# Impact of Ambient Conditions of Arab Gulf Countries on the Performance of Gas Turbines Using Energy and Exergy Analysis

^{*}

## Abstract

**:**

## 1. Introduction

_{2}O-LiBr) absorption chillers in the United Arab Emirates. The power requirements of several inlet air cooling techniques for the GE Frame 6B gas turbine power plants in two Omani locations, Marmul and Fahud, were evaluated using typical meteorological year (TMY) data by Dawoud et al. [24]. Chakerand Meher-Homji [25] analyzed the impact of the inlet fogging on the performance of simple gas turbines (GE Frame 7EA and GE Frame 9FA gas turbines for 60- and 50-Hz applications). They explained the methodology and data analysis used to derive the cooling potential. The study considered the weather data for 106 major locations over the world.

- Those references have dealt each and in general with the analysis of the performance of gas turbines for one specific or very few locations. The work of Chaker and Meher-Homji [25] considered however the weather data for a good number of locations.
- The humidity effect on the gas turbines’ performance calculations, particularly the exergy ones, was not systematically investigated.
- Very few studies have focused on the analysis of the effect of actual weather conditions using average hourly temperature and relative humidity for several Gulf cities.

## 2. Gas Turbine Cycle

- Each component of the gas turbine is analyzed as a control volume assumed to be at steady state with neglected pressure drop, except in the combustion chamber.
- Fuel is supposed to be pure methane, and its temperature is constant and equal to the ambient temperature.
- All components of the system are operated under adiabatic conditions. In particular, the combustion chamber is considered as an insulated chamber.
- All fluid thermo-physical properties are modeled as temperature and pressure dependent.
- Kinetic and potential energy and exergy variations in different components of the system and in the pipelines are neglected.
- The ISO conditions are considered as the reference state conditions.

_{1}, P

_{1}and ${\omega}_{1}$). The moist air density is calculated based on the ambient conditions. The compression work can be estimated as:

_{c}is the compressor pressure ratio, ${\gamma}_{a}$ is the ratio of air specific heat, ${C}_{pa}$ is the air specific heat at constant pressure and ${\eta}_{c}$ is the compressor is entropic efficiency that can be evaluated as [29]:

_{4}) [18]. As the combustion products are assumed to behave as an ideal gas, the exergy rate of the flue gas after the combustion chamber can be calculated as:

## 3. Model Validation

## 4. Results and Discussion

#### 4.1. Weather Data of Cities

#### 4.2. First Law Analysis

#### 4.3. Second Law Analysis

## 5. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## Nomenclature

C_{p} | Specific heat at constant pressure (kJ/kg·K) |

f | Fuel to air mass ratio (kg_{f}/kg_{a}) |

LCV | Lower Calorific Value of the fuel (kJ/kg) |

h | Specific enthalpy (kJ/kg) |

HR | Heat rate (kJ/kWh) |

$\dot{m}$ | Mass flow rate (kg/s) |

N | Number of days in the month |

P | Pressure (kPa) |

Pr | Power output (kW) |

${Q}_{in}$ | Heat added at combustion chamber (kW) |

$R$ | Ideal gas constant (kJ/kg·K) |

${r}_{c}$ | Pressure ratio |

$s$ | Specific entropy (kJ/kg·K) |

SFC | Specific fuel consumption (kg/kWh) |

T | Temperature (K) |

$\dot{V}$ | Volume flow rate of moist air (m^{3}/s) |

W | Work (kW) |

$X$ | Exergy rate (kW) |

Greek letters | |

$\gamma $ | Ratio of the specific heats |

$\Delta $ | Difference, change |

η | Efficiency (%) |

$\rho $ | Densityof moist air (kg/m^{3}) |

ϕ | Relative humidity (%) |

$\psi $ | Specific exergy (kJ/kg) |

$\omega $ | Humidity ratio (kg_{w}/kg_{a}) |

Subscript | |

1,2,3,… | Number of state |

a | Air |

an | Annual |

c | Compressor |

com | Combustion chamber |

f | Fuel |

g | Flue gases |

gen. | Generator |

i | Time of the day |

m | Month |

am | moist air, humid air |

th | Thermal |

tu | Turbine |

tot | Total |

w | Vapor water, steam |

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**Figure 2.**Comparison between the results of the present model and those of Najjar and Zaamout [33] for a simple gas turbine.

