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In the present study, an advanced type of artificial intelligence, a deep neural network, is employed to learn the physic of conduction heat transfer in 2D geometries. A dataset containing 44,160 samples is produced by using the conventional finite volume method in a uniform grid of 64 × 64. The dataset includes four geometries of the square, triangular, regular hexagonal, and regular octagonal with random sizes and random Dirichlet boundary conditions. Then, the dataset of the solved problems was introduced to a convolutional Deep Neural Network (DNN) to learn the physics of 2D heat transfer without knowing the partial differential equation underlying the conduction heat transfer. Two loss functions based on the Mean Square Errors (MSE) and Mean of Maximum Square Errors (MMaSE) are introduced. The MMaSE is a new loss function, tailored for the physic of heat transfer. The 70%, 15%, and 15% of images are used for training DNN, testing DNN, and validation of the DNN during the training process, respectively. In the validation stage, the 2D domain with random boundary conditions, in which DNN has never seen them before, is introduced to DNN. Then, DNN is asked to estimate the temperature distribution. The results show that the DNNs are capable of learning physical problems without knowing the underlying fundamental governing equation. The error analysis for various training methods is reported and discussed. The outcomes reveal that DNNs are capable of learning physics, but using MMaSE as a tailored loss function could improve the training quality. A DNN trained by MMaSE provides a better temperature distribution compared to a DNN trained by MSE. As the 2D heat equation is a Laplace equation, which is practical in multiple physics, the results of the present study indicate a new direction for future computational methods and advanced modeling of physical phenomena, using a big dataset of observations. [ABSTRACT FROM AUTHOR]

The present study develops the influence of inclined border temperature variations on the isotherms, streamlines, and isoconcentrations for unsteady free convection in a trapezoidal region filled with the water-based nanofluid. The considered mathematical nanofluid approach was formulated based on the Buongiorno's model. The set of governing partial differential equations formulated using non-dimensional primitive variables such as velocity, pressure, temperature, and nanoparticles concentration volume fraction was solved numerically using the finite element method for various magnitudes of control characteristics. It was revealed that control characteristics affected the liquid circulation and energy transport coefficients. The Nusselt number is a growing function of wave number, amplitude, and the Rayleigh number. [ABSTRACT FROM AUTHOR]

• Fluid-Structure Interaction (FSI) for non-Newtonian natural convection is addressed. • There is a flexible elastic fin on the hot wall of the cavity. • The Arbitrary Lagrangian-Eulerian (ALE), along with the moving mesh is used. • The ALE technique is employed to track the deformation of the flexible fin. • The dilatant and pseudoplastic effects of the working fluids are investigated. In the present study, the flow and heat transfer of a power-law non-Newtonian fluid in a cavity are addressed. The top and bottom walls of the cavity are well insulated, the left vertical wall is at a hot temperature, and the right wall is at a low temperature. A flexible elastic fin is mounted at the hot wall of the cavity. The non-Newtonian fluid circulates inside the cavity due to the buoyancy forces. Fluid-Structure Interaction (FSI) and the non-Newtonian flow within the cavity and the hot fin are coupled. The flow interaction with the fin leads to the deformation of the fin, and the change in the shape of the fin changes the flow and heat transfer. Hence, the coupling between the fluid and the structure is two ways. The Arbitrary Lagrangian-Eulerian (ALE) along the moving mesh method is employed to model the deflection of the structure inside the fluid domain. The finite element method is adopted to solve the governing equations. The results show that the deflection of the fin is higher for a dilatant non-Newtonian fluid, compared to the pseudoplastic and Newtonian fluids. The number of flow vortexes and flow hydrodynamic notably change by the variation non-Newtonian index. The variation of the non-Newtonian index produce minimal effects on the heat transfer rate. Moving from pseudoplastic effects to Newtonian and dilatant effects reduces the heat transfer rate and increases the internal stresses in the fin. Moreover, the maximum stress in stiff-fins is higher than soft-fins. [ABSTRACT FROM AUTHOR]

• Convective boiling of micro-pin-finned channels with fins for FC-72 dielectric fluid is studied. • A minimum superheat temperature difference of 4.7 °C is observed for low mass velocity of 94 kg/m2 s. • The liquid first goes through some superheat states and then the boiling phase change starts. The boiling convective heat transfer of dielectric fluid of FC-72 in a microchannel with etched micro fins is experimentally studied. The microchannel test surface is a square of 10 mm size with a height of 100 μm. The surface of the microchannel is covered with parallel-nucleated fins of a cubic size of 100 μm. The fins are nucleated with the central pore size of 60 μm and an opening of 45 μm. The fins are arranged in the equal space of 400 μm. There is a planar electrical element below the microchannel, which produces an adjustable surface heat flux below the channel. The dielectric liquid enters the test microchannel and flows over the test surface and the fins. In the experiments, the mass velocity (94–275 kg/m2 s) and heat flux (0–6 W/cm2) are tested with a saturation temperature of either 35 or 50 °C. The heat transfer, the outlet vapor quality, and the pressure drop across the microchannel are measured and reported. The boiling behavior of FC-72 over the etched fins is also investigated using photos. The results show that the liquid first go through some superheat states and then the boiling phase change starts. When the boiling heat transfer occurs, a significant pressure-drop can be observed across the microchannel, but the surface temperature difference would also drop significantly. In the case of very low mass velocity of 94 kg/m2 s, the minimum superheat temperature-difference of 4.7 °C is observed. [ABSTRACT FROM AUTHOR]

• Heterogeneous metal foams with phase change heat transfer were modeled. • The anisotropic medium was modeled using permeability and thermal conductivity tensors. • The medium provides different permeability and thermal conductivity in certain directions. • A well-designed heterogeneous metal foam improves the heat transfer rate by 24%. • A heterogeneous metal foam shortens the charging time by 11% for a fixed-weight foam. Embedding phase change material in metal foams improves the heat transfer characteristics of a thermal energy storage device. Here, the melting heat transfer of phase change materials embedded in a heterogeneous metal foam was addressed in a cavity heated from a side wall. The heterogeneity of the metal foam can be controlled through a heterogeneity parameter and heterogeneity angle. The thermal conductivity and permeability of the metal foam were introduced by tensors. The governing equations for the natural convection flow and phase change heat transfer, including anisotropic thermal conductivity and permeability, were introduced and solved by the finite element method. The impact of the heterogeneity parameter and angle on the melting time and isotherm and streamline patterns were investigated. The results showed an increase in heterogeneity could increase the heat transfer rate and shorten the melting time. A heterogeneity angle significantly changes the melting (thermal charging time) by 24% when the heterogeneity parameter was 0.2. Depending on the heterogeneity angle, the melting time could be significantly shortened or extended compared to a simple metal foam. For a fixed weight of foam, a heterogeneous metal foam could shorten the charging time by 11% compared to a simple foam. [ABSTRACT FROM AUTHOR]

