This paper explores the effect of varying the number and configuration of internal cooling channels on the thermal performance of gas turbine blades. The findings demonstrate the significance of this parameter for improving blade cooling efficiency. Actually, such a study is lacking in the currently available literature. Therefore, six internal cooling configurations were designed using Autodesk Inventor employing the real turbojet airfoil RS1S. The high-pressure gas turbine rotor blades were designed with an 11° twist angle in order to predict the actual behavior of the blade cooling under operating conditions. A series of numerical tests were carried out by coupling the CAD software with COMSOL Multiphysics. A conjugate heat transfer and computational fluid dynamics model were performed. Convective heat flux (CHF), temperature, Nusselt number, air velocity, Reynolds number, and friction force were evaluated for each studied case. The findings showed that adding a second cooling channel to the trailing edge improved the convective heat flux by 63%. On the other hand, creating a new cooling channel increased the blade’s thermal inertia, leading to a cooling limitation. It was also observed that hot spots on the blade surface can develop as a result of air thermal saturation due to extended residence time in the blade channels. In fact, the blade average temperature decreased by 8% using five disconnected channels rather than five serpentine channels. The blade temperature and CHF were reduced by 16 and 22%, respectively, as a result of adding a third channel in the blade mid-zone. Overall, this paper highlighted the potential for improving blade internal cooling through the careful optimization of the number and configuration of internal channels.

This study presents a numerical investigation of a parabolic trough absorber tube equipped with a novel Angularly Segmented Ring Turbulator (ASRT), designed to enhance heat transfer through periodic flow disturbance and improved wall–fluid interaction. The proposed ASRT geometry consists of segmented annular rings arranged along the tube length, characterized by two key parameters: the number of angular segments per ring (Nr = 4, 6, 8) and the angular spacing of each segment (α = 20° and 40°). Three dimensional simulations were performed using the finite volume method under turbulent flow conditions, with Reynolds numbers ranging from 3300 to 11,000. A non-uniform solar heat flux, obtained via Monte Carlo Ray Tracing (MCRT), was applied as a boundary condition at the outer wall to replicate realistic solar concentration. The results reveal that the ASRT significantly improves convective heat transfer, with the Nusselt number ratio $\left(Nu/{Nu}_s\right)$ reaching up to 3.7 for α = 20° and Nr = 8. This enhancement is accompanied by a moderate rise in the friction factor ratio $\left(f/f_s\right)$, reaching approximately 7.5 at Re = 3300, indicating efficient turbulence promotion with acceptable hydraulic penalties. The Performance Evaluation Criterion (PEC) ranges from 1.7 to 1.9, confirming the superiority of ASRT over the smooth tube.

One of the main challenges of solar parabolic trough collectors (PTCs) is their requirement for large land areas. To address this, a novel tri-pass receiver design has been experimentally developed, which is less sensitive to misalignments, easy to fabricate, maintain, and repair. First of all, the testbed thermal and optical efficiencies were evaluated. The PTC testbed comprises a polished stainless-steel reflector with a 44% optical efficiency integrated into a supervisory control and data acquisition system. No-load tests were initially performed, followed by an in-load test. These tests took place in North Africa, precisely in the northeast of Algeria. Initial experiments revealed a low PTC thermal efficiency of 20%. To address this issue, five different receiver configurations were manufactured, tested, and compared. the reference configuration is an uncoated copper tube. Therefore, a single black-coated copper tube receiver achieved a 27% increase in thermal efficiency. A bypass black-coated receiver showed a significant improvement, achieving 71% thermal efficiency. However, a three black-coated receiver with two centralized tubes experienced a 12% decrease in thermal efficiency. Yet, the three black-coated receiver with one central tube achieved the highest thermal efficiency of 85% due to the triangular pitch arrangement, which effectively focuses solar rays on the central tube while capturing deviated rays with the backside tubes. The no-load test determined the optimal fluid path for this configuration, ensuring smooth progression from preheating to heating as the fluid moved through increasingly hotter tubes. The in-load test confirmed the receiver's effectiveness.

Ordinary water spray cooling is connected with very high temperatures where heat transfer during evaporation plays a key role. However, during cooling without phase change, the behaviour of the spray cooling parameters is rarely considered. The purpose of this paper is to study the influence of spray hydrodynamic parameters on heat transfer without liquid phase change during the cooling of an aluminium 3003-H18 plate at a temperature of 92 °C. First of all, the flow rate was varied from 0.497 up to 1 l/min. Then, the inlet pressure varied from 0.7 to 2.1 bars. The influence of nozzle-to-target distance is also tested since the simulations were carried out in a wide height range, from 100 mm to 505 mm. The present simulation was achieved using the version 5.2 of COMSOL Multiphysics code.

This paper investigates the influence of fire protection systems and insulation materials on the thermal performance of steel columns. An unprotected column and several columns insulated with different fire protection materials were analyzed using the SAFIR^® (2022 version) and ABAQUS simulation (2017 Version). Thermal and mechanical properties of steel were defined according to Eurocode (EC3), and fire exposure was simulated following the ISO-834 standard fire. The following two insulation systems were considered: contour encasement and box encasement. Results show that, for identical material properties and thickness, box encasement significantly slows the temperature rise compared to contour encasement. Vegetable-based fire protection materials such as wood fiber, sheep wool, and expanded cork reduced the steel temperature to 400 °C for up to 80 min and extended fire resistance of steel columns 40 to 310 min. These findings demonstrate that such insulation materials can markedly enhance the fire performance and structural integrity of steel columns, offering a sustainable and effective solution to fire protection.