Access to safe drinking water is universally recognized as a fundamental human right; however, millions of people worldwide continue to face limited access to clean and safe water resources. The presence of contaminants such as heavy metals, organic compounds, dyes, pesticides, pharmaceuticals, and pathogenic microorganisms poses significant threats to human health and aquatic ecosystems. Conventional water treatment technologies, although effective in certain applications, are often associated with high operational costs, energy requirements, and limited efficiency toward emerging pollutants. Consequently, the development of sustainable, low-cost, and efficient water purification materials has gained increasing scientific attention. This review investigates the effectiveness of activated carbon as a promising adsorbent for drinking water purification and examines the principal mechanisms involved in pollutant removal. Various forms of activated carbon produced from agricultural waste-derived precursors were comparatively evaluated. Reported studies indicate that activated carbon exhibits a high specific surface area ranging from 300 to 2500 m2.g−1 and achieves removal efficiencies exceeding 90% for volatile organic compounds (VOCs), chlorine, dyes, and toxic heavy metals including Pb2+, Cd2+, and Cr6+. The adsorption capacities of activated carbon for different contaminants were reported to range from 50 to more than 500 mg.g−1, depending on precursor type, activation process, and operational conditions. Furthermore, regeneration efficiencies commonly remained within 70–85% after multiple adsorption–desorption cycles, highlighting the economic feasibility and environmental sustainability of activated carbon.
This work investigates the use of activated carbon in a batch system for the adsorption of cadmium from aqueous solutions. Two adsorbents were assessed: Commercially available activated carbon (CAC) and synthesized activated carbon (SAC) produced from walnut shell–derived agricultural waste. Adsorption efficiency increased with increasing pH, according to research on the impact of solution pH on cadmium removal. In the pH range of 7–12, maximum removal efficiencies of 81.9% for SAC and 80.5% for CAC were found at an initial cadmium concentration of 100 mg/L. Freundlich and Langmuir isotherm models were used to analyze the adsorption data. The Freundlich model provided a marginally better fit, suggesting heterogeneous adsorption sites on the activated carbon surfaces, while both models demonstrated good agreement with the experimental results. The highest adsorption capacities that were obtained from adsorption isotherms, under conditions of 4 h of contact time and 30 °C, were 69.5 mg/g for SAC and 81.2 mg/g for CAC.
This research considers the impact of a point/line heat source/sink on steady magnetohydrodynamic (MHD) natural convection flows in a vertical channel subjected to a transverse magnetic field with a thermal boundary condition of the third-kind thermal (Robin) boundary conditions. A constant point/line heat source/sink generates convection current within the flow. The governing dimensional equations regulating the physical situation at hand are presented in dimensionless form with the associated boundary conditions. Exact solutions are derived for the momentum and energy equations using the Laplace transform technique. The effects of key controlling parameters involved in flow formations are studied, such as the magnetic parameter, point/line heat source/sink parameter and Biot number on flow behaviour are analyzed. MATLAB software is employed to obtain line graphical and tabular results. The findings indicate that lower values of the Biot number account for reduced heat transfer to the surroundings, whilst higher values lead to higher surface heat transfer. Furthermore, the heat transfer rate, frictional drag force and mass flow rate retard as the line heat source/sink approaches a point heat source. In addition, the mass flow rate increases by almost 49% as the interval between the line heat source increases. for both equal and unequal values of the Biot number. There is remarkable agreement between the current results and the previously published studies.
This study estimates minimal entropy production, the corresponding distribution of heat exchange surfaces and contact temperatures for heat exchange systems with given total heat load and heat transfer coefficient. The analysis proves that an optimal heat exchange system requires constancy of the temperature ratio for the contact flows and equal heat flows’ output temperatures. The requirement that the entropy production in the system be greater than the minimum entropy generation marks the boundary of the reachable set of heat exchange systems.