Suspensions containing the Nano-encapsulated Phase Change Material (NEPCM) are an innovative type of fluid that combines the advantages of nanofluids with the heat storage capabilities of phase change materials. The focus of this study is to analyze how external vibrations influence the natural convection of an NEPCM suspension inside an enclosure saturated with a porous medium. The enclosure is subjected to periodic vibrations in the vertical direction, and the energy equations of the porous medium are subjected to the application of the local thermal non-equilibrium condition. It is found that among the studied parameters, the Rayleigh number, the interfacial coefficient, and the porosity have the highest impact. Increasing the vibration Rayleigh from 1e6 to 1e7 increases by >3.5 times the Nusselt number in the fluid. Reducing the interfacial heat transfer coefficient from 5000 to 100 decreases the Nusselt amplitude in the solid by 4 times and raises the Nusselt amplitude in the fluid by 7 times. Augmenting the porosity from 0.6 to 0.95 decreases the Nusselt number by 15% in the solid. Altering the properties of the nanoparticles, i.e., their fraction and fusion temperature, also affects heat transfer but to a lesser extent. [ABSTRACT FROM AUTHOR]

Carbon capture and storage is recognized as one of the most promising solutions to mitigate climate change. Compared to conventional separation technologies, supersonic separation is considered a new generation of technology for gas separation and carbon capture thanks to its advantages of cleaning and efficient processes which are achieved using energy conversion in supersonic flows. The supersonic separation works on two principles which both occur in supersonic flows: the energy conversion to generate microdroplets and supersonic swirling flows to remove the generated droplets. This review seeks to offer a detailed examination of the cutting-edge technology for gas separation and carbon dioxide removal in the new-generation supersonic separation technology, which plays a role in carbon capture and storage. The evaluation discusses the design, performance, financial feasibility, and practical uses of supersonic separators, emphasizing the most recent progress in the industry. Theoretical analysis, experiments, and numerical simulations are reviewed to examine in detail the advances in the nucleation and condensation characteristics and the mechanisms of supersonic separation, as well as new applications of this technology including the liquefaction of natural gas. We also provide the perspective of the challenges and opportunities for further development of supersonic separation. This survey contributes to an improved understanding of sustainable gas removal and carbon capture by using the new-generation supersonic separation technology to mitigate climate change. [ABSTRACT FROM AUTHOR]

This study proposed an innovative combined ejector-enhanced organic Rankine cycle and two-stage compression refrigeration cycle (EORC-TCRC), to investigate its potential to revolutionize energy utilization and offer a sustainable solution for the current energy challenge. Energy, exergy, economic, and environmental (4E) analysis of the novel EORC-TCRC system was conducted first. The performance appraisal of the novel system compared to the conventional combined power and ejector refrigeration system has been evaluated. The evolutionary non-dominated Sort Genetic (NSGA-II) optimization algorithm was implemented to ascertain triple-objective optimal system operating conditions. The results revealed a significant improvement in refrigeration output, energy, and exergy efficiency with values of 220.06 kW, 11.67%, and 17.07%, respectively, compared to the conventional Rankine power and ejector refrigeration system. By different selections of the objective functions, four groups comprised of Multi-Objective C T –ղ ex , Multi-Objective C T –ղ Th , Multi-Objective ղ ex –ղ Th , and Triple-Objective mode presented to sought NSGA-II optimization results. The optimization results of Multi-Objective C T –ղ Th mode indicated that the best thermal efficiency and overall system cost rate operating conditions are 28.25% and 78,820 ($/year), respectively. While the optimal system operating condition occurs in the Triple-Objective ղ ex - ղ Th -C T with the exergetic efficiency of 41.69%. • Energy, exergy, economic and environmental (4E) analysis of a novel solar-driven EORC-TCRC system is performed. • The evolutionary NSGA-II optimization algorithm was implemented to ascertain triple-objective optimal system operating conditions. • A significant improvement in refrigeration output, energy, and exergy efficiency has been observed. • A comparative analysis has been conducted to determine the position of the current research in comparison to the other works. • The proposed cycle achieved the highest performance enhancement in both terms of energy and exergy efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flow, heat, and mass transfer of hybrid nanofluids in a wavy chamber were addressed. • A two-phase approach, including the Brownian motion and thermophoresis forces, was introduced. • The drift flux of composite hybrid nanoparticles was computed. • The concentration distribution of composite nanoparticles was investigated. • The location of the solid block and undulation of surfaces are investigated. Mixed convection flow and heat transfer within various cavities including lid-driven walls has many engineering applications. Investigation of such a problem is important in enhancing the performance of the cooling of electric, electronic and nuclear devices and controlling the fluid flow and heat exchange of the solar thermal operations and thermal storage. The main aim of this fundamental investigation is to examine the influence of a two-phase hybrid nanofluid approach on mixed convection characteristics including the consequences of varying Richardson number, number of oscillations, nanoparticle volume fraction, and dimensionless length and dimensionless position of the solid obstacle. The migration of composite hybrid nanoparticles due to the nano-scale forces of the Brownian motion and thermophoresis was taken into account. There is an inner block near the middle of the enclosure, which contributes toward the flow, heat, and mass transfer. The top lid cover wall of the enclosure is allowed to move which induces a mixed convection flow. The impact of the migration of hybrid nanoparticles with regard to heat transfer is also conveyed in the conservation of energy. The governing equations are molded into the non-dimensional pattern and then explained using the finite element technique. The effect of various non-dimensional parameters such as the volume fraction of nanoparticles, the wave number of walls, and the Richardson number on the heat transfer and the concentration distribution of nanoparticles are examined. Various case studies for Al 2 O 3 -Cu/water hybrid nanofluids are performed. The results reveal that the temperature gradient could induce a notable concentration variation in the enclosure. The location of the solid block and undulation of surfaces are valuable in the control of the heat transfer and the concentration distribution of the composite nanoparticles. [ABSTRACT FROM AUTHOR]

