Nanoparticle-enhanced Phase Change Materials Research Articles

Sustainable hydrogen production by integrating solar PV electrolyser and solar evacuated tube collector with hybrid nanoparticles enhanced PCM

The investigation is motivated to analyze the influence of Phase change material (PCM), nano PCMs, and hybrid Nano PCM in sustainable hydrogen production systems. An emerging and highly effective method for hydrogen production involves the use of proton exchange membrane (PEM) technology, which separates water into its constituent parts through electrolysis. Its susceptibility to performance deterioration over time, however, demandsroutine maintenance and component replacement, which negatively impacts operational effectiveness and cost-effectiveness. In this study, the PEM system for electricity and water heating was integrated with the evacuated tube collector and photovoltaic panel to produce hydrogen. Additionally, hybrid Al2O3 and SiO2 nanoparticles with a combined concentration of 0.1 % in equal shares improved the thermal characteristics of PCM in heat exchangers. The research result shows that the heat exchanger of the ETSC circuit with the hybrid nanoparticles enhanced PCM demonstrated improved thermal performance as well as increased hydrogen production. With hybrid nanoparticles enhanced PCM in the heat exchanger, the maximum energy and electrical energy were observed as246.5 kWh and 44.7 kWh, respectively. The ETSC efficiency, electrical efficiency, and PEM electrolyser efficiency reached their highest points at 93.1 %, 15.5 %, and 39.2 %, respectively. Furthermore, hybrid nanoparticle-enhanced PCM produces an average of 25.9 g of hydrogen.

Augmenting thermal performance in tubular solar stills: A multifaceted strategy with wick cords, integrated baffles, reflectors, and nano-PCM

This study investigates the enhancement of freshwater production using a modified cords wick tubular solar still (CWTSS) compared to a traditional tubular solar still (TSS). The CWTSS design increased freshwater yield by 102 % over the baseline TSS. Also, the impact of using baffles (CWTSS-B) was tested. Incorporating reflectors into the CWTSS (CWTSS-B-R) further improved performance, achieving a 201 % increase in production with reflectors and 160 % without reflectors, highlighting the significant role of reflectors in solar energy capture and distillation efficiency. Various wick cord numbers (12, 22, 32, and 42) were tested to identify the optimal configuration. The use of nanoparticle-enhanced Phase Change Material (PCM) in the CWTSS (CWTSS-PCM) resulted in a 240 % production increase compared to the TSS, demonstrating the effectiveness of PCM in thermal energy storage and management. The most significant improvement was observed in the CWTSS-fan configuration, which employed a fan and an external condenser, leading to a 256 % increase in water production, reaching 15,300 mL/m2 compared to 4300 mL/m2 for the TSS. The modified design's freshwater production cost was $0.01/L, a 50 % reduction from the conventional design's cost of $0.02/L.

Performance enhancement of photovoltaic/thermal collector semicircle absorber tubes using nanofluid and NPCM

This experimental measurement examines Photovoltaic/Thermal (PVT) systems with semicircle absorber tubes, focusing on the impact of nanoparticle-enhanced phase change material (NPCM). Four PVT systems are analyzed, all using a standard PV module: a. PVT1: cooled by water; b. PVT2: cooled by water and NPCM; c. PVT3: cooled by nanofluid; d. PVT4: cooled by nanofluid and NPCM.The research evaluates their thermal, electrical, and overall performance and efficiencies at volumetric flow rates of 1–5 LPM under harsh outdoor conditions. The results reveal that the PVT4 system demonstrates the highest efficiency. At a volumetric flow rate of 5 LPM and a surrounding temperature of 47.94 °C, it achieves electrical, thermal, and total efficiencies of 12.70 %, 78.99 %, and 91.83 %, respectively. By enhancing the heat transfer between nanofluids and NPCMs, system cooling is enhanced and thermal efficiency is greatly increased. Additionally, the use of such systems notably reduced the surface temperature, exhibiting a decrease of about 35.09 % compared to the standard PV module while the use of nanofluid cooling only without NPCM caused a reduction of 29.93 % compared to the PV module. Importantly, the PVT4 setup outperforms the unenhanced PV module (PVT3) in overall efficiency by 14.04 %. In this study, PV modules are cooled by a heat exchanger made up of semicircular tubes attached to their backs. The study confirms that a PCM enhanced with nanoparticles performs well in the PVT system when semicircular absorption tubes are used. A significant reduction in surface temperatures is achieved with the use of this heat exchanger, resulting in remarkable thermal efficiency. As a result of this cooling effect, the PV module is more efficient than a traditional solar module in terms of electrical output. This type of system is likely to influence the development of more convenient and efficient solar energy systems. It is possible to use the heat absorbed by PV modules in other ways as well.

