Exergy and Exergo-Economic Based Analysis of a Gas Turbine Power Generation System

Abstract

In this research study, energy, exergy and exergo-economic analysis of Montazer Ghaem gas turbine power plant which is located near Tehran, capital city of Iran is carried out. The results of this study reveal that the highest exergy destruction occurs in the combustion chamber (CC), where the large temperature difference is the major source of the irreversibility. In addition, the effects of the gas turbine load variations and ambient temperature are investigated to see how system performance changes: the gas turbine is significantly affected by the ambient temperature which leads to a decrease in net power output. The results of the load variation of the gas turbine show that a reduction in gas turbine load results in a decrease in the exergy efficiency of the cycle as well as all the components. As was expected, an increase in ambient temperature has a negative effect on the exergy efficiency of the cycle, so this factor could be countered by using gas turbine air inlet cooling methods. In addition, an exergo-economic analysis is conducted to determine the cost of exergy destruction in each component and to determine the cost of fuel. The results show that combustion chamber has the largest cost of exergy destruction, which is in line with the exergy analysis.

Nomenclature

$\dot{C}$ :

Cost per unit of exergy ($/MJ)

${\dot{C}}_D$ :

Cost of exergy destruction ($/h)

CRF :

Capital recovery factor

ex :

Specific exergy (kJ/kg)

$\dot{e}x$ :

Specific exergy rate (kW/kg)

$\dot{E}x$ :

Exergy flow rate (kW)

h :

Specific enthalpy (kJ/kg)

LHV :

Lower heating value (kJ/kg)

$\dot{m}$ :

Mass flow rate (kg/s)

P:

Pressure (kPa)

$\dot{Q}$ :

Heat transfer rate (kW)

R :

Gas constant (kJ/kg K)

s:

Specific entropy (kJ/kg K)

T:

Temperature (K)

$\dot{W}$ :

Work transfer rate (kW)

$\dot{Z}$ :

Capital cost rate ($/s)

Z _k :

Component purchase cost ($)

η _ex :

Exergy efficiency

φ :

Maintenance factor

ξ :

Coefficient of fuel chemical exergy

C :

Compressor

CC :

Combustion chamber

ch :

Chemical

D :

Destruction

e :

Exit condition

GT :

Gas turbine

f :

Fuel

i :

Inlet Condition

k :

Component

ph :

Physical

0 :

Reference ambient condition

⋅:

Rate