Low thermal response of latent heat thermal energy storage (LHTES) systems has been their main barrier in large-scale applications and commercialization. Amongst all proposed techniques, the incorporation of metal foam appears to be more promising owing to the notable thermal conductivity and high ratio of surface-area-to-volume. Nonetheless, metal foams augment the thermal response of the LHTES systems at the expense of reducing their thermal capacity and weakening natural convection. The principal aim of the present study is to numerically assess the capability of hybrid heat transfer enhancement of an LHTES through a combination of partial metal foam and nano-additives. Capric acid is considered as the phase change substance in a circular-shape thermal energy storage unit with a two-pass heat pipe. A combination of Copper foam and Cu/GO nano-additives is analyzed as the hybrid enhancement approach. The outcomes show that the combination of partial copper foam with Cu/GO nano-additives is more effective than each enhancement technique separately. Moreover, the results reveal that the charging power of the LHTES can be enhanced to about four times higher than the case of pure PCM at the cost of only a 3% reduction of the thermal storage's capacity. [ABSTRACT FROM AUTHOR]

Heat transfer and phase change flow inside a Li-ion battery enclosure filled with a copper metal foam embedded in paraffin wax phase change material (PCM) are studied numerically. For simplicity and due to the axisymmetric of the enclosure geometry, half of the battery cell is considered as the heat source on the right wall. The vertical walls are considered symmetric, while the bottom wall is insulated, and the top wall is subjected to the convective heat transfer. The governing equations of the flow and heat transfer are presented as partial differential equations and then transformed into non-dimensional forms and solved by employing the finite element method. The local thermal equilibrium model was used, which limits the model to metal foams with high pore densities. For validation, results are compared with some of the well-known studies in the literature. The isotherms and streamlines are presented for three levels of heat pulse intensity. Both melting and solidification occur as a result of the unsteady heat pulses induced by the thermal source. The vertical location of the battery inside the enclosure can affect the streamlines and isotherm contours. Results show that for higher heat pulse powers, the melt volume fraction (MVF) increases, and heatsink will have higher efficiency. For a comparatively strong heat pulse, the efficiency was increased about seven times. [ABSTRACT FROM AUTHOR]

• Transient free convection of a suspension of phase change particles is addressed. • The nanoparticles are made of a phase change core and a shell. • The heat transfer in a cavity with time-periodic wall temperature investigated. • The presence of encapsulated nanoparticles enhances the transient heat transfer. • The fusion temperature of nanocapsules is an essential parameter in the heat transfer. • A 0.025 increase in the volume fraction of nanoparticles improved the nusselt by 21%. The natural convection of a Nano Encapsulated Phase Change Materials (NEPCMs) suspension in a cavity with a hot wall having a time-periodic temperature is investigated. The top and bottom walls of the enclosure are insulated, the right side wall is kept at a constant temperature of T c while the left side wall is considered as hot wall and is subjected to a time-periodic temperature. The NEPCM consist of capsules with phase change material PCM in their core. The phase change core of the capsules is covered by a shell. During the fusion or the solidification of the core, the phase change will absorb or release heat in the surrounding, when the temperature is close to the PCM fusion temperature. The partial differential equations governing the flow and heat transfer in the enclosure are formulated in the dimensionless form, and affective key dimensionless numbers and parameters are introduced. The finite element method is used to solve the governing equations. The accuracy of the results is verified by comparison to the benchmark solutions available in the literature. The average Nusselt number in the enclosure, as an indicator of the heat transfer performance, is analyzed. It is shown that the average Nusselt number in the enclosure follows a periodic variation with the same frequency of the temperature of the hot wall and with an amplitude that varies correspondingly with the temperature amplitude. The heat transfer in the cavity is enhanced when a higher fraction ϕ of the NEPCM is used, and a fraction of 5% provides the highest heat transfer. Increasing the volume fraction of nanoparticles from 2.5% to 5% enhanced the average Nusselt number by 21% and the maximum value of Nusselt number by 18.5%. The fusion temperature of nanocapsules is an important parameter affecting the thermal performance of the enclosure, mainly, when the fusion temperature is notably different from cold or hot-wall temperatures. [ABSTRACT FROM AUTHOR]

• Boiling heat transfer in a microgap with staggered micro-pin-fins were investigated. • For a high mass flux, 196–275 kg/m2 s, the superheat temperature was higher. • At the initiation flow boiling, a notable jump in the pressure drops can be found. • The boiling flow initiated inside the nucleation pores of micro pin-fins. The boiling flow and heat transfer of FC-72 in a microgap channel are experimentally addressed. The heated surface of the microgap with a test area of 10 mm × 10 mm was enhanced using a staggered array of 613 columnar micro pin fins. Inside the micro pin-fins are nucleated with a 60 μm pore and opening of 45 μm. The test surface of the channel is a square of 10 mm, and the height of the channel is 100 μm. The saturation working temperatures of FC-72 is 50 °C, the surface heat flux was up to 60 kW/m2, and the mass flux was selected in the range of 94–275 kg/m2 s. The on nucleated boiling temperatures (ONB), convective heat transfer coefficient, outlet dryness, and pressure drop are measured and reported. The boiling behavior of FC-72 is also recorded using an image capturing device and reported. A comparison between the superheat temperature of nucleated pin fins and plane pin fins (with no nucleation) shows that nucleation of pin fins reduces the superheat temperature. The outcomes reveal that for a high mass flux, 196–275 kg/m2 s, the superheat temperature is high, and the degree of superheat increases as the surface heat flux increases. When the surface heat flux is high (q ″ > 30 kW/m2), the convective heat transfer is almost independent of mass flux. At the initiation flow boiling, a notable jump in the pressure drops can be seen. After that, the pressure drop increases gradually by the increase in surface heat flux. The boiling images reveal that the boiling flow initiated inside the nucleation pores of micro pin-fins. [ABSTRACT FROM AUTHOR]

