Search

The major challenge of the current and future miniature compact high-tech electronic devices is thermal management. Micro-scale cooling is one of the promising thermo-fluidic implications possess a great potential in this cutting-edge research area. In this research work, newly emerged MXene (Ti 3 C 2) and functionalized graphene (f-Gr) hybrid nanoflake is implied for the first time in the preparation of Silicon oil (Si-oil) based heat transfer media (MXene:f-Gr/Si-oil hybrid nanofluid) for the micro-scale cooling application. This research concentrates on development, characterization, thermal stability and thermal properties evaluations of new class of hybrid (MXene:f-Gr/Si-oil) nanofluids of three different concentrations of MXene and f-Gr hybrid nanoflakes. The thermal conductivity of the as produced MXene:f-Gr/Si-oil hybrid nanofluids is measured (up to 250 °C) by a Transient Hot Bridge (THB) 500 (Linseis, Germany, current 5 mA, heater-power 18 mW) with Hot Point Sensor (HPS). The measurement is conducted in a newly customized designed industrial grade hotplate heat loss protection chamber with a PID controller. Viscosity is evaluated by a Rheometer with varying temperature of 25 °C from 25 to 125 °C. Optical absorbance is measure using PerkinElmer Lambda 750. The optimum thermal conductivity enhancement is acquired about ∼68% for the MXene and f-Gr hybrid nanoflakes concentration of 0.02 wt% over the pure Si-oil base fluid at 200 °C. The viscosity of MXene:f-Gr/Si-oil hybrid nanofluids is revealed to be autonomous of adding the MXene and f-Gr hybrid nanoflakes into the Si-oil base fluid. However, viscosity of hybrid nanofluid samples is decreased by ∼36% within the increase of temperature from 25 to 50 °C. MXene:f-Gr/Si-oil hybrid nanofluid sample of concentration 0.02 wt% shows the thermal stability up to ∼393 °C (∼14% enhancement over the Si-oil). This significant improvement is advantageous for the cooling of future high-tech electronic systems. This subsequently increases thermal energy acquisition which is valuable for various other applications. [Display omitted] • Synthesizing a unique MXene and f-Gr hybrid composition. • Novel formulation MXene:f-Gr/Si-oil hybrid nanofluids with improved heat transfer attributes. • High temperature thermal conductivity enhancement of new nanofluids using a heat-trap chamber. • Enhanced thermal conductivity of the new hybrid nanofluids over pure Si-oil. • Improved thermal stability of synthesized hybrid nanofluids. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Taibah University Medical Sciences is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

MXenes are layered 2D materials with fascinating properties such as large surface area, good electrical conductivity, good chemical, and electrochemical stabilities, etc. However, the high cost of MAX phases remains a major bottleneck for the large-scale synthesis of Ti 3 C 2 T x MXene for industrial applications. This motivated us to strategically design a method for the large-scale synthesis of Ti 3 C 2 T x MXene using low-cost waste-derived precursors. Initially, we used carbon soot obtained from car exhaust as a low-cost carbon precursor for the synthesis of the Ti 3 AlC 2 MAX phase. Further, the Ti 3 C 2 T x MXene is synthesized from this MAX phase with better purity. Furthermore, the Ti 3 C 2 T x MXene-activated carbon (AC) composite is prepared and coated over a natural biodegradable sponge (NBS) in order to use it as an efficient photothermal/solar absorber to produce steam using solar energy. The NBS layer exhibits a microporous structure that provides adequate water transportation and concentrated heat for interfacial water evaporation whereas the Ti 3 C 2 T x MXene and AC provide large surface area and stability to the absorber. The Ti 3 C 2 T x MXene-AC@NBS composite successfully produced solar evaporation rates of up to 1.8 kg m2/h with a solar steam conversion efficiency of 89.82 % with one sun solar irradiation. [ABSTRACT FROM AUTHOR]

