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Limited thermal conductivity and leakage of phase change material (PCM) are among the most challenging obstacles that impede their effective applications in real-world scenarios. This study focussed on enhancing the thermal conductivity (TC), address leakage issues and incorporate thermoelectric conversion capabilities by using a single multifunctional scaffold. The shape stable PCM (ss-PCM) composite has been prepared using medium temperature range (~46 °C) commercial grade paraffin wax (PW) as organic PCM while expanded graphite (EG) as an encapsulating scaffold. The composite was prepared using vacuum impregnation method, incorporating various weight percentages (wt.%) of EG. In particular, the three wt.% of EG that has been used to encapsulate PCM are 5 % (ss-PCM1), 10 % (ss-PCM2) and 15 % (ss-PCM3). Then the composite was evaluated for its thermal stability, potential chemical interactions, leakage prevention, optical properties, thermal conductivity and thermo-electric conversion capability. Results revealed that the incorporation of 15 wt% EG in PCM (ss-PCM3) demonstrated no traces of leakage even after heating the composite at 60 °C. In addition, a significant increment of 447 % in thermal conductivity and 98 % in light absorbance has been observed. However, the composite showed a slight decrement of 13.83 % in latent heat related to base PCM. Finally, ss-PCM3 was put through to 500 heating-cooling cycles to evaluate its reliability and potential defects due to thermal fatigue. The characterization results of the composite were in close agreement before and after the thermal cycling, indicating its potential for practical applications. The electro-thermal conversion measurement findings indicate that the ss-PCM3 can achieve a conversion ability of 61.89 % when operated at 4.8 V. Several potential applications for this composite include energy-efficient buildings, infrared thermal concealment, solar energy utilization, and heat insulation.

Ionogels have emerged as promising thermoelectric materials with Seebeck coefficient 2–3 orders of magnitude higher than Seebeck coefficient of their inorganic counter parts. However, they suffer from the problem of low ionic conductivity, which can be improved with the addition of inorganic nanofillers to the ionogels. In the present work, thermoelectric performance of multiwall carbon nanotubes (MWCNTs) based ionogels (IGs) has been investigated. IGs were synthesized via in situ radical polymerization of polyethylene glycol 200 dimethacrylate (PEG200DMA) difunctional monomer in the presence of 1-butyl-3-methyl imidazolium tetrafluoroborate (an ionic liquid) and MWCNTs. Three composites namely MWCNTs-0.25, MWCNTs-0.5 and MWCNTs-1 were prepared having the concentration of MWCNTs by 0.25, 0.5 and 1 wt% respectively. A remarkable 75.3% enhancement in ionic conductivity was achieved for the MWCNTs-1 wt% ionogel compared to the base IG at 40 °C. This substantial improvement can be attributed to the "breathing polymer chain model," which describes the dissociation of ion aggregates due to the interaction between the ionic liquid and polymer chains. In terms of thermoelectric performance amongst the MWCNT ionogels, 0.25 wt% MWCNT-based ionogels was the optimized concentration with very high Seebeck coefficient of 1.70 mV/K and power factor of 4.1 µW/m. K along with excellent thermal stability up to 386 °C. These high-performing ionogels hold great promise for efficient utilization of low-grade thermal energy.

Solar energy is one of the most efficient origins of energy for a wide range of environmentally beneficial purposes. Water desalination by steam generation with the help of solar energy is not only an economical and straightforward approach, but it also utilizes free energy sources to solve the problem of increasing freshwater scarcity. Solar water evaporation is an essential component of the low-energy method for generating fresh water, which is required for economic development and human health. Freshwater productivity determines how effectively the system captures incoming solar energy and transforms it into usable heat. Effective water distillation has recently gained a lot of attention. The photothermal conversion process is built on the performance of the evaporator. This review thoroughly examines the most recent developments in photothermal materials, structure design, and engineering strategies, including design principles for highly efficient photothermal conversion, thermal management, water transport phenomena, salt rejection behavior, and improved evaporation rate. The prospective applications of this technique in saline water desalination, waste water purification, and energy generation are highlighted. Furthermore, the most recent scientific advancements are utilized to demonstrate the potential, prospects, and challenges of solar-driven evaporation in energy conversion.

MXene, a two-dimensional (2D) carbide, carbonitride, and nitride, was discovered in 2011. A certain number of elements in the periodic table have contributed to the synthesis of MXene from the beginning to the present. Most researchers, however, are focused on a particular type of MXene, Ti3C2Tx, although the scientific community seldom considers the synthesis cost of this outstanding and potentially helpful substance. Herein, we explore the cost of MXene by going through each stage of the production process. Instead, the actual cost may vary by a small margin due to differences in the materials and procedures. However, this study provides a clear understanding of the cost, which is governed by the steps directly involved in the synthesis and characterization of MXene. The cost associated with various essential characterization tools like scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet–visible spectroscopy (UV–Vis), and x-ray diffraction (XRD) is necessary to ensure the successful synthesis of MXene. All local expenses are converted into USD, except for the instrumental life cycle analysis and infrastructure cost values. The cost of each gram of MXene is predicted to be $20.33. The predicted cost is close to the market price of MXene, proving the accuracy of the cost calculation presented in this research. This work will assist the scientific community in planning and optimizing MXene's synthesis procedures so that the production cost can be potentially reduced if this material is produced on a larger scale.

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.

One promising solution to the freshwater crisis is solar-driven interfacial evaporation-based desalination. However, an alternate strategy is needed to address both water and energy shortages in parallel. Additionally, the disposal of desalination brine necessitates specific consideration while designing a sustainable solar interfacial desalination system. Herein, we demonstrate a single system that utilizes incident solar irradiance to produce interfacial steam using reduced graphene oxide (rGO) coated cotton fabric (CF) to desalinate seawater with an evaporation efficiency of 86.98%. The high thermal conductivity and excellent optical absorption of rGO contribute to the absorption of a broad solar spectrum. The system also produces 339.26 mW of electricity simultaneously by deploying commercially available thermoelectric generator (TEG) modules that use the squandered heat, increasing the overall system efficiency by 7.3%. The use of a custom-made power electronics module ensures operating at the maximum power point which has also been verified by computer simulation. Finally, hydrogen gas with zero carbon emission is produced by electrolyzing the seawater utilizing the electricity generated by the TEG module using solar-induced heat at a rate of 0.52 mmol h −1. Converting brine into hydrogen and oxygen gas by electrolysis demonstrates a potential in situ approach for desalination waste remediation.

Herein, we examine the influence of controllable polarization reversal and built-in electric fields on pyroelectric and electrocaloric effects in a BaTiO3 thin film using a modified indirect method. We find that the magnitude of the sample's change in polarization with temperature is sensitive to the degree of polarization reversal. The pyroelectric response is small at low fractions of switched polarization and grows larger by several factors as larger fractions of polarization are reversed. This polarization reversal-sensitive pyroelectric behavior is the result of an internal built-in field, which has the effect of destabilizing low fractions of switched polarization and producing diminished pyroelectric effect. Greater fractions of switched polarization are more stable against backswitching and permit a larger pyroelectric response. Our findings highlight a characterization method for polarization-dependent pyroelectric effects in ferroelectric thin films, where built-in field effects are also present.

Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells. A promising candidate catalyst for the cathode in direct methanol fuel cells must have excellent activity toward oxygen reduction reaction and resistance to methanol oxidation reaction. This review focuses on the methanol tolerant noble metal-based electrocatalysts, including platinum and palladium-based alloys, noble metal-carbon based composites, transition metal-based catalysts, carbon-based metal catalysts, and metal-free catalysts. The understanding of the correlation between the activity and the synthesis method, electrolyte environment and stability issues are highlighted. For the transition metal-based catalyst, their activity, stability and methanol tolerance in direct methanol fuel cells and comparisons with those of platinum are particularly discussed. Finally, strategies to enhance the methanol tolerance and hinder the generation of mixed potential in direct methanol fuel cells are also presented. This review provides a perspective for future developments for the scientist in selecting suitable methanol tolerate catalyst for oxygen reduction reaction and designing high-performance practical direct methanol fuel cells.

In recent decades, due to alarming increase of carbon dioxide (CO2) 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 CO2 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 CO2 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, CO2 breakthrough measurements were performed by a continuous CO2 concentration (15 %) with an inlet flow rate at 200 mL/min at different temperatures (25–55 °C). The highest CO2 adsorption capacity (∼8.9 mg/g) was achieved by AC/MXene sandwich adsorbent at 25 °C. This corresponds to ∼37 % improvement in CO2 adsorption capacity over AC. Importantly, AC/MXene sandwich offers an excellent regeneration performance with constant CO2 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 CO2 capture application.

MXene, a recently created nanomaterial, offers significant potential for thermal, electrical, and a variety of other uses. MXene was utilized to generate heat transfer nanofluids with improved thermophysical properties for thermal applications and to establish the optimal parameters for achieving the best thermal performance. In this study, a palm oil/MXene nanofluid was used as the heat transfer fluid in a circular pipe to evaluate its thermal impact at different Reynolds numbers and applied heat fluxes at a range of introduced MXene nanoparticles’ concentrations. Thermal conductivity and viscosity were shown to be linked to temperature and nanoparticle concentrations ranging from 0.01 to 0.1 mass%. The influence of concerted MXene nanoparticles (0.01 to 0.1 mass%) on the behavior of the PO/MXene nanofluid was studied using CFD simulations at various flow Reynolds numbers (2,500–5,000) and wall heat fluxes (40,000–90,000 W.m−2). The results indicate that increasing the nanoparticle concentration resulted in higher heat transfer coefficients and lower Nusselt numbers. MXene nanoparticles were more efficient at lowering the wall temperature and increasing the pace of cooling when applied at larger heat fluxes and lower Re numbers. The results reported in this article indicate that MXene nanomaterials have a strong potential for overcoming the low heat transfer difficulties encountered in heat exchange systems.

The primary objective of the present analysis is to investigate the thermophysical properties of hybrid nanocellulose and copper (II) oxide nanoparticles added to engine oil as a lubricant for piston ring-cylinder liner application. Kinematic viscosity, viscosity index (VI) and dynamic viscosity have been performed for measurement of properties at varying temperatures (ranging from 30 °C to 90 °C) and different concentrations (ranging from 0.1 % to 0.9 % volume concentration). Thermal characteristics have been measured using similar temperatures and concentrations to determine thermal conductivity and specific heat capacity. In the results, as the concentration of the CNC-CuO nanoparticle increases, the VI also increases. This proves the combination of CNC-CuO particles with engine oil improves the lubricity of the base oil concerning its viscosity by 44.3 %-47.12 %. The lowest and highest improvements in the dynamic viscosity were 1.34 % and 74.81 %. The highest increment of thermal conductivity ratio for the selected nanolubricant was 1.80566 % in the solid concentration of 0.1 % at 90 °C. The specific heat capacity of nanolubricant tends to reduce slightly with an increase in temperature. Overall, the addition of CNC-CuO nanoparticle in the engine improved thermophysical properties behaviour's performance at 0.5 % concentration. The results can benefit the heat transfer application, especially tribological.

Energy Storage Technology is one of the major components of renewable energy integration and decarbonization of world energy systems. It significantly benefits addressing ancillary power services, power quality stability, and power supply reliability. However, the recent years of the COVID-19 pandemic have given rise to the energy crisis in various industrial and technology sectors. An integrated survey of energy storage technology development, its classification, performance, and safe management is made to resolve these challenges. The development of energy storage technology has been classified into electromechanical, mechanical, electromagnetic, thermodynamics, chemical, and hybrid methods. The current study identifies potential technologies, operational framework, comparison analysis, and practical characteristics. This proposed study also provides useful and practical information to readers, engineers, and practitioners on the global economic effects, global environmental effects, organization resilience, key challenges, and projections of energy storage technologies. An optimal scheduling model is also proposed. Policies for sustainable adaptation are then described. An extensive list of publications to date in the open literature is canvassed to portray various developments in this area.

The vanadium redox flow battery (VRFB) is a highly regarded technology for large-scale energy storage due to its outstanding features, such as scalability, efficiency, long lifespan, and site independence. This paper provides a comprehensive analysis of its performance in carbon-based electrodes, along with a comprehensive review of the system‘s principles and mechanisms. It discusses potential applications, recent industrial involvement, and economic factors associated with VRFB technology. The study also covers the latest advancements in VRFB electrodes, including electrode surface modification and electrocatalyst materials, and highlights their effects on the VRFB system‘s performance. Additionally, the potential of two-dimensional material MXene to enhance electrode performance is evaluated, and the author concludes that MXenes offer significant advantages for use in high-power VRFB at a low cost. Finally, the paper reviews the challenges and future development of VRFB technology.

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 (Ti3C2Tx) with Pt and Ru bimetal. The aimed of this study is to investigates the optimum electrocatalyst loading for PtRu/Ti3C2Tx 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/Ti3C2Tx 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.