In this study, the heat transfer, fluid flow and heat capacity ratio are analyzed in an annulus enclosure filled with porous and saturated by a suspension of nanoencapsulated phase change materials (NEPCMs). It consists of phase change material core and a polymer or non-polymer shell. The presence of nanoparticles in the base fluid and the phase change capability of the nanoparticle's core improve the thermal properties of the base fluid and thermal control process. The inner cylinder wall is reserved at hot temperatures where the encapsulated particles absorb the heat, while the outer cylinder wall is reserved at cold temperatures where the encapsulated particles release the heat. A local thermal non-equilibrium model is adopted for the porous medium. The parameters studied are Rayleigh number (104 ≤ Ra ≤ 106), Stefan number (0.2 ≤ Ste ≤ ∞), melting point temperature of the core (0.05 ≤ θf ≤ 1), the concentration of the NEPCM particles (0% ≤ ϕ ≤ 5%), radius ratio (1.67 ≤ Rr ≤ 2.5), eccentricity (− 0.67 ≤ Ec ≤ 0.67), Darcy number (10−4 ≤ Da ≤ 10−1), porosity (0.3 ≤ ε ≤ 0.9) and interface heat transfer coefficient (1 ≤ H ≤ 1000). The results show that the dimensionless temperature of fusion (θf) plays the main role in the improvement in NEPCM on the heat transfer process. [ABSTRACT FROM AUTHOR]

• Mixed convection due to two oscillating fins investigated. • Arbitrary Lagrangian–Eulerian technique employed to model fluid structure. • Tips of the fins exhibited harmonic oscillation in a nanofluid. • Effects of amplitude and frequency of oscillations on heat transfer investigated. • Nanofluid enhanced the effects of fin oscillation on heat transfer. This study investigated the effects of two oscillating fins on the heat transfer rate and flow characteristics of a nanofluid inside a square enclosure. Both fins were attached to the hot wall and both fins oscillated at the same frequencies and amplitudes. The finite element method implemented in the arbitrary Lagrangian–Eulerian (ALE) technique was used to solve the equations describing the interactions and movements of the nanofluid and fins. Comparisons of our results and those reported in previous studies demonstrated that the modeling and numerical investigations were valid and reliable. The results showed that the increase in the heat transfer rate was due to the oscillation of the fins. In addition, the increasing trend in the heat transfer rate due to the oscillating fins decreased as the ratio of the thermal conductivity of the fins relative to the nanofluid increased. Increasing the thermal conductivity and viscosity parameters enhanced and weakened the heat transfer rate, respectively. [ABSTRACT FROM AUTHOR]

The present study aims to examine the effect of nitrogen and carbon monoxide concentrations as well as the working temperature and the stoichiometry number on the performance of a self-made five-cell high-temperature Proton-exchange membrane fuel cell stack (PEMFC). The concentration of hydrogen in a reformed gas can be varied, and it may contain poisonous substances such as carbon monoxide. Hence, the composition of the fuel gas could affect the performance of the PEMFC. The polarization curve and the electrochemical impedance spectrogram are utilized to examine the behaviors of PEMFC. The cell temperature of 160 °C is found as an optimal working temperature in this study for high-temperature PEMFC. Measured results show that the stoichiometry of the anode gas has a minimal effect on the PEMFC performance. A high percentage of nitrogen makes hydrogen dilute and leads to poor cell performance. When carbon dioxide exceeds 3%, the pt-catalyst was covered with the CO and the cell performance significantly decreased. Finally, a raise of the PEMFC temperature boosted the catalyst energy and improved the detachment of the carbon monoxide and eventually enhanced carbon monoxide tolerance. • A five-cell high-temperature proton exchange membrane fuel cell is studied. • The effect of different mixtures of hydrogen fuel is investigated. • The influence of carbon monoxide on performance of PEMFC is examined. • The effect of working temperature on the behavior of PEMFC is studied. • The increase of temperature improves the carbon monoxide tolerate of PEMFC. [ABSTRACT FROM AUTHOR]

In cavities differentially heated at the sides and subjected to mechanical vibration, the natural convection incoming from buoyancy effects is not the only factor affecting the flow dynamic and heat transfer. The current work aims to address vibrational convection in a square chamber filled with a Nano-Encapsulated Phase Change Material (NEPCM) suspension. The non-dimensional equations of fluid and heat flows in the cavity are developed and solved numerically. The gravity term in the momentum equation is modified to include the effect of vibration. It is shown that the vibrational Rayleigh number has the most effect on the convective heat transfer, followed by the conductivity of the NEPCM suspension. Increasing the vibrational Rayleigh number from 10 3 to 10 7 leads to up to 3 times rise in the time-averaged Nusselt number. The NEPCM concentration has a moderate influence, as around 12% increase in the time-averaged Nusselt number is found when a 5% volume fraction of particles is employed. An increase in the Stefan number from 0.2 to 0.8 is associated with a 6.1% reduction in the time-averaged Nusselt number. Additionally, the peak heat transfer is achieved at the melting point of 0.5, with a 6.5% increase compared to the melting temperature of 0.1. [ABSTRACT FROM AUTHOR]

A scientometric approach is utilized to investigate the dynamic maps of relationships among researchers, institutes, and countries in the field of Artificial Intelligence for Fluid-flow and Heat-transfer (AIFH). The Web of Science database was searched for related publications during the last 40 years (1982 and 2022). A total of 6151 articles were discovered, which were analyzed in detail. Using a bibliometric analysis, the most relevant and most cited sources of publications were identified. The most active researchers, institutions, and countries leading AIFH were reported. Then, the worldwide dynamic collaboration maps and coupling maps of relationships were reported. The Islamic Azad University (1893 T.C.), the Chinese Academy of Sciences (1374 T.C.), and Beihang University (1266 T.C.) were the most influential institutes in AIFH. The most influential countries were China, the USA, and Iran. The dynamic map of collaborations shows a good worldwide collaboration distribution. The USA and China established the most connection with the rest of the world. ANNs are the most studied topic (19.5% of publications), followed by Machine Learning (17.9%) and Neural Networks (15.4%). Support Vector Machines lag behind at 1.4%. ANNs boast the highest total citations (17,064) and H-index (63). Most ANIF papers were published by Medical Physics (119 T.P.). Half of the articles in AIFH were published by five journals of Medical Physics, Neurocomputing, International Journal of Heat and Mass Transfer, International Journal of Radiation Oncology Biology Physics, and IEEE Access. The International Journal of Heat and Mass Transfer received the most citations in AIFH. [ABSTRACT FROM AUTHOR]