The time‐fractional ISPH method for fin circular rotation on MHD bioconvection flow of oxytactic microorganisms and NEPCM within a hexagonal‐shaped cavity

AbstractThis work investigates the bioconvection flow of oxytactic microorganisms and nanoparticle‐enhanced phase change material (NEPCM) within a hexagonal‐shaped cavity containing a rotated cross fin, utilizing the incompressible smoothed particle hydrodynamics (ISPH) method based on a time‐fractional derivative. The study considers the circular rotation of an inner cross fin and the presence of two rectangular heat sources on the plane walls inside the hexagonal cavity. The novelty of this work is its integration of a hexagonal‐shaped cavity with a rotated cross fin and the use of a time‐fractional derivative in the ISPH method to analyze bioconvection flow, offering new insights into the interaction between microorganism motion and heat transfer dynamics in complex geometries. The effects of Darcy, Hartmann, Lewis, Peclet, Rayleigh, and bioconvection Rayleigh numbers on isotherms, heat capacity ratio, microorganism density, velocity fields, and average Nusselt number are analyzed. The key findings demonstrate the significant impact of Rayleigh and bioconvection Rayleigh numbers in enhancing heat distribution and velocity fields, thereby significantly influencing microorganism motion. Due to Lorentz forces, the velocity field decreases by with an increase in the Hartmann number from 0 to 50. The resistance of the nanofluid's velocity becomes apparent as the Darcy number decreases. Increasing Lewis and Péclet numbers cause the microorganisms to shift towards the cavity's boundaries.

The magnetic field on the bioconvection flow of NEPCM in A Z-shaped cavity containing three circular cylinders

This work adopts an incompressible smoothed particle hydrodynamics (ISPH) method for handling the bioconvection flow of nanoparticle-enhanced phase change materials (NEPCM) inside a Z-shaped containing three circular cylinders and oxytactic microorganisms. The fractional time derivative of a system of controlling equations is solved by the ISPH method. The influences of magnetic field on thermosolutal convection of NEPCM in Z-shaped cavity. The mesh-free nature of the ISPH method helps in simulating the nanofluid flow in complex geometries. The Z-shaped cavity was chosen in this work for bioconvection flow because of its uses in semiconductors in solar cells, electronic devices, biomedicine, and thermal batteries. The bioconvection flow and heat transfer of the embedded circular cylinders are significant in heat exchangers and renewable energies. The scales of physical parameters are bioconvection Rayleigh number Rab=1−1000, Lewis number Le=1−20, Hartmann number Ha=0−80, fractional-time derivative α=0.9−1, Rayleigh number Ra=103−106, the radius of embedded circular cylinders Rc=0.05−0.2, and nanoparticles’ parameter ϕ=0−0.15. The results introduced the importance of Rab in enhancing the distributions of oxytactic microorganisms, and oxygen concentrations as well as the intensity of the velocity field. The size of embedded circular cylinders is effective in adjusting the distributions of oxytactic microorganisms, oxygen concentration, and temperature inside a Z-shaped cavity. The maximum velocity field decreases by 86.79 % as nanoparticle concentration increases from 0 % to 15 % due to the resulting high viscosity of the suspension fluid. An expanded radius of embedded circular cylinders improves the values of Nu‾ and Sh‾. This research provides crucial insights into optimizing thermal management and efficiency across diverse technological applications, from electronics to renewable energy and biomedical devices.

