Nanoencapsulated Phase Change Materials Research Articles

HEAT DISSIPATION IN HEAT-GENERATING BLOCKS USING NANO-ENCAPSULATED PCMS AND FINNED ANNULAR DESIGNS

This study advances the thermal management of high-power-density electronic components by introducing a hybrid cooling system that integrates nano-encapsulated phase change materials with adjustable-length aluminum fins. The system is designed with a partitioned cylindrical configuration, featuring a porous internal zone filled with NEPCM and an air-filled external zone equipped with aluminum fins. Using COMSOL Multiphysics 5.6, the system's governing equations are approximated with the Galerkin finite element method. The analysis investigates the impact of key parameters including emissivity (0 ≤ ε ≤ 1), porosity (0.1 ≤ ε<sub>p</sub> ≤ 0.9), nanoparticle concentration (0 ≤ φ ≤ 5%), permeability (5 × 10<sup>-4</sup> cm<sup>2</sup> ≤ K ≤ 0.5 cm<sup>2</sup>), and fin length (0.3 cm ≤ L ≤ 1.6 cm). The results indicate that the effect of incorporating NEPCMs with a 5% nanoparticle concentration and varying porosity on the maximum temperature reduction is minimal, with a decrease not exceeding 0.5°C. Extending the aluminum fins from 0.3 cm to 1.6 cm reduces the maximum temperature by up to 10°C, demonstrating the significant role of fin length in thermal management. Increasing the permeability of the porous medium from 5 × 10<sup>-4</sup> cm<sup>2</sup> to 0.5 cm<sup>2</sup> results in a notable temperature decrease of about 3.5°C. Additionally, enhancing the emissivity from 0 to 0.6 lowers the maximum temperature by approximately 19°C.

Bioconvective Flow Characteristics of NEPCM–Water Nanofluid over an Inclined Cylinder in Porous Medium: An Extended Darcy Model Approach

Bioconvection phenomena play a pivotal role in diverse applications, including the synthesis of biological polymers and advancements in renewable energy technologies. This study develops a comprehensive mathematical model to examine the effects of key parameters, such as the Lewis number (Lb), Peclet number (Pe), volume fraction (φ), and angle of inclination (α), on the flow and heat transfer characteristics of a nanofluid over an inclined cylinder embedded in a non-Darcy porous medium. The investigated nanofluid comprises nano-encapsulated phase-change materials (NEPCMs) dispersed in water, offering enhanced thermal performance. The governing non-linear partial differential equations are transformed into dimensionless ordinary differential equations using similarity transformations and solved numerically via the Network Simulation Method (NSM) and an implicit Runge–Kutta method implemented through the bvp4c routine in MATLAB R2021a. Validation against the existing literature confirms the accuracy and reliability of the numerical approach, with strong convergence observed. Quantitative analysis reveals that an increase in the Peclet number reduces the shear stress at the cylinder wall by up to 18% while simultaneously enhancing heat transfer by approximately 12%. Similarly, the angle of inclination (α) significantly boosts heat transmission rates. Additionally, higher Peclet and Lewis numbers, along with greater nanoparticle volume fractions, amplify the density gradient of microorganisms, intensifying the bioconvection process by nearly 15%. These findings underscore the critical interplay between bioconvection and transport phenomena, providing a framework for optimizing bioconvection-driven heat and mass transfer systems. The insights from this investigation hold substantial implications for industrial processes and renewable energy technologies, paving the way for improved efficiency in applications such as thermal energy storage and advanced cooling systems.

