Introduction

The increasing global energy consumption and the limited availability of resources have prompted countries to reevaluate their energy policies and focus on energy efficiency and conservation. This has led to a shift in research toward thermal analysis and improving the efficiency of power plants rather than solely relying on new energy sources [1,2,3,4]. Thermodynamics, specifically the first and second laws, have become crucial tools in analyzing the performance of power plants. While the first law of thermodynamics provides insights into the overall energy efficiency of the system, exergy analysis, which incorporates both the first and second laws, offers a more comprehensive understanding of the system's performance. Exergy analysis enables the examination of entropy changes, exergy destruction, and energy degradation in individual components of the thermal system. Additionally, second law analysis enhances the understanding of the system as a whole and the performance of each component. By employing exergy and second law analyses, researchers can gain valuable insights into the energy efficiency and thermodynamic performance of power plants, facilitating the development of strategies to optimize energy utilization and mitigate the impact of hot climates on energy systems [5,6,7].

Exergy analysis is a highly effective technique for optimizing energy systems as it provides a detailed understanding of their thermodynamic performance. This analysis plays a crucial role in identifying areas for improvement and optimizing the design and operation of energy systems, with the ultimate goal of enhancing efficiency, reducing energy consumption, and minimizing environmental impact. One of the key advantages of exergy assessment is its ability to provide a comprehensive view of energy flows and losses within a system. By quantifying exergy destruction in each component, engineers can pinpoint areas where energy is being lost and develop strategies to minimize these losses. This can lead to significant improvements in energy efficiency and lower operating costs [8, 9].

Furthermore, exergy analysis allows for the optimization of energy systems under different operating conditions. Engineers can utilize this technique to determine the system's ideal operating parameters, such as optimal temperature and pressure levels, in order to maximize efficiency and minimize energy consumption. However, there are certain limitations to exergy analysis. One major challenge is the complexity and time-consuming nature of the analysis. It requires detailed knowledge of the system being analyzed and accurate data on the properties of working fluids and operating conditions. This can be particularly challenging for complex systems or situations with limited data availability. Additionally, exergy analysis may not encompass all relevant factors that impact the overall performance of an energy system. Economic, environmental, and social factors also need to be considered in conjunction with exergy analysis to develop a comprehensive optimization strategy.

Despite these challenges, exergy analysis remains a valuable tool for energy system optimization. It provides crucial insights into the thermodynamic performance of energy systems, enabling the identification of areas for improvement and the optimization of system design and operation. By leveraging the benefits of exergy analysis and considering other relevant factors, engineers can work toward creating more efficient and sustainable energy systems [10,11,12,13,14,15].

In recent years, the pursuit of enhancing thermal power generation efficiency and sustainability garnered significant attention, reflecting the pivotal role of thermal power plants in meeting global energy demands. Elwardany et al. [16] presented a comprehensive synthesis of energy and exergy studies across various plant types, including coal, gas, biomass, oil, and combined cycle plants. Their review underscored the importance of achieving a balance between performance, cost-effectiveness, and environmental responsibility, highlighting critical aspects such as optimizing operations, economic evaluations, and assessing environmental impacts. Key findings emphasized the primary sources of exergy destruction, with boilers accounting for over 50% of losses, while turbines and condensers also significantly contributed to energy losses. Elwardany [17] contributed to the literature by delving into enhancing steam boiler efficiency through comprehensive energy and exergy analysis. The study identified optimization strategies crucial for improving efficiency, such as combustion air preheating and excess air ratios. Higher-pressure designs, particularly ultra-supercritical units, exhibited substantial reductions in exergy destruction. The review highlighting the importance of energy–exergy analysis in promoting sustainability and competitiveness in thermal power plants.

In a technical review by Ibrahim et al. [18], a comprehensive analysis of gas turbine (GT) power plants from simple to complex cycles was presented. The study focused on modeling, simulation, and operational conditions, with a systematic approach to assessing the performance of GT power plants. The review delved into the influence of operating conditions on plant performance, particularly in complex configurations. Ibrahim et al. [19] further explored optimum performance-enhancing strategies for GT plants based on effective temperatures. Through thermodynamic analysis and modeling, the study evaluated various strategies to improve overall performance, highlighting the significant impact of ambient and turbine inlet temperatures on GT plant performance. The study underscored the importance of ongoing modeling and assessments in steering toward more sustainable GT power generation. In a theoretical analysis by Basrawi et al. [20], the integration of microgas turbines (MGTs) with solar farms for power output stabilization was explored. The study aimed to address the challenge of fluctuating output from solar farms by integrating MGTs to stabilize power generation. While the study demonstrated the feasibility of balancing power output throughout the year, it also highlighted the operational constraints and efficiency considerations associated with MGTs. The assessment of simple gas turbine models has been explored by various researchers. Ibrahim et al. [21] conducted a study focusing on energy and exergy assessment, revealing that the combustion chamber incurred the most significant exergy loss. In their analysis, they found energetic and exergetic efficiencies of the air compressor to be 92% and 94.9%, respectively, while the combustion chamber exhibited energy and exergy efficiencies of 61.8% and 67.5%, compared to gas turbines' 82% and 92%, respectively. Furthermore, Ibrahim et al. [22] presented a statistical analysis and optimum performance evaluation of gas turbine power plants, utilizing response surface methodology for analyzing GT operation and performance. The study developed correlations with high accuracy in predicting performance, validated against real plant data. The findings underscored the strong influence of ambient temperature and turbine inlet temperature on GT plant performance, emphasizing the importance of these factors in optimization strategies.