MXene-based nanofluids are novel trends with improved dispersion stability and thermophysical characteristics over previously established nanofluids. In the present work, the thermohydraulic characteristics of a double pipe heat exchanger (DPHEX) with a Therminol55(TH55)/MXene + Al2O3 nanofluid and various geometrically shaped (triangular, rectangular) ribbed twisted tape (TT) inserts are numerically investigated using the ANSYS Fluent interface. A counter flow arrangement with three different types of inserts (RRTT, TRTT, TT) and TH55/MXene + Al2O3 nanofluid at 0.20 wt% are studied inside the heat exchanger. Adding ribbed inserts to the conventional TT insert enhances the turbulence intensity by creating extra vortices. The thermal boundary layer grows thinner due to increased axial and radial velocity. Due to the substantial flow obstruction, adding ribs increases the overall pressure drop between the inlet and outlet. The maximum increase in Nu is 11.04 % using nanofluid instead of water, whereas the combination of insert and nanofluid exhibited up to 105 % enhancement for rectangular-ribbed TT compared to the plain tube. Nevertheless, the pressure decrease is found to be maximum in rectangular-ribbed TT because of significant flow disruption. This was likewise true with triangular-ribbed TT and TT insert. According to the PEC assessment, the RRTT insert had a maximum PEC value of 1.67 greater than TRTT and traditional TT for both TH55 and nanofluid flowing inside the tube. To summarize, the combination of TH55/MXene + Al2O3 RRTT insert may be a promising choice for improving heat exchanger performance in a new generation efficient thermal system. © 2023 The Authors

This article comprehensively investigates single (GNP) and hybrid nanofluids (GNPs/CNC nanoparticles), including nanofluid preparation and thermophysical properties. Nanoparticles were characterized using field emission scanning electron microscope, transmission electron microscope and X-ray diffraction analysis. A two-step approach is used in nanofluid preparation, and various analytical practices determine the prepared nanofluids. The range of the temperature set to measure the thermal conductivity of nanofluids is 20 °C to 50 °C using the ASTM D2717–95 norm. The present study range of the nanofluid volume concentration is from 0.01 vol% to 0.2 vol%. For the single GNP nanofluid, temperatures at room level indicated the thermal conductivity value in the range of 0.366 W·m−1·K−1 to 0.441 W·m−1·K−1; for hybrid nanofluid, the thermal conductivity values are 0.501 W·m−1·K−1 to 0.551 W·m−1·K−1. In addition, nanofluid's viscosity, density and specific heat capacity are the experimental density value increased with the concentration of nanoparticles with 1050 kg/m3 and 1060 kg/m3 for 0.01 % concentration of single/hybrid nanofluids, respectively. Finally, based on the findings, it can be determined that the thermal properties of the selected nanoparticles are beneficial, and hybrid nanofluid is an acceptable alternative to conventional/water-based fluids in terms of thermal properties in operational systems.

Solar steam generation is widely regarded as one of the potential green approaches for freshwater regeneration by utilizing solar energy. Herein, the MXene/MnO2 nanocomposite-coated biodegradable luffa sponge (Ti3C2-MnO2@LS) is proposed as an efficient solar evaporator for solar steam generation. The thin layer of Ti3C2-MnO2 coated on the surface of the luffa sponge (LS) serves as the solar absorber and enhances the hydrophilicity of the LS, while the thermally insulating LS layer with microporous structure endows sufficient water transportation and localizes heat for interfacial water evaporation. Combining MXene with MnO2 can increase the surface area as well as the stability. The Ti3C2-MnO2@LS delivers a solar evaporation rate as high as 1.36 kg m−2 h−1, with a solar steam conversion efficiency of 85.28 % under one sun irradiation. Furthermore, this Ti3C2-MnO2@LS exhibits superior salt-rejecting properties even under highly concentrated saltwater desalination and excellent wastewater purification performance. This work demonstrates the prospects of combining novel 2D materials with biomass-based materials for practical solar steam generation.

Finding a low-cost method to improve the heat transfer rate in thermal energy storage (TES) is essential in the modern world. In the current research, the comparison of inclined systems, which are among the inexpensive methods, with the new combined system employing the auxiliary fluid of water is discussed. Oleic acid is selected as an unsolvable PCM in water to reuse chosen materials at the end of the melting process in more TES cycles. In the combined system, the density difference between water and PCM is utilized to enhance the melting rate of PCM by placing water on the top of PCM to make direct contact. Therefore, water, which has a heavier density than PCM, takes the place of the melted PCM at the bottom of the enclosure during the melting of PCM. At first, the inclined system is examined at seven different inclination angles to identify the energy storage rate. A mathematical model is formulated using the water-PCM system's continuity, momentum, and energy equations. Then, the melting process of the combined system is studied to compare the energy storage rate of combined and inclined systems. Comparing the combined system with the optimal case of inclined systems, the average fluid velocity is 5.44 times higher, which shows the improvement of convection. It was found that the energy storage rate of the combined system (0.299136 kW/kg) is 1.85 times higher than the inclined system (0.161983 kW/kg at the inclination of 30°). As a result, the comprehensive study of the combined system is essential in future research to replace expensive methods.

The poor interparticle connectivity between the nanoparticles architecture of photoanode due to insufficient sintering temperature has been an issue for developing flexible dye sensitised solar cell (DSSC). This issue has led flexible DSSC to yield low conversion efficiency. This research aims to implement lead (Pb) as sintering aid to improve the interparticle connection of the photoanode by using the concept of liquid phase sintering. With low melting point of Pb (327.5 °C), necks were formed at the titanium dioxide (TiO2)–Pb interface that improved the connection and lowered the electronic resistance even at low sintering temperature of 150–250 °C. Morphological studies showed the formation of these necks, while phase analysis indicated the more desirable TiO2 anatase phase was present. Specimens containing 5 wt% Pb in the TiO2 matrix showed the highest efficiency value of 8.73% at 250 °C, which is even higher compared to their high-temperature (450 °C) counterpart by 12.21%. This is due to surface fusion of Pb at a lower temperature, leading to enhanced interparticle contact and reduction in recombination reactions. Further increase in Pb did not improve the conversion efficiency which can be due to high charge trapping sites and layer cracking due to high amounts of Pb in TiO2 matrix.

In recent years, phase change materials (PCMs) have attracted considerable interest due to their capacity to store and release enormous energy during phase transitions. However, low thermal conductivity and leakage are significant obstacles that hinder the efficacy of PCMs. Foams and porous matrices have been investigated as potential solutions to the leakage problem in PCMs. This review examines the use of foam to improve the thermal energy storage performance of PCMs. The primary objective of this paper is to unveil the leakage control using foams and discuss the effect on the thermophysical properties of foam-based PCMs. To achieve this objective, we have reviewed previous research in this area, established the research's rationale, and filled any voids in the literature. The paper examines the utilization of carbon-based and metallic foams for PCMs at varying temperatures. It evaluates the methodologies used to evaluate the efficacy of PCMs with foam reinforcement. Key findings include the significant enhancement in thermo-physical properties of PCM performance due to the use of foam and the potential applications of these materials in various fields, including thermal management of batteries, heating and cooling of buildings, smart textiles and electronic heat sinks. The study also summarizes the foams and other porous matrices to compare their performance with PCM. Foam-based PCMs prove to be a strong candidate by solving the leakage issue in PCMs without compromising their thermophysical properties.