Heat transfer fluids (HTFs) are critical in numerous industrial processes, enabling efficient heat exchange and precise temperature control. HTF degradation, primarily from thermal cracking and oxidation, negatively impacts system performance, reducing fluid lifespan and increasing operational costs, thus necessitating regular monitoring and proactive management. This review assesses optimal sampling frequencies for organic and synthetic HTFs, considering degradation mechanisms, relevant analytical parameters, and the economic advantages of proactive monitoring. The objective of this review is to examine HTF degradation mechanisms, compare organic and synthetic fluid properties and their impact on sampling frequency, and discuss strategies for optimising system performance and extending fluid life through effective HTF condition management. The article highlights the importance of fluid management, including appropriate fluid selection, to optimise system and fluid health, which is crucial for maximising their lifespans, ensuring safe operation, and minimising costs.
In response to the prevailing energy crisis, this research focuses on elevating the potential of lithium niobate (LN) thin films for advanced optoelectronic applications. Employing electron beam evaporation, films undergo precise annealing (700 °C to 1100 °C), revealing a structural evolution through X-ray diffraction—crystallite sizes transition from 69.34 nm (unannealed) to 47.90 nm (1100 °C). Scanning electron microscopy captures the transformation from coarse grains to photonic crystal clusters, while energy dispersion X-ray analysis discloses LN's composition (97.27 wt.% oxygen, 2.73 wt.% niobium). Rutherford backscattering spectroscopy illustrates surface damage post-Helium ion implantation, proportionate to depth. UV-VIS spectrophotometry highlights a significant blue shift in the optical band gap (3.70 eV to 2.52 eV), with further reduction at 700°C (2.48 eV) and a climactic shift at 1100°C (2.68 eV). This study not only addresses the pressing energy crisis but also emphasizes the indispensable role of lithium niobate in shaping the future of optoelectronics. It provides insights into tailoring LN properties for sustainable advancements in optoelectronic devices, marking a crucial chapter in our collective journey towards energy resilience. The urgency of innovation in the face of global challenges is underscored, marking a crucial chapter in our collective journey towards energy resilience.
Access to clean drinking water is universally recognized as a fundamental human right, yet millions globally still lack safe water. Contaminants such as heavy metals, organic compounds, and microbial pathogens pose significant health risks. Traditional water purification methods, while effective, often come with high costs and may not remove all types of contaminants. There is a need for more accessible and comprehensive solutions to improve drinking water quality. This study aims to explore the efficacy of activated carbon as a viable solution for enhancing drinking water quality and to identify the mechanisms through which it purifies water. The research involved a review of existing literature on activated carbon, including its various forms (powdered, granular, black carbon filters) and sources (coal, coconut shells, wood, peat). The study analyzed the physical and chemical processes of adsorption and the factors influencing these mechanisms. Activated carbon significantly increases surface area and adsorption capacity, enabling effective removal of a diverse range of pollutants, including volatile organic compounds (VOCs), chlorine, heavy metals, and certain harmful microbes. The findings suggest that activated carbon is a promising and cost-effective alternative for improving drinking water quality, with potential applications in various contexts to enhance public health and access to safe water.
Based on the application of phase diagram calculation technique (CALPHAD), the Fe-Nd-B magnetic materials were investigated, and alloy design and microstructure evolution concerning. According to the thermodynamic database of Fe-Nd-B ternary system, the equilibrium solidification process of Fe78Nd15B7 alloy is simulated, and we explained well the reason of this experimental phenomenon by the metastable extension of the equilibrium phase diagram.
The heat extraction from the conventional channels under two-phase flow boiling conditions with water as the coolant is investigated numerically in this work. The numerical investigation was carried out by using ANSYS Fluent 2022R1 commercial software by selecting the Rensselaer Polytechnic Institute (RPI) wall heat flux partitioning approach by employing the Eulerian-Eulerian two-phase model. A three-dimensional computational domain was used for the simulation to understand the fluid boiling inside the conventional channel under steady state conditions, focusing on the effect of aspect ratio (AR) on the vapor volume fraction. The simulations were performed for a constant mass flux of 150.46 kg/m2-s with the heat flux value ranging from 10-100 kW/m2and at the inlet subcooled temperatures of 303 K, 313 K and 323 K. The temperature of the channel bottom surface and the heat transfer coefficient (HTC) obtained numerically were compared with the experimental results and it was found that the results matched well. The volume of vapor fraction increased with the increase in heat flux for all values of inlet subcooled temperature considered in this study for all the test sections. At low inlet subcooled temperature, the volume of vapor fraction decreased with an increase in AR at all heat fluxes. However, there was no observable trend at higher heat flux and high inlet subcooled temperature.