**Figure 3.**Effect of ambient temperature on the gas turbine performance variation ($\omega =0.006284\frac{{\mathrm{kg}}_{\mathrm{w}}}{{\mathrm{kg}}_{\mathrm{a}}})$.

**Figure 7.**Effect of ambient conditions on the hourly thermal efficiency of the gas turbine in all cities.

**Figure 9.**Effect of ambient conditions on the hourly compressor exergy efficiency of the gas turbine in all cities.

**Figure 10.**Effect of ambient conditions on the hourly combustion chamber exergy efficiency of the gas turbine in all cities.

**Figure 12.**Effect of ambient conditions on the gas turbine functional exergy efficiency in all cities.

Country | Capacity (MW) |
---|---|

Kuwait | 1200 |

Saudi Arabia (East Region) | 1200 |

Bahrain | 600 |

Qatar | 750 |

UAE | 900 |

Oman | 400 |

Description | Unit | Value |
---|---|---|

Pressure ratio ^{1}, ${r}_{c}$ | - | 12.2 |

Turbine inlet temperature ^{1}, ${T}_{3}$ | K | 1362 |

Volume flow rate of dry air ^{1}, ${\dot{V}}_{a}$ | m^{3}/s | 117.302 |

Air specific heat at constant pressure, ${C}_{pa}$ | kJ/kg·°C | Equation (8) |

Gas specific heat at constant pressure ^{2}, ${C}_{pg}$ | kJ/kg·°C | 1.147 |

Combustion chamber specific heat at constant pressure, ${C}_{pcom}$ | kJ/kg·°C | Equation (8) |

Air specific ratio ^{2}, ${\gamma}_{a}$ | - | 1.4 |

Gas specific ratio ^{2}, ${\gamma}_{g}$ | - | 1.333 |

Lower calorific value ( LCV) (methane) ^{3} | kJ/kg | 50,050 |

Isentropic efficiency of compressor, ${\eta}_{c}$ | - | Equation (7) |

Isentropic efficiency of turbine ^{4}, ${\eta}_{tu}$ | - | 0.868 |

Combustion chamber efficiency ^{2}, ${\eta}_{com}$ | - | 0.98 |

**Table 3.**Comparison of typical and calculated performance parameters for gas turbine at ISO conditions.

Performance Parameter | Unit | Ref. ^{1} | Calculated ^{2} | Difference ^{3} (%) |
---|---|---|---|---|

Gas turbine power output, Pr | kW | 42,100 | 42,734 | 1.5 |

Hate rate, HR | kJ/kWh | 11,223 | 11,292 | 0.62 |

Exhaust flow rate, ${\dot{m}}_{tot}$ | kg/s | 145.833 | 145.9 | 0.05 |

Turbine outlet temperature, ${T}_{4}$ | K | 816.2 | 812.7 | −0.43 |

^{1}Ref. refers to the performance of a typical gas turbine [30];

^{2}Calculated refers to the performance calculated using the present model;

^{3}Difference (%) = (Calculated − Ref.) × 100/Ref.

