1. Unit 1 : Basic concepts and first law
Classical and statistical approaches
Zeroth law of thermodynamics
1st law of thermodynamics applied to closed and
Steady flow process with reference to various engg
The term thermodynamics derived from Greek
Thermodynamics can be defined as the study of
relationship between work, heat and energy.
3. “Thermodynamics is the science of energy
transfer and its effect on the physical properties
Thermodynamic laws and principles are found in
all fields of energy technology, notably
Steam and nuclear power plant
Internal combustion engines
Air conditioning & refrigeration
Gas dynamics & jet propulsion
Chemical process plants
Direct energy conversion devices.
4. Thermodynamic system and control volume
• Thermodynamic system: a quantity of fixed mass
system → fixed mass, closed
• Surroundings: everything external to the system,
• System boundary: interface separating system and
• Universe: combination of system and surroundings.
8. Properties of a system
Any measurable or observable characteristics are
called property of a system
1.Intensive property: Independent of the mass
of the system.
Ex: pressure, temp, volume
2.Extensive property: dependent of the mass of
EX: mass, energy
9. State of a system
State is the condition of the system at any particular
moment or time the state is identified by the
properties of the system such as p , v, temp etc.
Change of a state:
even if the values of one property
change the state will change to diff state, is called
change of a system
11. Reversible process
The reversible process also known as equilibrium
A system passes through an infinite number of
continuous equilibrium states , and it traces the
same path when the process is reversed
Ex: constant volume, constant pressure, isothermal,
adiabatic & isentropic process.
12. Non-reversible process
A system passes through an infinite number of
continuous non-equilibrium states, and it does not
trace the same path when the process is reversed.
Ex:1. mixing of two different substances
2.when we are driving the car uphill, it consumes
a lot of fuel and this fuel is not returned when we are
driving down hill.
13. Flow and non flow process
In a flow process, the working fluid enters the
system and leaves it to atmosphere after doing work.
Ex: steady flow process applied to various systems
such as compressors.
In non-flow process, the same working fluid
recirculated again and again , does not leave the
system after doing work
Ex: constant volume & pressure process,etc.
14. Thermodynamic equilibrium
A system is said to be in mechanical
equilibrium, when there are no unbalanced forces
acting 0n it.
characterized by equal pressure,
A system is said to be in thermal
equilibrium, when there is no temperature difference
throughout the system
characterized by equal temperature
A system is said to be in
chemical equilibrium, when there is no chemical
reaction throughout the system
characterized by equal chemical potentials.
16. Thermodynamic cycle
A thermodynamic cycle is a series of
thermodynamic processes which returns a system
to its initial state.
Initial to final=cycle
There are two types
1. open cycle.
The working substance is recirculated again and
again within the system without taking any mass
transfer. Energy transfer takes place
The working substance is exhausted to
atmosphere after completing the process.
So, here both mass and energy transfer
19. Point and path function
When a gas undergoes a process from initial state to
final state, the thermodynamic properties will
Point: P,V,T are dependent.
Path: heat and work transfer are dependent
21. Concept of continuum
A continuous homogeneous medium is called as
Continuum is based on the macroscopic approach.
From the macroscopic perspective, the description of
matter is simplified by considering it to be
distributed continuously throughout a region.
Energy is the ability to do work.
Energy cannot be created or destroyed , it can only be
stored or transferred
1.Potential energy=stored energy
P.E=m g z
2.Kinetic energy= energy of motion or speed.
23. Work transfer
Work is an energy interaction b/w system and
Usually , the energy can cross the boundary of any
system in the form of either heat or work.
Work=force x distance moved.
W=F x X
Work is expressed in terms of N-m or J or kJ.
Power: work done per unit time is called power
unit: kJ/s or kW.
24. Heat transfer
Heat is defined as the energy crossing the boundary
of a system due to the temperature difference
between system and surroundings.
It is usually expressed in joule or kJ.
26. FIRST LAW OF THERMODYNAMICS
“When a system undergoes a thermodynamic cyclic
Process, the cyclic integral of heat energy is equal to
the cyclic integral of Work energy”.
𝑑𝑄 = 𝑑𝑊
dQ= dW + dU
Q1-2= W1-2+ U1-2
29. SPECIFIC HEAT CAPACITIES
The specific heat is defined as the heat required to
raise unit mass through one degree temperature rise.
dQ = mCdT
where, m = mass,
C = specific heat, and
dT = temperature rise
There are two specific heats for gas,
Cv - Specific heat at constant volume
Cp - Specific heat at constant pressure
32. FOR AIR
CP = 1.005 kJ/kg K
Cv = 0.718 kJ/kg K
Gas constant,R= CP - Cv
R= 1.005-0.718 kJ/kg K
γ = CP / CV = 1.4