Oluwaseyi Omotayo Alabi

Solar water heating systems are promising technologies to decrease reliance on conventional energy sources, but they are restricted by the limited convective heat transfer and ineffective thermal-fluid interaction in the collector channels. In this study, a Computational Fluid Dynamics (CFD) based study and optimization of fin geometry of a solar water heating collector using TiO ₂ /chlorophyll bio-hybrid nanofluid is presented. Fin configuration and nanofluid concentration were coupled and systematically investigated on the thermal and hydrodynamic performance of the collector. The fin configurations (triangular and hexagonal) were tested in the Reynolds number range of 2000–15,000 for the three different concentrations of TiO ₂ /chlorophyll (1.0%, 2.0%, and 3.0%). The thermal-hydraulic properties of the collector were determined by analyzing the temperature distribution, thermal efficiency, Nusselt number, heat-transfer coefficient, and friction factor. The results show that the convective heat transfer is improved with rise in nanofluid concentration and Reynolds number in general. The temperature distribution in hexagonal configuration was more desirable and the thermal performance was better than in triangular configuration. In the 3.0% concentration the peak thermal efficiency of the hexagonal collector was 86.1% and daily average was 67.2% while for the triangular collector, the peak and daily average thermal efficiencies were 80.9% and 63.7% respectively. The Nusselt number and heat-transfer coefficient also increased gradually with the increase of Reynolds number and nanofluid concentration, but with flow resistance increasing as well. The novelty of the study is that the model integrates the assessment of nanofluid concentration of bio-hybrid systems and the optimization of fin geometry in a CFD based thermal-hydraulic study to select an optimum fin geometry for efficient solar water heating. The results show that the configuration with the hexagonal fin and 3.0% TiO ₂ /chlorophyll nanofluid is the most advantageous thermally among the studied conditions.

This study presents a systematic experimental investigation of the thermal performance of a flat-plate solar water heating (SWH) system employing Al₂O₃/water nanofluid as the working fluid across three nanoparticle mass concentrations (1, 2, and 3 wt%) and four mass flow rates (5, 10, 15, and 20 kg/h) under real outdoor climatic conditions. The nanofluids were prepared via the two-step method, combining mechanical stirring and ultrasonication to ensure colloidal homogeneity and suspension stability. Thermal performance was evaluated in terms of collector outlet temperature, useful energy gain, and instantaneous thermal efficiency, benchmarked against a pure water baseline under identical operating conditions. The results demonstrate that increasing nanoparticle concentration from 1 wt% to 3 wt% enhanced thermal conductivity by up to 4.4%, yielding a corresponding improvement in collector thermal efficiency of approximately 23.6% relative to pure water. The maximum thermal efficiency of 80.3% was recorded at 3 wt% and 20 kg/h during peak solar irradiance hours (14:00–15:00 h), compared to 65.1% for pure water under equivalent conditions representing an absolute gain of 15.2 percentage points. Useful energy gain increased by 31.7% at the optimal concentration relative to the water baseline. Notably, the rate of efficiency improvement diminishes beyond 2 wt%, suggesting that this concentration represents the practical optimum at which thermal enhancement is maximised without incurring disproportionate viscosity penalties and pumping power demand. The experimental results show good agreement with established correlations reported in the open literature, validating the reliability of the measurement methodology. These findings provide quantitative engineering guidance for the design and optimisation of nanofluid-based solar water heating systems, demonstrating that Al₂O₃/water nanofluid at 2–3 wt% offers a technically viable and practically deployable route to significantly improving solar thermal energy conversion efficiency.

Residential water heating constitutes a significant share of household energy consumption, yet the performance of conventional solar water heating (SWH) systems is limited by the low thermal conductivity of water. This study presents a techno-economic and environmental assessment of nanofluid-enhanced flat-plate SWH systems using 2 wt% Al₂O₃/water and a novel 2 wt% TiO₂–chlorophyll bio-hybrid nanofluid. Experimental characterization showed thermal conductivity enhancements of 24.7% and 14.2% for Al₂O₃/water and TiO₂–chlorophyll, respectively, resulting in collector efficiency improvements of 14.9% and 9.0% compared with the base fluid. Annual energy yields increased to 3520.6 kWh for Al₂O₃/water and 3339.2 kWh for TiO₂–chlorophyll, compared with 2978.5 kWh for the conventional system. Economic analysis over a 20-year lifetime revealed payback periods of 2.24 and 2.28 years, with net present values of $7430 and $7028, respectively. Life-cycle assessment indicated that although Al₂O₃/water achieved the highest annual CO₂ reduction (1697 kg CO₂-eq/year), the TiO₂–chlorophyll system exhibited the lowest life-cycle emissions (46.1 kg CO₂-eq/m²) and shortest carbon payback period (4.1 months). The results demonstrate that while Al₂O₃/water maximizes thermal and economic performance, the TiO₂–chlorophyll bio-hybrid provides the most balanced and sustainable solution for residential solar water heating applications.