Numerical analysis of Nano-encapsulated PCM magnetohydrodynamics double-diffusive convection and entropy generation in vertical enclosures with porous layer

This study investigates the effects of Nano-Encapsulated Phase Change Materials (NEPCMs) on double diffusive free convection in a partially porous cavity, considering Soret-Dufour effects and magnetohydrodynamics. The problem is modeled using non-dimensional governing equations, solved numerically through a Galerkin finite element method. The research examines the influence of key parameters including Rayleigh number (Ra: 103–105), Darcy number (Da: 10–4 -10–1), Hartmann number (Ha:0−80), NEPCM volume fraction (ϕ:0−0.04), Lewis number (Le:0.1−10), fusion temperature (θf:0.1−0.9), and Stefan number (Ste:0.1−0.9) on heat and mass transfer characteristics and entropy generation. Results show that increasing Ra significantly enhances heat and mass transfer, with Nusselt and Sherwood numbers rising by 424.8 % and 547.3 % respectively as Ra increases from 103 to 105. Higher Da and ϕ improve heat transfer, while stronger magnetic fields suppress both heat and mass transfer. An optimal fusion temperature (θf=0.5) is identified for maximum heat transfer enhancement. Total entropy generation, considering thermal diffusion, nanofluid friction, magnetic effects, porous medium, and mass diffusion contributions, increases by 15,957 % with Ra and decreases by 42.5 % with increasing Ha. The Bejan number analysis reveals that non-thermal irreversibilities become increasingly dominant at higher Ra and Ha values. The study concludes that NEPCMs can effectively enhance heat transfer in partially porous cavities, with their performance strongly influenced by Ra, Da, and Ha. The findings provide valuable insights for optimizing thermal management systems incorporating NEPCMs, particularly in applications involving porous media and magnetic fields.

Simulation of Magnetic Field Effects on Heat and Mass Transfer in a Porous Spline Half‐Cylinder Using ANN and ISPH Approaches

ABSTRACTThis study utilizes Artificial Neural Networks (ANNs) and Incompressible Smoothed Particle Hydrodynamics (ISPH) simulations to explore the effects of magnetic fields on heat and mass transfer in a porous spline half‐cylinder filled with Nano‐Encapsulated Phase Change Material (NEPCM). Simulations were conducted over a range of physical parameters: buoyancy ratio () from −2 to 2, Darcy number () from 10−5 to 10−2, Hartmann number () from 0 to 50, Rayleigh number (Ra) from 103 to 106, and fusion temperature from 0.05 to 0.9. The results demonstrate that increasing the Ha reduces heat transfer efficiency by up to 15%, as the magnetic field stabilizes fluid flow and enhances conduction. Conversely, increasing the Ra improves heat transfer efficiency by approximately 25% due to enhanced convection and mixing. The buoyancy ratio significantly influences fluid flow, with higher values favoring concentration‐driven buoyancy, while lower values enhance temperature‐driven convection. The Da affects permeability, with higher values promoting convective heat transfer and dynamic flow, whereas lower values result in stable, conductive heat transfer. Fusion temperature impacts phase change behavior, affecting heat capacity and flow dynamics through latent heat absorption. These insights underscore the critical role of optimizing these parameters to enhance performance in applications such as thermal energy storage and industrial processes involving phase change materials.

Impacts of Double Rotating Cylinders on the Forced Convection of Nanoencapsulated Phase Change Material

ABSTRACTMany engineering and industrial applications rely on heat transfer (HT) as a basic and central process. Therefore, engineers and researchers place significant emphasis on optimizing HT rates. Here, we numerically attempt to maximize the heat transmission rate of mixed convection of nanoencapsulated phase change material in a square compartment. The compartment is differentially heated and incorporates two cold rotating cylinders. The Galerkin finite element approach is utilized for addressing the system governing equations. A range of various factors affecting the thermal activity in the compartment were considered. These factors include the speed of spinning cylinders (Re = 0–1000), the porousness of the compartment (Da = 10−5–10−2), the magnetic field intensity (Ha = 0–100), and the concentration of nanoadditives (ϕ = 0%–8%). The obtained numerical findings demonstrated that the thermal activity inside the compartment is positively correlated to the speed of the spinning cylinders, the concentration of nanoadditives, and the porousness of the compartment. In contrast, increasing the intensity of the magnetic field obstructs the heat transmission. It was noted that at the highest Re number, the average Nusselt number augmented by 257% and 13.6% when increasing Da and ϕ, respectively.