The pressing concern of escalating water scarcity has spurred the creation of advanced technologies, such as interfacial solar steam generation (ISSG), to tackle the challenge. ISSG employs solar energy for efficient water desalination and purification. This comprehensive review delves into various aspects of ISSG, primarily focusing on elucidating its mechanisms, optimizing substrate materials, implementing thermal management strategies, and exploring applications. The study dissects the intricate mechanism of ISSG, highlighting photothermal behaviors across different materials, including the significant role of nanoparticles in vapor generation. The impact of substrate composition and shape on solar evaporation efficiency is investigated, with multi-surface evaporators considered for environmental energy harnessing. To enhance performance, thermal management strategies, including innovative water transport paths for improved heat distribution, are assessed. Addressing key challenges like salt accumulation, biofouling, corrosion, and oil fouling, the review offers insights for issue mitigation. Practically, ISSG is spotlighted for its role in seawater desalination, wastewater treatment (e.g., dye and heavy metal removal), oil-water separation, and sterilization, extending its relevance across industries and healthcare. By comprehensively examining ISSG's mechanisms, substrate considerations, thermal strategies, and applications, this review advances its implementation as a transformative solution for global water challenges. [Display omitted] • A comprehensive exploration of ISSG mechanisms and photothermal behaviors. • Scrutiny of nanoparticles' pivotal role in optimizing vapor generation. • In-depth analysis of substrate attributes elevating solar evaporation. • Review of strategies for efficient heat distribution, salt rejection, corrosion resistance, microbial & oil resistance. • Highlighting ISSG's role in desalination, water treatment, and industrial processes. [ABSTRACT FROM AUTHOR]

Research and development of desalination technologies are becoming highly critical because of the rapid increase in freshwater demand. Researchers are continually working on improving the existing desalination technologies and exploring new methods and ideas to desalinate salty water. The main goal is to come up with cost-effective systems. Renewable energy desalination is becoming an attractive option nowadays because of its viability of producing fresh water, technology improvement continuation, limitation of conventional sources and compatibility between water needs and renewable resources availability. More importantly, using renewable energy to power desalination systems is extremely important for reducing global emissions and protecting the environment. This research is an attempt to provide a systematic methodology for determining the most cost-effective combination of renewable energy powered reverse osmosis desalination system for a given location and required capacity. Two combinations are compared which are RO-Wind and RO-PV. Results show that for Dhahran, Saudi Arabia cost of water produced by RO-Wind is 1.366 $/m³ to 1.273 $/m³ and by RO-PV is 2.119 $/m³ to 2.048 $/m³ for a system capacity of 1000 m³ to 10,000 m3, respectively. [ABSTRACT FROM AUTHOR]

Highlights • Review on modeling of nanofluid thermal conductivity using data-driven approaches. • Discussed different influential parameters on the thermal conductivity of nanofluids. • Multilayer perceptron ANN modeling approach is considered as the most widely used. • Particle volume and temperature are most input variables in majority of research. Abstract There is a growing body of work in the field of nanofluids and several investigations have been conducted on their thermal conductivities. While the experimental works require considerable investments to provide a highly equipped laboratory and proper instruments, the predictive models are useful to promote understanding nanofluids under different operational conditions. However, the restrictions on the traditional predictive models require scholars to develop reliable models that are capable of simulating the thermophysical properties of nanofluids. Data-driven models have attracted huge attention and been widely applied in various fields. There is no specific review on application of data-driven models in thermal conductivity of nanofluids till now and thus this is the first review paper which gives a state of the art review of research progress in this field of study. It was identified that the effective thermal conductivity of nanofluids is reflected well by the new predictive models. The authors believe that the data-driven models are fast, reliable, simple-to-use, and practical. This may open a new door for the scientists, engineers, and researchers in the field of nanofluid for calculating the effective thermal conductivity with excellent precision. This investigation leads to the recognition of the main problems and the opportunities in the research area for the future works. [ABSTRACT FROM AUTHOR]

Methanol oxidation reaction (MOR) is the main reaction that takes place in an anodic electrode of a direct methanol fuel cell (DMFC), whichis a promising electrochemical energy conversion technology. This study presents a novel approach for enhancing the electrocatalytic activity of MOR performance using composite of MXene (Ti 3 C 2 T x) with Pt and Ru bimetal. The aimed of this study is to investigates the optimum electrocatalyst loading for PtRu/Ti 3 C 2 T x to improve and stand out the potential of electrocatalysts in the MOR catalytic activity. The study also provides detailed physical characterizations and electrochemical measurements. The results show that the electrocatalyst loading of 0.40 mgcm−2 has the highest ECSA value and better reaction activity compared to other loadings. The electrocatalytic activity, CO tolerance, and stability of the electrocatalyst also show the better result for this loading. The comparative study with previous research shows that the PtRu/Ti 3 C 2 T x electrocatalyst exhibits the highest catalytic activity, which is 5.13 times better than that of the previous study on the Pt/C electrocatalyst. Thus, the novel combination of MXene structure and PtRu indicates a promising electrocatalyst for MOR. [Display omitted] • Ti 3 C 2 T x embedded Pt and Ru as electrocatalyst to enhance the MOR performance. • PtRu/Ti 3 C 2 T x electrocatalyst was synthesized using simple reduction method. • The proposed electrocatalyst exhibits the increment of catalytic activity. • The catalyst poisoning tolerance and charge-transfer resistance are improved. [ABSTRACT FROM AUTHOR]

