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The penta-hybrid nanofluid is a nanofluid that contains five different types of nanoparticles. It can achieve higher heat transfer rates than conventional hybrid nanofluids due to the synergistic effects of the nanoparticles. It also has more diverse physical and thermal properties, which make it more adaptable for various applications. Therefore, this research examines the influence of localized magnetic fields on the vortex dynamics in a penta-hybrid nanofluidic flow in a vertical cavity with an aspect ratio of 1:10, driven by a top and bottom lid moving in the opposite direction. The stream-vorticity formulation is used to solve the dimensionless governing partial differential equation. A confined magnetic field in the form of horizontal and vertical strips has been applied instead of a uniform magnetic field throughout the flow domain, which is more realistic. Moreover, MATLAB codes developed by the authors are used to investigate how these parameters affect the flow and thermal properties of the nanofluids. The results suggest that magnetic fields have an impact on how stress, flow patterns, and temperature are distributed. Moreover, the presence of a magnetic field influences the spacing of isotherms, indicating a more even temperature distribution. It has also been observed that stress distribution is affected by the magnetic field, with higher stress levels near walls and regions with velocity-induced stress. However, in certain areas, the magnetic field can decrease shear stress depending on its strength and orientation. These study findings have implications for designing and operating nanofluidic devices. For instance, utilizing a magnetic field can help regulate flow patterns, temperature distribution, and stress distribution within nanofluidic channels. This capability could prove beneficial for a range of applications, such as cell separation, drug delivery, and nanofluidic heat exchange systems.

In this study, a novel tilted axis hydrokinetic turbine system is presented and tested to generate electricity from surface water streams in off-grid locations. This system consists of a turbine, differential, reducer, and alternator, and resembles a Pelton turbine. It is used in shallow waters near river banks with the free flow velocity. This study reports significant hydrodynamic efficiencies with field tests consistent with theoretical estimates obtained at the design and fabrication stage, for different flow velocities (0.5–3 m/s in 0.5 m/s internal) and blade numbers (7, 9, and 11 blades) on the Namnam Stream in the Muğla province/Turkey. On the same turbine system, 7, 9, and 11 blades can be disassembled in the center of the turbine. In order to facilitate testing at different water flow velocities, the flow velocity is adjusted by excavation operations in the stream bed. The results of the study indicate that as the water speeds increase, the turbine power, speed, and efficiency of all blade turbines also increase. In terms of hydrokinetic energy potential, the water flow velocity and turbine speed are 2 m/s and 3 r/min, respectively. Because of parasitic drag and lift-induced drag, 7- and 11-blade turbines have higher mechanical losses, lower turbine efficiency, and increased cost due to weight. A 9-blade turbine is preferred for such a prototype due to torque, load power (800 W), and efficiency (15.9%) compared to the others. As a result, this study reports that such a prototype can be used in unpowered riverbanks or free surface currents. [ABSTRACT FROM AUTHOR]

This research provides an in-depth analysis of solar radiation's impact on the thermal efficiency of a solar air collector. Using advanced Computational Fluid Dynamics (CFD) simulations in ANSYS Fluent, the study examines temperature distribution and airflow dynamics within the collector across varying levels of solar radiation. The simulations were carefully configured to replicate real-world solar radiation conditions, ranging from 680 W/m² to 1220 W/m², enabling a precise evaluation of the collector's performance under different environmental conditions. Results indicate that at the lowest radiation level (680 W/m²), the collector's outlet air temperature reached a peak of 26 °C, increasing progressively to a maximum of 29°C at 1220 W/m². Temperature patterns varied with radiation intensity, especially at the start of the collector's second pass, where temperatures rose from 30°C at the lowest radiation level to 34°C at the highest. Thermal efficiency calculations for each radiation level reveal that efficiency increases with radiation intensity, peaking at 26.25% at 1220 W/m². These findings highlight the effectiveness of the collector's design in heat absorption and retention, particularly in the second pass, indicating potential opportunities for enhancing solar air collector designs in the future. [ABSTRACT FROM AUTHOR]

In the evolving landscape of sustainable energy, optimizing geothermal power systems presents a critical challenge. This study explores the energy and exergy efficiencies of a power production system utilizing a single‐flash geothermal cycle integrated with a trans‐critical CO2 cycle. The study's methodology involves a detailed examination of key performance parameters—separator pressure, CO2 turbine intake pressure, and steam turbine output pressure. Utilizing the EES software environment, the study innovatively employs a combination of Genetic Algorithm (GA), Nelder–Mead Simplex (NMS) method, and Direct algorithm (DA). When using GA, NMS and DA, the system's exergy efficiency increases from 32.46% in the default operating mode to 39.21%, 36.16%, and 38.82%, respectively. One of the notable outcomes is the identification of optimal separator pressure for maximum energy efficiency. Furthermore, the study reveals that increasing the CO2 turbine's inlet pressure adversely impacts the system's efficiency. The study's results contribute significantly to the field of renewable energy, offering practical guidelines for enhancing the performance of geothermal power systems. [ABSTRACT FROM AUTHOR]

Facing the dual challenges of environmental impact and the finite nature of fossil fuels, the shift toward sustainable energy sources is imperative. Geothermal energy, a renewable and underutilized resource, offers a promising alternative. This study ventures into a novel domain, exploring the integration of trans‐critical CO2 (tCO2) cycle with a double‐flash geothermal (DFG) cycle, an area not extensively covered in existing research. This study aims to develop a recovery system that utilizes a tCO2 cycle powered by a DFG cycle. A crucial part of this study involves conducting a sensitivity analysis to evaluate the system's energy and exergy performance. This analysis focuses on understanding the impact of changes in key system design parameters, such as energy efficiency, exergy efficiency, net power output, and total exergy destruction rate, to determine the optimal values for these parameters. The results indicate that the recovery system shows a significant improvement of 22% in energy efficiency over the basic cycle. However, there is a decrease in exergy efficiency in the recovery system, which represents a 5.26% decline. As a result, this study paves the way for innovative approaches in geothermal energy use, suggesting potential breakthroughs in renewable technologies. [ABSTRACT FROM AUTHOR]