Machine learning analysis for heat transfer enhancement in nano-encapsulated phase change materials within L-shaped enclosure with heated blocks

Phase change materials(PCMs) are crucial to energy storage systems due to their enhanced thermal properties. They significantly boost energy efficiency and promote sustainability. Nevertheless, the low thermal conductivity of PCMs presents a significant challenge, which is addressed by utilizing nano-encapsulation to enhance energy efficiency in energy storage systems. Motivated by this, the current study conducts a theoretical investigation to explore the heat transfer characteristics in a buoyancy-driven Nano-Encapsulated Phase Change Materials(NEPCM) nanofluid within an L-shaped porous enclosure with the impacts of a heated block and magnetic field. Furthermore, the fusion temperature plays a crucial role in initiating phase change in NEPCM, thereby impacting the heat transfer process. Hence, identifying the optimal fusion temperature is essential. To accomplish this, a machine learning approach was employed to identify the ideal fusion temperature. A dataset of 160 data points across four different fusion temperature values was used in this analysis. Additionally, the machine learning model analyzed how variations in fusion temperatures impact physical parameters. An in-house Matlab code is utilized to solve the dimensionless fluid transport equations employing the finite difference method. The results indicate that increasing the nanoparticle volume fraction significantly enhances the heat transfer rate across all physical parameters. Specifically, under higher thermal buoyancy force, increasing the volume fraction from 1% to 5% results in a 90.04% increase in the heat transfer rate. The numerical analysis demonstrates that heat transfer rates improve significantly when the fusion temperature is adjusted to 0.5, a result further validated by machine learning techniques. At this temperature, thermal buoyancy force increases by 0.98% and 2.68% compared to values of 0.1 and 0.9, respectively, while the Stefan number shows increases of 159.42% and 87.48% under these conditions; thereby, the heat transfer rate increases at this value. This computational study provides important insights into the significance of fusion temperature, emphasizing the need to determine its optimal value for improving heat transfer. Identifying this optimal value can enhance the efficiency of thermal energy storage systems and improve cooling performance in electronic devices.

Magneto-convection ?ow of Nano-encapsulated phase change material (NEPCM) confined within a trapezoidal porous enclosure

This research attempts to study the thermal activity of suspension consisting of water and NEPCM elements inside a cavity with a trapezoidal cross-section. In addition, the cavity center contains a cold circular object rotating at a constant speed. The cavity is thermally characterized by the following: the upper and lower walls are thermally insulated (adiabatic), while the two lateral walls have a high temperature. The purpose of this study is to find out how the suspension interferes with the transfer of heat from hot walls to the cold body through the intervention of some initial conditions, which are: The effects of rotating cylinder speed (Re = 1 -500), medium permeability (Da = 10-5 – 10-2) and the magnetic field strength (Ha= 0 -100). The study used a digital simulation by solving the differential equations related to fluid mechanics and heat transfer using the Galerkin finite element (GFEM) method.to understand the influences of studied parameters (Re, Da and Ha numbers), the contours of isotherms, heat capacity and pathlines are presented in terms of these parameters. The findings indicated that as the rotation speed of the obstacle increased, the forced convection became dominant, and the thermal transmission rate improved. The improvement of the thermal transfer rate was also observed for higher Da numbers. Increasing the strength of the magnetic field hiders the fluid motion and reduces the thermal activity. At the highest studied Re, increasing Da from 10-5 to 10-2 augmented the Nusselt number by 10 times, while augmenting Ha from 0 to 100 reduced the Nu by 46%.

Convection flow of NE-phase change material-water mixture in evacuated tube solar collector manifold: Numerical analysis of MHD double-diffusive convection and exothermic reaction

