Nanoencapsulated Phase Change Materials Research Articles

The magnetic field on thermosolutal convection in an annulus between two super ellipses

ABSTRACT The current study deals with the impacts of an inclined magnetic field on the double-diffusive convection of the nano-encapsulated phase change materials (NEPCM) suspended in an annulus between two super ellipses. A novel shape between two super ellipses having the positive numbers and . The controlling transformed equations are solved by employing the (ISPH) method. The heat/mass source with variable length is put on the left side of an annulus. Impacts of , , , , , , and on the melting/solidification zone and heat/mass transfer performance are investigated. It was remarked that the melting/solidification zone shifts nearly to the heat/mass source according to a growing on . The induces an improvement of the heat/mass transmission and nanofluid movements within an annulus. Increasing the is working well in enhancing the melting/solidification zone and make it much closer to the heater within an annulus, and it boosts the nanofluid velocity by 4.24%. Increasing to 0.04 strengthens the melting/solidification zone and declines the nanofluid velocity by 14.68%. An augmentation in powers the nanofluid speed, heat/mass transport, and melting/solidification zone within an annulus. Average , and average are decreasing as and are increased.

Time-Conformable fractal systems of natural convection of tall fin inside two circular cylinders suspended by NEPCM

The incompressible smoothed particle hydrodynamics (ISPH) scheme is advanced to handle the conformable fractal differential equations of natural convection for a tall fin inside a cavity barred by nano encapsulated phase change material (NEPCM). The bottom circular cylinder is occupied by a porous medium plus a nanofluid, while the upper circular cylinder is filled by a nanofluid only. The conformable fractal operators generalize the classic idea of differentiability and allow for the generation of new and universal rates of variation. So, the study's novelty is revealing the validity of these operators in creating a new environment to look for more extended natural convection systems. The pertinent parameters are dimensionless time parameter τ(0-0.325), Rayleigh number Ra(103-106), Darcy parameter Da(10-2-10-5), cold source length LCold0.5-2.5, Stefan parameter Ste0.2-0.8, conformable fractal parameter α(0.93-1), and fusion temperature θf(0.05-0.95). The main outcomes showed the responsibility of α in speeding up the phase change process and the transition procedure of the convection flow. The nanofluid speed is reduced in the porous layer of a cavity, especially at the lower Darcy parameter. Different thermal conditions are altering the phase change material and strength of isotherms within a cavity.

Energy storage performance and irreversibility analysis of a water-based suspension containing nano-encapsulated phase change materials in a porous staggered cavity

This paper reports the methodology and results of a numerical investigation on energy storage performance of a water-based suspension of nano-encapsulated phase change material in a porous staggered cavity. A high order Galerkin finite element method was applied to solve the governing equations. The effects of different parameters like Darcy number, Stafan number, Rayleigh number, Bejan number and thermal conductivity ratio on entropy generation and heat transfer were examined. Results showed that in increase in Darcy number leads to enhance the average heat transfer, entropy generation and kinetic energy. The kinetic energy also grows considerably with any increase in the nanoparticle volume fraction, especially at lower thermal conductivity ratios.

Cooling three integrated circuits by embedding them inside an inclined cavity using nano-encapsulated phase change material

Being heated Integrated Circuits (ICs) significantly reduces their efficiency, and cooling of ICs is one of the major problems of the electronics industry. In this study, three ICs were installed in the middle of an inclined square enclosure to be cooled by using the natural convection of water/Nano-Encapsulated Phase Change Material (NEPCM). The NEPCM's core was filled with a PCM called n-nonadecane with melting temperature of 30.44 ° C, which adding them to the host fluid causes a significant improvement in the heat transfer process. In the present simulation, various parameters such as volume fraction of NEPCM (0 < φ < 3%), Rayleigh number (102 < Ra < 104), and inclined angle (0 < ζ < 60) were investigated on the heat transfer parameters from the surface of the ICs. At Rayleigh number of 102, the inclined angle had not influence on the total heat transfer rate; however, the inclined angle of 60 was optimal value at Rayleigh number of 104. Given that the total heat transfer rate was increased by 29% with injection of 3% volume fraction of NEPCM at Rayleigh number of 104.

