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Phase change material (PCM) is an effective thermal management method to improve the thermoelectric conversion performance of a system. PCM can not only absorb excessive thermal energy at high temperature to protect the thermoelectric module (TEM) and increase the maximum available temperature range, but also compensate for intermittent energy to extend the working time of the TEM. In the paper, the transient performance is improved by adding PCM to a traditional thermoelectric generator (TEG) system. Due to the low thermal conductivity of PCM, metal fins are used to improve the thermal conductivity of PCM. To achieve maximum efficiency of the TEG system, the Taguchi method is employed. Four factors are heat source thermal power, PCM type, height of the PCM box, and filling ratio of the PCM, respectively. The results show that heat source thermal power has the greatest effect, and PCM has the least effect on the conversion efficiency of the TEG system. Conversion efficiency from thermal to electricity is about 1.472% during 2300 s of the heating and cooling stages. [ABSTRACT FROM AUTHOR]

In electric vehicles and hybrid electric vehicles, insulated-gate bipolar transistor (IGBT) power module trends to dissipate higher heat flux due to increased power rating and reduced package size. An inefficient cooling method will result in stringent thermal reliability problems. Therefore, there is a strong need for innovative and efficient cooling technologies in order to tackle these issues. In this article, a localized direct phase-change cooling strategy is applied and integrated with direct bonded copper in IGBT power module. Vapor chamber with light weight, high thermal conductivity, and even temperature uniformity replaces original copper baseplate. Layers of thermal grease and original cooling plate are removed, leading to a further reduction in thermal resistance. In order to evaluate the new module, a thermal model and an experiment were built to analyze temperature distribution in layers, junction temperature, temperature uniformity, and thermal resistance. Results indicate the integrated thermal management system outperforms traditional cooling solutions on the cooling capacity. Improvements on junction temperature, temperature uniformity, and total thermal resistance are 34.6%, 76.6%, and 41.6%, respectively. The results illustrate the potential of phase-change cooling by vapor chamber. It provides a new perspective in the compact and efficient design of power electric modules. [ABSTRACT FROM AUTHOR]

Summary: With advancement in technology—nanotechnology, various thermal energy storage (TES) materials have been invented and modified with promising thermal transport properties. Solid‐liquid phase change materials (PCMs) have been extensively used as TES materials for various energy applications due to their highly favourable thermal properties. The class of PCMs, organic phase change materials (OPCMs), has more potential and advantages over inorganic phase change materials (IPCMs), having high phase change enthalpy. However, OPCMs possess low thermal conductivity as well as density and suffer leakage during the melting phase. The encapsulation technologies (ie, micro and nano) of PCMs, with organic and inorganic materials, have a tendency to enhance the thermal conductivity, effective heat transfer, and leakage issues as TES materials. The encapsulation of PCMs involves several technologies to develop at both micro and nano levels, called micro‐encapsulated PCMs (micro‐PCM) and nano‐encapsulated PCMs (nano‐PCM), respectively. This study covers a wide range of preparation methods, thermal and morphological characteristics, stability, applications, and future perspective of micro‐/nano‐PCMs as TES materials. The potential applications, such as solar‐to‐thermal and electrical‐to‐thermal conversions, thermal management, building, textile, foam, medical industry of micro‐ and nano‐PCMs, are reviewed critically. Finally, this review paper highlights the emerging future research paths of micro‐/nano‐PCMs for thermal energy storage. [ABSTRACT FROM AUTHOR]

The paper is related to the use of magnetic nanofluids (ferrofluids) in a direct absorption solar parabolic trough collector, which enhances thermal efficiency compared to conventional solar collectors. By applying the right magnetic intensity and magnetic field direction, the thermal conductivity of the fluid increased higher than typical nanofluids. Moreover, the ferrofluids exhibit excellent optical properties. The external magnetic source is installed to alter the thermo-physical properties of the fluid, and the absorber tube does not have selective surface allowing ferrofluids to absorb the incoming solar irradiance directly. In this paper, an experimental investigation of the performance of small scale direct absorption solar collector using ferrofluids as an absorber was conducted. Nanoparticle concentrations of 0.05 vol% at the operational temperatures between 19°C and 40°C were used in the current study. The results show that using ferrofluids as a heat transfer fluid increases the efficiency of solar collectors. In the presence of the external magnetic field, the solar collector efficiency increases to the maximum, 25% higher than the conventional parabolic trough. At higher temperatures, the ferrofluids show much better efficiency than conventional heat transfer fluid. The study indicated that nanofluids, even of low-content, have good absorption of solar radiation, and can improve the outlet temperatures and system efficiencies. The study shows the potential of using ferrofluids in the direct absorption solar collector. [ABSTRACT FROM AUTHOR]