Heat transfer enhancement (HTE) is a topic of everlasting importance in thermal engineering research. The latest focuses in this field are on nanosolutions for more efficient thermal transmission fluids (a) and designs of metallic foams (b) Metallic foams provide extended surfaces for HTE and possess advantages such as a high value of Cp, high thermal conductivity (TC) and being light weight. nanosolutions, on the other hand, can be used as an efficient HT medium as they exhibit higher TCs in comparison to base fluids. This review paper summarizes the physical properties of nanosolutions and or within the metal foam, focusing on HT and flow properties of nanosolutions, metal foam and combined NS-metal foam systems. The inspiration novelty for this review is the basic transference identifications for the HT enhancement of nanosolutions in porous media. The aim of the work is to provide insight on how nanosolutions in conjunction with porous media can be useful for HTE.
Exposure to high-frequency (HF) electromagnetic fields (EMF) has various effects on living tissues involved in biodiversity. Interactions between fields and exposed tissues are correlated with the characteristics of the exposure, tissue behavior, and field intensity and frequency. These interactions can produce mainly adverse thermal and possibly non-thermal effects. In fact, the most expected type of outcome is a thermal biological effect (BE), where tissues are materially heated by the dissipated electromagnetic energy due to HF-EMF exposure. In case of exposure at a disproportionate intensity and duration, HF-EMF can induce a potentially harmful non-thermal BE on living tissues contained within biodiversity. This paper aims to analyze the thermal BE on biodiversity living tissues and the associated EMF and bio-heat (BH) governing equations.
The role of trace gases in the storage of heat in the atmosphere of the Earth and in the exchange of energy between the atmosphere and outer space is discussed. The molar heat capacities of the trace gases water vapor, carbon dioxide and methane are only slightly higher than those of nitrogen and oxygen. The contribution of trace gases carbon dioxide and methane to heat storage is negligible. Water vapor, with its higher concentration and conversion energies, contributes significantly to the heat storage in the atmosphere. Most of the heat in the Earth’s atmosphere is stored in nitrogen and oxygen, the main components of the atmosphere. The trace gases act as converters of infrared radiation into heat and vice versa. They are receivers and transmitters in the exchange of energy with outer space. The radiation towards space is favored compared to the reflection towards the surface of the Earth with increasing altitude by decreasing the density of the atmosphere and condensation of water vapor. Predictions of the development of the climate over a century by extrapolation are critically assessed.
To investigate the effect of the location of vacuum insulation panels on the thermal insulation performance of marine reefer containers, a 20ft mechanical refrigeration reefer container was employed in this paper, and the physical and mathematical models of three kinds of envelopes composed of vacuum insulation panels (VIP) and polyurethane foam (PU) were numerically established. The heat transfer of three types of envelopes under unsteady conditions was simulated. In order to be able to analyze theoretically, the Rasch transform is used to analyze the thermal inertia magnitude by calculating the thermal transfer response frequency and the thermal transfer response coefficient for each model, and the results are compared with the simulation results. The results implied that the insulation performance of VIP external insulation is the best. The delay times of each model obtained from the simulation results are 0.81 h, 1.45 h, 2.03 h, and 2.24 h, while the attenuation ratios are 8.93, 20.39, 20.62, and 21.78, respectively; the delay times calculated from the theoretical analysis are 0.78 h, 1.43 h, 1.99 h, and 2.20 h, respectively; and the attenuation ratios are 8.84, 20.31, 20.55, and 21.72, respectively. The carbon reduction effect of VIP external insulation is also the best. The most considerable carbon reduction is 3.65894 kg less than the traditional PU structure within 24 h. The research has a guiding significance for the research and progress of the new generation of energy-saving reefer containers and the insulation design of the envelope of refrigerated transportation equipment.