The effect of nano encapsulated phase change materials and nanoparticles on turbulent heat transport: A conical diffuser scenario

The present work investigates turbulent flow of single and hybrid nanofluids filled in a conical diffuser. The heat transfer coefficients and pressure losses are analyzed at various Reynolds numbers and nanoparticle volume fractions. The diffuser is filled with Al2O3, nano encapsulated phase change material NEPCM, and NEPCM_Al2O3 nanofluids. The thermophysical parameters of all nanofluids were determined using a novel methodology based on the thermodynamic equilibrium data for binary liquid mixtures. A notable novelty in the current work is the introduction of an innovative method of hybrid nanofluids composed of nanoparticles with and without phase change material (PCM). When compared to the other nanofluids tested, the NEPCM nanofluid presented the lowest pressure loss and the greatest heat transfer improvement within the diffuser. The Nusselt number of NEPCM nanofluids is enhanced by 15%, while for NEPCM_Al2O3 and Al2O3 nanofluids is increased by 10% and 6%, respectively. Similarly, the pressure drop is greater as compared to the base fluid, where the pressure drop is increased by 1%, 3.5%, and 5% for NEPCM, Al2O3, and NEPCM_Al2O3 nanofluid, respectively.

Designing a system for battery thermal management: Cooling LIBs by nano-encapsulated phase change material

This study has designed and employed computational fluid dynamics to cool lithium-ion batteries (LIBs) to keep the temperature constant between 35 a n d 45 ° C . A duct was designed for installing three hot LIBs to be cooled by water and nano-encapsulated phase change material (NEPCM) flow. for this simulation, n-nonadecane with the fusion temperature of 30.44 °C was used for NEPCM's core and also water entered the channel with temperature of 30 ° C . The impacts of the various surface temperature of LIB, Reynolds numbers, and the concentration of NEPCM were analyzed on flow pattern, dimensionless isotherms, melted NEPCM, and heat transfer rate of each LIB. Increasing Reynolds number from 70 to 100 raised the heat transfer rate of LIBs in order of 12.1–17.2%. Furthermore, increasing the volume fraction from 0 to 0.03 escalated the heat transfer rate by 8.2–13.6%.

Thermal management and natural convection flow of nano encapsulated phase change material (NEPCM)-water suspension in a reverse T-shaped porous cavity enshrining two hot corrugated baffles: A boost to renewable energy storage

Renewable energy systems may be turning to be more effectual and inexpensive and contributing lion's share of whole energy utilization in today's power hungry planet. The efficacious usage of solar energy needs a storage appliance which could simplify the storage of surplus energy, and finally provide such energy when it desires. One of the efficacious approach of storing thermic energy of higher density from renewable source is executed in a varying range of temperature positions by phase change materials (PCMs) or nano encapsulated phase change material (NEPCM) as their significant role in air-conditioning systems, thermal energy storage, computer chipsets, and thermal management of buildings. In view of this, the present investigations aims at natural convection flow, heat transfer, and entropy of NEPCM-water suspension in a reverse T-shaped porous cavity enshrining two hot corrugated baffles. The thermal control within the cavity is maintained by hot corrugated baffles, cooling of bottom and upper walls and managing the side walls as adiabatic. The governing equations are well established and converted into dimensionless structure and then solved subsequently by Finite Element method (FEM). Simulated outcomes might well be validated accurately and the influence of Rayleigh number (104≤Ra≤106), porosity (0.4≤ε≤0.8), Darcy number (10−4≤Da≤10−2), NEPCM particle volume fraction (0≤φ≤5%), length of the corrugated walls (0.10L≤b≤0.20L), and fusion temperature (0.2≤θf≤0.8) on the heat transfer features, isotherms, heat capacity ratio and streamlines is explored efficaciously. The outcomes of this study are that amplifying Raleigh number leads to the intensification of streamlines, velocity fields and structural change of phase change zone while decaying of Darcy number exhibits the opposite effect. Strengthening porosity of porous medium intensifies the streamlines, horizontal and vertical velocity. Growth of the length of baffles yields emaciation of streamlines, flow fields, and enormous rate of heat transfer. Heat capacity ratio attains a constant value 0.97 outside melting-solidification zones within the cavity. Rise in the fusion temperature results in the expansion and shifting of melting-solidification zone. When φ rises from 1% to 2%, Nuave uplifts and yields its minimum enhancement while with rise of φ from 1% to 5%, Nuave upgrades and yields its maximum enhancement at fixed Darcy and Raleigh numbers.

