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Variable geometry turbine (VGT), a key component of modern internal combustion engines (ICE) turbochargers, is increasingly used for better efficiency and reduced exhaust gas emissions. The aim of this study is the development of a new meanline FORTRAN code for accurate performance and loss assessment of VGTs under a wider operating range. This code is a useful alternative tool for engineers for fast design of VGT systems where higher efficiency and minimum loss are being required.

The proposed meanline code was applied to a variable geometry mixed flow turbine at different nozzle vane angles and under a wide range of rotational speed and the expansion ratio. The numerical methodology was validated through a comparison of the predicted performance to test data. The maps of the mass flow rate as well as the efficiency of the VGT system are discussed for different nozzle vane angles under a wide range of rotational speed. Based on the developed model, a breakdown loss analysis was carried out showing a significant effect of the nozzle vane angle on the loss distribution.

Results indicated that the nozzle angle of 70° has led to the maximum efficiency compared to the other investigated nozzle vane angles ranging from 30° up to 80°. The results showed that the passage loss was significantly reduced as the nozzle vane angle increases from 30° up to 70°.

This paper outlines a new meanline approach for variable geometry turbocharger turbines. The developed code presents the novelty of including the effect of the vane radii variation, due to the pivoting mechanism of the nozzle ring. The developed code can be generalized to either radial or mixed flow turbines with or without a VGT system.

The purpose of this paper is to study a solar thermal system. Solar chimney power plants (SCPPs) produce electrical energy and thermal heat from solar radiation. The thermal study of SCPPs is required, as these solar systems are characterized by high costs.

This study presents a numerical study of unsteady airflow characteristics inside an SCPP. In fact, the generated power of the SCPP depends on environmental conditions. To validate this study, a solar prototype is built in the National School of Engineers of Sfax, University of Sfax, Tunisia, North Africa. The system is mainly composed by a collector, an absorber, a chimney and a turbine. The collector diameter is 2750 mm, the collector roof height is 50 mm, the chimney height is 3,000 mm and the turbine diameter is 150 mm.

The local characteristics of the air flow are presented and analyzed, such as the distribution of the temperature, the magnitude velocity and the total pressure. Analysis confirms that ambient air temperature and solar radiation are important environmental variables for the improvement of solar chimney efficiency.

Although much work has been done to date, it has been noted that the most published works have presented the profiles of air velocity and air temperature in a specific position within the solar setup. However, these profiles could sometimes be misinterpreted. In fact, some researchers did not focus on the distribution of air temperature, air velocity and pressure. These parameters are important to optimize the solar system. Indeed, the most published works deal with a larger prototype, such as the Manzanares prototype. However, it has not found connections between larger and small prototypes of SCPP.

The reliability prediction is among the most important objectives for achieving overall system performance, and this prediction carried out by anticipating system performance degradation. In this context, the purpose of this research paper is to development of methodology for the photovoltaic (PV) modules' reliability prediction taking into account their future operating context.

The proposed methodology is framed by dependability methods, in this regard, two methods of dysfunctional analysis were used, the Failure Mode and Effects Criticality Analysis (FMECA) method is carried out for identification of the degradation modes, and the Fault Tree Analysis (FTA) method is used for identification the causes of PV modules degradation and the parameters influencing its degradation. Then, based on these parameters, accelerated tests have been used to predict the reliability of PV modules.

The application of the proposed methodology on PWX 500 PV modules' in different regions of Algeria makes it possible to predict its reliability, taking into account the future constraints on its operation. In this case, the temperature and relative humidity vary from one region to another was chosen as constraints. The results obtained from the different regions confirms the reliability provided by the designer of the Saharan cities Biskra, In Salah, Tamanraset, and affirms this value for the two Mediterranean cities of Oran and Algiers.

The proposed methodology is developed for the reliability prediction of the PV modules taking into account their future operating context and, the choice of different regions confirms or disproves the reliability provided by the designer of the PV modules studied. This application confirms their performance within the framework of the reliability prediction.