Lecture Note
Definition
 Thermodynamics is derived from two words: ‘Thermo’
which means ‘Heat energy’ and ‘Dynamics’ which
means ‘conversion’ or ‘transformation’
 Concisely, thermodynamics is a division of science that
deals with conversion of energy from one form to
another
 The main forms of energy of interest in engineering
thermodynamics are heat and work
Definition contd.
 Work is the form of energy useful in displacement of a
body
Work  Force  Distance (Joules)
 Heat is the form of energy transferred due to
temperature gradient between two bodies
Heat  Mass  Specific  Temperatur e difference
(Joules)
Applications of Engineering Thermodynamics
 Engineering application of thermodynamic principles
is the design of various systems using fluid properties
to cause energy transformation
 Applications in design of heat engines, refrigeration
machines, air conditioning systems
Scope of Thermodynamics
 It is limited to macroscopic properties of matter i.e.
properties of large number of particles of systems
 It considers the initial and final states of a system and
not the mechanism of the process
Important fluid properties in thermodynamics
 Density
 Specific heat capacity
 Temperature
 Internal energy
 Entropy
 Enthalpy
 Pressure
 Specific volume
 Mass
Fundamental concepts
 System
 Boundary
 Surrounding
 Open, Closed and Isolated
 Homogenous and heterogeneous
 Energy
Kinetic energy
Potential
energy
Internal energy
Heat Engines
 Heat engines are devices designed for the purpose of
converting other forms of energy (usually in the form
of heat) to work. Heat engines differ considerably
from one another, but all can be characterized by the
following:
1. They receive heat from a high-temperature source
(solar energy, oil furnace, nuclear reactor, etc.).
2. They convert part of this heat to work (usually in the
form of a rotating shaft).
3. They reject the remaining waste heat to a lowtemperature sink (the atmosphere, rivers, etc.).
4. They operate on a cycle.