Description of Thermal Engineering (Part 1)

Description of Thermal Engineering (Part 1)

Thermodynamics is a branch of science which deals with the relation among heat, work and

properties of the system which are in equilibrium. It describes state and changes in state

of physical systems.

Thermodynamic system:-

It is defined as the region of space or a finite quantity of matter upon which attention is

focussed in order to study the transfer of mass and energy

There are three types of systems namely Closed system, Open system, Isolated system.

In closed system there is no mass transfer takes place within the system but energy transfer

takes place.

In Open system both mass and energy transfer takes place.

In Isolated system neither mass nor energy can cross the boundary of the system

Type of system	Mass flow	Work	Heat
Open	Yes	Yes	Yes
Closed	No	Yes	Yes
Isolated	No	No	No

Thermodynamics basically entails 4 laws known as Zeroth law, first law, second law. third law.

Zeroth law of Thermodynamics:-

When a body 'A' is in thermal equilibrium with a body 'B', and also separately with a body 'C',

then 'B' and 'C' will be in thermal equilibrium with each other.

First law of Thermodynamics:-

Heat and work are mutually convertible. First law is the basis for internal energy.

Second law of Thermodynamics:-

Kelvin Planck's statement:- It is impossible to construct a y\heat engine with 100%

efficiency.

Clausius statement:- It is impossible for self acting machine working in a cyclic process to

transfer heat from lower temperature to the high temperature without the aid of external agency.

Third law of Thermodynamics:-

The entropy of a perfect crystal approaches zero as the absolute temperature approaches zero.