The closed cycle gas turbine operates in a cycle where the working fluid is recycled and does not interact with the atmosphere. The fluid is compressed, heated at constant pressure, expanded through the turbine, and cooled in a heat exchanger before being recirculated. This achieves higher efficiency than an open cycle gas turbine. The closed cycle has advantages like higher efficiency, ability to use different working fluids, and no need for internal cleaning. However, it also has disadvantages like increased complexity and cost due to operating at high pressures. Closed cycle gas turbines are used for power generation, industrial applications, marine and locomotive propulsion, and aviation jet propulsion.

1. PES COLLEGE OF
PES COLLEGE OF
ENGINEERING
ENGINEERING
TOPIC :
CLOSED CYCLE OF GAS TURBINE.
Created by
MITHUN RP
4PS21CS055

2. Heat exchanger
Cooler
Heat added
High pressure
and
high temperature gas
CLOSED CYCLE OF A GAS TURBINE
Compressor
Heat exchanger
Gas Turbine
Q
Q
IN
OUT
FIGURE:
Exhaust gas
Turbine
shaft
High pressure gas
Cooled exhaust gas
Shaft returning from compressor
Heat rejected
Heater

3. The efficiency of this can be given as,
n = (available network) / input heat
n = Cp(Wt – Wc) / input heat
n= 1 – [(T4-T1) /(T3-T2)].
Where,
‘Wt’ = work is done by the gas turbine per kg of air.
Wt = Cp(T2-T3).
‘Wc’ = work is done by the compressor per kg of air.
Wc = Cp(T1-T4).
‘Cp’ = constant pressure is taken in KJ or Kg
‘T’ = temperature
Input heat = Cp (T3-T2)
The efficiency of this turbine is higher than the open
cycle gas turbine.
Efficiency of closed cycle gas turbine
The efficiency of a closed cycle gas turbine can be explained with the help
of the T-S and P-V diagram.

4. Working Principle of closed cycle gas turbine
In a closed cycle gas turbine, the working fluid does not come in contact with
atmospheric air. The working fluid is air or some other suitable gas.
The compression and expansion process remain the same, but the
combustion process is replaced by a constant-pressure heat addition process
from an external source.
The exhaust process is replaced by a constant-pressure heat rejection process
to the ambient air.
The cold gas is drawn into the compressor, where it's temperature and
pressure are raised.
The high pressure air proceeds into the combustion chamber, where the fuel
is burned at constant pressure.
The high temperature gases then enter the turbine where they expand to
atmospheric pressure while producing power output.
Some of the output power is used to drive the compressor and the remaining
is available as shaft work.
The exhaust gases leaving the turbine are cooled in heat exchanger called
sink where it rejects heat. The gas is restored to its initial state.
Therefore, in this cycle the same working fluid is recirculate causing the cycle
to be classified as a closed cycle.

5. Advantages of closed cycle gas turbine
High thermal efficiency at any temperature limit and pressure ratio.
Any type of working fluid can be used with low caloric value. For example
helium.
No corrosion.
Internal cleaning is not required.
Re-heaters can be used to heat the water for the supply of hot water for
domestic and industrial purposes.
The size of the gas turbine is small.
An increase in pressure gives a better heat transmission coefficient in the
exchanger.
Fluid friction loss is less.
The closed-cycle gas turbine advantages are:

6. Disadvantages of closed cycle gas turbine
As the whole system work under high pressure with a working fluid
(medium), it increases the cost.
It requires a large air heater and it is not enough when the combustion
chamber is used in the open cycle.
Not used in aeronautical engines because this type of gas turbine uses
cooling water.
Complex system and should resist at high pressure.
The closed-cycle gas turbine disadvantages are:

7. Applications of closed cycle gas turbine
Used in the generation of electric power.
Used in many industrial applications.
Used in marine propulsion, locomotive propulsion, automotive propulsion.
Used in aviation to provide power to the jet Propulsion.
The closed-cycle gas turbine applications include the following:

8. Difference between Closed and Open cycle gas turbine

9. THANK
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