The commercial application of flexible dye sensitized solar cells (DSSCs) is somewhat limited due to the devices’ low conversion efficiency. The low sintering temperature in preparing the photoanode has caused poor interparticle contact, low charge transfer and low efficiency. Hence, this research aims to improve the interparticle contact of titanium dioxide (TiO2) photoanode with the novel use of lead (Pb) nanoparticles as sintering aid at low temperature. TiO2-Pb composite photoanode was prepared with different composition of Pb including 4% and 7% sintered at low temperature of 250°C. The research discovered that TiO2 photoanode mixed with 4% Pb composition showed the lowest charge transfer resistance (RCT) even at low sintering temperature. The RCT value was even lower than a commercial TiO2 photoanode sample that was sintered at 450°C. The addition of Pb sintering aid has improved interparticle contact in the photoanode via the neck formation at the TiO2-Pb interface and enhanced charge transfer despite the low temperature. The prepared photoanode samples displayed potential in developing highly efficient flexible DSSC.

Developing stable, economic, safer and carbon-based nanoparticles from agro solid waste facilitates a new dimension of advancement for eco-friendly nanomaterials in competition to existing nanoparticles. Herewith, a three dimensional highly porous honeycomb structured carbon-based coconut shell (CS) nanoparticle is prepared through green synthesis technique using tube furnace to energies organic phase change material (PCM). CS nanoparticle synthesis using a green approach is incorporated with polyethylene glycol (PEG) using a two-step technique to develop PEG/CS nanocomposite PCM. Thermophysical features of the nanocomposites are characterized using transient hot bridge (ThB), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), whereas optical property and chemical stability is evaluated using UV–Vis and FTIR spectrometers. Resulting nanocomposite demonstrates higher thermal conductivity by 114.5 % (improved from 0.24 W/m⋅K to 0.515 W/m⋅K). Energy storage enthalpy increased from 141.2 J/g to 150.1 J/g with 1.0 % weight fraction of CS nanoparticles. Optical absorbance of the nanocomposite is improved by 2.14 times compared to base PCM. The developed nanocomposite samples exhibit extreme thermal stability up to 215 °C. The 3D porous structure of CS nanoparticles shows better contact area with PEG, causing low interfacial thermal resistance for improved thermal network channels and pathways for extra heat transfer and phonon propagation.

Low-dimensional nanomaterials are zero-, one- and two-dimensional nanomaterials, in which the aspect ratio and surface-to-volume ratio vary as the dimension varies. In nanofluids, suspended nanomaterials’ movement in the base fluid can be due to Brownian motion and thermophoresis effect, which causes heat transfer. However, the emergence of nanomaterials with various dimensions has led to more advanced heat transfer mechanisms. The high aspect ratio and surface-to-volume ratio of the nanomaterials are believed to be among the factors in nanofluids’ properties enhancement. However, the morphological effect on the heat transfer enhancement in nanofluids is still ambiguous. Hence, this paper aims to explore this significant gap by reviewing the reports that investigate the effect of morphology to the heat transfer enhancement in nanofluids containing low-dimensional nanomaterials and observe the trend. The heat transfer mechanisms in nanofluids are discussed to improve understanding of the phenomena, including its methods of study. This review also includes the material characterization techniques since these approaches can provide morphological information; hence, heat transfer can be studied. Heat transfer mechanisms associated with the movement of nanoparticles were the most researched mechanism, mostly by experimentations and theoretical predictions. However, there has not been a substantial amount of research linking the morphological studies to the heat transfer enhancement in nanofluids. The study of nanolayer, nanoclustering and phonon heat transport has also been made possible by recent advancements in high-performance computing applications such as molecular dynamics simulation and machine learning, offering a more efficient method for exploring novel low-dimensional nanomaterials beyond zero-dimension.

Employing a small oscillator plate is proposed as a novel idea to improve the performance of phase change material (PCM) based thermal energy storage unit. This idea could make mixing heat flow toward the PCM solid-liquid interface to hasten the melting and heat transfer rates. Opposite to the vibration of the whole PCM heat sink suggested in the literature, it needs very slight mechanical energy for oscillation. The oscillator plate was installed at three positions for the horizontal and vertical PCM heat sink: i) the middle of the hot plate, ii) the bottom of the hot plate, and iii) the corner of the heat sink. A computational fluid dynamics model has been employed to model the PCM melting process and evaluate the induced mixing heat flow and its effect on natural convection. A new mechanical method using vibration energy accelerates heat flow to improve heat transfer and thermal energy absorption. The results reveal that in the best case with transversal oscillation at the corner of the heat sink, the melting rate and heat transfer rate (Nusselt number) increase by 39 % and 64.2 % compared to no vibration case, respectively. Also, the absorbed heat energy rate (AHR) within the PCM heat sink is elevated from 0.51 to 0.79 (54.9 %), while the oscillator just consumed as small as 438 mJ of mechanical energy, reflecting this mechanical approach's uniqueness.

Energy Storage Technology is one of the major components of renewable energy integration and decarbonization of world energy systems. It significantly benefits addressing ancillary power services, power quality stability, and power supply reliability. However, the recent years of the COVID-19 pandemic have given rise to the energy crisis in various industrial and technology sectors. An integrated survey of energy storage technology development, its classification, performance, and safe management is made to resolve these challenges. The development of energy storage technology has been classified into electromechanical, mechanical, electromagnetic, thermodynamics, chemical, and hybrid methods. The current study identifies potential technologies, operational framework, comparison analysis, and practical characteristics. This proposed study also provides useful and practical information to readers, engineers, and practitioners on the global economic effects, global environmental effects, organization resilience, key challenges, and projections of energy storage technologies. An optimal scheduling model is also proposed. Policies for sustainable adaptation are then described. An extensive list of publications to date in the open literature is canvassed to portray various developments in this area.

The vanadium redox flow battery (VRFB) is a highly regarded technology for large-scale energy storage due to its outstanding features, such as scalability, efficiency, long lifespan, and site independence. This paper provides a comprehensive analysis of its performance in carbon-based electrodes, along with a comprehensive review of the system‘s principles and mechanisms. It discusses potential applications, recent industrial involvement, and economic factors associated with VRFB technology. The study also covers the latest advancements in VRFB electrodes, including electrode surface modification and electrocatalyst materials, and highlights their effects on the VRFB system‘s performance. Additionally, the potential of two-dimensional material MXene to enhance electrode performance is evaluated, and the author concludes that MXenes offer significant advantages for use in high-power VRFB at a low cost. Finally, the paper reviews the challenges and future development of VRFB technology.

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 (Ti3C2Tx) with Pt and Ru bimetal. The aimed of this study is to investigates the optimum electrocatalyst loading for PtRu/Ti3C2Tx 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/Ti3C2Tx 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.