Latent heat thermal energy storage improves the utilization efficiency of renewable energy. Phase change materials (PCMs) commonly suffer from low thermal conductivity and many heat transfer enhancement methods have been developed. However, conventional methods need additional material preparation and processing, which increases the cost and makes them less environmentally friendly. In the current study, natural stones are used to enhance the heat transfer of the PCM in a shell-and-tube unit, forming a hybrid sensible-latent heat storage configuration. Namely, stones, which are widely accessible, low-cost and environmentally friendly, not only act as sensible heat storage media but as the thermal enhancer of the PCM. Results indicate that the energy storage rate of cases with 25 mm-sized stones increased by 8.3%–92.6%. The case with a filling height of 72.8 mm is superior owing to the high energy storage rate and large total stored energy. The stone size rarely influences the total stored energy that increases almost linearly with the void fraction, while it affects the energy storage rate significantly. Cases with 20 mm and 40 mm-sized stones generally have a higher storage rate. Finally, the mechanism is analysed. [ABSTRACT FROM AUTHOR]

• ANN models of HFC/HFO Refrigerants' viscosity and thermal conductivity were proposed. • Inputs of ANN models were reduced pressure, reduced temperature, mole mass and acentric factor. • The correlation coefficient and the AAD of viscosity model were 0.9998 and 1.21%. • The correlation coefficient and the AAD of thermal conductivity model were 0.9992 and 1%. Accurate prediction models for the viscosity and thermal conductivity of refrigerants are of great importance and have drawn wide attention from scholars. Considering the great advantage of artificial neural network (ANN) models in solving non-linear problems, two fully connected feed-forward ANN models were proposed to predict the viscosity and thermal conductivity of the HFC/HFO refrigerants in this paper. The reduced pressure (p r), reduced temperature (T r), mole mass (M) and acentric factor (ω) of the refrigerants were selected as the input variables for both ANN models. Regarding the ANN model for viscosity, the neural number of the hidden layer was optimized to be 9 by trial-and-error method. The prediction results coincided with the experimental data very well. The correlation coefficient and the average absolute deviation (AAD) of regression were 0.9998 and 1.21%, respectively. The prediction of thermal conductivity also showed a good agreement with the experimental data, and the AAD of the model was 1.00%. The paper is expected to provide valuable methods to predict the viscosity and thermal conductivity of HFC/HFO refrigerants. [ABSTRACT FROM AUTHOR]

• Thermal and electrical contact resistances of 3.65 × 10−5 m2⋅K⋅W−1 and 1.18 × 10−10 Ω⋅m2⋅K are obtained. • Time average ZT value and effective efficiency are greatly improved by periodic heating. • Efficiency of 5.75% and ZT value of 1.12 are achieved under the optimal transient heat source. • Smaller leg height, larger leg area, more TE couples, and lower thermal conductivity are suggested. Thermoelectric power generation is regarded as a promising technology to convert waste heat into electricity. This study aims to address the low conversion efficiency of thermoelectric modules and introduces a novel periodic heating method to enhance their performance. Two new indicators, time average ZT ta value and effective conversion efficiency, are introduced to assess the dynamic behavior of thermoelectric modules. A Bi 2 Te 3 -based thermoelectric module with n-type Bi 2 Te 3-x Se x and p-type Bi x Sb 2-x Te 3 materials is adopted as the research objective and tested on a designed transient experimental setup. Besides, a transient numerical model is developed to explore the optimal transient heat source and study the effect of various parameters on dynamic behavior. Compared with the steady-state efficiency of 3.76% and ZT ta value of 0.78 at a heat supply of 60 W, the time average efficiency and ZT ta value are improved by 52.93% and 43.59% respectively using the periodic heating method. Also, a smaller leg height, a larger leg area, more TE couples, and lower thermal conductivity are suggested for improving the dynamic behavior. This work offers a new periodic heating method to improve the output performance of thermoelectric modules, which may promote the broader application of thermoelectric power generation technology. [ABSTRACT FROM AUTHOR]