Highlights • Fluid flow and heat transfer characteristics of falling film over tube bundle are experimentally examined. • Results show that arrangement of nozzles induces significant impact on fluid flow and heat transfer characteristics. • The nozzles pitch is a key parameter for heat transfer enhancement and the flow behaviors. Abstract The fluid flow characteristics, film thickness and heat transfer of falling liquid films over an array of horizontal tubes are experimentally studied. The effects of the flow rate, the heat flux and nozzles-holes arrangements on the averaged convective heat transfer coefficient are addressed. An experimental setup was constructed including a water circulation system, isothermal water bath, a feeder nozzle, three horizontal test tubes, aligned vertically, the setup structure frame and measuring system. The tubes wall temperatures were measured using K-type thermocouples embedded in the test tube walls. The fluid flow and the film thickness were captured using a high-speed camera. The measurements were performed at 20 °C for two kinds of nozzles-holes configurations of single space (nozzles pitch of 12 mm) and double space (nozzles pitch of 24 mm), three flow rates of 50, 100 and 150 mLPM and four heat fluxes of 5, 10, 15 and 20 kW/m2 °C. The measured results are reported in the form of flow-behavior photos in various time consequences, and the steady state film thickness in photos with marked measures. The tubes wall temperatures and heat flux are reported in tables and graphs. The measured results demonstrate that the arrangement of nozzles induces significant impact on the fluid flow and heat transfer characteristics of the test tubes. However, in the case of low flow rate (50 mLPM), the differences on the thermal performance are not notable. The results also show that the type and shape of film formation over the test tubes are very important on the heat transfer performance. When the liquid film extends over the test tube or covers it, the heat transfer rate increases. The heat transfer coefficient (h) for the test tube 1, just below the nozzles, is the highest; then test tube 2 in the middle receives better heat transfer rate, and test tube 3 at bottom is the last with lowest heat transfer rate. The nozzles pitch is a key parameter, which allows film bonding and can be considered as a controlling parameter for heat transfer enhancement and the flow structure. [ABSTRACT FROM AUTHOR]

Highlights • Transient cooling characteristics of Al 2 O 3 -water nanofluid flow in a microchannel are studied. • Results show that top wall temperature is under the significant influence of MEPCM layer. • Increase of amplitude of heat flux pulse results in better cooling effect of MEPCM layer. Abstract Transient cooling characteristics of Al 2 O 3 -water nanofluid flow in a microchannel subject to sudden-pulsed heat flux are numerically examined in details. The attention is focused on the effects of microencapsulated phase change material (MEPCM) inside top wall of a microchannel on the transient cooling heat transfer behaviour of the microchannel. Two small portion of the bottom channel wall are exposed to a pulse heat flux. The Al 2 O 3 - water nanofluid as the working fluid with a fully developed velocity profile flows into the microchannel to cool the channel walls. Transient conjugate heat transfer is studied using a three-dimensional model in the three parts of the microchannel which are the nanofluid flow, the solid walls of the channel, and the MEPCM layer. The partial differential equations governing the energy conservation are presented and transformed into a dimensionless form. The finite volume method is employed to numerically integrate the equations for the temperature distribution in the microchannel. The numerical results are compared with the available works in the literature and found in good agreement. Besides, the predictions show that the presence of the MEPCM layer cannot effectively control the rise of the temperature of the microchannel in the presence of a pulse heat flux. For a typical pulse heat flux, the bulk temperature of the channel can be raised up to 2°C while the presence of the MEPCM layer would only suppress the temperature rise by 0.2°C. It is also found that the temperature of the top wall is under the significant influence of the MEPCM layer. The increase of the amplitude of the heat flux pulse results in better cooling effect of the MEPCM layer. Graphic abstract Image, graphical abstract The average temperature at top wall of the channel with/without MEPCM for various mass fractions of nanoparticles during one cycle and Re bf = 1000, γ = 0.9. [ABSTRACT FROM AUTHOR]

This research examines the melting characteristics of nano-enhanced, non-Newtonian PCMs-multi-walled carbon nanotube (MWCNT). The process includes analyzing the impacts of various nanoparticle concentrations and trapezoidal angles by conducting simulations with these nanocomposites filled within the enclosure. The power-law shear-thinning effects are incorporated into the governing equations, which are then converted into a generalized dimensionless form using scaled parameters and solved using the finite element method. The findings underscore the significant role of enclosure geometry in influencing the melting dynamics and heat transfer process. Critical outcomes include the effect of nanoparticle concentration on the initiation of natural convection and the overall melting process, the influence of trapezoidal angle on the distribution of the molten liquid and melting dynamics, and the alteration of the melting interface shape due to nanoparticle concentration. The Nusselt number displayed intricate behavior during the melting process, changing with nanoparticle concentration. The study found that altering trapezoidal angles and nanoparticle concentrations could significantly affect melting time, with changes up to 62.5% observed. It was concluded that a trapezoidal enclosure with a slight outward angle (γ = 10°) was most effective in reducing interference and shortening melting time, offering valuable insights for optimizing PCM design for diverse applications. [ABSTRACT FROM AUTHOR]

This review peruses a comprehensive implementation of inner bodies involved in cavities filled with regular and nanofluids for both natural and mixed convection modes. The topic of nanofluid acquired its importance in the heat transfer field about two decades ago. Many experimental studies have been conducted to establish accurate correlations between the nanoparticle's specifications (volume fraction, size, shape, and type) and the thermophysical properties (such as dynamic viscosity and thermal conductivity). However, most of the theoretical investigations focused on the use of nanoparticles in various geometrical conduits and enclosures. The review covers the implementation of nanofluid in cavities involving inner bodies using single and two-phase models. It is found that about 34% of the total reviewed studies have considered the nanofluid inside the cavities involving inner cylinders. The authors of this review have concluded that the extra numerical cost of the two-phase models has curbed the researcher's use of the single-phase model. It is found that the studies that adopt the two-phase model are only 19% of the total nanofluid studies. The two-phase model gave an essential detail about the collection of the nanoparticles on the surfaces of the inner bodies (primarily stationary bodies) and the segments of the undulations of wavy walls of the cavities. This phenomenon lowers the exchange of heat transfer. [ABSTRACT FROM AUTHOR]