MXene-based nanofluids are novel trends with improved dispersion stability and thermophysical characteristics over previously established nanofluids. In the present work, the thermohydraulic characteristics of a double pipe heat exchanger (DPHEX) with a Therminol55(TH55)/MXene + Al2O3 nanofluid and various geometrically shaped (triangular, rectangular) ribbed twisted tape (TT) inserts are numerically investigated using the ANSYS Fluent interface. A counter flow arrangement with three different types of inserts (RRTT, TRTT, TT) and TH55/MXene + Al2O3 nanofluid at 0.20 wt% are studied inside the heat exchanger. Adding ribbed inserts to the conventional TT insert enhances the turbulence intensity by creating extra vortices. The thermal boundary layer grows thinner due to increased axial and radial velocity. Due to the substantial flow obstruction, adding ribs increases the overall pressure drop between the inlet and outlet. The maximum increase in Nu is 11.04 % using nanofluid instead of water, whereas the combination of insert and nanofluid exhibited up to 105 % enhancement for rectangular-ribbed TT compared to the plain tube. Nevertheless, the pressure decrease is found to be maximum in rectangular-ribbed TT because of significant flow disruption. This was likewise true with triangular-ribbed TT and TT insert. According to the PEC assessment, the RRTT insert had a maximum PEC value of 1.67 greater than TRTT and traditional TT for both TH55 and nanofluid flowing inside the tube. To summarize, the combination of TH55/MXene + Al2O3 RRTT insert may be a promising choice for improving heat exchanger performance in a new generation efficient thermal system. © 2023 The Authors

Finding a low-cost method to improve the heat transfer rate in thermal energy storage (TES) is essential in the modern world. In the current research, the comparison of inclined systems, which are among the inexpensive methods, with the new combined system employing the auxiliary fluid of water is discussed. Oleic acid is selected as an unsolvable PCM in water to reuse chosen materials at the end of the melting process in more TES cycles. In the combined system, the density difference between water and PCM is utilized to enhance the melting rate of PCM by placing water on the top of PCM to make direct contact. Therefore, water, which has a heavier density than PCM, takes the place of the melted PCM at the bottom of the enclosure during the melting of PCM. At first, the inclined system is examined at seven different inclination angles to identify the energy storage rate. A mathematical model is formulated using the water-PCM system's continuity, momentum, and energy equations. Then, the melting process of the combined system is studied to compare the energy storage rate of combined and inclined systems. Comparing the combined system with the optimal case of inclined systems, the average fluid velocity is 5.44 times higher, which shows the improvement of convection. It was found that the energy storage rate of the combined system (0.299136 kW/kg) is 1.85 times higher than the inclined system (0.161983 kW/kg at the inclination of 30°). As a result, the comprehensive study of the combined system is essential in future research to replace expensive methods.

Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells. A promising candidate catalyst for the cathode in direct methanol fuel cells must have excellent activity toward oxygen reduction reaction and resistance to methanol oxidation reaction. This review focuses on the methanol tolerant noble metal-based electrocatalysts, including platinum and palladium-based alloys, noble metal-carbon based composites, transition metal-based catalysts, carbon-based metal catalysts, and metal-free catalysts. The understanding of the correlation between the activity and the synthesis method, electrolyte environment and stability issues are highlighted. For the transition metal-based catalyst, their activity, stability and methanol tolerance in direct methanol fuel cells and comparisons with those of platinum are particularly discussed. Finally, strategies to enhance the methanol tolerance and hinder the generation of mixed potential in direct methanol fuel cells are also presented. This review provides a perspective for future developments for the scientist in selecting suitable methanol tolerate catalyst for oxygen reduction reaction and designing high-performance practical direct methanol fuel cells.

This article comprehensively investigates single (GNP) and hybrid nanofluids (GNPs/CNC nanoparticles), including nanofluid preparation and thermophysical properties. Nanoparticles were characterized using field emission scanning electron microscope, transmission electron microscope and X-ray diffraction analysis. A two-step approach is used in nanofluid preparation, and various analytical practices determine the prepared nanofluids. The range of the temperature set to measure the thermal conductivity of nanofluids is 20 °C to 50 °C using the ASTM D2717–95 norm. The present study range of the nanofluid volume concentration is from 0.01 vol% to 0.2 vol%. For the single GNP nanofluid, temperatures at room level indicated the thermal conductivity value in the range of 0.366 W·m−1·K−1 to 0.441 W·m−1·K−1; for hybrid nanofluid, the thermal conductivity values are 0.501 W·m−1·K−1 to 0.551 W·m−1·K−1. In addition, nanofluid's viscosity, density and specific heat capacity are the experimental density value increased with the concentration of nanoparticles with 1050 kg/m3 and 1060 kg/m3 for 0.01 % concentration of single/hybrid nanofluids, respectively. Finally, based on the findings, it can be determined that the thermal properties of the selected nanoparticles are beneficial, and hybrid nanofluid is an acceptable alternative to conventional/water-based fluids in terms of thermal properties in operational systems.

Solar steam generation is widely regarded as one of the potential green approaches for freshwater regeneration by utilizing solar energy. Herein, the MXene/MnO2 nanocomposite-coated biodegradable luffa sponge (Ti3C2-MnO2@LS) is proposed as an efficient solar evaporator for solar steam generation. The thin layer of Ti3C2-MnO2 coated on the surface of the luffa sponge (LS) serves as the solar absorber and enhances the hydrophilicity of the LS, while the thermally insulating LS layer with microporous structure endows sufficient water transportation and localizes heat for interfacial water evaporation. Combining MXene with MnO2 can increase the surface area as well as the stability. The Ti3C2-MnO2@LS delivers a solar evaporation rate as high as 1.36 kg m−2 h−1, with a solar steam conversion efficiency of 85.28 % under one sun irradiation. Furthermore, this Ti3C2-MnO2@LS exhibits superior salt-rejecting properties even under highly concentrated saltwater desalination and excellent wastewater purification performance. This work demonstrates the prospects of combining novel 2D materials with biomass-based materials for practical solar steam generation.

The poor interparticle connectivity between the nanoparticles architecture of photoanode due to insufficient sintering temperature has been an issue for developing flexible dye sensitised solar cell (DSSC). This issue has led flexible DSSC to yield low conversion efficiency. This research aims to implement lead (Pb) as sintering aid to improve the interparticle connection of the photoanode by using the concept of liquid phase sintering. With low melting point of Pb (327.5 °C), necks were formed at the titanium dioxide (TiO2)–Pb interface that improved the connection and lowered the electronic resistance even at low sintering temperature of 150–250 °C. Morphological studies showed the formation of these necks, while phase analysis indicated the more desirable TiO2 anatase phase was present. Specimens containing 5 wt% Pb in the TiO2 matrix showed the highest efficiency value of 8.73% at 250 °C, which is even higher compared to their high-temperature (450 °C) counterpart by 12.21%. This is due to surface fusion of Pb at a lower temperature, leading to enhanced interparticle contact and reduction in recombination reactions. Further increase in Pb did not improve the conversion efficiency which can be due to high charge trapping sites and layer cracking due to high amounts of Pb in TiO2 matrix.

In recent decades, due to alarming increase of carbon dioxide (CO2) 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 CO2 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 CO2 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, CO2 breakthrough measurements were performed by a continuous CO2 concentration (15 %) with an inlet flow rate at 200 mL/min at different temperatures (25–55 °C). The highest CO2 adsorption capacity (∼8.9 mg/g) was achieved by AC/MXene sandwich adsorbent at 25 °C. This corresponds to ∼37 % improvement in CO2 adsorption capacity over AC. Importantly, AC/MXene sandwich offers an excellent regeneration performance with constant CO2 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 CO2 capture application.