Multi-objective prediction and optimization of performance of three-layer latent heat storage unit based on intermittent charging and discharging strategies

An intermittent heat charging and discharging strategy is proposed for on-demand thermal utilization in a three-layer latent heat storage unit filled with nanoparticle-enhanced phase change materials. To optimize the utilization ratio of phase change materials, and the stored and released thermal exergy amounts, a multi-objective prediction and optimization methodology combining orthogonal experimental design, range and variance analyses, multi-nonlinear regression models, and non-dominated sorting genetic algorithm-II is introduced while considering the variables of nanoparticle concentration, heat transfer fluid velocity, and intermittent time interval. Results show that the time interval presents the most significant influence. Multi-nonlinear regression models for the above three variables are established with determination factors of 0.9871, 0.9625, and 0.9253, respectively. The ultimate optimal results are 0.8, 57094.03 J, and 43066.73 J, achieved at the three variables of 44.37 min, 0.38 m s−1 and 8.99%, respectively. The maximum verification error of 5.11% indicates the reliability of this methodology. The methodology aims to enhance the overall performance of the three-layer latent heat storage system by mitigating the constraints associated with single-performance optimization.

Experimental investigation of thermal energy storage in shell-and-multi-tube unit with nano-enhanced phase change material

This paper deals with thermal energy storage with use of nanoparticle enhanced phase change material in shell-and-multitube unit. The experiments are conducted under atmospheric pressure. Paraffin wax and two different fatty acids are used as base phase change material. Graphite and multi-walled carbon nanotubes serve as nanoparticles. Graphite nanoparticles are tested at the concentrations of 0.1 %, 1 % and 5 % by weight, while multi-walled carbon nanotubes only at 0.1 %wt. Ultrasonic vibration and homogenizer are used in order to stabilize the dispersion of the nanoparticles. Polyvinylpyrrolidone surfactant is used to stabilize the suspension and the tested nano-enhanced phase change material exhibit satisfactory stability. Experimental measurements are performed for a bundle of 7 tubes with outside diameter of 6 mm in a staggered arrangement and a pitch ratio of 4.5. It is found that, regardless of the tested base phase change material, the addition of graphite nanoparticles with mass concentration of 0.1 % does not significantly affect the charging and discharging times compared to base phase change material. The differences in charging and discharging times did not exceed 11 %. For a graphite nanoparticles mass concentration of 5 %, an increase in the charging time by up to 21 % and a reduction in the discharging time by 24 % was observed, depending on the type of base phase change material. An addition of multi-walled carbon nanotubes with mass concentration of 0.1 % shows an increase in charging time regardless of the type base phase change material up to 144 % with negligible influence on the discharging time. It was also observed that adding a surfactant to the produced nano-enhanced phase change material results in a reduction in charging time by up to 83 % depending on the type of base phase change material.

Nanoparticle-Enhanced Phase Change Materials (NePCM) in Passive Cooling Systems to Improve Solar Panel Efficiency

Nanoparticle-Enhanced Phase Change Materials (NePCM) in Passive Cooling Systems to Improve Solar Panel Efficiency

Investigation of MHD oxytactic microorganisms with NEPCMs in rectotrapezoidal enclosure with FEM: Applications to energy storage technologies

Nanoparticle-enhanced phase change materials (NEPCMs) have gained significant attention in recent years due to their unique ability to enhance the thermal properties and overall performance of phase change materials (PCMs). The present work investigates the bioconvection flow of nano-encapsulated phase change material within a rectotrapezoidal cavity. The left wall of the is fixed at the constant high temperature whereas the right vertical wall is kept at cold temperature. The higher order Galerkin finite element method (GFEM) has been employed to simulate the proposed problem. The discrete systems of nonlinear equations are linearized by implementing the adaptive Newtons method. Influence of various pertinent parameters such as inclined magnetic field, oxytactic bacteria, radiation and Lewis number has been analyzed. It is observed that the average Sherwood and Nusselt number exhibit a positive correlation with the Hartmann and radiation parameter. Moreover, the average heat transfer exhibits a decreasing trend as the Hartmann, bioconvection Rayleigh and Peclet increase.

