The application of zero-dimensional mathematical modelling offers significant advantages in the domain of energy systems. Firstly, it serves as a crucial support tool for the design process. Secondly, it facilitates the optimisation of operating parameters, thereby enhancing the efficiency of energy systems. Furthermore, it offers, depending on the accuracy of a model, a comprehensive analysis of the impact of various factors on the performance of a specific system. The present article focuses on a model of a gas turbine unit that has been developed using the EBSILON Professional software. The model was employed to assess the operating parameters that are characteristic of gas turbines, including the turbine inlet temperature and compression ratio, that are crucial for the efficiency and unit power of the abovementioned power system. Moreover, this approach enables the determination of the optimal operating points for the considered assumptions. Next, for the selected case, an analysis was conducted to determine the impact of changes in atmospheric air parameters on the operation of the gas turbine, applying two different approaches. Research has demonstrated that daily, and particularly seasonal, fluctuations in temperature can exert a substantial influence on the efficiency and capacity of the system, while fluctuations in pressure and relative humidity have a much smaller impact on turbine operation. Finally, the simplified model was utilised to ascertain the effect of incorporating hydrogen into fuel on the operational parameters of a gas turbine, indicating the effect of both quantitative and qualitative changes of stream in the combustion chamber and turbine.
The article presents the results of thermal and flow analysis of the working conditions of neighbouring waterwall tubes, loaded with heat streams of different values for two different widths of tube spacing. The numerical model used for the analysis allows us to calculate the temperature distribution in the tubes and in the fluid flowing through them at each time step, depending on the thermophysical parameters of the fluid and the material from which the tubes and fins were made. By using the algorithm, it is possible to precisely determine the three-dimensional temperature distribution in the tubes, allowing us to identify the locations where the greatest temperature differences occur and where the highest thermal stresses may develop. The analysis of several adjacent tubes makes it possible to determine the effect of temperature differences in the tubes and the fins connecting them, and to collect data that may be used to determine the stress distribution in the tubes and fins. In the presented Case 3, smooth tubes connected by fins were used, and the heat flux on the centre tube was 50% higher than that on the outer tubes.
In the present review article, an effort has been made to review various experimental and numerical research, which include heat transfer rate and fluid flow characteristics of a modified solar air heater (SAH) using various artificial roughness. As it is clear that artificial roughness enhances the heat transfer and performance, in this review study, various types of roughened SAH performances have been examined. These various roughness patterns are V-shape, W-rib, arc shape, spherical ball and S-type, and their placement arrangements, like transverse, inclined and longitudinal, are discussed in this article. The comparative studies of thermo-hydraulic performance with heat transfer and fluid flow investigations of various roughened SAHs have been described to identify optimal performance parameters to select the optimum configuration that can be further used for various applications. In addition to this, various correlations of the Nusselt number and friction factor developed by various investigators have also been reported. The main aim of this study is to evaluate the SAH performance using various roughness patterns. It also provides several essential recommendations for effectively designing and implementing SAHs. This review encompasses a comprehensive analysis of 178 research articles published between 1988 and 2024, focusing on advancements in the field. The findings showcase the peak values for the Nusselt number as 7.61, the friction factor reaching 6.48 times that of a smooth duct for discrete multiple-arc ribs, and the maximum thermal-hydraulic performance reported at 4.73 for dimple or protrusion ribs.
Solar air heaters are attractive for low-carbon thermal applications, but their performance is constrained by weak convective heat transfer in the near-wall region. In this work, a single-pass rectangular solar air heater duct equipped with spherical turbulators is investigated numerically and then accelerated using machine-learning surrogate models for rapid prediction of thermal–hydraulic responses. Five turbulator arrangements (V-, M-, W-shaped, inclined, and arc-shaped) were evaluated at three discrete spacing levels (pitch ratio P/D = 3, 6, 9) with a constant sphere diameter of 25 mm over Re = 3500–23 500, consistent throughout all the simulations. The computational fluid dynamics model employed a constant heat flux of 1000 W/m² and standard pressure–velocity coupling/discretisation practices, and was validated against established previous work. A leakage-safe machine-learning dataset (675 samples, 36 variables) was constructed from computational fluid dynamics outputs and physics-informed engineered features; models were trained using geometry-grouped cross-validation to ensure generalisation across turbulator arrangements and spacing levels. Among candidate regressors, histogram gradient boosting provided the best Nu surrogate (OOF RMSE = 3.299, R² = 0.9908, MAPE = 2.44%), while ridge regression yielded the most accurate friction factor surrogate (OOF RMSE = 4.70×10⁻⁴, R² = 0.9886, MAPE = 1.12%). The combined computational fluid dynamics and machine-learning framework enables fast, reliable evaluation of solar air heater thermo-hydraulic performance for configuration screening and optimisation within the validated operating envelope.
This experimental study examines the efficiencies of a cogeneration plant under various constant turbine inlet temperatures. The study considers the effects of changes in mass flow rate, inlet pressure, and inlet temperature on the electrical and overall efficiencies of the system. The findings indicate that the electrical and overall efficiencies are relatively consistent across different mass flow rates but vary slightly across different inlet pressures. The highest overall efficiency and electrical efficiency are obtained at a mass flow rate of 21.56 kg/s, an inlet pressure of 83 kG/cm², and an inlet temperature of 507°C. Under these operating conditions, the overall efficiency reached 58.06%, and the electrical efficiency was 26.26%. These findings suggest that the optimum operating conditions for this system depend on the specific requirements and priorities.