Photovoltaic–thermal (PVT) solar water‐heating systems simultaneously generate thermal and electrical energy; however, their performance is limited by the low thermal conductivity of conventional working fluids, resulting in inadequate heat removal and elevated photovoltaic cell temperatures. Although nanofluids have been widely investigated to overcome this limitation, studies have focused primarily on inorganic nanoparticles, while bio‐hybrid nanofluids remain unexplored in PVT applications. This study presents the first comparative experimental and numerical investigation of Al ₂ O ₃ /water and TiO ₂ /chlorophyll bio‐hybrid nanofluids against water in a flat‐plate PVT collector. Both nanofluids were prepared at 0.5 wt.% using the two‐step method and evaluated experimentally under outdoor conditions, while a three‐dimensional CFD model developed in ANSYS Fluent was validated against experimental measurements ( R ² > 0.999; RMSE < 0.062°C). Thermal, electrical, overall, and energy‐saving efficiencies, together with entropy generation and thermal performance factor, were analyzed. The TiO ₂ /chlorophyll nanofluid exhibited the highest thermal efficiency (38.74%), outperforming Al ₂ O ₃ /water (35.96%) and water (27.77%), while achieving electrical, overall, and energy‐saving efficiencies of 12.61%, 51.35%, and 71.89%, respectively. The superior performance is attributed to enhanced thermal conductivity, improved surface wettability, and additional solar absorption by chlorophyll. The validated CFD model identified an optimum nanofluid concentration of 3 vol.% that minimized entropy generation and maximized thermal performance. These findings establish TiO ₂ /chlorophyll as a promising sustainable working fluid for high‐efficiency PVT systems and provide validated design guidance for future PVT solar energy applications.

Worldwide, cervical cancer is a major public health concern, and early detection is essential for successful management and treatment. Ensemble machine learning (ML) has emerged as a promising approach for improving the accuracy and reliability of cervical cancer diagnosis systems. This study evaluated the performance of various ensemble ML models for cervical cancer diagnosis using a large dataset of cervical cell images. The performance of different ensemble models was compared, including random forest (RF), gradient boosting (GB), and stacking, with conventional ML models, such as logistic regression and support vector machine (SVM). The bagging ensemble model developed reported training of 0.991667, 0.827586, 1.0, and 0.90566 for accuracy, precision, recall, and F-measure (F1-score), respectively. Furthermore, the interpretability of ensemble models was investigated using feature importance and partial dependence plots. The interpretability analysis revealed that ensemble models can provide valuable insights into the key features and factors that contribute to cervical cancer diagnosis. In conclusion, the findings suggest that ensemble ML is a promising approach for developing accurate and reliable cervical cancer diagnosis systems and improving the interpretability of these models.

Logistics, as a vital component of economic growth, relies on fossil fuel burning, which accelerates carbon emissions into the atmosphere and harms the environment. Logistics, encompassing transportation, warehousing, and supply chain operations, is among the fastest-growing sources of carbon emissions globally, contributing significantly to GHG emissions. Climate change causes forced migration, extinctions, natural disasters, and health problems that disrupt the ecosystem’s dynamics. This work aims to critically examine the current palliative measures to limit the negative impact on global climate change while also methodically examining various aspects of the human world affected by the growing rate of carbon emissions globally, as the world turns to low-carbon economics as a powerful and inventive way to mitigate the climate crisis from carbon emissions. Under themes such as climate impacts, ecological disruption, socioeconomic ramifications, health implications, and mitigation techniques, a broad range of integrated publications focused on logistics and climate-related concerns were examined. The final section of the document emphasises the significance of zero emissions and outlines the regulations set by the Intergovernmental Panel on Climate Change (IPCC). It also makes a strong case for investing in sustainable and cutting-edge technologies in order to quickly achieve favourable global climate conditions.