Boiler is a widely used steam generating system in industries and power plants. A significant portion of the world energy consumption is being used in boilers. A small improvement on the boiler efficiency will help to save a large amount of fossil fuels and to reduce CO 2 emission. This study describes the amount of energy used in boilers, ways employed to evaluate their energy efficiency, losses occurred and their causes, ways of waste heat recovery and minimizing heat loss using technologies, role of maintenance activities, and technical education to make people aware of the energy usage. Latest published literature on the above mentioned topics which includes PhD and MSc theses, journal articles, conference proceedings, reports and web materials have been reviewed and reported. It is found that a substantial amount of energy is wasted through high temperature flue gas or exhaust of the boiler. Also, some other unavoidable losses occurr due to various reasons. However, waste heat could be recovered using different technologies as a useful form of energy such as electricity, heat, refrigeration effect, etc. The efficiency of the boiler can be improved by doing scheduled maintenance work, which helps to run a boiler at its highest efficiency. In order to create awareness about energy use, education programs and seminars need to be arranged on regular basis for the staff involved. This will help them to understand the importance of the energy as being used in the boiler system as well as the impact of their actions during the operation of the boiler. [ABSTRACT FROM AUTHOR]

Energy storage has become an important part in renewable energy technology systems. Solar thermal systems, unlike photovoltaic systems with striving efficiencies, are industrially matured, and utilize major part of sun's thermal energy during the day. Yet, it does not have enough (thermal) backup to keep operating during the low or no solar radiation hours. New materials are selected, characterized, and enhanced in their thermo-physical properties to serve the purpose of a 24 h operation in an efficient thermal energy storage system (TESS). Solar absorption refrigeration system requires a continuous operation in many of its applications (food storage, space cooling etc), which in turn requires an efficient TES system utilizing material with high heat of fusion, eg. phase change materials (PCMs). This review is a comprehensive evaluation of suitable PCM selection, methodologies of integration, enhancements and challenges for operating temperatures of each component in a single-effect solar absorption system affecting its performance. Observations and lessons from previous studies are discussed in detail. Recommendations based on investigation results, advantages and drawback of PCMs, PCM enhancement options, energy, exergy and cost analysis are made for the future research direction. [ABSTRACT FROM AUTHOR]

Different properties of nanofluids have been studied by the researchers since the last two decades. Most of the studies have focused on the thermal properties of the nanofluids. However, optical properties have considerable contribution to heat absorbance in nanofluids. Therefore, it is necessary to study the different parts of solar spectrum (optical properties) to utilize nanofluids in solar thermal applications. The optical properties (absorption, transmittance, scattering, and extinction coefficient) based on metal, metal oxide, carbon nanotubes, graphite, and graphene have been reviewed thoroughly in variation with particle size and shape, path length, and volume fraction. The present investigational outcomes about the nanofluids showed that optical solar absorption increased accordingly with increasing nanoparticle size and volume concentration. However, there were some conflicting results on the effects of nanoparticle size on absorption, in which the particle size has an insignificant effect on overall optical properties. Moreover, it was observed that path length has some remarkable effects over optical absorption of nanofluids. The experimental results revealed that the transmittance of nanofluids has indirect relation with nanoparticle size, volume fraction, and path length. The scattering of light is directly proportional to the volume concentration and particle size of metallic particles. Overall, results of various elements showed that the presence of large particles and particle agglomerates leads to significant amount of light scattering. As a result, overall extinction coefficient will be increased. Therefore, an optimization of these properties need to be maintained for stable and cost-effective nanofluid. [ABSTRACT FROM AUTHOR]