Kurt et al. [23] investigated the impact of various operational parameters on gas turbine power plants. The results indicated that the overall power output reached its maximum at a turbine inlet temperature (TIT) of 1600K, compressor inlet temperature (CIT) of 288.15K, and pressure ratio (PR) of 22. Conversely, when considering compressor inlet temperature, the maximum power output was achieved at a CIT of 273.15K, TIT of 1423.15K, and PR of 18. Sa et al. [24] proposed an empirical relationship between the capacity of a gas turbine to generate electricity and ambient air conditions that deviate from standard ISO conditions. Their data indicated that for every degree increase in ambient temperature above ISO conditions, the gas turbine experienced a power output loss of 1.47 MW and a decrease in thermal efficiency of 0.1%. Abou Al-Sood et al. [25] examined the operational efficiency of a gas turbine with an irreversible intercooler regeneration and reheat gas cycle. The optimization analysis identified the optimal lowest temperature range between 302 and 315 K and the highest temperature range between 1320 and 1360 K. The highest pressure in the cycle was suggested to range from 1449 to 2830 kPa to ensure the optimization of all performance parameters. Salah et al. [26] investigated the impact of compression ratio, relative humidity, and ambient temperature on the thermal energy and exergy of a gas power plant over the course of a year under actual weather conditions. Through ChemCad simulation, the study identified system weaknesses, losses, and the influence of external variables on the performance of the turbine unit. The results revealed that the combustion chamber exhibited the highest exergy distortion, followed by the compressor and the gas turbine. The maximum energy efficiency of 37% was observed in November when the ambient temperature (Ta) was 19.39 °C. Additionally, the specific fuel consumption (SFC) was found to increase with rising ambient temperature, reaching its peak at 33.27 °C, as observed in both practical and software calculations.

Our review methodology involved a systematic search of literature databases such as Scopus, Google Scholar, and IEEE Xplore, using keywords related to gas turbine performance, exergy analysis, and energy efficiency. We prioritized studies aligned with our research objectives and assessed their methodology, findings, and implications. The selection encompassed diverse methodologies, geographical locations, and power plant types to provide a comprehensive overview. The synthesis aimed to elucidate challenges and opportunities in enhancing gas turbine efficiency and sustainability, particularly in high-temperature environments like Assiut, Egypt.

The problem addressed in this research is the performance degradation of gas turbine power plants operating under high-temperature conditions. Hot climates, like those in Assiut, Egypt, negatively impact the efficiency of these plants due to thermodynamic limitations. Traditional energy analysis provides limited insight into these inefficiencies. This research proposes using exergy analysis, a more comprehensive technique that considers both energy quantity and quality, to identify areas of wasted potential within the gas turbine cycle. The novelty of this study lies in its focused exergy analysis of a gas turbine power plant situated in Assiut, Egypt, operating under high-temperature conditions. While previous research has examined gas turbine performance using various approaches, including energy analysis, this study employs exergy analysis as the basis for assessment. Exergy analysis provides a more comprehensive understanding of thermodynamic inefficiencies within the system by considering both energy quantity and quality. Comparing this research with existing literature, previous studies have explored energy and exergy assessments of gas turbine cycles, but few have focused specifically on plants operating under high-temperature conditions, such as those in Assiut, Egypt. Additionally, while some research has touched upon the influence of ambient temperature on gas turbine performance, this study delves deeper into the topic by quantifying the impact on exergy efficiency, exergy destruction, and net power output across a range of ambient temperatures.

