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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.

This article investigates the integration of circular economy methodologies and biorefinery concepts for the sustainable recovery of bio‐based products from industrial effluents, addressing the critical need for resource efficiency and environmental sustainability in the face of climate change and resource depletion. Emphasizing the valorization of industrial by‐products, the study explores innovative, eco‐friendly recovery processes within a biorefinery framework to transform waste into valuable resources such as biofuels, biochemicals, and biomaterials. Through a systematic search in various bibliographic databases and a comprehensive literature review, the study critically analyzes existing studies, identifies research gaps, and offers new perspectives on the integration of biorefinery and circular economy principles. The findings reveal that strategic integration of biorefinery processes and circular economy principles can significantly reduce environmental footprints and foster sustainable industrial practices. Key challenges such as feedstock variability, technological barriers, and economic scalability are identified, along with recommendations for overcoming these obstacles through interdisciplinary collaboration, technological innovation, and supportive policy interventions. The main contribution of this research lies in its comprehensive approach, integrating cutting‐edge technologies and circular economy principles to offer viable strategies for sustainable bio‐based product recovery, thus significantly advancing the field of industrial sustainability. The article contributes to the advancement of sustainable technologies, policies, and strategies, advocating for a transition towards a more circular, resource‐efficient industrial sector. Continued innovation and research are emphasized to optimize recovery processes and explore new applications, supporting a sustainable and thriving future for our planet. [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]

The combustion of natural gas consisted of methane CH4, ethane C2H6, and propane C3H8 is theoretically investigated to obtain the optimum adiabatic flame temperature (AFT). The investigation includes the development of combustion equations that take into consideration different compositions of natural gas. The final equation to calculate the AFT is derived and used in the optimization study. The optimization study using genetic algorithm investigates the effect of changing the composition of the gas mixture, the inlet temperature of used air, and the amount of excess air used on the AFT. It is possible to get the required composition of each component, the air inlet temperature, and the excess air by reading the chart to get the required AFT. The heat capacity of all reactants and products is used as a function of temperature. Results showed that the optimum values for CH4,C2H6,C3H8, percentages in the gas mixture, air inlet temperature, and the amount of excess air are 0.478, 0.166, 0.356 mol %, 1.848, 382.104 K, respectively. These optimum values lead to a value of about 1300 K for the AFT. The derived equation shows the AFT at different natural gas compositions along with different process parameters such as the amount of excess air. Thus, the required combustion temperature can be controlled by adjusting the natural gas composition or the combustion temperature can be specified based on the provided composition of the natural gas stream by using either the derived equations or output chart. (R1. 1). [ABSTRACT FROM AUTHOR]

The global utilization of RES, particularly geothermal energy, is rising and the inefficient nature of geothermal cycles necessitates recovering lost heat. This research proposes a combined power generation cycle that simulates integrating a trans-critical CO2 cycle with a single flash geothermal cycle, utilizing the engineering equation solver. The study contrasts the system's performance between two operating states: "Without Economizer" and "With Economizer". The investigation analyzes the impact of an economizer on key output parameters, including energy efficiency, exergy efficiency, and net power output. In the "With Economizer" operating state, the net power output experiences a noticeable increase from 201.5 kW to 204.7 kW, resulting in a 1.58% enhancement in the performance of the "With Economizer" system. The energy efficiency metric demonstrates a corresponding improvement, rising by 1.55% from 3.28% in the "Without Economizer" system to 3.331% in the "With Economizer" system, aligning with the principles of the First law of thermodynamics. Furthermore, the energy efficiency, expressed as a percentage of energy units, shows an increase from 16.3% in the "Without Economizer" system to 16.56% in the "With Economizer" system, representing a 1.595% improvement based on the Second law of thermodynamics or exergy. Regarding cost analysis, the study identifies the optimal separator pressure value for the system without an economizer, equivalent to 23. This configuration achieves a total cost rate of 01 $ per GJ. Conversely, in the system with an economizer, the optimal pressure value for the production cost rate is 322.4 kPa, resulting in a cost rate of 23.57 $ per GJ. [ABSTRACT FROM AUTHOR]

This work proposes a new chimney design that allows for the development of a multi‐stage solar updraft tower (SUT). The new design consists of two successive divergent chimneys. A 3D model was established to inspect the air flow behaviour within the SUT in six configurations: four multi‐stage systems with four divergence angles of the second stage were compared to the simple conventional SUT and the simple SUT with a divergent chimney. The new SUT performs better than the conventional one, while the two‐stage solar tower multiplied the system efficiency. Two high‐velocity zones appeared for the two‐stage SUT, whereas one zone occurred for the conventional system. The velocity in the two zones achieved a significant value, like that of the conventional system. In addition, the second stage's divergence angle directly impacts the velocity value inside the two stages. The static pressure distribution varies with the change in chimney design. The depression area occurs twice for the multi‐stage SUT in the inlet of each stage. [ABSTRACT FROM AUTHOR]

At temperatures below 60 °C, the best way to use geothermal sources for heating is to use heat pumps. A heat pump can provide air conditioning for a residential, commercial, etc., all year round by heating in winter and cooling in summer using a low temperature source. Also, a heat pump can be used for water distillation through evaporation. The ground source heat pump with a high COP and low temperature thermal energy sources is one of the best technologies for using RES. In the present study, the effects of changing ambient temperature and soil temperature on a heat pump's overall COP and energy efficiency are investigated using a simulated geothermal heat pump with an economizer. The system's thermodynamic simulation is first performed in the engineering equation solver software for R134a and R513a working fluids. The exergy destruction of different components for both working fluids was calculated and displayed as a figure. The COP of the heat pump for R134a working fluid is equal to 3.916, equal to 3.729 for R513a working fluid, which indicates that R134a fluid has about 5% better performance. The COP of the system for R134a working fluid is equal to 3.662, which is equal to 3.504 for R513a working fluid, which indicates that R134a fluid has about 4.5% better performance. [ABSTRACT FROM AUTHOR]