Thermo-economic Optimization and Exergy Analysis of a Simple Cycle Gas Turbine Power Plant under High Ambient Temperature Conditions: A Case Study of Libya

الملخص

The energy sector of Libya is dealing with an increase in demand and severe weather conditions that limit the generation of electricity. Most of the grid's electricity generation comes from gas turbines, but their thermodynamic output is diminished due to hot weather, averaging 303 K in the coastal regions. This research breaks from standard air assumptions and develops a more complex mathematical model to account for temperature-dependent specific heat changes, using the NASA 9-coefficient polynomials for more accurate predictions. A multi-objective parametric optimization was used to investigate the trade-offs between thermodynamic efficiencies and total cost rates. The primary results of the thermal simulation show efficiencies of 27.38%, 26.33% for exergy and thermic efficiencies, respectively. It also identifies the combustion chamber as the primary source of exergy destruction due to the destruction of an estimated 74.5% of the exergy. However, the economic analysis presents a financial cliff. While the efficiency is at an all-time optimum pushing toward a TIT of 1600 K], the relationship between efficiency and costs becomes exponential beyond $30 million/h. Therefore, the analysis identifies an optimal design region of r_p ≈ 16 and TIT ≈ 1350 – 1450 K where the LCOE is at 11.6 cents/kWh, given the opportunity cost of fuel $5/GJ. This analysis is of great Techno-Economic importance to the energy planners intending to modernize the power supply system of Libya.