Gas turbine power plants are a mainstay of electricity generation, offering high power-to-mass ratios and flexibility in fuel selection. However, their performance is significantly impacted by ambient temperature. In hot climates, like those experienced in Assiut, Egypt, efficiency suffers due to thermodynamic limitations. This study addresses this challenge by employing exergy analysis, a technique that goes beyond traditional energy analysis to identify areas of wasted potential. This research focuses on a specific gas turbine power plant located in Assiut, Egypt. By leveraging real operational data from the plant's control system, a comprehensive model is developed in EES software [27]. This model allows us to perform an exergy analysis, pinpointing the primary sources of inefficiency within the gas turbine cycle. The key objective of this study is to investigate the influence of varying ambient temperatures on the plant's performance. We aim to quantify the impact on factors such as exergy efficiency, exergy destruction, and net power output. By understanding these relationships, we can identify strategies to improve the plant's performance, particularly under hot weather conditions. This research offers valuable insights for engineers and researchers working to optimize gas turbine power plants in hot climates. The findings contribute to the body of knowledge on gas turbine optimization, particularly in regions with challenging environmental conditions, and can inform engineering practices aimed at enhancing efficiency and sustainability in thermal power generation.

Modeling and analysis

In this study, we undertake an energy and exergy investigation of an actual gas turbine power cycle using real operating data. The analysis encompasses both exergy and energy assessments, aligned with the first and second laws of thermodynamics, respectively, to comprehensively evaluate the plant's thermodynamic performance. Table 1 presents raw operational data from the Assiut Power Plant, a fossil fuel power facility that operates by combusting fuel to generate high-pressure combustion gases, subsequently used to drive a turbine for electricity production. These data encompass various crucial variables pivotal for determining the system's performance. Additionally, Table 2 outlines the technical parameters specific to the gas turbine [27]. Figure 1 offers an extensive overview of the Assiut Gas Turbine Power Plant, while Fig. 2 presents a detailed process flow schematic, enhancing visual comprehension of the gas turbine power plant's operations.

Table 1 Key operational parameters of the gas turbine power plant
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Table 2 Technical specifications of the gas turbine [27]
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Fig. 1
figure 1

Assiut gas turbine power plant

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Fig. 2
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An illustration depicting the schematic flow of the gas turbine power plant

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During the analysis, several assumptions are taken [28, 29]. These assumptions can be given as shown in Table 3.

Table 3 Thermodynamic assumptions used for the gas turbine power cycle model based on [28, 29]
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Energy analysis

The energy evaluations of the gas turbine power plant are related to the Brayton cycle. The computation will include evaluating the input and output energy of the system. The primary elements of the gas turbine cycle include air compressors, combustion chambers, and gas turbine. Following are the equations required for analyzing each part of the system [12].

Compressor:

$${T}_{2}={T}_{1}\left(1+\frac{1}{{\eta }_{\text{AC}}}\left({r}_{\text{AC}}^{\frac{k-1}{\text{k}}}-1\right)\right)$$
(1)
$${\dot{W}}_{\text{AC}}={\dot{m}}_{\text{a}}{c}_{\text{pa}}\left({T}_{2}-{T}_{1}\right)$$
(2)
$${c}_{\text{pa}}(T)=1.048-\left(\frac{1.83T}{{10}^{4}}\right)+\left(\frac{9.45{T}^{2}}{{10}^{7}}\right)-\left(\frac{5.49{T}^{3}}{{10}^{10}}\right)+\left(\frac{7.92{T}^{4}}{{10}^{14}}\right)$$
(3)

In Eq. (1), T1 and T2 represent the air temperature at the compressor input and discharge sections, k is the specific heat ratio, and r is the compression ratio. The power consumption of the compressor is calculated using Eq. (2). Equation (3) provides the air specific heat depending on the varying temperatures.

Combustion chamber:

$${\dot{m}}_{\text{a}}{h}_{2}+{\dot{m}}_{\text{f}}\text{LHV}={\dot{m}}_{\text{g}}{h}_{3}+\left(1-{\eta }_{\text{cC}}\right){\dot{m}}_{\text{f}}\text{LHV}$$
(4)
$${\dot{m}}_{\text{g}}={\dot{m}}_{\text{f}}+{\dot{m}}_{\text{a}}$$
(5)

The lower heating value of a fuel (LHV) differs based on the characteristics of the used fuel. In Eq. (4), \({h}_{2}\) and \({h}_{3}\) represent the working fluid's enthalpy at the combustion chamber inlet and discharge sections, \({\eta }_{\text{CC}}\) is the combustion chamber efficiency, \({\dot{m}}_{\text{a}}\) and \({\dot{m}}_{\text{f}}\) represents the mass flowrate of air and fuel, respectively, while \({\dot{m}}_{\text{g}}\) is the mass flowrate of combustion gases.