City | Temperature (°C) | Relative Humidity (%) | ||
---|---|---|---|---|

Max. | Min. | Max. | Min. | |

Dammam | 45.19 | 9.9 | 68.4 | 7.8 |

Abu Dhabi | 43.02 | 14.9 | 78.6 | 15.9 |

Dubai | 42.13 | 16.44 | 72.2 | 20.5 |

Kuwait | 46.9 | 7.9 | 69.8 | 5.05 |

Doha | 42.02 | 15.24 | 73.3 | 15.3 |

Bahrain | 39.7 | 15.7 | 69.4 | 23.7 |

Muscat | 37.8 | 17.8 | 87.3 | 30.4 |

Performance | Value |
---|---|

First Law of Thermodynamic | |

Power output (kW) | 42,734 |

Thermal efficiency (%) | 31.882 |

Heat rate (kJ/kWh) | 11292 |

Specific fuel consumption (kg/kWh) | 0.2256 |

Second Law of Thermodynamic | |

Compressor exergy destroyed (kW) | 2769 |

Compressor exergy efficiency (%) | 94.37 |

Combustion chamber exergy destroyed (kW) | 52,621 |

Combustion chamber exergy efficiency (%) | 71.92 |

Turbine exergy destroyed (kW) | 5089 |

Turbine exergy efficiency (%) | 94.75 |

Gas turbine exergy destroyed (kW) | 60,479 |

Gas turbine functional exergy efficiency (%) | 30.31 |

Dammam | Abu Dhabi | Dubai | Kuwait | Doha | Bahrain | Muscat | |
---|---|---|---|---|---|---|---|

Pr (GWh) | 342.25 | 335.30 | 333.29 | 342.90 | 334.72 | 337.86 | 333.36 |

$P{r}_{ISO}$ (GWh) | 375.38 | 375.38 | 375.38 | 375.38 | 375.38 | 375.38 | 375.38 |

$\Delta Pr$ (GWh) | −33.13 | −40.08 | −42.09 | −32.47 | −40.65 | −37.51 | −42.02 |

$\Delta Pr$ (%) | −8.8 | −10.7 | −11.2 | −8.7 | −10.8 | −10 | −11.2 |

${\dot{m}}_{f}$ (10^{6} × kg/year) | 79.84 | 79.08 | 78.65 | 79.67 | 78.97 | 79.58 | 79.04 |

${{\dot{m}}_{f}}_{ISO}$ (10^{6} × kg/year) | 86.42 | 86.42 | 86.42 | 86.42 | 86.42 | 86.42 | 86.42 |

$\Delta {\dot{m}}_{f}$ (10^{6} × kg/year) | −6.59 | −7.34 | −7.77 | −6.75 | −7.45 | −6.84 | −7.39 |

$\Delta {\dot{m}}_{f}$ (%) | −7.62 | −8.5 | −9 | −7.8 | −8.6 | −7.9 | −8.6 |

SFC (kg/kWh) | 0.2333 | 0.2358 | 0.2360 | 0.2323 | 0.2359 | 0.2355 | 0.2371 |

SFC_{ISO} (kg/kWh) | 0.2302 | 0.2302 | 0.2302 | 0.2302 | 0.2302 | 0.2302 | 0.2302 |

© 2017 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).

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**MDPI and ACS Style**

Baakeem, S.S.; Orfi, J.; Alaqel, S.; Al-Ansary, H. Impact of Ambient Conditions of Arab Gulf Countries on the Performance of Gas Turbines Using Energy and Exergy Analysis. *Entropy* **2017**, *19*, 32.
https://doi.org/10.3390/e19010032

**AMA Style**

Baakeem SS, Orfi J, Alaqel S, Al-Ansary H. Impact of Ambient Conditions of Arab Gulf Countries on the Performance of Gas Turbines Using Energy and Exergy Analysis. *Entropy*. 2017; 19(1):32.
https://doi.org/10.3390/e19010032

**Chicago/Turabian Style**

Baakeem, Saleh S., Jamel Orfi, Shaker Alaqel, and Hany Al-Ansary. 2017. "Impact of Ambient Conditions of Arab Gulf Countries on the Performance of Gas Turbines Using Energy and Exergy Analysis" *Entropy* 19, no. 1: 32.
https://doi.org/10.3390/e19010032