of conservation
of energy.
 It simply states that,
“ During an interaction, energy can change from one
form to another but the total amount of energy
remains constant.”
e.g. a rock falling off a cliff, picks up speed as a
result of its potential energy being converted to
kinetic energy.

5. Application
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 This science is applicable to all branches of
engineering.
 Specially in designing & development of various
systems like,
Power producing devices : IC engines, steam & gas
turbines, nuclear power plants
Power absorbing devices : compressors, pumps,
refrigerators, A/C.
Other devices such as heat exchangers, chemical
process plants.

6. Thermodynamic System
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 It’s a fixed mass in space under consideration to
analyse a problem.
 System is identified
by a boundary drawn
around the system.
 Boundary may be real
or imaginary.
 Everything external to system is known as
Surroundings or environment.
 A system & surrounding together, is called the
universe.

7. Classification of Thermodynamic System
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 Based on mass & energy transfer between system &
surroundings,
1. Closed System
2. Isolated System
3. Open System
1. Closed System :
A System without mass transfer across its
boundaries.
 These systems have only energy transfer in the form
of heat & work.
 e.g. piston-cylinder arrangement of an engine.

8. Closed System
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 Here boundary of the system moves with the
movement of the piston.

9. Isolated System
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 In this system there is no mass & energy transfer
between the system & its surroundings.
 e.g. perfectly insulated thermos flask.
 Universe is also an isolated system.

10. Open System
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 A system with mass transfer along with energy
transfer.
 e.g. turbine
 Here high pressure gases enter into turbine & low
pressure gases leave the turbine.
 It’s not necessary that the quantity of matter within
the boundaries of an open system to remain fixed.
 Here, fixed volume in space is known as control
volume & surface surrounding this volume is called as
control surface.

11. Closed, Isolated & Open System
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