Gas turbine:

$${T}_{4}={T}_{3}\left(1-{\eta }_{\text{GT}}\left(1-{\left(\frac{{P}_{3}}{{P}_{4}}\right)}^{\frac{k-1}{k}}\right)\right)$$
(6)
$${\dot{W}}_{\text{GT}}={\dot{m}}_{\text{g}}{c}_{\text{p,g}}\left({T}_{3}-{T}_{4}\right)$$
(7)
$${C}_{\text{pg}}(T)=0.991+\left(\frac{6.997T}{{10}^{5}}\right)+\left(\frac{2.712{T}^{2}}{{10}^{7}}\right)-\left(\frac{1.2244{T}^{3}}{{10}^{10}}\right)$$
(8)

In Eq. (6), T3 and T4 represent the turbine input and output combustion gas temperatures, respectively.

Power output from the turbine is calculated using Eq. (7). Equation (3) evaluates the specific heat of air based on varying temperature. The equations below used to determine the overall energy efficiencies and net power output [30].

$${\dot{W}}_{\text{Net }}={\dot{W}}_{\text{GT}}-{\dot{W}}_{\text{AC}}$$
(9)
$${\eta }_{\text{ I}}=\frac{{\dot{W}}_{\text{net }}}{{\dot{m}}_{\text{fuel}}\text{LHV}}$$
(10)

Exergy analysis

Exergy is the largest valuable work achieved as a system reaches equilibrium with its surroundings. Utilizing the second law of thermodynamics, mass and energy balances, exergy analysis is an efficient technique for evaluating the performance of energy systems. Exergy includes four components: chemical, physical, kinetic, and potential exergies. Only physical and chemical exergies are accounted for in the analyses, while kinetic and potential exergy are ignored. The maximum amount of work a system can do is shown by its physical exergy. Chemical exergy, on the other hand, is related to how the chemical composition of a system changes from equilibrium state [31]. General exergy analysis equations are shown below:

$${\dot{E}}_{{\rm x, heat }}+\sum_{\text{i}} {\dot{m}}_{{\rm i}}{e}_{{\rm x,i}}=\sum_{\text{e}} {\dot{m}}_{\rm e}{e}_{\rm x,e}+{\dot{E}}_{\rm x,w}+{\dot{I}}_{\text{dest.}}$$
(11)
$${\dot{E}}_{\rm x,W}=\dot{W}$$
(12)
$${\dot{E}}_{{\rm x, heat }}=\left(1-\frac{{T}_{\rm o}}{{T}_{\rm i}}\right){\dot{Q}}_{\rm i}$$
(13)
$${\dot{E}}_{\rm x}={\dot{E}}_{{\rm x,physical}}+{\dot{E}}_{\text{x, chemical}}$$
(14)

Using Eq. (11), the exergy flow rate for each system component can be determined [30]. Equation (12) demonstrates the work performed by the system from exergy flow [30]. The rate of exergy generation with heat is shown in Eq. (13) [30]. The chemical and physical exergies of the component are shown in Eq. (14) [30].

Physical exergy

The physical exergy is produced due to the system deviation from its dead-state condition in terms of pressure and temperature [21]. Use the following equations to calculate the system physical exergy [46].

$${e}_{\rm x}={e}_{\text{x, physical}}+{e}_{{\text{x, \,chemical}}}$$
(15)
$${e}_{{\text{x,physical}}}={e}_{\rm x}^{\rm T}+{e}_{\rm x}^{\rm P}$$
(16)
$${e}_{\rm x}^{\rm T}={c}_{\rm p}\left(\left(T-{T}_{\rm o}\right)-{T}_{\rm o}\text{ln}\frac{T}{{T}_{\rm o}}\right)$$
(17)
$${e}_{\rm x}^{\rm p}=R{T}_{\rm o}\text{ln}\frac{P}{{P}_{\rm o}}$$
(18)

The physical exergy calculation is shown in Eq. (16). Equations (17) and (18) determine physical exergy based on temperature and pressure. Po and To represent the surrounding pressure and temperature, whereas R and Cp denote the gas constant and the specific heat at constant pressure, respectively [30].

Chemical exergy

Chemical exergy is caused when the chemical composition of the system deviates from the surrounding dead-state condition [21]. The fuel's exergy flow can be identified by using the following equation.

$$\upxi =\frac{{\text{e}}_{\text{x, fuel }}}{{\text{LHV}}_{\text{fuel}}}$$
(19)

Based on Eq. (19), \(\xi \) denotes the ratio of exergy flow to the LHV of the fuel \(( {\text{LHV}}_{\text{fuel }}=48, 806 \text{ kJ }\text{kg}^{-1}).\) Usually, the value for \(\xi \) is 1.06 for NG [21]. Thus, the value of fuel exergy can be calculated using the ratio of exergy and the LHV. The exergy of the combustion products can be found with the help of the following equation [21].

$${{e}}_{\mathrm{x,cg}}= \frac{\left[\sum_{\mathrm{i}=1}^{\mathrm{n}} {{x}}_{\mathrm{i}}{{e}}_{\mathrm{x, che ,i}}+ {\mathrm{RT}}_{\mathrm{o}}\sum_{\mathrm{x}=\mathrm{i}}^{\mathrm{n}} {\mathrm{x}}_{\mathrm{i}} \mathrm{ln}({{x}}_{\mathrm{i}})\right]}{\sum (x_{\mathrm{i}})} $$
(20)

The subscripts I in Eq. (20) determine the type of air fraction, where x is the molar fraction of air, and \({e}_{\rm x,ch}\) is the standard chemical exergy of each element of air fraction. Table 4 contains the molar fraction of each gas and Standard chemical exergy. The following equations can achieve a more accurate result [32].