This study investigates the convection flow of nano-encapsulated phase change material (NEPCM)-water mixture in an evacuated tube solar collector manifold, focusing on the effects of magnetohydrodynamic (MHD) double-diffusive convection and exothermic reaction. Computational fluid dynamics simulations using the Galerkin finite element method were employed to analyze temperature and concentration distributions, fluid flow, melting zone of PCM nanocapsules, Nusselt number, Sherwood number, entropy generation, and thermal performance. The numerical analysis considers a range of dimensionless parameters, including Rayleigh number (Ra=103−105), Lewis number (Le=0.1−10), buoyancy ratio (Nz=1−5), nanoparticle concentration (ϕ=0.01−0.035), fusion temperature (ϴf=0.1−0.9), Stefan number (Ste=0.1−0.9), Hartmann number (Ha=0−50), magnetic field inclination angle (γ=0°−90°), and Frank-Kamenetskii number (FK=0−2.5). Results show that increasing Ra enhances the average Nusselt number (Nuav) by up to 156.1 % and the average Sherwood number (Shav) by up to 104.5 %, while increasing the total entropy generation by up to 13,155 %. Increasing FK reduces Nuav by up to 42.2 % but increases Shav by up to 13.1 %. The Lewis number and buoyancy ratio significantly influence the hydrothermal performance, with Nuav exhibiting non-monotonic behavior and Shav increasing by up to 240.9 % as Le increases. The nanoparticle concentration enhances Nuav by up to 49.7 %. Interestingly, the magnetic field effects are less pronounced than in previous studies, with Ha having a minor impact on Nuav and Shav. These findings have significant implications for the design and optimization of evacuated tube solar collectors and other thermal energy storage systems, potentially leading to improved efficiency and performance in real-world applications.

Heat transfer in a non-uniformly heated enclosure filled by NEPCM water nanofluid

PurposeThis paper aims to focuses on by investigate the heat transmission and free convective flow of a suspension of nano encapsulated phase change materials (NEPCMs) within an enclosure. Particles of NEPCM have a core-shell structure, with phase change material (PCM) serving as the core.Design/methodology/approachThe enclosure consists of a square chamber with an insulated wall on top and bottom and vertical walls that are differently heated. The governing equations are investigated using the finite element technique. A grid inspection and validation test are done to confirm the precision of the results.FindingsThe effects of fusion temperature (varying from 0.1 to 0.9), Stefan number (changing from 0.2 to 0.7), Rayleigh number (varying from 103 to 106) and volume fraction of NEPCM nanoparticles (changing from 0 to 0.05) on the streamlines, isotherms, heat capacity ratio and average Nusselt number are investigated using graphs and tables. From this investigation, it is found that using a NEPCM nano suspension results in a significant enhancement in heat transfer compared to pure fluid. This augmentation becomes more important for the low Stefan number, which is around 16.57% approximately at 0.2. Secondary recirculation is formed near the upper left corner as a result of non-uniform heating of the left vertical border. This eddy expands notably as the Rayleigh number rises. The study findings indicate that the NEPCM nanosuspension has the potential to act as a smart working fluid, significantly enhancing average Nusselt numbers in enclosed chambers.Research limitations/implicationsThe NEPCM particle consists of a core (n-octadecane, a phase-change material) and a shell (PMMA, an encapsulation material). The host fluid water and the NEPCM particles are considered to form a dilute suspension.Practical implicationsUsing NEPCMs in energy storage thermal systems show potential for improving heat transfer efficiency in several engineering applications. NEPCMs merge the beneficial characteristics of PCMs with the enhanced thermal conductivity of nanoparticles, providing a flexible alternative for effective thermal energy storage and control.Originality/valueThis paper aims to explore the free convective flow and heat transmission of NEPCM water-type nanofluid in a square chamber with an insulated top boundary, a uniformly heated bottom boundary, a cooled right boundary and a non-uniformly heated left boundary.

Numerical Study of Heat Transfer Enhancement Using Nano-Encapsulated Phase Change (NPC) Slurries in Wavy Microchannels

Researchers have attempted to improve heat transfer in mini/microchannel heat sinks by dispersing nano-encapsulated phase change (NPC) materials in base coolants. While NPC slurries have demonstrated improved heat transfer performance, their applications are limited by decreasing enhancement at increased flow rates. To address this challenge, the present study numerically investigates the effects of wavy channels on the performance of NPC slurries. Simulation results reveal that a wavy channel induces Dean vortices that intensify the mixing of the working fluid and enlarge the melting fractions of the NPC material, thus offering a significantly higher heat transfer efficiency than a straight channel. Moreover, heat transfer enhancement by NPC slurries varies with the imposed heat flux and flow rate. Interestingly, the maximum heat transfer enhancement obtained with the wavy channel not only exceeds the straight one, but also occurs at a higher heat flux and faster flow rate. This finding demonstrates the advantage of wavy channels in management of intensive heat fluxes with NPC slurries. The study also investigates wavy channels with varying amplitude and wavelength. Increasing the wave aspect ratio from 0.2 to 0.588 strengthens Dean vortices and consequently increases the Nusselt number, optimal heat flux, and overall thermal performance factor.