Natural convection of a water-based suspension containing nano-encapsulated phase change material in a porous grooved cavity

The work is adopting the high order Galerkin finite element method (GFEM) for handling the natural convection of nano-encapsulated phase change material (NEPCM) within a grooved cavity saturated by a porous medium. The grooved cavity is containing an oval shape with zero velocities and an adiabatic condition. The impacts of the pertinent parameters Darcy parameter, a radius of an inner oval shape, Rayleigh number, porosity, fusion temperature, and Stefan number are investigated. The major findings are concluded that an increment of a fusion temperature shrinks the intensity of the streamlines and shifts the heat capacity position toward the hot wall. Increasing the Darcy parameter lows the porous resistance of the nanofluid flow and accordingly, the nanofluid movements and intensity of the streamlines are enhanced. A lower Darcy parameter enhances the isotherms and changes the heat capacity patterns inside a grooved cavity. The inner oval shape represents blockage in a grooved cavity and therefore the nanofluid movements are slowing in a cavity during an expanded radius of an inner oval shape. An extra Rayleigh number improves the intensity of the fluid flow and convective heat transfer in a grooved cavity.

The conformable fractal systems of natural convection in an annulus suspended by NEPCM

The incompressible smoothed particle hydrodynamics (ISPH) method is improved by the Taylor expansion to manage the unsteady conformable fractal systems of natural convection within a porous annulus amongst the circular cylinders. The annulus is suspended by a nano-encapsulated phase change material (NEPCM). The inner circular cylinders are fixed at a cool temperature. The ISPH numerical investigations are performed for variable values of the conformable fractal parameter α (0.93 − 1), adiabatic length LAdiab(0.5 − 2), Darcy parameter Da (10−2 − 10−5), thermalradiation parameter Rd (0 − 5), Rayleigh number Ra (103 − 106), the radius of an inner cylinder RCylind(0.15 − 0.4), and the fusion temperature θf (0.05 − 0.75). The outcome results indicated the novel significance of the conformable fractal parameter in speeding the transition process to a stable condition. The changes in the thermal boundary conditions of the outer walls by altering the adiabatic length affect the temperature distributions, phase change zone, and nanofluid velocity. Increasing thermal radiation improves the isotherms and shrinks a phase change zone. The fusion temperature has a good role in adjusting the situation and power of a phase change zone within a cavity. Contributions of Rayleigh number are less in enhancing convection and phase change zone due to a small area of an annulus. Rayleigh number strengthens the nanofluid velocity in an annulus.

Synthesis and application of paraffin/silica phase change nanocapsules: Experimental and numerical approach

The present study has been focused on the synthesis of silica encapsulated paraffin phase change materials and its application in cement-based systems. One-pot in-situ hydrolysis of tetraethyl orthosilicate as silica precursor and subsequent polycondensation have successfully encapsulated the paraffin droplets into nano-sized capsules of phase change materials (PCMs). The fabricated nanoencapsulated PCMs (NEPCMs) possess distinct core-shell structures with spherical geometry. Encapsulation ratio and encapsulation efficiency have been accomplished up to 92.9 and 90.24% with the latent heats of melting and solidification of 173.79 and 158.93 J/g, respectively. Calorimetry studies of the fabricated NEPCMs with ordinary Portland cement (OPC) have demonstrated 11% temperature reduction during the evolution of the heats of hydration, with the addition of only 3% NEPCMs. The synthesized PCMs are found to perform as high thermal energy storage materials with the capability of congruent heat storage and release without affecting their structure and geometry, therefore, can be considered as reliable and durable PCMs for concrete and building materials. The use of these NEPCMs can control the maximum temperature rise due to heat of hydration and therefore reducing the defects and cracks formation inside the mass concrete structures.