Table 4 Standard exergy and molar fraction [32]
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$$\uplambda =\frac{0.058{\dot{\text{m}}}_{\text{air }}}{{\dot{\text{m}}}_{\text{fuel}}}$$
(21)
$${\text{x}}_{{\text{N}}_{2}}=\frac{(7.524)\uplambda }{1+(9.6254)\uplambda }$$
(22)
$${\text{x}}_{{\text{O}}_{2}}=\frac{2(\uplambda -1)}{1+(9.6254)\uplambda }$$
(23)
$${\text{x}}_{{\text{CO}}_{2}}=\frac{1+(0.0028)\uplambda }{1+(9.6254)\uplambda }$$
(24)
$${\text{x}}_{{\text{H}}_{2}\text{O}}=\frac{2+(0.0972)}{1+(9.6254)\uplambda }$$
(25)

Equations (21–25) can compute the molar fraction of each element of the combustion products; the equations are only useful when NG is used as the fuel. Subscript k represents the fuel–air ratio [32].

The exergy efficiency of a system is a significant indication of how efficiently it uses energy. It is the ratio of the amount of useful work a system produces to the energy it receives. The efficiency with which the energy may be used is considered. Increasing a system's exergy efficiency leads to less wasted energy and more productivity. Therefore, exergy efficiency is crucial for determining the long-term viability and financial viability of energy systems. To quantify the exergy destruction, the exergy flow rates for each component were determined. The exergy flow effectively decreases after each process. Table 5 summarizes the equations utilized to calculate the exergy destruction and exergy efficiency at various gas turbine power plant components [32].

Table 5 Exergy destruction and exergy efficiency and for different parts of the cycle [29]
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Results and discussion

This section presents the analysis of findings and the impact of operational conditions on the performance of gas turbine power cycles. A computer model developed using EES software was utilized to investigate the influence of outside temperature on overall exergy efficiencies, total exergy destruction, and net power output. Figure 3 illustrates the overall energy and exergy efficiencies of the gas turbine unit, which are measured at 28.8% and 27.17%, respectively. These results are in line with previous studies on gas turbine cycle power plants [5, 33,34,35]. The distinction between energy efficiency and exergy efficiency lies in the fact that energy efficiency solely considers the quantity of energy, whereas exergy efficiency takes into account the quality of energy. In other words, exergy efficiency considers the potential of energy to perform useful work and provides a more comprehensive indicator of system efficiency. Furthermore, Fig. 4 presents a breakdown of the exergy efficiency for different components of the system, namely the gas turbine, combustion chamber, and air compressor. The air compressor exhibits an exergy efficiency of 87.45%, while the combustion chamber demonstrates an exergy efficiency of 71.2%. Finally, the gas turbine component displays the highest exergy efficiency at 95.38%. By analyzing the exergy efficiency of each component, it becomes possible to identify the most efficient parts of the system as well as areas that can be improved to enhance overall system performance [36].

Fig. 3
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Overall system energy and exergy efficiency

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Fig. 4
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Second low efficiency of system components

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The data presented in Figs. 5 and 6 provides insights into the exergy destruction within the system and the percentage distribution of exergy destruction among its components. It is observed that the combustion chamber is responsible for the highest amount of exergy destruction, amounting to 113,338 kW, which corresponds to 85.22% of the overall exergy destruction in the system. Our results align with studies that have identified combustion chamber as critical sites of exergy loss in gas turbine power plants [37,38,39,40]. This indicates that the combustion process is the primary contributor to the system's total exergy destruction. The air compressor also plays a significant role in exergy destruction, accounting for 11,195 kW, which is 8.42% of the total exergy destruction. This suggests that the compression process contributes significantly to the overall exergy destruction within the system. On the other hand, the gas turbine exhibits the lowest exergy destruction among the components, with a value of 8464 kW, representing 6.36% of the total exergy destruction. These findings emphasize the importance of optimizing both the combustion process and the compression process to reduce exergy destruction and improve the operational performance of the system. By focusing on these areas, it is possible to mitigate exergy losses and enhance the overall efficiency of the gas turbine power cycle [38].