Energy and exergy analysis of photovoltaic systems integrated with pulsating heat pipe and hybrid nanofluids

Solar energy is harnessed from solar radiation and converted into various forms of energy, primarily electricity. It is a crucial part of the renewable energy landscape due to its abundance, sustainability, and potential to reduce greenhouse gas emissions. Photovoltaic (PV) panels have become a critical component in the transition toward sustainable energy; however, the efficiency and longevity of PV systems are significantly influenced by their operating temperature. Excessive heat can reduce the efficiency of PV cells and accelerate material degradation. Pulsating heat pipes (PHPs), with their excellent thermal management capabilities, present a promising solution to these challenges. This paper comprehensively investigates the effect of incorporating a three-dimensional PHP into PV systems, using working fluids with varying thermal properties, namely water, graphene oxide (GO) nanofluid with three different concentrations (0.2, 0.4, and 0.8 g/L) and their mixture with nano-encapsulated phase change material (Nano PCM), forming a hybrid nanofluid, at a concentration of 5 g/L. The collected data are analyzed from energy and exergy perspectives. The findings show that using Nano PCM in the nanofluid-based PV system (at the highest concentration) produces 22.3 Wh/day, increasing the system’s electrical power output by approximately 12 % compared to a PV panel with no cooling system. It outperforms the other systems studied, with the highest overall exergy efficiency of 35.4 %. The results also indicate an average improvement in first-law efficiency. Additionally, the study shows varying levelized costs of energy (LCOE) for the system cooled with different coolants.

Nanoencapsulation of phase change material with CuO nanoparticles: Development of thermal properties for energy storage

Today, the efficient use of energy resources has become essential due to the increasing need for energy. Therefore, thermal energy storage systems are used to minimize lost energy and more efficient energy consumption can be achieved by preventing energy losses. Phase change materials (PCMs) can be effectively used in thermal energy storage and are among the promising materials for a carbon–neutral future. In this study, the synthesis of nanoencapsulated phase change material (NEPCM) containing CuO NPs for use in thermal energy storage systems is included. In the production of phase change material, Copper oxide Nanoparticles were added into urea–formaldehyde resin as shell material, and an NEPCM, a eutectic mixture of capric acid-myristic acid, was prepared. Since the final product will be used in the structure, the phase change material was optimized for room temperature. In-situ polymerization, the synthesis process was carried out to obtain a better shell material to improve thermal properties and prevent leakage. Scanning Electron Microscopy and Fourier-transform infrared spectroscopy analysis were used to determine the morphology and chemical structure of the prepared NEPCM. Elemental analysis was performed to determine the presence of CuO NPs as shell material in urea–formaldehyde resin. Differential scanning calorimetry analyses were performed to determine the thermophysical properties. While the thermal degradation for CuO NPs-NEPCM occurred between 22.78–29.45 °C, the thermal degradation temperature shifted and the thermal degradation status in the first stage was less than that of normal NEPCM. It was observed that the thermal stability and strength of NEPCM increased with the addition of CuO NPs. NEPCM containing CuO NPs has thermal energy storage and energy conservation potential in buildings as a heat storage material. This study can provide an effective way to synthesize form-stable CuO-doped NEPCMs that are economically feasible for thermal applications and have the potential to contribute to future energy storage requirements.