MXene, a recently created nanomaterial, offers significant potential for thermal, electrical, and a variety of other uses. MXene was utilized to generate heat transfer nanofluids with improved thermophysical properties for thermal applications and to establish the optimal parameters for achieving the best thermal performance. In this study, a palm oil/MXene nanofluid was used as the heat transfer fluid in a circular pipe to evaluate its thermal impact at different Reynolds numbers and applied heat fluxes at a range of introduced MXene nanoparticles’ concentrations. Thermal conductivity and viscosity were shown to be linked to temperature and nanoparticle concentrations ranging from 0.01 to 0.1 mass%. The influence of concerted MXene nanoparticles (0.01 to 0.1 mass%) on the behavior of the PO/MXene nanofluid was studied using CFD simulations at various flow Reynolds numbers (2,500–5,000) and wall heat fluxes (40,000–90,000 W.m−2). The results indicate that increasing the nanoparticle concentration resulted in higher heat transfer coefficients and lower Nusselt numbers. MXene nanoparticles were more efficient at lowering the wall temperature and increasing the pace of cooling when applied at larger heat fluxes and lower Re numbers. The results reported in this article indicate that MXene nanomaterials have a strong potential for overcoming the low heat transfer difficulties encountered in heat exchange systems.

The primary objective of the present analysis is to investigate the thermophysical properties of hybrid nanocellulose and copper (II) oxide nanoparticles added to engine oil as a lubricant for piston ring-cylinder liner application. Kinematic viscosity, viscosity index (VI) and dynamic viscosity have been performed for measurement of properties at varying temperatures (ranging from 30 °C to 90 °C) and different concentrations (ranging from 0.1 % to 0.9 % volume concentration). Thermal characteristics have been measured using similar temperatures and concentrations to determine thermal conductivity and specific heat capacity. In the results, as the concentration of the CNC-CuO nanoparticle increases, the VI also increases. This proves the combination of CNC-CuO particles with engine oil improves the lubricity of the base oil concerning its viscosity by 44.3 %-47.12 %. The lowest and highest improvements in the dynamic viscosity were 1.34 % and 74.81 %. The highest increment of thermal conductivity ratio for the selected nanolubricant was 1.80566 % in the solid concentration of 0.1 % at 90 °C. The specific heat capacity of nanolubricant tends to reduce slightly with an increase in temperature. Overall, the addition of CNC-CuO nanoparticle in the engine improved thermophysical properties behaviour's performance at 0.5 % concentration. The results can benefit the heat transfer application, especially tribological.

The present study numerically investigates the optimization of thermal performance in a dimpled channel using a promising genre of nanofluid which is equipped with the inclusion of two-dimensional (2D) MXene (Ti3C2) nanoparticles to the soybean oil. The stream-wise and span-wise variation of the spherical dimples was kept 3.00 and 3.15 over the flow domain with an elongation of 2.5 mm. The detailed evaluation of both the local and global parameters is carried out for 0.025%, 0.075%, and 0.125% mass concentrations of MXene. The Reynolds number is varied from 1000 to 6000 to understand the effect of both the laminar and turbulent flow characteristics in predicting the thermal performance. The simulations are carried out using finite volume method (FVM) under constant heat flux, assuming the mixture of nanoparticles as homogeneous mixture. The results show that with the increase in the mass concentration of nanoparticles, thermal performances of the nanofluid increase. However, it is also identified that with the increase in Reynolds number, the thermal performance increases under turbulent flow regime. On the contrary, thermal performance was observed to be decreased with the increase in Reynolds number under laminar flow regime. An astounding improvement in 88.9% thermal performance is found for 0.125% mass concentrations of soybean-based MXene nanofluid which exclusively indicates the credibility of MXene nanofluid as a next generation potential candidate for heat exchanger industries.

Dye sensitised solar cells (DSSCs) have been in extensive development in recent years in the field of solar energy due to its cost-effectiveness, ease in fabrication, flexibility, and being able to be transparent and coloured as well. Two broad categories of DSSCs based on their fabrication temperature are (1) high-temperature DSSCs and (2) low-temperature DSSCs. Although the low-temperature DSSCs (sintered at less than 150 °C) can be flexible and printed on a plastic roll, however, their power conversion efficiency (PCE) is way less compared to their high-temperature counterpart. Research is underway to improve the PCE of low-temperature DSSCs and modules to optimum levels. In this review, an attempt has been made to evaluate different materials and fabrication methods for improved performance of flexible low-temperature DSSCs while also comparing them with the usual rigid high temperature device. Another objective of this study is to critically discuss the progress being made in flexible module development. This review paper would be able to provide comprehensive summary of the recent developments of flexible low-temperature dye sensitised solar cells and modules for reference and also serve as guide for further research in this area.

The characteristic effect of nanoparticles, boron nitride nanotubes in the nanofluid with and without surfactant, were investigated using numerical CFD. A simplified microchannel heat sink model was created and discretized for numerical analysis. The numerical prediction was validated with previous experiment data for promising numerical agreement. Then, the effect of different Triton X-100 surfactant volume fractions and nanotube mass fractions in the base fluid were carried out on thermal and hydraulic performance. The significant finding revealed that the thermal resistance was reduced by as much as 90% compared to pure water with a surfactant concentration of 0.35 vol.% and adding 0.02 wt.% at the Reynold number (Re) of 400. However, the Nusselt number (Nu) increased twice from the pure water with an additional surfactant of 0.35 vol.% after the Re of 400. Despite improving the thermal performance, the pressure drop seems to be a drawback for the nanotube with surfactant implementation. The present study resulted in a greater comprehension of the nanofluid flow with surfactant effect in the nanofluid in the microchannel heat sink, allowing for better design decisions to be made for the improvement of this application for various purposes. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Carbon emissions and excessive power usage are addressed by applying thermoelectric cooling, which benefits from its ability to be portable, economical, and reliable. However, a conventional thermoelectric air conditioner's coefficient of performance (COP) is much less due to the sustained heat generated on the thermoelectric module's hot side. This work presents a novel idea of utilizing a nanofluid cooled radiator as an external cooling jacket around the thermoelectric module's hot side to enhance the heat transfer rate of thermoelectric air conditioners. In this research, the performance of a newly designed thermoelectric air conditioner (TEAC) powered by photovoltaic systems (PV) installed in a residential building is analyzed using nanofluid as a coolant. Furthermore, by supplying different input currents (2-6A), the cooling characteristics and performance of the newly designed nanofluid assisted thermoelectric air conditioner (NTEAC) system were experimentally studied in a test room of 25.6 m3 volume in Malaysia's tropical climate. The system's best performance was at 6A, with a maximum temperature drop of 4.9 °C, a cooling capacity of 571 W, and a coefficient of performance of 1.27. In addition, the NTEAC system showed an energy saving of 67% and CO2 emission mitigation of 76% when compared with a conventional split air conditioner. Thus, an alternative to the traditional air conditioning system was developed from this research, which is Freon free. This system is expected to consume less energy and emit less CO2 for the tropical climatic conditions.