Fig. 5
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Exergy destruction of system parts

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Fig. 6
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Share of exergy destruction of each system parts

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Figure 7 enables a comparative analysis of exergy efficiency among various components in the Assiut gas turbine power plant and the MARAFIQ gas turbine power plant in Saudi Arabia [21]. This comparison offers valuable insights into the efficiencies and operational performances of these systems. By examining the exergy efficiencies of key components, a nuanced understanding of each system's strengths and weaknesses is gained. In Assiut's gas turbine power plant, the gas turbine itself demonstrates notably higher efficiency at 95.3%, surpassing MARAFIQ's 91.9%. Additionally, Assiut achieves higher efficiency in the combustion chamber, reaching 71.2% compared to MARAFIQ's 68.3%. Conversely, MARAFIQ's gas turbine cycle excels in air compressor efficiency, boasting an impressive 94.9% compared to Assiut's 87.4%, suggesting a potentially optimized compression process in the Saudi Arabian plant. However, when considering overall cycle efficiency, MARAFIQ significantly outperforms Assiut, achieving 32.3% compared to Assiut's 27.17%. This difference may be attributed to more efficient integration and operation of the entire cycle in the MARAFIQ plant. Overall, this comparison highlights the importance of evaluating individual component efficiencies alongside overall cycle efficiency to comprehensively understand gas turbine power plant performance.

Figure 7
figure 7

Exergy efficiency for all components in both Assiut and MARAFIQ plants [21]

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Impact of the outside temperature on exergy efficiency and exergy destruction

The operational efficiency of a gas turbine power plant is influenced by various parameters, and one of the most significant factors is the ambient temperature. It is crucial to maintain predetermined ranges of humidity and temperature in the incoming air to ensure the optimal operating conditions of the unit [21, 26, 39,40,41].

Figures 8 and 9 present valuable information regarding the impact of outside temperature on the exergy efficiency, exergy destruction rate, and net power output in a gas turbine power cycle. The data reveals that as the outside temperature increases, the exergy destruction in both the combustion chamber and the compressor also rises. This indicates that higher ambient temperatures result in increased energy losses in the form of exergy destruction, thereby reducing the overall efficiency of the power plant. Figure 8 illustrates that as the outside temperature rises from 0 to 45 °C, the total exergy efficiency of the power plant declines from 27.91 to 26.63%. Additionally, the exergy destruction, which represents the amount of available energy lost during the electricity generation process, increases with higher ambient temperatures. At 0 °C, the exergy destruction is 126,407 kW, while at 45 °C, it increases to 138,135 kW. This implies that more energy is being lost as exergy destruction at higher ambient temperatures, which is not utilized for electricity generation. The relationship between ambient temperature and both efficiency and destruction appear to be close to linear based on the steady changes in the values. This highlights the importance of monitoring and adjusting the operation of gas turbine power plants according to the external temperature conditions in order to maximize total exergy efficiency and minimize exergy destruction. Figure 9 demonstrates that as the outside temperature rises, the net power output decreases. At 0 °C, the net power output is 88,084 kW, whereas it decreases to 84,051 kW at 45 °C. The decrease in net power output with increasing ambient temperature is a common phenomenon in power generation systems. This is because the efficiency of the power generation process is influenced by the temperature of the working fluid, typically water or steam. Higher temperatures result in lower fluid density and higher vapor pressure, which can lead to increased losses due to friction, leaks, and other system inefficiencies. Moreover, high temperatures can cause thermal stresses on the equipment, leading to premature wear and tear and reducing the lifespan of the system. The information provided in the figures underscores the importance for power plant operators and engineers to make informed decisions and take appropriate actions to maintain optimum system operation at different ambient temperatures. By considering these factors, they can effectively manage gas turbine power plants to achieve maximum exergy efficiency, minimize exergy destruction, and ensure optimal performance [37, 40, 42].

Fig. 8
figure 8

Variation in total exergy destruction and overall exergy efficiency with respect to ambient temperature

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Fig. 9
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variation in net power production with regard to the temperature of the surroundings

