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This study aims to investigate the effect of regeneration on the output power and the thermal efficiency of the gas turbine power plant. The effect of ambient air temperature, regeneration effectiveness, and compression ratio on the cycle thermal efficiency was also investigated. An existed gas turbine power plant of AL ZAWIA is used as a base in this study, and the calculations were carried out utilizing MATLAB code. This intensive parametric study was conducted based on the fundamental of thermodynamics and gas turbine relations considering the effect of the operation conditions (ambient air temperature, regeneration effectiveness and compression ratio). It was found that adding regeneration to the simple gas turbine cycle results in an increase in the thermal efficiency of cycle. It was also found that including regeneration in gas turbine cycle results in an increase in the output power of the cycle, and it results in a decrease in the exhaust gas temperature. The effect of the regeneration effectiveness was also predicted. It was found that increasing of regeneration effectiveness results in an increase in the output power of the cycle. It was also found that the cycle thermal efficiency increases with increasing of the regenerative effectiveness. The effect of ambient air temperature was also predicted. Increasing of the ambient air temperature results in a decrease in the thermal efficiency of the cycle.

Increasing the thermal efficiency is the concern of many researchers in the last few decades. Increasing the thermal efficiency results in a decrease in the operation cost by reducing the fuel consumption, which, in turn, reduces the emission of flue gases (CO_{x}, NO_{x}) to the environment.

Therefore, intensive research activities have been under going to increase the thermal efficiency of thermal power generation of gas and steam turbine cycles. There are different methods are utilized to increase the thermal efficiency of the cycles. Reheating is a process utilized to increase the thermal efficiency of the gas and the steam turbine cycles. Regeneration is also a procedure utilized to increase the thermal efficiencies of both the simple gas turbine and the steam turbine cycles. Another important procedure to increase the thermal efficiency of the power plant cycle is the combined cycle, which consists of a gas turbine and a steam turbine cycles [

Regenerative is a thermal process that utilizes the remaining heat energy of the exhaust gases leaving the gas turbine. This can be done by exchanging the heat between the exhaust hot gases exit from gas turbine with the compressed air exit from the compressor utilizing shell and tube heat exchanger [

Several approaches are available in the literature concerning the effect of ambient air temperature inlet to the compressor on the thermal efficiency of the gas turbine cycle [

These approaches [

In case of utilizing gas turbine with regeneration in a combined cycle, the thermal efficiency could reach to a higher thermal efficiency [

This study aims to predict the effect of regeneration in a gas turbine cycle for certain design parameters of AL-ZAWAI station in Libya. The effect of other parameters in the performance of the gas turbine will also be performed in this study.

Using the first law of thermodynamics and the intake pressure drop (ΔP_{intake}) is taken to be 0.004 bar, the intake temperature is the same as the ambient temperature.

The compressor pressure ratio (r_{p}) can be defined as Equation (1):

where P_{1} and P_{2} are the compressor inlet and outlet air pressures, respectively.

The isentropic outlet temperature leaving the compressor is determined by Equation (2).

Take specific heat ratio for air

The isentropic efficiency of the compressor expressed as Equation (3):

where T_{1} and T_{2} are the compressor inlet and outlet air temperatures, respectively.

The work of the compressor (W_{c}) when blade cooling is not taken into account can be calculated as Equation (5):

where the specific heat of air is

From the energy balance in the combustion chamber:

where _{4} is turbine inlet temperature, C_{pf} is the specific heat of fuel, and T_{f} is the temperature of the fuel.

The specific heat of flue gas is

outlet pressure from the combustor is determined from the following equation:

where natural gas high heating value is assumed to be around 49,291 kJ/kg and air/fuel ratio (A/F) is determined from the following equation:

The exhaust gases temperature from the GT is given by Equation (10).

The isentropic outlet temperature leaving the turbine is determined by Equation (2).

Take specific heat ratio for gases

The actual temperature drop is obtained from the definition of turbine’s isentropic efficiency:

The effectiveness of regenerator (heat exchanger) (ε) are considered in this study.

The total mass flow rate is given by:

The work produced from the turbine is determined by the following equation:

The network of the GT (W_{Gnet}) is calculated by Equation (15):

The output power from the gas turbine (

The specific fuel consumption (SFC) is determined by

The heat supplied is also expressed as Equation (18):

The GT efficiency (

The heat rate (HR) can be expressed as Equation (20):

The overall efficiency (

The results validation for similar design conditions is presented in

1) Effect of Ambient Temperature (T1)

ZAWIA | Plant location | |
---|---|---|

ALSTOM | Manufacture | |

119.32 | program | Output power [MW] |

118 | Data | |

556 | program | Exhaust temperature [˚C] |

550 | Data |

efficiency of a simple gas turbine cycle and gas turbine cycle including regeneration. As shown in

the inlet air temperature results in an increase in the specific fuel consumption. This could be interpreted as follow: when the ambient temperature decreases, the air mass flow rate inlet to compressor increases, and this causes the specific fuel consumption to increase.

As shown in

2) Effect of Compression Ratio (r_{p})

In general, in gas turbine cycles, the increase of the compression ratio results in an increase in the thermal efficiency of the cycle, as shown in

results in increase of specific fuel consumption, as shown in

ranges between 2 and 6. Then it becomes stable in the range of compression ratio between 6 and 22. Increasing of regeneration effectiveness results in a decrease in the specific fuel consumption, as shown in

An intensive parametric study in gas turbine cycle including regenerative is presented in this paper.

The parametric study showed that the compression ratio and inlet air temperature had a major effect on the thermal efficiency of a simple and generative gas turbine cycles. Adding regeneration to simple gas turbine cycle results in the increase of thermal efficiency of the cycle. Increasing of compression ratio results in the increase of the thermal efficiency of simple and regenerative gas turbine cycle.

Omar, H., Kamel, A. and Alsanousi, M. (2017) Performance of Regenerative Gas Turbine Power Plant. Energy and Power Engineering, 9, 136-146. https://doi.org/10.4236/epe.2017.92011