Magnetohydrodynamic double diffusion natural convection of power-law Non-Newtonian Nano-Encapsulated phase change materials in a trapezoidal enclosure

PurposeThe present numerical investigation examines the magnetohydrodynamic (MHD) double diffusion natural convection of power-law non-Newtonian nano-encapsulated phase change materials (NEPCMs) in a trapezoidal cavity.Design/methodology/approachThe governing Navier-Stokes, energy and concentration equations based on the Cartesian curvilinear coordinates are solved using the collocated grid arrangement’s finite volume method. The in-house FORTRAN code is validated with the different benchmark problems. The NEPCM nanoparticles consist of a core-shell structure with Phase Change Material (PCM) at the core. The enclosure, shaped as a trapezoidal hollow, features a warmed (Th) left wall and a cold (Tc) right wall. Various parameters are considered, including the power law index (0.6 ≤ n ≤ 1.4), Hartmann number (0 ≤ Ha ≤ 30), Rayleigh number (104 ≤ Ra ≤ 105) and fixed variables such as buoyancy ratio (Br = 0.8), Prandtl number (Pr = 6.2), Lewis number (Le = 5), fusion temperature (Θf = 0.5) and volume fraction (ϕ = 0.04).FindingsThe findings indicate a decrease in local Nusselt (Nu) and Sherwood (Sh) numbers with increasing Hartmann numbers (Ha). Additionally, for a shear-thinning fluid (n = 0.6) results in the maximum local Nu and Sh values. As the Rayleigh number (Ra) increases from 104 to 105, the structured vortex in the streamline pattern is disturbed. Furthermore, for different Ra values, an increase in n from 0.6 to 1.4 leads to a 67.43% to 76.88% decrease in average Nu and a 70% to 77% decrease in average Sh.Research limitations/implicationsThis research is for two-dimensioal laminar flow only.Practical implicationsPCMs represent a class of practical substances that behave as a function of temperature and have the innate ability to absorb, release and store heated energy in the form of hidden fusion enthalpy, or heat. They are valuable in these systems as they can store significant energy at a relatively constant temperature through their latent heat phase change.Originality/valueAs per the literature review and the authors’ understanding, an examination has never been conducted on MHD double diffusion natural convection of power-law non-Newtonian NEPCMs within a trapezoidal enclosure. The current work is innovative since it combines NEPCMs with the effect of magnetic field Double diffusion Natural Convection of power-law non-Newtonian NEPCMs in a Trapezoidal enclosure. This outcome can be used to improve thermal management in energy storage systems, increasing safety and effectiveness.

Chitosan-based bilayer shell phase change nano-capsules with excellent anti-permeability for thermal regulation dressings

Nano-encapsulated phase change materials (NEPCMs) with appropriate phase change temperature range and excellent anti-permeability have significant application value in the field of thermal regulation dressings. In this study, NEPCMs were synthesized using the microemulsion polymerization method, with eutectic fatty acids (LA-SA) as the core material and poly(methyl methacrylate) (PMMA) as the shell material. Subsequently, using the electrostatic adsorption method, chitosan (CS) was successfully coated onto the outer surface of NEPCMs, resulting in the preparation of a novel bilayer shell nano-encapsulated phase change materials (BS-NEPCMs) for thermal regulation dressings. The impact of core/shell ratio, CS acid solution concentration and cross-linking agent content on capsule properties was investigated. It was found that BS-NEPCMs exhibited excellent cyclical stability and thermal stability. In particular, the CS shell layer provided excellent interfacial impermeability effects for the capsules, achieving an anti-permeability efficiency of 96.21 %. This not only helps address the problem of high leakage rates in single wall capsules, but also ensures that the capsules maintain high phase change enthalpies of 99.32 J/g and 96.38 J/g, respectively. The dressings based on BS-NEPCMs demonstrated good thermal regulation at 33–42 °C with maximum phase change enthalpies of 39.53 J/g and 34.08 J/g, respectively. Swelling and rheological analysis showed that the dressing exhibits a gel state, with a swelling ratio of 343 %, an elastic modulus of 15 kPa and a viscous modulus of 4 kPa. This study indicated that BS-NEPCMs hold significant promise for various applications in energy storage and body thermal regulation fields.