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In Fig. 10, data on the exergy destruction and exergy efficiency of the air compressor at various ambient temperatures ranging from 0 to 45 °C reveal significant trends. As the surrounding temperature increases, there is a noticeable decrease in the air compressor's exergy efficiency alongside a corresponding rise in exergy destruction. At 0°C, the air compressor demonstrates its highest exergy efficiency, reaching 88.4%, while concurrently registering the lowest exergy destruction at 10,251 kW. Conversely, at 45 °C, the air compressor exhibits its lowest exergy efficiency of 86.825%, accompanied by the highest recorded exergy destruction of 11,941 kW. These findings underscore the pronounced impact of elevated ambient temperatures on the air compressor's efficiency and performance in power generation systems [40, 41]. Similarly, Fig. 11 provides insights into the exergy efficiency and destruction of the combustion chamber across varying surrounding temperatures from 0 to 45 °C. Here, a consistent pattern emerges as the outside temperature increases, the exergy efficiency of the combustion chamber declines, while exergy destruction escalates. At 0 °C, the combustion chamber achieves its peak exergy efficiency of 71.97%, contrasting sharply with the lowest exergy efficiency of 70.6% observed at 45 °C. Furthermore, the maximum exergy destruction of the combustion chamber is recorded at an ambient temperature of 45 °C, reaching 117,167 kW. These results underscore the substantial impact of high ambient temperatures on the combustion chamber's efficiency and performance in power generation systems [34, 37, 38]. Finally, Fig. 12 delineates the exergy efficiency and exergy destruction of the gas turbine across varying outside temperatures, from 0 to 45 °C. Here, a discernible trend emerges with increasing ambient temperature, the gas turbine's exergy efficiency declines, while exergy destruction increases. At 0 °C, the gas turbine attains its highest exergy efficiency of 95.63%, while registering its lowest exergy efficiency of 95.20% at 45 °C. Similarly, the gas turbine experiences its highest exergy destruction of 9,028 kW at 45 °C, contrasted with the lowest exergy destruction of 7750 kW observed at 0 °C. These findings underscore the significant impact of high ambient temperatures on the efficiency and performance of the gas turbine in power production systems [26, 37].

Fig. 10
figure 10

Air compressor's exergy efficiency and exergy destruction change with ambient temperature

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Fig. 11
figure 11

Variation in combustion chamber exergy destruction and exergy efficiency with respect to ambient temperature

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Fig. 12
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Variation in gas turbine exergy destruction and exergy efficiency with respect to ambient temperature

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Figure 13 provides insights into the exergy efficiency of the main components at various ambient temperatures from 0 to 45 °C. With increasing ambient temperature, the exergy efficiency reduces for all three components. The gas turbine demonstrates the highest exergy efficiency among the three, reaching its peak value of 95.63% at 0 °C. The combustion chamber exhibits an intermediate level of exergy efficiency, with its highest value of 71.97% also observed at 0 °C. In contrast, the air compressor displays the lowest exergy efficiency, with its highest value of 88.4% recorded at 0 °C. Overall, the data emphasizes the negative impact of rising ambient temperatures on power generation system efficiency. Therefore, it is crucial to consider the effects of ambient temperatures and implement suitable measures to enhance system efficiency under high-temperature conditions. Such measures can involve the utilization of cooling systems and heat recovery systems to mitigate the adverse effects of elevated temperatures on power generation systems' performance [26, 39, 41]. Similarly, Fig. 14 highlights the exergy destruction of the main parts of the gas turbine power cycle across ambient temperatures from 0 to 45°C. As ambient temperature rises, the exergy destruction increases for all three components. Among them, the air compressor exhibits the lowest exergy destruction, reaching its peak value of 11,941 kW at 45°C. Conversely, the combustion chamber experiences the highest exergy destruction, peaking at 117,167 kW at 45 °C. The gas turbine falls in between, with a peak exergy destruction of 9028 kW at 45 °C.

Fig. 13
figure 13

Exergy efficiency of various parts of the system

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Fig. 14
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Exergy destruction of different components

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Parametrical exergy destruction and exergy efficiency analysis

The temperature coefficient is calculated to determine the rate of change of net power output concerning temperature, aiding in predicting system performance under varied ambient conditions and determining the optimal operating temperature range. Table 6 provides specific details regarding the relationship between exergy destruction and exergy efficiency of different system components and their susceptibility to ambient temperature. The positive correlation observed between outside temperature and exergy destruction for the compressor, combustion chamber, and gas turbine implies that higher ambient temperatures correspond to increased exergy destruction. Conversely, the negative correlation between outside temperature and exergy efficiency indicates that higher ambient temperatures result in decreased exergy efficiency.

Table 6 Correlation between ambient temperature and exergy destruction vs. efficiency of system components
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Conclusions

This study conducts an exergy assessment of a gas turbine power plant operating under high-temperature conditions in Assiut, Egypt, using real operational data. The analysis aims to quantify the exergy efficiencies and destruction of key components within the system and assess the impact of varying ambient temperatures on plant performance. The results reveal that the combustion chamber accounts for the highest exergy destruction at 85.22%, indicating its significant role in thermodynamic inefficiency. The compressor and turbine contribute lesser amounts at 8.42% and 6.36% respectively, while the gas turbine exhibits the highest exergy efficiency at 95.38%, contrasting with the combustion chamber's lower efficiency of 71.2%.