Abstract A wide range of heat transfer systems require efficient heat transfer management from source to sink and vice versa. Over the last decade, graphene nanoparticles, matrix nanofluids have been one of the most investigated nanoparticles for a wide range of engineering applications. Graphene–based nanoparticles have several advantages over other nanoparticles: high stability, high thermal conductivity, low erosion and corrosion, and higher carrier mobility. Graphene–based nanofluids have found applications such as heat transfer, defect sensor, anti–infection therapy, energy harvesting systems, biomedical and cosmetics. With advancement of technology, more compact and efficient cooling media are needed to ensure efficiency and reliability of engineering systems and devices. This research study reports an overview of experimental and numerical investigations of graphene nanometer–sized particles with different base host fluids for major engineering applications of energy transfer systems and further thermophysical properties of graphene nanofluids. Highlights • Various synthesis and preparation methods of graphene oxide are discussed in detail. • Preparation methods of graphene nanofluids with different base fluids are summarized in detail using different techniques. • Stability evaluation, enhancement and mechanism methods of graphene nanofluid are described thoroughly. • Effective parameters which influence the thermal properties are discussed. • The applications of graphene based nanofluid in major heat transfer systems are detailed summarized. [ABSTRACT FROM AUTHOR]

Conjugate natural convection heat transfer in an open-ended square cavity, which is partially filled with porous media, is a useful research prototype to deepen our insight into many important practical applications, such as solar energy collectors. But surprising, until now there is no open literature on it. In addition, for traditional numerical approaches, it is a great challenge to model conjugate problems on fluid-porous interfaces. In the present work, firstly we develop a new lattice Boltzmann (LB) approach to overcome such difficulty. The present LB model is validated by three benchmark tests. With the aid of this LB approach, we investigate the effects of thickness of porous layer, fluid-to-porous thermal conductivity ratio and permeability of porous layer on conjugate natural convection heat transfer in an open-ended porous-partially-filled square cavity, for the first time. It is found that these factors all influence the patterns of flow field and temperature field significantly. Especially, there exist some critical values. A small offset from them will cause a substantial change of heat and mass transfer. Sometimes the change trends are completely reversed. The present results may provide useful theoretical guides for the relevant practical applications. [ABSTRACT FROM AUTHOR]

Structural optimization is one of the effective means to improve thermoelectric generator (TEG) performance. Considering the inconsistent material parameters between P-type and N-type thermoelectrics, this paper proposes an L-type TEG configuration, where P-type and N-type semiconductors are designed with different heights and connected by L-shaped conductive strips. In addition, a thermal-electric-mechanical numerical model is established to evaluate and optimize the thermoelectric and mechanical performance of the L-type TEG. Results show that when the temperature difference is 400 K and the height ratio of the P-type to N-type semiconductor is 0.385, the L-type TEG achieves a maximum output power of 1.96 W and a maximum efficiency of 7.8 %. This is 2.39 % and 1.44 % higher, respectively, than the traditional π-type TEG. Although the temperature difference is not related to the optimal configuration of the L-type TEG, it will affect the extent of performance improvement, and the smaller the temperature difference, the greater the percentage gains of the L-type TEG compared to traditional design. In addition, the greater the difference in parameters (including Seebeck coefficient, thermal and electrical conductivity) between P-type and N-type is, the more significant the improvement of the L-type design will be. Specifically, the difference in electrical conductivity contributes to the increase of the output power, while the increase in the efficiency is affected by both the electrical conductivity and the thermal conductivity. This study provides a new perspective on the structural optimization of TEGs. • An innovative L-type configuration for thermoelectric generators is proposed. • A thermal-electric-mechanical numerical model is established to predict the TEG performance. • Power and efficiency are increased by 2.39 % and 1.44 % compared with traditional π-type design. • Greater disparities between P- and N-type lead to more gains when changing the π-to L-type design. [ABSTRACT FROM AUTHOR]