Thermal energy storage is at the height of its popularity to harvest, store, and save energy for short-term or long-term use in new energy generation systems. It is forecasted that the global thermal energy storage market for 2015–2019 will cross US$1,300 million in revenue, where the highest growth is expected to be in Europe, Middle East, and Africa followed by Asia-Pacific region. Thermal energy storage has become an inevitable component of fluctuant renewable energy systems due to their significant role in increasing efficiency and Quality of Service (QoS). Currently, one major research stream in such systems is improving the efficiency of heat exchangers and heat carriers. Hence, studying thermal behavior and thermophysical properties of heat storages is of great importance. In this study, we review a common but not very well-known problem of supercooling of Phase Change Materials (PCM). Supercooling is a thermophysical property of PCMs that is problematic in thermal storage applications. This review looks at supercooling from another point of view and investigates applications (such as specialized thermal storage applications) that can put supercooling into operation. To achieve this, development of techniques to increase state stability and designing reliable and stable supercooled heat storage systems will be investigated. The study will look at the thermal energy storage of supercooled liquids, degree and measurement of supercooling. Furthermore, factors that influence degree of supercooling and their effect on output capacity will be discussed. It looks at the supercooled material in four major categories and looks into the mechanisms for triggering crystallization in supercooled liquids. Applications including solar thermal storage will be the discussed in details. From the results discussed in this review researchers will identify and gain insight into supercooling control techniques, which are necessary for developing efficient heat exchangers, and also essential for promoting adoption of sustainable renewable energies. [ABSTRACT FROM AUTHOR]

Waste-heat utilization holds great potential for cleaner production by improving energy efficiency, reducing energy usage and enhancing engineering functionality of an industry. Utilization of waste-heat is highly neglected in textile industries of the developing countries. This study quantified the energy and cost saving potential of waste-heat utilization in textile industries with several case studies. It focused on the common waste-heat sources and readily implementable technologies considering both technical and economic aspects. A waste-heat recovery boiler with a capacity of 2.70 t/h ran by hot exhaust from onsite electricity generators was estimated to save annually 15,094 MWh of energy and energy cost of USD 141,280. Installing economizer reduced 4.9% of boiler fuel consumption. Approximately 10% of energy used in stenter-setting machines was saved by installing a heat-exchanger that extracted waste-heat of stenter exhaust to preheat fresh air supplied to stenter operations. A counter-flow heat-exchanger was set up for utilizing waste-heat of dyed waste water. The yearly energy saving potential was 5716 MWh along with minimizing annual energy cost of USD 47,100. A proper stem-condensate recovery system reduced water loss and 10.50% of energy saving was achieved for steam production. [ABSTRACT FROM AUTHOR]

In recent decades, due to alarming increase of carbon dioxide (CO 2) in the atmosphere, capturing carbon has gained an intense attention from researchers to address its adverse effect in terms of climate change. However, yet it is of utmost interest to come up with an optimum CO 2 adsorbent that can substitute chemical adsorption for the future large-scale implication. In this paper, we describe the utilization of newly emerged two-dimensional (2D) nanomaterial MXenes side-by-side with activated carbon (AC) in the form of sandwich and as well as in a nanocomposite (embedded) form to evaluate their CO 2 adsorption performance using a fixed-bed adsorption column. Advanced characterization of the as produced adsorbents is conducted using XRD, FTIR, HRTEM with EDX and BET analysis to elucidate their surface morphology, functional groups, chemical compositions, and properties. In the adsorption column, CO 2 breakthrough measurements were performed by a continuous CO 2 concentration (15 %) with an inlet flow rate at 200 mL/min at different temperatures (25–55 °C). The highest CO 2 adsorption capacity (∼8.9 mg/g) was achieved by AC/MXene sandwich adsorbent at 25 °C. This corresponds to ∼37 % improvement in CO 2 adsorption capacity over AC. Importantly, AC/MXene sandwich offers an excellent regeneration performance with constant CO 2 adsorption capacity in regenerative cycles. Finally, the novel work with an outstanding result opens a new window of implication of emerging nanomaterials for highly efficient media large-scale CO 2 capture application. [Display omitted] • Unique AC/MXene nano-sandwich adsorbent in CO2 adsorption using fixed-bed column. • Gained significant CO2 adsorption capacity (∼8.9 mg/g) with ∼4 % MXene in column. • Acquired > 37 % enhancement in CO2 adsorption with this new nano-sandwich adsorbent. • A robust CO2 adsorption capacity obtained in regeneration analysis. • An introduction to MXene embedded AC composite for future CO2 adsorption studies. [ABSTRACT FROM AUTHOR]