Effect of novel fin distribution on the melting process of thermal storage units

Thermal storage units play a crucial role in storing excess energy and utilizing it when required. Enhancing the thermal performance of these units is of utmost importance for better thermal energy management. Therefore, this paper suggests introducing new fin distributions to decrease the thermal resistance of the storage unit and, thus, enhance the melting process. An octagonal tube and shell unit with nanoparticle-enhanced phase change material are suggested. Three considered fin distributions to improve the heat transfer inside the unit are straight dual-radial fins, tree-like fins, and roots-like fins. Also, since copper has high thermal conductivity, its nanoparticles are incorporated with the phase change material with different concentrations, i.e., 0, 4, and 8 vol%. The Galerkin finite element technique is employed to model the storage unit. The results show that using roots-like fins has a significant effect in reducing the phase change material melting time by 56% and 91% lower than dual-radial fins and tree-like fins, respectively. The higher nanoparticle concentration (8 vol%) can also improve the thermal storage unit performance by 28.9% compared to the pristine phase change materials. Thus, this study recommends using roots-like fins with nanoparticles in the thermal storage units to enhance thermal performance.

Incompressible smoothed particle hydrodynamics solutions of double diffusion of nanoparticle-enhanced phase change materials in vertical mounted circular cylinders

The scheme of incompressible smoothed particle hydrodynamics (ISPH) method is developed to solve the time-conformable systems that control the double diffusion of nanoparticle-enhanced phase change materials (NEPCM) inside two circular cylinders saturated by a porous medium. The use of the time-conformable operator in the ISPH approach for addressing the double diffusion of NEPCM in a new domain is what distinguishes this work. This investigation revealed a comprehensive rate of change that impacts the quickening and slowdown of the monotonicity for the nonlinear systems. The physical parameters are time-conformable operator α , time parameter τ , nanoparticles parameter ϕ , Hartmann number Ha , thermal radiation parameter Rd , Darcy parameter Da , Rayleigh number Ra , and fusion temperature θ f . The principal outcomes of the numerical simulations revealed that the nanofluid flow is slowing down by an augmentation in ϕ , Ha , and Rd . The Rayleigh number is working well in enhancing the nanofluid flow and thermosolutal convection within the two circular cylinders. As a result, variable values of Ra are affecting the phase change material. The fusion temperature parameter controls the position/intensity of the phase change material within the two circular cylinders. Besides, the numerical results indicate the significance of α on the transition process of reaching the steady state. The thermosolutal convection and nanofluid speed are varied with the changes on the time-conformable derivative.

Enhanced performance and stability of a solar pond using an external heat exchanger filled with nano-phase change material

Salinity gradient solar ponds are a promising technology for harnessing/storing solar thermal energy. The energy storage capacity of solar ponds can be enhanced by incorporating phase change materials (PCMs). However, the low thermal conductivity of PCMs can negatively affect energy charging/discharging rates. In this study, an external energy storage system filled with CuO nanoparticle-enhanced PCM was employed to improve the performance and stability of a solar pond. The results were compared with water and pure PCM (paraffin) as control materials. Energy and exergy analysis was used to assess the effects of nanoparticles and their concentration on the overall solar pond performance. According to the results, the upper convective zone temperature remained consistent across all experiments and varied within the same range throughout the day. A slight temperature variation at specific times indicated the stability of the developed solar pond system. The system's exergy (energy) efficiency was increased from 10.72% (51.83%) for water to 14.71% (70.1%), 22.77% (82.13%), and 25.93% (87.58%) for PCM, PCM with 1 wt% nanoparticles, and PCM with 2 wt% nanoparticles, respectively. Incorporating nanoparticle-enhanced PCMs in external heat exchangers can effectively improve the stability and performance of solar pond systems.