Solar water heating systems (SWHS) offer a sustainable solution for reducing reliance on conventional energy sources; however, their performance is often limited by insufficient heat transfer within the collector. This study presents a CFD-based numerical investigation on the optimization of finned thermal collectors in a solar water heating system using Al₂O₃/water hybrid nanofluid. The effects of nanoparticle volume fraction (1–3%), fin geometry (triangular and hexagonal), and mass flow rate (5–20 kg/h) on the thermal and heat transfer performance of the system were analyzed. Key performance indicators including absorber/PV temperature, outlet fluid temperature, convective heat transfer coefficient, thermal efficiency, and improved daily efficiency were evaluated under transient operating conditions. The results show that increasing Al₂O₃ concentration enhances heat transfer and thermal efficiency due to improved thermophysical properties of the working fluid. Fin geometry significantly influences thermal behavior, with hexagonal fins generally producing higher outlet temperatures and thermal efficiency of 65%, while triangular fins provide higher daily efficiency improvement under optimized conditions. The convective heat transfer coefficient increased with both nanoparticle concentration and flow rate, reaching peak values during mid-day hours corresponding to maximum solar input. The study confirms that combining optimized fin structures with Al₂O₃/water nanofluids provides an effective strategy for improving the thermal performance of solar water heating collectors, while CFD modelling offers a reliable approach for system design and performance prediction.

Solar Water Heating Systems (SWHS) are increasingly recognized as vital technologies for reducing dependence on conventional energy sources and supporting sustainable thermal energy solutions. This study reviews recent advancements in the numerical modeling and simulation of SWHS, with a particular focus on improving heat transfer efficiency and overall system performance. The primary aim is to evaluate how Computational Fluid Dynamics (CFD) and other simulation approaches accurately predict thermal behavior, fluid flow characteristics, and energy storage dynamics. The study identifies key objectives, including the analysis of critical design parameters, collector geometry, material properties, working fluid selection, and operating conditions, and their impact on thermal efficiency. This review integrates heat transfer, fluid dynamics, and energy storage within a unified numerical modeling framework. The current study also emphasizes advanced simulation techniques, including multi-physics analysis and optimization to enhance prediction accuracy and reduce computational cost. The outcomes indicate that validated numerical models provide reliable performance predictions under varying operating conditions and facilitate the development of high-efficiency, cost-effective SWHS for residential, commercial, and industrial applications. The findings also outline future research directions, including transient analysis, experimental validation, and advanced optimization frameworks, thereby contributing to the next generation of solar thermal technologies.

Harnessing solar energy, solar water heating systems (SWH) offer a reliable and eco‐friendly way to meet hot water requirements, reducing reliance on fossil fuels and mitigating climate change. This review comprehensively assesses experimental efforts to enhance the thermal performance of SWH systems. It examines innovations in collector configurations, selective optical coatings, and advanced working fluids, such as nanofluids. The analysis evaluates key metrics, such as thermal and exergy efficiencies, by comparing experimental results with theoretical models, emphasising the importance of empirical data in addressing operational challenges. Comparative evaluations indicate that specific enhancements have improved thermal efficiency by over 60% compared to conventional designs. Nevertheless, issues related to cost, material durability, and scalability persist. The study highlights research gaps, including the need for sustainable phase change materials (PCMs), extended studies on nanofluid stability, and AI‐driven optimisation of system performance. These findings underscore the crucial role of experimental research in bridging the gap between theoretical models and practical applications, thereby supporting the broader adoption of SWH systems to promote global energy sustainability and decarbonization objectives.

The long-term reliability and performance of photovoltaic (PV) modules largely depend on the thermal stability and durability of encapsulation materials that protect solar cells from environmental and thermal degradation. Ethylene–vinyl acetate (EVA) is widely used as a solar cell encapsulant due to its excellent optical and mechanical properties; however, its thermal stability and resistance to degradation remain critical challenges under prolonged operating conditions. Although EVA-based nanocomposites have been investigated for solar cell encapsulation, limited studies have systematically examined how different nanoclay fillers and processing conditions influence the thermal stability and encapsulation efficiency of EVA materials. This study aims to optimize the thermal stability of EVA nanocomposites by incorporating different inorganic fillers mica, montmorillonite (MMT), and vermiculite, at varying concentrations and milling cycles. An 8% EVA solution was prepared and blended with these fillers to evaluate their effects on the thermal and structural properties of the nanocomposite materials. Thermal characterization using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) revealed noticeable changes in melting temperature, glass transition temperature, and thermal degradation behavior. The incorporation of nanofillers improved the thermal stability of the EVA matrix and influenced its crystallinity and mechanical properties. The optimized EVA nanocomposite demonstrated enhanced thermal resistance and improved durability compared with neat EVA, although a slight reduction in encapsulation efficiency was observed. These findings provide valuable insights into the formulation and optimization of EVA nanocomposites for solar cell encapsulation, contributing to the development of more thermally stable and durable encapsulation materials for sustainable photovoltaic applications.