The study underscores the strong influence of ambient temperature on the plant's thermodynamic performance. With increasing temperatures from 0 to 45 °C, the overall exergy efficiency declines from 27.91 to 26.63%, accompanied by a rise in total exergy destruction from 126,407 to 138,135 kW. Concurrently, the net power output decreases steadily from 88,084 to 84,051 kW across the same temperature range. To mitigate the adverse effects of hot ambient conditions, optimizing the combustion chamber through strategies such as intake air cooling or improving the air–fuel ratio is recommended. Additionally, exploring advanced gas turbine technologies may aid in maintaining efficiency at higher temperatures. Further techno-economic studies are advised to evaluate the costs and benefits of different optimization approaches for gas power plants in hot climates, considering both capital and operating expenses.

Overall, this study underscores the utility of exergy analysis in identifying thermodynamic inefficiencies in gas turbine power plants. The insights obtained can inform design modifications and operational practices to maximize plant efficiency and output, particularly in the face of increasing temperatures due to climate change. Continued research in this domain can contribute to the sustainable and efficient utilization of gas turbines worldwide.

Energy and exergy losses in gas turbine power plant can be reduced and efficiency can be improved by doing the following recommendation such as:

  1. 1.

    Intake Air Temperature Control: Reduce inlet temperature to increase air density and minimize compressor work, thereby reducing exergy destruction.

  2. 2.

    Combustion Chamber Optimization: Modify the combustion chamber to improve fuel–air ratio control and enhance combustion efficiency.

  3. 3.

    Enhanced Turbine Blade Materials: Explore materials that can withstand higher turbine inlet temperatures, enabling increased work output and improved system efficiency.

  4. 4.

    Advanced Cooling Techniques: Develop innovative cooling methods for critical components to maintain their integrity and minimize exergy losses.

  5. 5.

    Advanced Control Systems: Implement advanced control strategies for optimized gas turbine performance, including real-time monitoring and predictive maintenance.

  6. 6.

    Waste Heat Recovery: Explore opportunities to recover and utilize waste heat from exhaust gases or cooling streams to improve energy efficiency.

  7. 7.

    Computational Modeling and Simulation: Utilize advanced modeling and simulation techniques to optimize system performance and guide decision-making processes.

Implementing these recommendations can contribute to reducing energy and exergy losses, improving system efficiency, and enhancing the overall performance of gas turbine power plants.

While this study offers valuable insights into gas turbine performance under high-temperature conditions, there are a few limitations to consider:

  1. 1.

    Specificity: The findings are based on a particular gas turbine power plant in Assiut, Egypt, using real operational data. Results may not be universally applicable to gas turbine plants with different configurations or operating parameters.

  2. 2.

    Limited Parameters: The analysis primarily focuses on the impact of ambient temperatures on exergy efficiency and destruction of key components. Other operational factors like turbine inlet temperature and fuel characteristics were not extensively examined.

  3. 3.

    Component Focus: The study mainly investigates the combustion chamber, compressor, and turbine, without comprehensive evaluation of other components such as the generator and heat recovery system. A broader assessment of the entire system would provide a more holistic understanding.

  4. 4.

    Economic Considerations: The study does not address the economic aspects of implementing optimization strategies or advanced technologies. Future research should conduct techno-economic analyses to evaluate the feasibility and costs associated with different approaches.

  5. 5.

    Climate Change Scope: While the study examines the effects of rising temperatures due to climate change, it does not explore other environmental factors like air quality and extreme weather events, which can impact gas turbine performance. Further research should consider these broader implications.

Recognizing these limitations, future research can build upon these findings to develop more comprehensive assessments of gas turbine performance under high-temperature conditions. Additionally, addressing economic factors, considering broader climate change effects, and exploring innovative solutions will contribute to more sustainable and efficient gas turbine operations in hot climates.

Future Research Directions:

  1. 1.

    Techno-economic Analysis: Conduct cost–benefit analyses for optimization strategies and advanced technologies in gas turbine power plants, considering capital investments, operational expenses, and energy savings.

  2. 2.

    Long-Term Effects of Climate Change: Study how climate change impacts gas turbine performance over extended periods, including air quality, humidity, and extreme weather events.

  3. 3.

    Comprehensive System Evaluation: Assess the entire gas turbine system, including the generator and heat recovery system, to gain a holistic understanding of performance.

  4. 4.

    Novel Cooling Techniques: Develop innovative cooling methods for gas turbine components to mitigate high ambient temperatures.

  5. 5.

    Optimization of Combustion Processes: Investigate advanced combustion technologies to enhance the efficiency and emissions of gas turbines.

  6. 6.

    Environmental Implications: Assess broader environmental impacts and explore mitigation strategies for gas turbine power plants in hot climates.

Addressing these research directions will advance our knowledge of gas turbine operation in hot climates, leading to more sustainable and resilient energy generation practices.