• A shell-tube shape thermal energy storage unit with open inlet and outlet ports was studied. • A stream of liquid PCM was allowed in the thermal energy storage unit. • Liquid PCM can flow in the unit only after formation of a liquid film between the inlet and outlet. • The flow of the liquid PCM in the enclosure notably promotes the melting and heat transfer rate. • A full melting could be achieved in about 2.5 h for an 16-inch diameter enclosure. A new design of fast charging latent heat thermal energy storage (dynamic melting) is proposed to further reduce the charging time. The proposed new design benefits from a stream of pressurized and heated liquid PCM entering and leaving the storage unit. Two layers of metal foam were also added to accelerate the thermal charging process further. The governing equations for the flow and heat transfer with phase change were introduced as partial differential equations and integrated using the finite element method. The impact of the porosity of foam layers, the foam ratio, and the geometrical placement of layers was investigated in the proposed design. The mounting location of a horizontal foam layer was not much important. Interestingly, it was found that a metal foam with high porosity produces a short thermal charging time. It was since the most important parameter in controlling the thermal charging time was forming a liquid PCM film between the inlet and outlet ports of the enclosure. Such as liquid film allows a passage for the pressurized and heated liquid PCM enters the enclosure and accelerates the melting process by a mixed convection mechanism. A full melting could be achieved in about 2.5 h in a 16-inch diameter enclosure. [ABSTRACT FROM AUTHOR]

• The melting heat transfer in an anisotropic metal foam was modeled. • The permeability and thermal conductivity tensors were used to explain the foam behavior. • The impact of anisotropic angle and foam placement on the melting heat transfer was addressed. • An anisotropic metal foam could significantly improve the charging power with no mass addition. • A tilt angle of -45° or +45° and a 0° anisotropic angle provide maximum charging power. The metal foams are a promising candidate for the enhancement of heat transfer in latent heat thermal energy storage (LHTES) units. These foams can be synthesized with engineered local properties such as improved thermal conductivity or permeability in a specified direction. However, the impact of using anisotropic metal foams for thermal energy storage has not been addressed yet. In the current research, an anisotropic metal foam was modeled mathematically with engineered local properties in perpendicular directions. The solid-liquid phase transition of the copper-coconut oil LHTES unit was simulated using the finite element method. The anisotropic metal foam was defined by using an anisotropic parameter and angle. The simultaneous impact of the mounting tilt angle and the anisotropic angle of the copper foam were addressed in the phase transition behavior and charging time of the LHTES unit. The results revealed that the anisotropic angle could notably impact the thermal energy storage power. An optimum tilt angle of -45° or +45° along with a 0° anisotropic angle could lead to the maximum charging power. Thus, designing an LHTES unit using an anisotropic metal foam could save the charging about 15% (for a -45° inclination angle) and 20% (for zero inclination angle) compared to a regular metal foam. Such save in the charging time is without any penalty on the weight increase or capacity reduction for the LHTES unit. A schematic view of an LTHES unit and its modeling approach is depicted. A solar collector absorbs the heat and transfers it to an LHTES, where the PCM modules store the heat through a melting process. Each of the storage modules can be considered a rectangular channel which was modeled as a 2D rectangle. [Display omitted] [ABSTRACT FROM AUTHOR]

• A scientometrics analysis of magnetic nanofluids was performed. • Clarivate database (2018–2022) was used as a data source. • Dynamic maps of the connection of the authors, institutions, and countries were reported. • Chamkha, Ali J was the most productive and most cited author. • Many of the publications originated from India, Pakistan, and Saudi Arabia. The control of thermophysical, fluid flow, and structure of nanofluids using a magnetic field has attracted the focus of many recent researchers in the field. Despite the broad range and application of the magnetic nanofluids, there is no scientometric or thematic analysis revealing the number and distribution of the publications and citations in the field and dynamic maps of the connection of the authors, institutions, and countries. The current research aims to comprehensively analyze the publications and dynamic world network connections of authors, institutes, and countries. Recent five-year publications (2018–2022) were retrieved from the Clarivate database (2224 documents) and were analyzed using an in-house code. The VOSViwer software was also used for the plot of the maps. The results showed Chamkha, Ali J was the most productive author (104 publications) and also the most cited author in the field (2029 citations) with the highest H-Index (33). Babol Noshirvani University has the highest rank among top universities concerning two different parameters: total citations and citations per paper. King Khalid University and Islamic Azad University have the highest rank in total publications and h-index. The highest number of publications also belonged to India, Pakistan, and Saudi Arabia. Moreover, these countries were also influential contributors to MNF, and other countries were linked to these three countries. [ABSTRACT FROM AUTHOR]

The two-phase flow and heat transfer of a Cu–Al 2 O 3 water hybrid nanofluid in a wavy enclosure partially filled with a porous medium is investigated. The concentration gradient of the composite nanoparticles is modeled considering the thermophoresis and Brownian motion nanoscale forces. The porous medium is also modeled using the local thermal non-equilibrium model. The governing equations are converted into a non-dimensional form and then solved using the finite element technique. The impact of the Darcy number, convection interface, and the wave amplitude on the concentration distribution of nanoparticle flow and heat transfer is addressed. The outcomes show that the convective heat transfer in the liquid and solid phases could be increased by 4.5 and 2.7 folds by increasing the Darcy number from 1 0 − 5 to 1 0 − 2 . The growth of the concentration of the nanoparticles from 0 to 0.04 improves the liquid Nusselt number by 17%. The hybrid nanofluid shows a better heat transfer enhancement compared to simple nanofluids. [Display omitted] • Natural convection within nanofluid superposed wavy porous layers is investigated. • LTNE model and Forchheimer–Brinkman-extended Darcy approach are employed. • The impacts of amplitude on the three composite layers are examined. • As the porosity rises, both heat transfer phases declines for low D a and increases for high D a. [ABSTRACT FROM AUTHOR]

A cutting-edge achievement alleviating the shortage of energy sources and mitigating environmental pollution is latent heat thermal energy storage (LHTES). This system employs quality phase change materials (PCMs) to provide both large thermal capacity and slight temperature variation. This numerical work investigates the effects of structural parameters of a semi-elliptical LHTES unit, including aspect ratio (AR) and inclination angle (γ). In the semi-elliptical LHTES unit, heat is transferred from water as HTF to the PCM improved with graphite nanoplatelets (GNPs) through an interface copper wall. The investigation found that the melting time for AR = 0.5 decreases about 12% compared to that of AR = 1.0. Also, the LHTES unit of AR = 0.5 shows the highest power of the system, around 13.9% more than the unit having AR = 1.0. Furthermore, the temperature fluctuations are suppressed at lower AR s. Angular deviation of the system from the horizontal state is associated with an increase in the melting time, leading to a decrease in the unit power. It is seen that the unit of nano-plates mass fraction of φ = 1.0% has the highest power, 7.2% more than that of pure PCM. • The effects of structural parameters of a semi-elliptical LHTES unit are addressed. • The LHTES unit of AR = 0.5 shows the highest power. • The temperature fluctuations are suppressed at lower AR s. • Angular deviation of the system from the horizontal state leads to a decrease in the power of system. • The unit of GNPs mass fraction of φ = 1.0% has the highest power. [ABSTRACT FROM AUTHOR]