Simulation of heat transfer in a nanoparticle enhanced phase change material to design battery thermal management systems: A lattice Boltzmann method study

BackgroundIn the present paper, the natural convection of phase change material (PCM) in a T-shaped cavity is investigated by the lattice Boltzmann method (LBM). In recent years, LBM has become a powerful method for computational modeling of a broad variety of complex fluid flow concerns, including the simulation of the melting process in PCMs. MethodsThe enclosure contains CuO nanoparticles and two constant temperature heat sources on the sidewalls of the cavity. The obtained results are presented in different Rayleigh numbers (Ra=103–105), cavity angles (θ = 0 − 90), the volume fraction of nanoparticles (ϕ = 0 − 0.03), and aspect ratios. Results show that the PCM melting speed is lower for low Rayleigh numbers compared to when the number is equal to 105 by 50%. To alter melting time in a specific Ra number, adding nanoparticles, changing cavity slope, and aspect ratio are investigated. Results show that the melting rate is little affected by the addition of nanoparticles but, generally adding nanoparticles delays PCM melting. Significant findingsRaising the distance between the battery and the top of the cavity is known to delay melting by 70% when the distance ratio increase from H1/H = 0.25 to 075, whereas increasing or lowering the distance between the batteries does not affect the melting time. Such a study can be used to design battery thermal management systems (BTMS).

Enhancing the performance of water-based PVT collectors with nano-PCM and twisted absorber tubes

The study investigated the thermal performance of a photovoltaic thermal (PVT) collector with a twisted absorber tube and nanoparticle-enhanced phase change material (nano-PCM). The PVT collector consisted of twisted absorber tubes, a container filled with nano-PCM, and a photovoltaic (PV) panel. To assess its efficiency, five different configurations were tested using an indoor solar simulator. The configurations analyzed were as follows: (a) an unenhanced PV panel, (b) PVT with circular absorber tubes (C-PVT), (c) PVT with twisted absorber tubes (T-PVT), (d) C-PVT with nano-PCM (C-PVT-PCM), and (e) T-PVT with nano-PCM (T-PVT-PCM). The thermal, photovoltaic, and combined photovoltaic-thermal efficiencies were evaluated at varying mass flow rates (0.008-0.04kg/s) and a constant solar irradiance of 800W/m2. Among the configurations tested, the T-PVT-PCM configuration demonstrated the highest performance. Specifically, at a mass flow rate of 0.04kg/s, solar irradiance of 800W/m2, and an ambient temperature of 27°C, it achieved photovoltaic, thermal, and combined photovoltaic-thermal efficiencies of 9.46%, 79.40%, and 88.86%, respectively. The utilization of twisted absorber tubes in the design notably improved thermal efficiency by enhancing heat transmission between the liquid and the tube surface. Furthermore, the implementation of T-PVT-PCM led to a significant reduction in surface temperature. Compared to the unenhanced PV panel, it lowered the surface temperature by approximately 30°C, and when compared to C-PVT-PCM, it reduced it by around 10°C. Notably, T-PVT-PCM outperformed the unenhanced PV panel by exhibiting a 34.5% higher photovoltaic efficiency. Overall, the study highlights the performance of the PVT collector with twisted absorber tubes and nanoparticle-enhanced phase change material. The innovative design achieved remarkable thermal efficiency, reduced surface temperatures, and significantly enhanced photovoltaic efficiency compared to traditional configurations. These findings contribute to the development of more efficient and versatile solar energy systems with the potential for broader applications in renewable energy technology.