Shell effect on microstructure and diffusion in interface region of nanoencapsulated phase change material: A molecular dynamics simulation

A new simplified molecular dynamics model of nanoencapsulated phase change material (NEPCM) is constructed to investigate the shell effect in the shell-core interface. The amorphous silica wall with different thicknesses were built as the nanocapsule shell and paraffin (octadecane) was dispersed as the nanocapsule core. By MD method, the atom distribution was revealed by the linear density. The linear density of paraffin was reduced close to the shell and yet augmented far away from the shell compared with the pure paraffin density. Orientation order parameter (S) was greatly enhanced close to the silica shell, revealing that molecules near the surface were more orderly and packed perpendicularly to the shell. End-to-end distance (re) of each paraffin molecule was calculated and the distribution was revealed. The results showed the percentages of molecules fully stretched were more increased with the increasing shell thicknesses. S and re both showed the changes of the internal structures in the cases with the silica shell. The results of diffusion properties showed the addition of the silica shell broke the symmetry of the systems and the PCM diffusion was significantly weakened. Overall, the work presents the microstructures of paraffin and provides explanations for the thermophysical properties from paraffin morphology.

Thermo-hydraulic and entropy generation investigation of nano-encapsulated phase change material (NEPCM) slurry in hybrid wavy microchannel

PurposeThis study aims to capture the heat transfer and entropy generation characteristics of temperature-dependent nano-encapsulated phase change material (NEPCM) slurry in a hybrid wavy microchannel. In addition, the effect of substrate material combined with NEPCM slurry on conjugate heat transfer condition is captured for different microchannel heat sinks.Design/methodology/approachA novel “hybrid wavy microchannel” is proposed to enhance the overall heat transfer and reduce the pressure drop by combining wavy and raccoon geometry. NEPCM–water slurry is implied in the hybrid wavy, conventional wavy and raccoon microchannel. A user-defined function (UDF) is used to observe the effect of phase-change of paraffin material in thermophysical properties of NEPCM–water nanofluid. All three (hybrid, wavy, raccoon) microchannels are engraved on a rectangular substrate of 1.8 mm width (ωs) and 30 mm length (L), respectively. For hybrid, wavy and raccoon microchannel, waviness (γ) of 0.067 is selected for the investigation.FindingsThe result shows that NEPCM particle presence reduces the fluid domain temperature. The thermal performance of proposed Heat sink 2 is found better than the Heat sink 1. The effect of the geometrical modification, wall thermal conductivity, different volumetric concentrations of nanoparticles (ϕ ∼ 1 – 5%) and Reynolds number (Re ∼ 100 – 500) on thermodynamic irreversibility is also observed. Additionally, the effect of thermal and frictional entropy generation is reduced with a combination of NEPCM slurry and higher conductive material for all heat sinks.Practical implicationsA combination of NEPCM slurry with laminar flow microchannel cooling system emerged as a better alternative over other cooling techniques for higher power density devices such as microprocessors, electronic radar systems, aerospace applications, semiconductors, power electronics in modern electronic vehicles, high power lasers, etc.Originality/valueThe phase-change process of the NEPCM slurry is tracked under conjugate heat transfer in a hybrid wavy microchannel. Furthermore, the phase-change process of NEPCM slurry is captured with different heat sink materials (SS316, silicon and copper) under conjugate heat transfer situation for different heat sinks and concentrations (ϕ ∼ 1–5) of NEPCM.

