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MEC 213

Taraba State Polytecnic Suntai
Department of Mechanical Engineering
Diploma Two(2)
First Semester, 2019/2020 Session
Virtual Online Lecture Delivery(V-OLD)
Course Title: Thermodynamics
Course Code : Mec 213
Course Unit : 3
Course Lecturer : Engr. Kalus Emmanuel
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Welcome !!!
Lecture One (1)
Topic: Definition of Thermodynamics and Thermodymic properties
Aim : At the end of this studies students’ should be able to define
Thermodynamics and Thermodynamic Properties of a system
Learning Objectives : The Objective of this study is for students’ to understand
thermodynamic systems and surroundings
Specific Objectives are:
 Define Thermodynamics
 Describe the terms that are important to the definition above
 Understand What is a thermodynamic System
 Understand the three(3) thermodynamic Systems
 Understand different types of thermodynamic properties of a system
Instructional Materials : Lecture Notes, a “Textbook of Engineering
Thermodynamics” Fourth Edition by R.K. Rajput, and an Android Phone
Definition of Thermodynamics
The word “Thermo-dynamic,” derives its
etymology from two Greek words “ therme”
and “dynamis” meaning heat, and power or
action respectively. Therefore, combining the
two words gives “ heat Power” or “ heat action
”. therefore we can say that thermodynamics is
the science of engineering that study the effects
of heat action or heat power on a system or its
surroundings or vice versa.
Classification of Thermodynamics
Thermodynamics that deals with macroscopic properties such as heat, work,
internal energy, enthalpy, entropy, Gibbs free energy e.t.c of molecules is
called classical thermodynamics. It does not deal with the microscopic
properties of molecules.
Thermodynamics that deals with microscopic properties of molecules at the scale
of 10-9m and considers the behaviors of particles as waves as particles vice
versa is called quantum thermodynamics. It does not deal with the
macroscopic properties of molecules of a system.
Thermodynamics that bridges quantum mechanics and continuum (constant
progression of matter with small changes over time) and deals with the
probability of individual molecules of a system, there average properties and
energy levels is called statistical thermodynamics. So basically, there are
three(3) categories of thermodynamics.
Description of Terms important to the definition of
It is important to describe some terms that are very important to the definition of
• Thermodynamic system: A quantity of fixed mass under investigation, it is a
region containing matter or energy separated by walls or boundaries
• Surroundings: everything external to the system.
• System boundary: interface separating system and surroundings, it is the closed
surface surrounding the system through which energy or mass (matter) can
enter or leave a system.
• Universe: combination of system and surroundings.
For example : 1. Mixture of fuel + Air inside a cylinder = A Thermodynamic
2. The Piston, exhaust system, cooling system, lubrication system,
e.t.c = The thermodynamic surroundings.
Thermodynamic Systems and Surroundings
A thermodynamic system is a quantity of fixed mass under investigation, what is not in
the system is defined as the surroundings.
A system can be:
Open or closed, depending on whether it can exchange matter or not with its
surroundings. Non-isolated or isolated, depending on whether it can exchange
energy, or not, with its surroundings, movable or rigid. If the system is open, it
cannot be isolated. So in summary Systems can be:
• Open System ( Control Volume): Mass and Energy can transfer between the
System and the Surroundings
• Closed System (Control Mass): Energy can transfer between the System and the
Surroundings, but not mass e.g. A closed capped cup of coffee.
A thermodynamic system can also be said to be an isolated or non-isolated systems.
• Isolated systems : Neither Mass nor Energy can transfer between the System and
the Surroundings
Non- Isolated Systems : Both open and closed systems are non- isolated systems.
Thermodynamic Properties
Thermodynamic properties are basically categorized into two.
1. Intensive Properties: Intensive Properties are properties that is independent of
the mass of a system. They do not depend on the mass of a system, examples
of intensive properties are temperature and pressure.
2. Extensive Properties : Extensive properties are properties that depends on the
mass of the system, examples of extensive properties includes mass, volume,
Both intensive and extensive properties are all thermodynamic variables. A
thermodynamic variable are the quantities used to characterize a system that
is at equilibrium. Other thermodynamic variables are : volume (V), surface (S),
number of particles (N), amount of substance (n) in moles, applied force (F),
internal energy (U), magnetization (M), chemical potential, entropy (S),
enthalpy (h) etc.
Note 1. All students are to request for free thermodynamic steam table from
the lecturer for further lectures, this is critical for the next lecture.
2. students should see the course lecturer for the curriculum of the
course to enable study ahead in preparation for further lectures.
Assignment 1
Now that you have understood what is a thermodynamic system,
surroundings, and thermodynamic properties and variables, give an
example of a thermodynamic system aside the one mentioned in the
lecture, clearly highlighting the system and the surroundings. State also if
the system is an open, closed or isolated system( 5 marks),
Thank you and good luck