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
The main forms of energy of interest in engineering
thermodynamics are heat and work
Work is the form of energy useful in displacement of a
Heat is the form of energy transferred due to
temperature gradient between two bodies
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
Specific heat capacity
Open, Closed and Isolated
Homogenous and heterogeneous
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
1. They receive heat from a high
(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 low
temperature sink (the atmosphere, rivers, etc.).
4. They operate on a cycle.