In the present study, an evaporative cooling test system consisting of an elliptical-heat exchanger was examined. Tests were conducted for various airflow rates of 52, 68, 81, 96 Cubic Meter per Minute (CMM), sprinkler water flow rates of 30, 40, 50 Liter per Minute (LPM), and hot water flow rates of 18, 22, 28 LPM. The sprinkle nozzle types and outside wet-bulb temperatures were also investigated. The convective heat transfer of the sprinkle water film outside the tubes and the mass transfer between air and water film on tube bundles were probed. The film thickness and sprinkle water picture were studied using high-speed cameras and image processing techniques. The results show that the mass transfer performance of the evaporative cooler was enhanced with the growth of the airflow rate. When the sprinkler water flow rate rose to 50 LPM, the heat-mass transfer coefficient of the evaporative cooler decreased since the water film on the tube was thickened. The low hot water flow rate at the tube side (18 LPM) resulted in a superior performance due to a high local temperature and improved local mass transfer. The experimental data were used to obtain empirical correlations for the heat coefficient of the liquid film and mass transfer. [ABSTRACT FROM AUTHOR]

The enhancement of heat transfer between parallel surfaces, including parallel plates, parallel disks, and two concentric pipes, is vital because of their wide applications ranging from lubrication systems to water purification processes. Various techniques can be utilized to enhance heat transfer in such systems. Adding nanoparticles to the conventional working fluids is an effective solution that could remarkably enhance the heat transfer rate. No published review article focuses on the recent advances in nanofluid flow between parallel surfaces; therefore, the present paper aims to review the latest experimental and numerical studies on the flow and heat transfer of nanofluids (mixtures of nanoparticles and conventional working fluids) in such configurations. For the performance analysis of thermal systems composed of parallel surfaces and operating with nanofluids, it is necessary to know the physical phenomena and parameters that influence the flow and heat transfer characteristics in these systems. Significant results obtained from this review indicate that, in most cases, the heat transfer rate between parallel surfaces is enhanced with an increase in the Rayleigh number, the Reynolds number, the magnetic number, and Brownian motion. On the other hand, an increase in thermophoresis parameter, as well as flow parameters, including the Eckert number, buoyancy ratio, Hartmann number, and Lewis number, leads to heat transfer rate reduction. [Display omitted] • Nanofluid flow and heat transfer between parallel surfaces are studied. • Parallel plates, parallel disks, and concentric pipes are considered. • Physical phenomena and influential parameters are evaluated. [ABSTRACT FROM AUTHOR]

The incorporation of simultaneous passive and active techniques for enhancing heat transfer has been a promising area of research in the last decades. As such, in the present study, thermal convection heat transfer of a hybrid nanofluid in a square cavity subjected to simultaneous effects of gravitational and vibrational forces has been addressed. Initially, the cavity, saturated with Ag-MgO hybrid nanofluid, is stagnant and in thermal equilibrium. Then, the sidewalls of the cavity are heated isothermally, and the cavity starts vibrating in a vertical direction. The upper and lower walls are kept adiabatic. Galerkin finite element method with a very small- and adaptive-time step has been used to precisely capture the impact of vibrational force on the flow and thermal fields in high frequencies. Impacts of vibration frequency, gravitational and vibration Rayleigh numbers, and the volume fraction of hybrid nano-additives are studied. It has been revealed that the external vibration amplifies the rate of heat transfer for all the studied frequencies. Moreover, although the presence of the nanoparticles seems to have a very limited effect on the effectiveness of heating, the effect of the nanoparticle concentration on the heat transfer intensity varies with time. [ABSTRACT FROM AUTHOR]

Due to their superior thermophysical properties, there is a growing body of work on nanofluids in the field of thermal systems. However, there is no specific review of the role of the nanoparticle shape, which has been found crucial to their performance adjustment. A comprehensive literature review of the effect of nanoparticle shape on the hydrothermal performance of thermal systems utilizing nanofluids was compiled. The review covered the forced, mixed, and natural convection regimes and included heat exchangers, boundary layer flows, channel flows, peristaltic flows, impinging jets, cavity flows, and flows of hybrid nanofluids. It indicated that the control of nanoparticle shape is a promising technique for the optimization of heat exchange and the required pumping power. However, no uniform conclusion was reached for the role of nanoparticle shape on the hydrothermal performance of thermal systems. In most of the previous studies in the natural and forced convection regimes, the platelet–like nanoparticle acquired the highest heat transfer rate. However, most of the works in the mixed convection regime reported the best heat transfer performance for the blade–like nanoparticle. More research studies are required in future to determine the role of nanoparticle shape for thermal management of energy systems. • Nanoparticle shape is crucial to the performance control of various nanofluids. • The effects of nanoparticle shape on thermal system performance were reviewed. • Nanoparticle shape control is a promising technique for heat transfer optimization. • More research is required for the role of nanoparticle shape in thermal systems. [ABSTRACT FROM AUTHOR]

Nano-encapsulated phase change materials (NEPCMs) are known to enhance the thermal characteristics of fluids; therefore, there is a rising interest in employing these materials in future thermal control systems. This paper investigates hydrodynamic and thermal characteristics of nanofluids, NEPCMs mixed in the host liquid, in glass balls as a porous structure. The geometry is a two-dimensional porous square cavity in which the left boundary is hot, the right boundary is cold, and the horizontal ones are considered to be insulated. The NEPCMs are composed of polyurethane (PU) as shell and nonadecane as a core. The impact of different non-dimensional parameters, such as Darcy number, 10−5 ≤ Da ≤ 10−1, porosity, 0.4 ≤ ɛ ≤ 0.9, Stefan number, 0.2 ≤ Ste ≤ 100, fusion temperature, 0 ≤ θ f ≤ 1, and volume fraction of the NEPCMs, 0 ≤ ϕ ≤ 0.05, is studied on the flow and heat transfer characteristics. It is shown that the volume fraction of NEPCMs is directly proportional to the strengthening of the heat transfer rate in such a way that applying 5% volume fraction of NEPCMs could enhance the heat transfer up to 20.1% and 14.1% at θ f = 0.5 in comparison to the cases of pure fluid and NEPCM mixture with no core-phase change, respectively. The effect of non-dimensional fusion temperature on the rate of heat transfer is also found to be noticeable. The maximum average Nusselt number emerges at θ f = 0.5, which is the optimum fusion temperature. [ABSTRACT FROM AUTHOR]