Numerical study of encapsulated nanoparticles enhanced phase change material in thermal energy cool storage packed bed system

A numerical study is performed to investigate the dynamic behavior of a packed bed containing spherical capsules filled with Al2O3 nanoparticles dispersed in pure water as an enhanced phase change material (NEPCM) that can be utilized in ice storage of air conditioning systems. The heat transfer fluid (coolant) employed in the current work is an aqueous solution of 30 vol% ethylene glycol. For energy conservation of the coolant and the NEPCM, coupled partial differential equations are used to create a two-dimensional axisymmetric time-dependent model. While the energy equation for the NEPCM is solved using a completely explicit scheme, the energy equation for the coolant is discretized using a finite difference method and solved using the Alternating Direction Implicit (ADI) technique. The Al2O3 nanoparticles are dispersed in PCM with a volume concentration range of 0–5 %. The coolant inlet temperature with a range of -5 °C to -15 °C and mass flow rate of range of 0.2 to 0.8 kg/s for a storage volume of 0.5 m3 are the parameters used in the current study. The effect of the nanoparticles volume concentration, coolant mass flow rate, and coolant inlet temperature are investigated. The timewise variation of the solidified volume fraction of the bed, the cool energy stored in the bed, the bed centerline temperature, and the coolant exit temperature are predicted for both charging and recovery modes under different operating conditions.

Spectrally selective nanoparticle-enhanced phase change materials: A study on data-driven optical/thermal properties and application of energy-saving glazing under different climatic conditions

The optical and thermal performances of energy-saving glazing require improvement to reduce peak thermal load and increase solar energy conversion and management efficiency. Herein, it is indispensable to develop novel composite materials that designate the ability to achieve multifunction by thermal load migration as well as radiation transmittance modulation. This study developed a nanoparticle-enhanced phase change material (NEPCM) with spectrally selective and phase change functions. A data-driven algorithm is first developed to evaluate the solar-weighted absorption fraction, integrated irradiance, and spectral irradiance for the considered nanoparticles. The base fluids, nanoparticle diameter, concentrations, and proportions are taken into account in the program, and adjustments to the properties of NEPCM can be easily made. The NEPCM properties exhibit a high blocking performance of near-infrared solar radiation by 30.9%, while keeping visible transmittance at 51.8% using ATO-Al2O3 NEPCM. Furthermore, the photothermal conversion performance of a NEPCM-filled energy-saving prototype window is explored, which yields a heat absorption rate of up to 0.27 °C/min when the solar irradiance is 800 W/m2. In addition, the energy consumption of transparent envelopes with NEPCM filler in a full-scale building is investigated. The results show that NEPCM regulated glazing potentially provides annual heating energy-saving from 5.1 to 41.7 kWh·m−2·year−1 in three representative climatic conditions in different global locations. Outcomes on the spectrally selective capabilities of the energy-saving window provide ideas for advancing the development of low-carbon transparent building envelopes.

Battery thermal management of a novel helical channeled cylindrical Li-ion battery with nanofluid and hybrid nanoparticle-enhanced phase change material

Electric vehicles (EVs) have emerged as a viable alternative to Internal Combustion (IC) engine-powered vehicles, and efforts have been directed toward developing EVs that are more reliable and safer to operate. The safe working of EVs necessitates the use of an efficient battery cooling system. In this paper, cooling of cylindrical type Li-ion battery embedded with helical coolant channels is proposed. The effects of nanoparticles on removing heat from the battery cooling system have been investigated for four different nanoparticle concentrations: 0, 2, 5, and 10% of Al2O3 in the base fluid. Two cases of base fluids are considered: phase change material kept in a concentric container surrounding battery volume and coolant water circulated through liquid channels attached to the outer walls of the PCM (phase change material) cylindrical container. This study presented the three configurations (i) base case PCM-WLC: battery cooling system with a cylindrical enclosure filled with RT-42 phase change material. (ii) base case nePCM-WLC: battery cooling system filled with nano-enhanced phase change material. (iii) nePCM-LC: battery cooling system with helical liquid channels and filled with nano-enhanced PCM. The nanofluid was circulated through the liquid passages connected to the PCM container. Results showed using the helical channels, the nePCM-LC arrangement efficiently removes accumulated heat from the phase change material and provides better battery cooling than straight rectangular channel-based BTMS (battery thermal management system).