This study comprehensively evaluates the system performance by considering the thermodynamic and exergy analysis of hydrogen production by the water electrolysis method. Energy inputs, hydrogen and oxygen production capacities, exergy balance, and losses of the electrolyzer system were examined in detail. In the study, most of the energy losses are due to heat losses and electrochemical conversion processes. It has also been observed that increased electrical input increases the production of hydrogen and oxygen, but after a certain point, the rate of efficiency increase slows down. According to the exergy analysis, it was determined that the largest energy input of the system was electricity, hydrogen stood out as the main product, and oxygen and exergy losses were important factors affecting the system performance. The results, in line with other studies in the literature, show that the integration of advanced materials, low-resistance electrodes, heat recovery systems, and renewable energy is critical to increasing the efficiency of electrolyzer systems and minimizing energy losses. The modeling results reveal that machine learning programs have significant potential to achieve high accuracy in electrolysis performance estimation and process view. This study aims to contribute to the production of growth generation technologies and will shed light on global and technological regional decision-making for sustainable energy policies as it expands.
This research investigates the effects of drying on some selected vegetables, which are Telfaria occidentalis, Amaranthu scruentus, Talinum triangulare, and Crussocephalum biafrae. These vegetables were collected fresh, sliced into smaller sizes of 0.5 cm, and dried in a convective dryer at varying temperatures of 60.0 °C, 70.0 °C and 80.0 °C respectively, for a regulated fan speed of 1.50 ms‒1, 3.00 ms‒1 and 6.00 ms‒1, and for a drying period of 6 h. It was discovered that the drying rate for fresh samples was 4.560 gmin‒1 for Talinum triangulare, 4.390 gmin‒1for Amaranthu scruentus, 4.580 gmin‒1 for Talinum triangulare, and 4.640 gmin‒1 for Crussocephalum biafrae at different controlled fan speeds and regulated temperatures when the mass of the vegetable samples at each drying time was compared to the mass of the final samples dried for 6 h. The samples are considered completely dried when the drying time reaches a certain point, as indicated by the drying rate and moisture contents tending to zero. According to drying kinetics, the rate of moisture loss was extremely high during the first two hours of drying and then steadily decreased during the remaining drying duration. The rate at which moisture was removed from the vegetable samples after the drying process at varying regulated temperatures was noted to be in this trend: 80.0 °C > 70.0 °C > 60.0 °C and 6.0 ms‒1 > 3.0 ms‒1 > 1.5 ms‒1 for regulated fan speed. It can be stated here that the moisture contents has significant effects on the drying rate of the samples of vegetables investigated because the drying rate decreases as the regulated temperatures increase and the moisture contents decrease. The present investigation is useful in the agricultural engineering and food engineering industries.
This study aims to investigate the enhancement in electrical efficiency of a polycrystalline photovoltaic (PV) module. The performance of a PV module primarily depends upon environmental factors like temperature, irradiance, etc. Mainly, the PV module performance depends upon the panel temperature. The performance of the PV module has an inverse relationship with temperature. The open circuit voltage of a module decreases with the increase in temperature, which consequently leads to the reduction in maximum power, efficiency, and fill factor. This study investigates the increase in the efficiency of the PV module by lowering the panel temperature with the help of water channel cooling and water-channel accompanied with forced convection. The two arrangements, namely, multi-inlet outlet and serpentine, are used to decrease the temperature of the polycrystalline PV module. Copper tubes in the form of the above arrangements are employed at the back surface of the panel. The results demonstrate that the combined technique is more efficient than the simple water-channel cooling technique owing to multi-heat dissipation and effective heat transfer, and it is concluded that the multi-inlet outlet cooling technique is more efficient than the serpentine cooling technique, which is attributed to uniform cooling over the surface and lesser pressure losses.