A second law analysis on flow of a PCM based nanofluid in a shell-and-tube heat exchanger: An experimental study for sustainable energy

In the foreseeable future, heat exchangers will continue to play an important role in environmental management and have numerous applications, their geometry has been the subject of interest for many researchers. The main goal of this research is to improve the heat exchangers' thermal performance and exergetic efficiency using new type of nanofluid. In this concept, the effect of nanoencapsulated phase change material (NEPCM) addition to water and producing NEPCM nanofluid for heat transfer augmentation in shell and tube heat exchanger (STHE) was investigated, experimentally. Nanocapsules were synthesized by miniemulsion polymerization containing phase change material (PCM) as core and chitosan (GO/CS) as shell material. After synthesis of nanocapsules, nanofluids with different concentration of NEPCM have been prepared and the stability and thermophysical properties of the nanofluids were characterized. In the subsequent stage, thermal and exergy efficiencies test was conducted on STHE using response surface method. The experiments were performed at different conditions; NPCM concentration (φ), inlet temperature (Tin) and Re number to optimse exergy efficiency. The optimum level of the φ, Tin and Re inlet for maximum ɛ (73 %) were found to be 10.55 %, 78.35 °C and 10365, respectively. The experimental results demonstrated that proposed nanofluid could enhance exergy efficiency for thermal system. It appears that a combination of NEPCM nanofluids gives a better cooling rate in the heat exchangers and could be a promising alternative along with other cooling techniques.

Revolutionizing bioconvection: Artificial intelligence-powered nano-encapsulation with oxytactic microorganisms

Using incompressible smoothed particle hydrodynamics (ISPH), this study examines the bioconvection flow of oxytactic microorganisms in a porous annulus populated by nano-encapsulated phase change material (NEPCM). Artificial neural network (ANN) is joined with the ISPH method to accurately predict the values of average Nu‾. Between the outside hexagonal-shaped domain and the embedded wavy cylinder, a new annulus is produced. The ranges of the pertinent parameters are wave amplitude of an embedded cylinder A=0.1−0.5, Hartmann number Ha=0−80, a radius of the cylinder Rcyld=0.05−0.5, Darcy number Da=10−2−10−5, undulation number Kund=2−32, bioconvection Rayleigh number Rab=1−1000, Rayleigh number Ra=103−106, and Lewis number Le=1−20. The regulated geometric characteristics of an embedded wavy cylinder, such as wavy amplitude, cylinder radius, and undulation numbers, have been found to contribute significantly to widening the cooling region and minimizing the oxytactic microorganisms. Hence, the embedded wavy cylinder can be applied for various thermal uses including cooling devices and heat exchangers. The average Nu‾ is enhanced under an increment in the geometric parameters of the embedded cylinder. Increasing Rayleigh/bioconvection Rayleigh numbers enhances the buoyancy forces that accelerate the velocity field.

Thermal and flow characteristics in a square chamber with a nanoencapsulated phase-change material–water nanofluid under a linear temperature variation at all walls

In this study, the two-dimensional, steady-state, and incompressible flow and thermal behaviors of a water-based nanoencapsulated phase-change material (NE-PCM) nanofluid within a closed chamber were investigated, considering the impact of buoyancy. A novel approach was introduced by implementing linearly varying temperature conditions along all chamber walls. The effective dynamic viscosity and thermal conductivity correlations, derived experimentally, were used to model the governing equations. These equations were then rendered dimensionless through suitable transformations and solved using the Galerkin finite-element method. Results showed that the phase change region’s width increased with higher Rayleigh numbers, scaled phase change bonds, NE-PCM volume fractions, and fusion temperatures between 0.1 and 0.5, but decreased with fusion temperatures between 0.6 and 0.9. The highest Nusselt number occurred along the bottom wall for a fusion temperature range of 0.4–0.5. For optimal thermal performance, a square chamber with linearly varying temperature walls and a fusion temperature of 0.5 is recommended.