Nanofluid-based photovoltaic thermal solar collector with nanoparticle-enhanced phase change material (Nano-PCM) and twisted absorber tubes

Photovoltaic thermal (PVT) collectors convert solar energy into thermal and photovoltaic energy. The thermal performance of a PVT collector with a twisted absorber tube and nanoparticle-enhanced phase change material (Nano-PCM) was evaluated. The experiments were aimed to evaluate the photovoltaic, thermal and combination photovoltaic thermal efficiencies using an indoor solar simulator. Circular and twisted absorber tubes with Nano-PCM were evaluated in two designs. The working fluid was water with 0%, 0.3%, and 0.6% volume fractions of SiC nanofluids. The highest photovoltaic, thermal, and combined photovoltaic thermal efficiencies for the PVT-PCM with twisted tube and 0.6% nanofluids were 9.57, 84.74, and 94.31, respectively. The use of twisted absorber tubes with Nano-PCM increased the efficiency of the PVT collector.

Fractional melting process in inclined containers using (NePCM) and hybrid nanoparticles

Using substances of high latent heat such as phase change materials is a perfect technique in the energy storage units. Additionally, examining the heat transport and melting process for these materials is beneficial for a wide variety of solar-related applications. Therefore, this study aims to examine the time-dependent fractional melting process within inclined containers filled with Nanoparticles-enhanced Phase-Change Materials (NePCM) via the model of the enthalpy-porosity. The used NePCM is octadecane and the fractional derivatives are considered for all the time-dependent variables, namely, velocities, temperature and liquid fraction. The Caputo definition is applied to estimate the non-integer derivatives and the fractional order takes the values between 0.75 and 0.95. The solution methodology is depending on the Finite Volume technique with SIMPLE approach. The range of the Fourier number is between 0.05 and 0.4 and the resulting data is presented in terms of melting interface, liquid fraction, streamlines, isotherms and heat transfer rate. The main findings revealed that the influences of order of the fractional derivatives more significant at the higher values of the Fourier number and the melting interface points move towards the heated wall as order of the fractional derivatives is reduced. Also, at higher values of the fractional derivative's order (0.9), the maximizing of inclination angle causes a diminishing in the rate of the heat transfer.

Passive thermal management strategy for cooling multiple portable electronic components: Hybrid nanoparticles enhanced phase change materials as an innovative solution

Modern electronics technologies have given great interest to phase change materials (PCMs). The present work is in line with this philosophy and deals with the effectiveness of a PCM-based heat sink and nanoparticles in insertion for thermal management of several electronic components. Present numerical study explores the solid-liquid phase change process of n-eicosane in an enclosure considered for cooling of electronics in the presence of one, two, and three protruding electronic components. To improve thermal management capability, four types of nanoparticles, namely, silver (Ag), magnesium oxide (MgO), multi-walled carbon nanotube (MWCNT), and silicon dioxide (SiO2), are inserted into the n-eicosane by single and hybrid ways at volume fractions ranging from 0 % to 4%, and by introducing a lateral fin playing the role of a motherboard. It should be noted that this study is interested in analysing the combined effects of the volume fraction of inserted nanoparticles ranging from 0 % to 4%, the type of inserted nanoparticles, and the number of electronic components installed at the heat sink on the overall heat transfer and flow structure of the fluid PCM. For this purpose, a mathematical model has been developed for the formulation of the governing equations of the conjugate natural convection. The enthalpy-porosity technique is applied for modelling the phase change process. Results reveal a significant relationship between the melting time and the operating temperature of the electronic component. A long phase change process is characterized by a high utilization of latent heat and subsequently the heat rejection becomes efficient. Hence, the longer melting times result in reduced operating temperatures. By insertion of SiO2-MWCNT hybrid nanoparticles, the melting time is increased by approximately 92 % compared to pure PCM, and the plateau temperature is mitigated by 11 °C by using one component in the enclosure. Furthermore, by increasing the number of electronic components, the flow structure, thermal field and melting front become more uniform. Thus, it can be recommended to use three electronic components with a lower heat generation rate instead of using one electronic component with three times higher heat dissipation in a PCM-based cooling system.