Cuprous oxide modified nanoencapsulated phase change materials fabricated by RAFT miniemulsion polymerization for thermal energy storage and photothermal conversion

Phase change materials (PCMs) have great promise in many fields related to energy utilization and thermal management. However, PCMs face great challenges in large-scale applications due to the intrinsic melting leakage, low thermal conductivity and poor photothermal conversion. Herein, nanoencapsulated phase change materials (NanoPCMs) were fabricated by RAFT miniemulsion polymerization using quaternized poly(2-(dimethylamino)ethyl methacrylate)-b-poly(methyl methacrylate) (QPDMAEMA-b-PMMA) as emulsifier. N-octadecane and n-butyl stearate were used as binary cores, and Cu2O nanoparticles were doped into PMMA as hybrid shell. The resulting Cu2O/PMMA-NanoPCMs had an encapsulation efficiency of 86.68%, excellent thermal stability and thermal cycle durability. The thermal conductivity was enhanced by 67.25% compared with the original nanocapsules. Furthermore, the cotton fabrics finished with Cu2O/PMMA-NanoPCMs showed fast thermal response and superior photothermal conversion. Therefore, the synthesized nanocapsules are considered as potential candidates in the field of solar energy utilization and smart thermo-regulated textiles.

Jet Impingement Cooling Enhanced with Nano-Encapsulated PCM

In the present study, the laminar flow and heat transfer of water jet impingement enhanced with nano-encapsulated phase change material (NEPCM) slurry on a hot plate is analytically investigated for the first time. A similarity solution approach is applied to momentum and energy equations in order to determine the flow velocity and heat transfer fields. The effect of different physical parameters such as jet velocity, Reynolds number, jet inlet temperature, and the NEPCM concentration on the cooling performance of the impinging jet are investigated. The volume fraction of NEPCM particles plays an essential role in the flow and heat transfer fields. The results show that NEPCM slurry can significantly enhance the cooling performance of the system as it improves the latent heat storage capacity of the liquid jet. However, the maximum cooling performance of the system is achieved under an optimum NEPCM concentration (15%). A further increase in NEPCM volume fraction has an unfavorable effect due to increasing the viscosity and reducing the conductivity simultaneously. The effect of adding nano-metal particles on the heat transfer performance is also investigated and compared with NEPCM slurry. NEPCM slurry shows a better result in its maximum performance. Compared with the water jet, adding nano and NEPCM particles would overall enhance the system’s thermal performance by 16% and 7%, respectively.

Heat transfer improvement between a pair of heater and cooler inside an energy storage by using nano-encapsulated phase change material/water: A numerical modeling

In the present study, the natural convection flow of water with Nano-encapsulated phase change material (NPCM) was simulated inside an insulated chamber, which a pair of pipes were considered as a heater and cooler sources with the boundary condition of uniform temperature. The NPCM's core was made of n-nonadecane with melting temperature of 30.44°C. This core has ability to change the liquid-solid phase to transfer heat between the heater and the cooler sources. Current simulation was steady state and was solved by SIMPLE algorithm based on FVM to investigate the effects of Rayleigh number, volume fraction and location of phase change zone on the convective heat transfer coefficient. Observations showed that, phase change of NPCM occurs at low Rayleigh numbers but had no effect on the convective heat transfer coefficient, but it was directly related to the thermal conductivity of mixture. Moreover, adding volume fraction of NPCM 0.02 into water increased the convective heat transfer coefficient by 10.43%, 19.1% and 18.3% compared to pure water for Rayleigh numbers 102,104,and106, respectively.

Thermal Management and Exergo-Economic Analysis of Lithium-Ion Batteries Using Force Convection of Water- Nano Encapsulated Phase Change Materials (NEPCMs) Nanofluids

Thermal Management and Exergo-Economic Analysis of Lithium-Ion Batteries Using Force Convection of Water- Nano Encapsulated Phase Change Materials (NEPCMs) Nanofluids

Embedding a Nickel Porous Medium Around Lib for Cooling by Mixture of Water and Nano-Encapsulated Phase Change Material: Exergoeconomic Analyses

Embedding a Nickel Porous Medium Around Lib for Cooling by Mixture of Water and Nano-Encapsulated Phase Change Material: Exergoeconomic Analyses

