laws of thermodynamics, process, cycle

1. Thermodynamics
Laws of
thermodynamics
SD-Tech

2. Prof. S. A. Dahake
Introduction of Thermodynamics
It is the study of energy and its transformation. It discusses the relationship
between heat, work and physical properties of working substance.
Applications of thermodynamics such as: pressure cooker, IC engine, steam
plant, Refrigeration & air conditioning , chemical plant, jet propulsion etc
Thermodynamics - Greek words Therme & Dynamicas
Therme = Heat
Dynamicas = Power
SD-Tech

3. Prof. S. A. Dahake
System
System is defined as region in space or a quantity of
matter upon which attention is focused for the study
of work and heat transfer and conversion.
In short it is finite quantity of matter or a prescribed
region of space.
Everything external to system is called as surrounding.
The system is separated from surrounding by system
boundary. The boundary may be real or imaginary.
The system and its surrounding together comprise a
universe.
SD-Tech

4. Prof. S. A. Dahake
Types of System
Closed system contain the fix mass. There is no ass transfer across the system boundary. There
may be energy transfer into or out of the system. Eg. Gas contain in Cylinder.
Open system is one in which matter crosses the boundary of the system. Also energy crosses
the system boundary. Most of the engineering devices belongs this type. Eg. Air compressor.
Isolated system is of fixed mass and energy and there is no mass or energy transfer across the
system boundary. Eg. Flow through pipe, thermos.
SD-Tech

5. Prof. S. A. Dahake
Zeroth law of thermodynamics
The zeroth law of thermodynamics states that if two thermodynamic systems are
each in thermal equilibrium with a third system, then they are in thermal
equilibrium with each other.
SD-Tech
If a body A, be in thermal equilibrium
with two other bodies, B and C,
then B and C are in thermal equilibrium
with one another.

6. Prof. S. A. Dahake
Macroscopic and Microscopic Approach
Macroscopic Approach Microscopic Approach
In this approach, a certain quantity of matter is
considered without taking into account the
events occurring at the molecular level.
The matter is considered to be comprised of a
large number of tiny particles known as
molecules, which move randomly in a disordered
fashion.
This approach is used in the study of classical
thermodynamics.
This approach is used in the study of statistical
thermodynamics.
The properties like pressure, temperature, etc.
needed to describe the system, can be easily
measured.
The properties like velocity, momentum, kinetic
energy, etc. needed to describe the system,
cannot be measured easily.
In IC engine the volume, pressure & temperature
of air-fuel mixture can be measurable
SD-Tech

7. Prof. S. A. Dahake
State Postulate
The state postulate is a term used in thermodynamics that defines the given
number of properties to a thermodynamic system in a state of equilibrium. The
state postulate allows a finite number of properties to be specified in order to fully
describe a state of thermodynamic equilibrium.
Thermodynamics Properties – Every system has certain characteristics by which its
physical condition may be described is called as thermodynamics properties.
1. Intensive Properties – which are independent of mass such as pressure &
temperature
2. Extensive properties – which are depend upon mass such as volume & energy
SD-Tech

8. Prof. S. A. Dahake
State & Equilibrium
Each unique condition of system is called state.
Example – water which may become vapor or solid(ice) on heating or cooling.
A system is said to be in thermal equilibrium when temperature in all point in
system is same.
SD-Tech

9. Prof. S. A. Dahake
Process and Thermodynamic Cycles
A process is said to be occur when the system
undergoes a change in state.
Process is shown on pressure-volume diagram.
The line representing the state of system
during change is known as processes.
If a number of processes in sequence bring
back the system to its original state, the
system is said as cycle.
SD-Tech

10. Thank You
SD-Tech
Comment your doubts and queries