An enormous amount of heat generated from a vehicle engine could be removed fractionally by using a radiator. The struggle to maintain efficient heat exchange in a vehicle cooling system is arduous as both active and passive methods require time to catch up with high-power engine technologies. This study reported the heat transfer performance of a novel hybrid nanocoolant with various mixing ratios. The hybrid nanocoolant consisted of carboxyl-functionalised graphene nanoplatelets (CGnP) and titanium dioxide (TiO2) nanoparticles in a mixture of distilled water and ethylene glycol. The thermal performance of the hybrid nanocoolant was conducted using a test rig equipped with a crossflow type radiator. The effect of different hybrid mixing ratios, Reynolds number, and air inlet velocity on heat transfer performance was studied. The Nusselt number obtained with distilled water and base coolant was close to the Dehghandokht's and Shah-London's correlations. When CGnP-TiO2 (70:30) with 0.1 wt% concentration was mixed into the base coolant, 4.94%, 35.87%, and 20.48% of maximum increments were observed for Nusselt number, overall heat transfer coefficient, and effectiveness of radiator, respectively. The maximum error in estimating heat transfer performance using proposed correlations was less than 8%. It can be concluded that hybrid nanocoolant with different mixing ratios significantly affects heat transfer performance. This characteristic is vital for determining the best possible attributes in various nanocomposite combinations. © 2022 Elsevier Ltd

Two design modifications to increase the evaporation/condensation and freshwater yield of conventional solar stills (CSS) are presented – absorber coating with black paint (BP) in which 10 wt % reduced graphene oxide (rGO) was dispersed, and use of a nano-silicon-coated glass cover alongside the rGO coated absorber. Water contact angle analysis revealed that the hydrophilic glass/condenser hindered water droplet movement, whereas the hydrophobic silicon-coated glass enabled significantly faster water droplet movement. The rGO-coated absorber SS, with 99.2% solar absorptivity, improved the average water temperature by 11% leading to an augmented full-day freshwater yield of 3031 mL (versus 2160 mL for the CSS). The synergistic effect of the nano-silicon-coated glass and rGO-coated absorber further enhanced the full-day freshwater yield to 3410 mL. Energy/exergy analysis demonstrated enhanced efficiencies of the combined condenser and absorber coated SS of 37% (energy) and 112% (exergy), compared to the CSS. Non-linear characteristic equations described the instantaneous gain in energy efficiency of the combined absorber and condenser coated SS. Absorber/basin exhibited the highest rate of irreversibility in all three SS. The cost of water was 0.01 $/L for the dual-modified still. Water physicochemical quality analysis before and after desalination revealed that the purified water was suitable for drinking. © 2022 Elsevier B.V.

Brackish water desalination using solar still (SS) is a low-cost sustainable solution to global water scarcity, but this technology suffers from low yield and efficiency. The judicious amalgamation of highly conductive materials with superior solar absorption behavior is one of the most effective approaches to overcome this limitation. In this regard, the present work synthesizes a novel multilayered 2-D MXene from 3-D MAX phase as a coating material for the solar absorber of a SS to improve its performance. Two different loadings of MXene (0.05 and 0.1 wt%) were dispersed in turpentine oil/black paint (1:4) and coated onto the solar absorber of the SS. Higher MXene loading significantly augmented the thermal conductivity and solar absorptivity of the turpentine oil/black paint solution. The 0.1 wt% MXene coated absorber provided a higher heat transfer rate from the absorber to the water, leading to a 6% increase in water temperature and a total water yield of 2.07 kg. The theoretical calculated water yield was identical to the experimental yield with a deviation of ±5%, demonstrating the accuracy of thermal modelling. The average energy efficiency of the SS with 0.1 wt% MXene in the absorber black paint coating was 36.31%. Water quality analysis has shown that the distilled water resulting from the desalination is suitable for drinking. In conclusion, MXene with its excellent thermo-physical properties and solar absorptivity will be beneficial in development of efficient solar desalination units with augmented performance for water purification.

The heat transfer capacity of any thermal cooling system depends on two factors, i.e., the selection of the coolant and the geometrical pattern of the approach. This article summarizes nanofluids' preparation ranging from 0.01 % to 0.2 % using Graphene nanoplatelets & CNC dispersed in a base fluid. The combination of water with ethylene glycol (EG) is a form of customary heat transmit liquids regularly utilized in numerous energy practices to maintain the water's decent cooling (or heating) capability; thus, 60:40 ratio of EG: W mixture used as the base fluid for thermo-physical properties enhancements. These nanofluids prepared are not used with surfactants as it results in generating bubbles and contaminating the heat transfer channels, influencing the overall performance. XRD & FESEM techniques were used to analyze the surface. The investigated nanofluids remained stable, with no substantial sedimentation for 30 days. The results of GNPs/CNC nanofluids at 0.1% volume concentration has proper stability showing excellent colloidal stability in the base fluid of EG: W at a ratio of 60:40. The present hybrid nanofluid has the ability to switch the traditional heat transfer fluids leading to efficient & compact thermal structures.

Bi-reforming of methane (BRM) is gaining an increase interest due to the critical requirements to mitigate global warming and provide alternative energy resources. However, there has been a serious challenge to the scale-up of the process to commercial production due to the catalyst deactivation. In the present study, the influence of ZrO2 modifications on the activity and stability of MgO-supported Ni catalyst in the BRM reaction was investigated. The ZrO2-MgO mixed oxide support was prepared by co-precipitation method with variation in the ZrO2 composition and subsequently impregnated with Ni. The characterization of the freshly prepared Ni/MgO and Ni/MgO-ZrO2 catalysts using N2 physisorption analysis, X-Ray Diffraction (XRD), FESEM, XPS, H2-TPR, and CO2-TPD techniques revealed suitable physicochemical properties for the BRM reaction. The Ni/MgO-ZrO2 catalysts showed an improved performance in the BRM reaction in terms of activity and stability compared to the Ni/MgO at 800°C and CH4, H2O, CO2 ratio of 3:2:1, respectively. The best performance was obtained using the Ni/15%ZrO2-MgO for the BRM with CO2 and CH4 conversion of 81.5% and 82.5%, respectively. The characterization of the spent Ni/MgO catalyst using Raman spectroscopy, FESEM, and High Resolution Transmission Electron Microscopy (HRTEM) analysis revealed the formation of amorphous carbon that could be responsible for its fast deactivation.