Nanoencapsulated n-tetradecane phase change materials with melamine–urea–formaldehyde–TiO2 hybrid shell for cold energy storage

A series of nanoencapsulated phase change materials with n-tetradecane as the core material and melamine–urea–formaldehyde (MUF)–TiO2 composite as the shell material was developed using a two-step method. Sol-gel and blending modification methods were respectively utilized after the in situ polymerization. The physical, chemical, and thermal properties of the nanoencapsulated phase change material (NEPCM) samples were characterized. Furthermore, a comprehensive performance evaluation system was established based on the efficacy coefficient method. The results indicated that the average diameter of the nanocapsules was significantly increased by the sol-gel modification and was slightly influenced by the blending method. All NEPCMs exhibited high chemical and thermal stability. The NEPCMs modified by the sol-gel method (C14@MUF–TiO2-S1) exhibited the best performance in terms of the encapsulation ratio, melting enthalpy, and onset decomposition temperature, which were 68.6%, 156.2 J·g-1, and 155.36 °C, respectively. C14@MUF–TiO2-S2 exhibited the lowest mass loss of 44.2% at 100 h. For the blending method, C14@MUF–TiO2-B1 had the highest yield of 53.87%. The thermal conductivity of C14@MUF–TiO2-B3 increased up to 88.15% compared with the unmodified NEPCMs. Therefore, modification by the sol-gel method with 2.2 g TiO2 sol had the highest total efficacy coefficient of 0.843 among the samples.

Cooling a central processing unit by installing a mini channel and flowing nanofluid, and investigating economic efficiency

CPUs are widely used in many industries. These components require electrical energy for processing and generating heat due to their electrical resistance. On the other hand, they have a very high heat flux due to their small size and high energy consumption. Therefore, their cooling with new methods helps their performance a lot. In this study, water flow with Nano-encapsulated phase change material (NPCM) was simulated to cool an embedded CPU inside a mini channel. These NPCMs have a significant effect on heat transfer parameters due to their ability to phase change in their core. On the other hand, examining the exert economy broadens our horizons to choose an appropriate system in practical problem engineering. Numerical simulation by the FVM method was utilized to study the effects of Reynolds numbers, heat flux of CPU's surface, and volume fraction on the temperature distribution, the maximum temperature of CPU's surface, and economic efficiency. Evidence showed that increasing Reynolds number from 50 to 100 at zero volume fraction reduces the maximum temperature of the CPU's surface from 98.4to82.5°C. Also, mixing a 3% volume fraction of NPCM with pure water can decrease the maximum temperature of the CPU's surface by 2.27°C relative to pure water. Moreover, rising Reynolds number from 50 to 100 enhanced the net profit per unit transferred heat load (ηp) by 100 times.

Performance of nano encapsulated phase change material slurry heat transfer in a microchannel heat sink with dual-circular synthetic jets

This study analyzes the hydrodynamic and heat transfer performance of the nano encapsulated phase change material (NEPCM) slurry in a microchannel heat sink (MCHS) equipped with two circular synthetic jets (SJs). It focuses on understanding the effects of major influencing parameters on energy efficiency, including the NEPCM concentration, frequency, amplitude, inlet velocity, latent heat storage, heat flux, inlet temperature, and phase actuation. The heat transfer coefficient (HTC) enhancement is maximized to 28.5% at the particle concentration of 0.2 and 180˚ out-of-phase actuation. However, the figure of merit (FOM) decreases as the NEPCM concentration increases. The optimum thermal performance is obtained at the NEPCM concentration of 0.05 in the 180˚ out-of-phase SJs. The convective heat transfer is remarkably improved using actuators with higher frequency and amplitude values. The thermal performance of 180˚ out-of-phase actuation is better than in-phase jets. The FOM is significantly enhanced by increasing the inlet Reynolds number. The latent heat of fusion intensifies the convection and conduction rate by 17% and 31%, respectively, as it increases from 107.1 to 250 kJ/kg. When the inlet temperature values are set to accommodate the melting range of the NEPCM, the maximum Nusselt number is obtained at the temperature of 297.15 K.