Industrial symbiosis (IS) involves sharing waste, by-products, heat, and logistics streams. Participating entities are benefitted by reducing resource utilization and waste disposal cost, improving reuse, and creating job opportunities. Hence, countries have used it to ensure clean and sustainable economic growth. The Kingdom of Saudi Arabia (KSA) has initiated a few IS-related approaches that focus mainly on the power sector. However, the role of IS in Saudi industries is still limited, and there is significant potential for the enhancement of the major sectors, including oil and gas, petrochemicals, iron and steel, power generation, desalination, cement, and paper and pulp industries. This study investigated 11 successful IS cases and proposed a symbiotic exchange framework. A roadmap for IS implementation is also developed by considering the enablers and the barriers and by outlining the framework, initial steps, and policy levels. However, to deploy IS activities in KSA, technological, economic, and regulatory obstacles must be overcome and the enablers should be enhanced to conserve resources, reduce environmental impacts, and improve social well-being. The future studies should focus on unique challenges of the Kingdom including availability of energy resources at low price, dependency on fossil-fuels, dispersed development, limited availability of water resources, and limited R&D focus on IS. • Saudi industries have been growing but the role of industrial symbiosis is limited. • Petroleum, utility, and metal industries have potential for symbiotic exchanges. • A roadmap for industrial symbiosis implementation is proposed. • Significant barriers and enablers are identified. • Obstacles include petroleum dependence, dispersed development, and little research. [ABSTRACT FROM AUTHOR]

Growing dependence of industry and technology on fossil energy and increasing population encounters all countries with challenge of energy for future. Therefore, investigation about renewable energies, particularly solar energy is considered. The use of nanofluids in solar collectors offers better performance, as they are very efficient in transporting heat even under small temperature difference. The effect of Aluminium oxide (Al 2 O 3 )–water nanofluid, as working fluid, is used to evaluate the thermal efficiency of a flat plate solar collector, experimentally. A volume fraction of 0.1% for size of (13 nm and 20 nm) nanoparticles, respectively was used for this study. The mass flow rates of the nanofluid varied from 0.5 to 1.5 kg/min. Experiments were carried out using a stable nanofluid. The stability of nanofluid was obtained by controlling the pH of the solution. An ASHRAE Standard 93-2010 (R2014) was used to analyze efficiency of the solar collector. The results reflect the contribution and significance of each of these parameters to the collector overall energetic and exergetic efficiencies. Two different sizes of Al 2 O 3 –water nanofluid 13 nm and 20 nm are examined, and results show that 13 nm Al 2 O 3 nanofluid shows higher thermal conductivity enhancement and efficiency, compared to that of 20 nm Al 2 O 3 nanofluid and water. Al 2 O 3 –H 2 O (13 nm) nanofluid with 0.1% volume fraction and at a flow rate of 1.5 kg/min showed the highest energy efficiency of about 73.7%, compared to Al 2 O 3 –H 2 O (20 nm) nanofluid, which showed an energy efficiency of 70.7%. Critical point of Al 2 O 3 –water nanofluid is also presented, which has not be reported in literature according to author's knowledge, which also shows the novelty of this work. [ABSTRACT FROM AUTHOR]

Photovoltaic/thermal (PV/T) solar systems, which produce both electrical and thermal energy simultaneously, represent a method to achieve very high conversion rates of sunlight into useful energy. In recent years, nanofluids have been proposed as efficient coolants and optical filter for PV/T systems. Aim of this paper is to theoretically analyze the life cycle exergy of three different configurations of nanofluids-based PV/T hybrid systems, and compare their performance to a standard PV and PV/T system. Electrical and thermal performance of the analyzed solar collectors was investigated numerically. The life cycle exergy analysis revealed that the nanofluids-based PV/T system showed the best performance compared to a standard PV and PV/T systems. At the optimum value of solar concentration C , nanofluid-based PV/T configuration with optimized optical and thermal properties produces ∼1.3 MW h/m 2 of high-grade exergy annually with the lowest exergy payback time of 2 years, whereas these are ∼0.36, ∼0.79 MW h/m 2 and 3.48, 2.55 years for standard PV and PV/T systems, respectively. In addition, the nanofluids-based PV/T system can prevent the emissions of about 448 kg CO 2 eq m −2 yr −1 . Overall, it was found that the nanofluids-based PV/T with optimized optical and thermal properties has potential for further development in a high-concentration solar system. [ABSTRACT FROM AUTHOR]