Improving the thermal performance of nano-encapsulated phase change material slurry by changing fins configurations in a rectangular cavity

The transition to renewable energy is heavily reliant on batteries and energy storage devices, making them a crucial technology of the modern era. The sensitivity of batteries to temperature has been a constant challenge in the development of this technology. Thermal management, creating uniform temperature and proper heat transfer by cooling is very critical in these systems. The popularity of nePCMs is increasing in energy storage and cooling systems due to their remarkable latent heat during phase change. This is because nano-encapsulated phase change materials are being widely used. They are considered to be one of the most promising particles in this application. This research is a case study free convection of nano-encapsulated Phase Change Materials (nePCM) slurry with a volume fraction of 5% and a polyurethane shell and n-nonadecane core in a rectangular chamber was homogeneously simulated and investigated. The temperature of the left wall remains consistent and there are three fins present to enhance the transfer of heat. The governing equations are transformed into dimensionless form and solved numerically using OpenFOAM software. Various parameters such as fin geometry, chamber angle, Rayleigh number, and melting point temperature are altered to assess their impact on velocity profile components, temperature distribution, Cr contours, Nusselt number, and fin efficiency. Based on the results, Y-shape and T-shape fin geometries can increase the efficiency of water-nePCM fluid by about 10% for Ra = 100 and about 26 % for Ra = 104 compared to I-shape fin. Also, increasing the Rayleigh number from Ra = 100 to Ra = 104 improves the average Nusselt number for water-nePCM nanofluids by about 100 % in each of the fin geometries.

Numerical analysis of MHD free convection in curvilinear porous enclosure with two active cylinders filled with NE-phase change material

In nuclear power industry, the energy conservation of heat exchangers is a crucial demand. The current study addresses the influence of nano-encapsulated phase change material (NEPCM) on free convection under magnetic force in a porous enclosure involving two active cylinders. The curvilinear geometry of the enclosure is set with undulated top wall. The top, horizontal and the inclined walls are set cold while the two cylinders presented the hot surface. All other walls are assumed to be adiabatically isolated. The considered parameters are Rayleigh number, Ra (103–105), Hartmann number, Ha (0–64), fusion temperature, θf (0.1–0.9), Stefan number, Ste (0.1–0.9), volume concentration, ϕ (0–0.05), Darcy number, Da (10−5–10−2). Finite element method has been used in the numerical analysis. Some of the most important results stated that fusion temperature has a significant influence on heat transfer only with high Ra number and low Ste number. Furthermore, the melting solidification region notably changed with the change of Da and θf with less influec under the magnetic force. Also, the heat transfer is enhanced with the increase of Ra, Da and ϕ while it diminished with the increase of Stephan number and MHD. It found that a promotion in the percentage of Nuavg when the volume concentration is raised from 0 to 0.05 is about 65 %, while the Nuavg dwindles by 14 % when Hartman number is raised from 0 to 64. It can be concluded that using NEPCMs is crucial for enhancing heat transfer and hence the improving the related engineering applications.

Comparative analysis of heat transfer performance in cavities with varied wall conditions and nano encapsulated phase change material–water

This numerical study investigates convective flow within a square cavity subjected to a temperature gradient established between hot and cold walls. The cold wall is subjected to three different conditions: standard, elastic, and open boundary. The cavity is filled with an advanced nanofluid comprising water and nano encapsulated phase change material (NEPCM). The NEPCM feature a polyurethane shell encapsulating a nonadecane core, known for its phase transition capabilities and efficient storage or release of substantial latent heat. Numerical solutions for the momentum and energy equations are obtained for the three wall types, considering variations in the volume fraction of NEPCM (0.0≤ϕ≤0.05), Rayleigh number (105≤RaH≤106), and the fusion temperature of the core (0.1≤θF≤0.3). The results reveal that the type of wall in the cavity (standard, elastic, or open) has a significant impact on the flow patterns and heat transfer characteristics. The open wall, in particular, showed a distinct behavior with a lower mid-region temperature and a higher heat transfer rate at lower NEPCM concentrations compared to the standard and elastic walls. Adjusting the concentration from 1% to 5% increases the heat transfer rates by 44, 49, and 37 percent for standard, elastic, and open wall conditions, respectively.