This study aims to assess the natural convection heat transfer in a square cavity wherein the buoyancy-induced flow is generated by a thin flexible heater-plate inside the cavity. The vertical walls of the cavity are cold and the horizontal walls are adiabatic. The thin hot plate is assumed to be isothermal and fixed at an alterable point in the middle of the cavity with different inclination angles. To analysis the fluid-structure interaction (FSI), the finite element method along with the Arbitrary Lagrangian-Eulerian (ALE) technique is employed. Isotherms and streamlines, as well as the average Nusselt number, the dimensionless temperature in the cavity, and the maximum applied stress on the flexible plate, are studied. The results are presented as a function of Rayleigh number, Prandtl number, inclination angle, and different positions of the fixed point. The outcomes indicate the importance of the inclination angle and the position of the fixed point of the hot plate. The plate experiences significantly large values of stress when it is mounted horizontally. In the case of a plate fixed at its top, the highest stress occurs with an inclination angle of 40°. In contrast, the lowest stress is associated with the plate when it is positioned vertically. • Free convection in an enclosure containing a flexible hot thin-plate is addressed. • An Arbitrary Lagrangian-Eulerian technique is utilized to model fluid-structure interaction. • The plate is fixed at different locations with different inclination angles. • The influence of the location of the fixed point on the heat transfer investigated. • The position of the fixed point notably influences the deformation of plate and heat transfer. [ABSTRACT FROM AUTHOR]

Fluid-solid interaction study is conducted to investigate the effects of the flexibility of thin plate on the natural convection inside an enclosure. The plate is assumed to be at a higher temperature while the side walls are at a colder temperature and the top and bottom walls are insulated. The inclination angle of the plate is considered constant; however, other parameters such as the height and length of the plate, the elasticity modulus, Rayleigh number, and Prandtl number are varied, and their effects are studied. The grid independence study is presented, and the results are verified against available data in the literature. The effects of the plate flexibility on the flow and heat transfer are addressed. It is found that the Nusselt number and the strength of the flow decrease as the plate become more flexible. Additionally, as the plate moves toward the bottom of the cavity, the Nusselt number increase but the strength of the vortices decreases. Finally, the effects of flexibility is found to be considerable and it completely depends on the flow regime and other parameters. • Free convection inside a cavity including a hot flexible plate is studied. • Finite element method as well ALE technique are employed to solve the governing equations. • The impacts of key parameters such as Prandtl number and the elasticity modulus. • The rate of heat transfer strongly depends on the elasticity modulus. [ABSTRACT FROM AUTHOR]

Introduction: Mixed convection flow and heat transfer within various cavities including lid-driven walls has many engineering applications. Investigation of such a problem is important in enhancing the performance of the cooling of electric, electronic and nuclear devices and controlling the fluid flow and heat exchange of the solar thermal operations and thermal storage., Objectives: The main aim of this fundamental investigation is to examine the influence of a two-phase hybrid nanofluid approach on mixed convection characteristics including the consequences of varying Richardson number, number of oscillations, nanoparticle volume fraction, and dimensionless length and dimensionless position of the solid obstacle., Methods: The migration of composite hybrid nanoparticles due to the nano-scale forces of the Brownian motion and thermophoresis was taken into account. There is an inner block near the middle of the enclosure, which contributes toward the flow, heat, and mass transfer. The top lid cover wall of the enclosure is allowed to move which induces a mixed convection flow. The impact of the migration of hybrid nanoparticles with regard to heat transfer is also conveyed in the conservation of energy. The governing equations are molded into the non-dimensional pattern and then explained using the finite element technique. The effect of various non-dimensional parameters such as the volume fraction of nanoparticles, the wave number of walls, and the Richardson number on the heat transfer and the concentration distribution of nanoparticles are examined. Various case studies for Al 2 O 3 -Cu/water hybrid nanofluids are performed., Results: The results reveal that the temperature gradient could induce a notable concentration variation in the enclosure., Conclusion: The location of the solid block and undulation of surfaces are valuable in the control of the heat transfer and the concentration distribution of the composite nanoparticles., (© 2020 The Authors. Published by Elsevier B.V. on behalf of Cairo University.)

Due to the instinctive temperature-dependent heat capacity of the Nano-Encapsulated Phase Change Material (NEPCM), there is a growing interest in the potential applications of such materials in heat transfer. As such, steady-state natural convection in a porous enclosure saturated with nanofluid using NEPCMs has been investigated in this study. The cavity is assumed to have constant hot and cold temperatures at the left and right vertical boundaries, respectively, and fully insulated from the bottom and top walls. Considering the Local Thermal Non-equilibrium (LTNE) approach for the porous structure, the governing equations are first non-dimensionalized and then solved by employing the finite element Galerkin method. The impact of different parameters, such as porous thermal conductivity ( k s ), solid-fluid interface heat transfer (10 ≤ H ≤ 10 5 ), Stefan number (0.2 ≤ Ste ≤ 1), and volume fraction of nanoparticles (0.0 ≤ φ ≤ 0.05) on the patterns of the fluid and solid isotherms, streamlines and the contours of the heat capacity ratio, fusion temperature (0.05 ≤ θ f ≤ 1), local and average Nusselt numbers, and overall heat transfer ratio has been studied. It is shown that improving the porous thermal conductivity not only leads to an increase in the rate of heat transfer but also augments the fluid flow inside the cavity. For low values of the Ste , the rate of heat, transferred in the porous enclosure, is intensified. However, regardless of the amount of the Stefan number, the maximum rate of heat transfer is achievable when the non-dimensional fusion temperature is approximately 0.5. Employing NEPCMs in a highly conductive porous structure is more efficacious only when the phases are in the state of local thermal equilibrium. Nonetheless, the rate of heat transfer is higher when the Local thermal non-equilibrium is validated between the phases. Besides, for poor thermal conductivity of the porous medium like glass balls (LTE condition), adding 5% of the nano-encapsulated phase change materials to pure water can boost the rate of heat transfer up to 47% (for Ste = 0.2 and θ f = 0.5). This thermal investigation of NEPCMs shows in detail how advantageous are these nanoparticles in heat transfer and opens up an avenue for further application-based studies., (© 2020 Published by Elsevier Ltd.)