In this research work, novel hybrid graphene-silver (Gr-Ag) nanomaterial has been used for first time with paraffin wax as a phase change material (PCM) to improve its thermo-physical properties. Thermal and electrical energy efficiencies of the novel synthesized nanocomposite (PCM/graphene-silver) has been investigated in solar thermal collector systems (CPV/T). This paper focuses on preparation, characterization, thermo-physical properties and energy efficiency in concentrated photovoltaic/thermal (CPV/T) system of new class of nanocomposites induced with hybrid Gr-Ag nanomaterial in three different concentrations. The specific heat capacity (cp) of hybrid PCM/graphene-silver nanocomposite increased by introducing hybrid Gr-Ag nanomaterial. Electrical and thermal energy performance of the hybrid PCM/graphene-silver is investigated in a CPV/T system using MATLAB 2017b program. The improvement of cp is found to be ~ 40% with 0.3 mass% of hybrid Gr-Ag nanomaterial loaded in PCM. The highest thermal conductivity increment is found to be ~ 11% at 0.3 mass% concentration of hybrid Gr-Ag nanomaterial in PCM. The endothermic enthalpy value of the hybrid PCM/graphene-silver nanocomposite is found to be ~ 75.6 J g−1 at 0.1 mass% loading concentration of hybrid Gr-Ag nanomaterial. Melting point of hybrid PCM/graphene-silver nanocomposite with loading concentration of 0.3 mass% is measured to be 73.2 °C. The highest thermal efficiency using the hybrid graphene-silver nanoparticles reached the value of 39.62% which represents 4.16% increment in comparison with the pure PCM. The equivalent electrical efficiency is improved by 2.8% at the loading concentration of 0.3 mass% of the hybrid Gr-Ag nanomaterial. These new class of nanocomposites represented the capability of enhancement in the performance of the CPV/T system consisting of lower PV temperatures, higher temperature gains across the cooling fluid and higher electrical and thermal efficiencies.

The present work aims to increase the amount of water generated by the hemispherical solar still (HSS) using paraffin wax as phase change material (PCM) encapsulated in waste aluminium-cans in two different shape of square pattern (4 PCM cans) and triangular pattern (3 PCM cans). Furthermore, a comparative analysis for the conventional HSS over the modified HSS with PCM two different arrangements was carried out to optimize the most suitable mass of PCM. Results showed that PCM encapsulated in aluminium cans in square and triangular patterns placed in HSS basin augmented the clean water production by 92.80 % (full day water generation of 5.63 kg/m 2) and 67.12 % (full day water generation of 4.88 kg/m 2) respectively, as compared to the bare HSS without any PCM (full day water generation of 2.92 kg/m 2). The effective utilization of the heat from the aluminium cans filled with paraffin wax augmented the potable water production with increased evaporation of water. The economic analysis revealed that with the use of PCM encapsulated cans in square and triangular pattern, the cost per liter of water produced reduced to 67.65 % and 45.31 % respectively than HSS without any PCM. It was concluded that the low-cost encapsulating material with excellent conductivity and maximum mass of PCM (4 PCM cans in present case) could be beneficial in generating higher amount of freshwater from brackish water.

Hybrid nanomaterials, which is a combination of two or more nanoparticles have been extensively evaluated as a promising candidate for energy storage and heat transfer applications, benefitting from the rise of synergistic effects between them. The unique form of this emerging combination of nanomaterials not only offers the improved features of the integrated nanoparticles but gives us the opportunity to tailor their physicochemical properties simply by modifying their composition and morphology. Scientific findings have demonstrated that the dispersion of hybrid nanomaterials in the base fluids, known as - hybrid nanofluids gives us the alternative way to replace mono nanofluid and the conventional heat transfer fluids as it provides a much better heat transfer enhancement that is beneficial for advanced heat transfer devices. On the other hand, when hybrid nanomaterials were utilized for energy storage devices, it exhibits an outstanding electrochemical performance, providing a significant contribution to the specific capacitance which permits a new strategy to design new electrodes for advanced energy storage devices. In this article review, we summarised the recent advancements made on the emerging hybrid nanomaterials, comprising of the general overview of the emerging nanomaterials, the synthesis routes for hybrid nanomaterials and their acquired hybrid structures along with their practical applications as electrodes in electrochemical energy storage and as heat transfer fluids for advanced heat transfer devices. Finally, we have also outlined some challenging issues associated with hybrid nanomaterials that requires further attention for future research.

This article discusses the electrical and thermal performance of a hybrid concentrator photovoltaic thermal and solar thermoelectric generator (CPV/T-STEG) system using a compound parabolic concentrator (CPC) and a parabolic trough concentrator (PTC). For the first time, the idea of merging imaging and non-imaging concentrators for a CPV and TEG hybrid system is examined, providing an option to retrofit or remodel existing PTC-based CSP systems. The thermal resistance concept is applied to establish a steady-state mathematical model of the proposed hybrid CPV/T-STEG system. A Newton-Raphson iterative approach is employed to solve the mathematical model and compute the temperature in every layer of the hybrid system. After validation, the mathematical model is employed to evaluate the overall performance of the hybrid system. The modelling results revealed that the electrical and thermal output of the developed hybrid system were higher by 2 and 1.6 times, respectively, when compared with the prior parabolic trough-based hybrid CPV/T-STEG system described in the literature. The effects of ambient temperature, wind speed, flow rate, number of TEGs, and solar concentration ratio on the electrical and thermal performance were investigated. The optimal number of TEGs required for maximum electrical performance under different solar concentration ratios is also obtained. Finally, the hybrid system's exergy efficiency is investigated for various solar concentration ratios. The simulation results revealed that the increase in the Reynolds number from 100 to 2000 improves the net electrical and thermal efficiency by 10.21% and 5.7%, respectively. At a fixed solar concentration ratio (CCPC=4suns and WPTC=2WCPC), the electrical efficiency of TEG drops by 81.4%, but the thermal efficiency increases by 16.81%, provided that the number of TEGs is increased from 1 to 17. The highest exergy of the hybrid system is 8.36% when CCPC=2suns and WPTC=2WCPC. Due to the poor efficiency of

In this study, a novel prototype of a hybrid concentrator photovoltaic/thermal and solar thermoelectric generator system has been designed and constructed for combined heat and power production. In the developed hybrid system, both the solar cells and thermoelectric modules that share a common heat transfer medium are exposed to concentrated irradiance via a compound parabolic concentrator and a parabolic trough concentrator, respectively. To assess the performance of the hybrid system, a prototype of the hybrid system was built and tested under outdoor operating conditions, and the findings were compared with those of a transient numerical simulation conducted using ANSYS Fluent. The average PV temperature obtained during the test period at a flow rate of 3.8 L/min is 318.19 K which is ∼5.6% lesser compared with a conventional hybrid CPVT-TEG system. The outdoor trials show maximum electrical efficiency of 4.86% and thermal efficiency of 40% when the solar irradiance is greater than or equal to 1000 W/m2. The overall efficiency of the developed prototype is 3 times higher compared to a standalone PV system. The hybrid system helps to reduce carbon emission by 0.5 kg/h, with an associated environmental cost of 0.025 €/h.