Describe different types of Gas power cycles used in different engines.

1. GAS POWER
CYCLES
The devices or systems used to produce a
net power output are often called
engines, and the thermodynamic cycles
they operate on are called power cycles.

2. TYPES OF POWER CYCLES
GAS CYCLES:-
• In gas cycles, the working fluid remains in the gaseous
phase throughout the entire cycle.
VAPOUR CYCLES:-
• In vapour cycles, the working fluid exists in the vapour
phase during one part of the cycle and in the liquid
phase during another part.

3. AIR STANDARD ASSUMPTIONS
 The cycle is considered closed with the same ‘air’ always remaining in the
cylinder to repeat the cycle.
 In the cycle, all the processes are reversible.
 Mass of working fluid remains constant through entire cycle.
 The working fluid is homogenous throughout the cycle and no chemical
reaction takes place.
 The air behaves as an ideal gas and its specific heat is constant at all
temperatures.
 The working fluid is air.

4. TYPES OF GAS CYCLES
 Carnot cycle
 Otto cycle
 Diesel cycle
 Dual cycle
 Brayton cycle

5. CARNOT CYCLE
 This cycle is a hypothetical cycle
having highest possible efficiency.
Process 1-2 : Isothermal expansion
Process 2-3 : Adiabatic compression
Process 3-4 : Isothermal compression
Process 4-1 : Adiabatic compression

6. APPLICATIONS
 Carnot cycle is an idealization, since no
real engine processes are reversible.
 All real processes involves some increase
in entropy.
 Heat transfer into the engine in isothermal
process is too slow to be of practical value.

7. OTTO CYCLE
 It is a constant volume cycle.
Process 1-2 : Reversible adiabatic compression
Process 2-3 : Addition of heat at constant volume
Process 3-4 : Reversible adiabatic expansion
Process 4-1 : Rejection of heat at constant volume

8. APPLICATIONS
 Two Stroke Petrol Engine
 Spark Ignition Petrol Engine
 Four Stroke Petrol engine

9. DIESEL CYCLE
 It is a constant pressure cycle.
Process 1-2 : Reversible adiabatic compression
Process 2-3 : Addition of heat at constant pressure
Process 3-4 : Reversible adiabatic expansion
process 4-1 : Rejection of heat at constant volume

10. APPLICATIONS
 Compression Ignition Diesel Engine
 Two Stroke Diesel Engine
 Four Stroke Diesel Engine

11. DUAL CYCLE
Process 1-2 : Reversible adiabatic compression
Process 4-5 : Reversible adiabatic expansion
Process 3-4 : Addition of heat at constant pressure
Process 5-1 : Rejection of heat at constant volume
Process 2-3 : Addition of heat at constant volume

12. APPLICATIONS
 Dual Combustion Engine
 Used for mobile propulsion in
vehicles and portable machinery.
 In mobile equipment.
 In aircrafts, helicopters, large
ships and electric generators.

13. BRAYTON CYCLE
Process 2-3 : Heat addition at constant pressure
Process 1-2 : Reversible adiabatic compression
Process 4-1 : Heat rejection at constant pressure
Process 3-4 : Reversible adiabatic expansion

14. APPLICATIONS
 Jet Engine  Turboprop Engine

15. THE
END