Metal iodide materials as novel components of thermal biological and medical systems at the interface between heat transfer techniques and therapeutic systems. Due to their outstanding heat transfer coefficients, biocompatibility, and thermally activated sensitivity, metal iodides like silver iodide (AgI), copper iodide (CuI), and cesium iodide (CsI) are considered to be useful in improving the performance of medical instruments, thermal treatment processes, and diagnostics. They are examined for their prospective applications in controlling thermal activity, local heating therapy, and smart temperature-sensitive drug carrier systems. In particular, their application in hyperthermia therapy for cancer treatment, infrared thermal imaging for diagnosis, and nano-based drug carriers points to a place for them in precision medicine. But issues of stability of materials used, biocompatibility, and control of heat—an essential factor that would give the tools the maximum clinical value—remain a challenge. The present mini-review outlines the emerging area of metal iodides and their applications in medical technologies, with a special focus on the pivotal role of these materials in enhancing non-invasive, efficient, and personalized medicine. Over time, metal iodide-based systems scouted a new era of thermal therapies and diagnostic instrumentation along with biomedical science as a whole.
A fresh interest has been accorded to metal iodides due to their fascinating physicochemical properties such as high ionic conductivity, variable optical properties, and high thermal stabilities in making micro and macro devices. Breakthroughs in cathodic preparation and metallization of metal iodides revealed new opportunities for using these compounds in various fields, especially in energy conversion and materials with luminescent and sensory properties. In energy storage metal iodides are being looked at due to their potential to enhance battery performance, in optoelectronics the property of the metal iodides is available to create efficient LEDs and solar cells. Further, their application in sensing devices, especially in environmental and medical monitoring has been quite mentioned due to their response towards environmental changes such as heat or light. Nevertheless, some challenges are still in question, including material stability, scale-up opportunities, and compatibility with other technologies. This work highlights the groundbreaking potential of metal iodide-based nanomaterials, emphasizing their transformative role in innovation and their promise for future advancements.
The intermittent flow cold storage heat exchanger is one of the most important components of the pulse tube expansion refrigerator based on the reverse Brayton cycle. In the experimental system, the volume and heat transfer of the helical tube play a decisive role in the stable operation of the whole experimental system. However, there are few studies on heat transfer in a helical tube under helium working medium and intermittent flow conditions. In this paper, a process and method for calculating the volume of a helical tube are proposed based on the gas vessel dynamics model. Subsequently, a three-dimensional simulation model of the helical tube was established to analyze the heat transfer process of cryogenic helium within the tube. The simulations revealed that the temperature of helium in the tube decreases to the wall temperature and does not change when the helical angle exceeds 720°. Moreover, within the mass flow rate range of 1.6 g/s to 3.2 g/s, an increase in the mass flow rate was found to enhance the heat transfer performance of the helical tube. This study provides a reference for the selection and application of a helical tube under intermittent flow conditions and also contributes to the experimental research of inter-wall heat exchanger and pulse tube expansion refrigerators.
The power and efficiency of the monocrystalline PV module increase by reducing its panel temperature. It depends on the solar irradiance and the operating temperature of the PV module. Due to an increase in the operating temperature of the PV module, the efficiency decreases. As the temperature rises, the power output of the PV module also decreases. To improve the efficiency of the PV module, two different cooling techniques are investigated in this paper, i.e., the water channel cooling technique and the water-channel cooling technique accompanied with forced convection. In the water-channel cooling technique, copper pipes with serpentine and multi-inlet outlet arrangements are utilized at the backside of the mono-crystalline PV module, and the water is passed through pipes, while in water-channel cooling along with forced convection, the copper pipes with serpentine and multi-inlet outlet arrangements along with fans are employed. It is observed that the multi-inlet-outlet arrangement is more efficient as compared to the serpentine arrangement owing to the better heat transfer between the cooling media and the PV module. The experimental results demonstrate an increase in power output and efficiency realized through the reduction in operating temperature of the PV module and thus improving the open circuit voltage.