Utilizing salt-based shape-stabilized phase change materials (ss-PCMs) for high-temperature thermal energy storage stands as a pivotal avenue in realizing carbon neutrality. However, the performance of ss-PCMs significantly deteriorates after thermal cycling. This study utilizes rice husk carbon (RHC) with an in-situ SiO 2 –C interconnected structure as the encapsulating material, along with expanded graphite (EG) and MgO, to encapsulate ternary chloride (TC). In this approach, RHC simultaneously acts as a thermal conductivity materials (TCM) and a ceramic supporting material (CCM). The results showed that this encapsulation method can effectively encapsulate up to 65% of TC. The 60 wt% TC-10 wt% RHC-10 wt% EG-20 wt% MgO sample named 60T/10R/10E/20M is considered a close to optimal formulation in terms of thermal conductivity and phase change enthalpy. This ss-PCM has a thermal conductivity of 8.86 W m−1 K−1, and phase change enthalpy of 153.6 J g−1. The ss-PCMs maintained shape stability even after 1000 cycles, with minimal mass loss and thermal conductivity degradation compared to the non-RHC-added ss-PCM. This study has prepared high performance and reliability thermal storage materials through a green and low-cost approach. [Display omitted] • Rice husk carbon exhibits an in-situ SiO 2 –C interconnectivity porous structure. • The ternary chloride is encapsulated using TC/EG/MgO and rice husk carbon. • RHC enhances the thermal conductivity and mechanical properties of ss-PCM. • Ss-PCMs containing RHC demonstrate stable performance after 1000 cycles. [ABSTRACT FROM AUTHOR]

The lattice Boltzmann (LB) method, as a mesoscopic approach based on the kinetic theory, has been significantly developed and applied in a variety of fields in the recent decades. Among all the LB community members, the pseudopotential LB plays an increasingly important role in multiphase flow and phase change problems simulation. The thermal immiscible multiphase flow simulation using pseudopotential LB method is studied in this work. The results show that it is difficult to achieve multi-bubble/droplet coexistence due to the unphysical mass transfer phenomenon of “the big eat the small” – the small bubbles/droplets disappear and the big ones getting bigger before a physical coalescence when using an internal energy based temperature equation for single-component multiphase (SCMP) pseudopotential models. In addition, this unphysical effect can be effectively impeded by coupling an entropy-based temperature field, and the influence on density fields with different energy equations are discussed. The findings are identified and reported in this paper for the first time. This work gives a significant inspiration for solving the unphysical mass transfer problem, which determines whether the SCMP LB model can be used for multi-bubble/droplet systems. [ABSTRACT FROM AUTHOR]

• Mono and hybrid NePCMs are synthesized dispersed by Al 2 O 3 , CuO, MWCNTs and GNPs. • Physical, chemical and thermal properties of NePCMs are analysed. • Optimum percentage of loading 25%/75% are explored for hybrid NePCMs. • Highest thermal conductivity enhancement of 96% is achieved by hybrid NePCM. • Optimum value of 245.18 J/g of phase-change enthalpy is obtained by hybrid NePCM. Efficient, clean and quiet thermal management has become a vital challenge in for cooling of electronic devices. To enhance the capability and efficiency of passive thermal management, novel composite materials have been designed by the combination of graphene nanoplatelets (GNPs), multiwall carbon nanotubes (MWCNTs), aluminium oxide ( Al 2 O 3 ) and copper oxide (CuO) dispersed in the RT-28HC used as a phase change material (PCM). The series of mono and hybrid nano-enhanced phase change materials (NePCMs) were synthesized using constant mass fraction of 1.0 wt% of each type of nanoparticles to establish the optimum NePCM in terms of thermal properties for deficient thermal management of microelectronics. Various material characteristic techniques such as ESEM, FT-IR, XRD, TGA, DTG, DSC, IRT and thermal conductivity apparatus were used. The microstructure, chemical composition, crystallinity, thermal and phase-change heat transfer characteristics were investigated extensively for each sample of NePCM. The results showed the good chemical and thermal stability of all NePCMs without changing the chemical structure of RT-28HC. The surface morphology and crystal formation analysis revealed the uniform dispersion of nanoparticles onto the surface of RT-28HC. In comparison of mono and hybrid NePCMs, the results showed that the hybrid NePCM of GNPs/MWCNTs at mass percentage ratio of 75 % / 25 % had the highest thermal conductivity enhancement of 96 % compared to the pure PCM having optimum value of phase-change enthalpy of 245.18 J/g. Finally, enhancement in phase transition while melting and thermal properties evidenced that hybrid NePCMs can be used as potential candidate for the thermal management of microelectronics. [ABSTRACT FROM AUTHOR]

• A novel vapour-liquid channel-separated ultra-thin vapour chamber was designed. • A mathematical model of heat transfer limit was established. • The effects of different etching structures on the thermal performance were studied. • The cooling modules with and without ultra-thin vapour chamber were compared. In this work, a novel vapour-liquid channel-separated ultra-thin (0.4-mm-thick) vapour chamber fabricated via etching and diffusion bonding was designed for cooling electronic devices. The heat performance of ultra-thin vapour chamber was tested under five states, and micropillar arrays were etched into the chamber to study their effect on heat transfer. Additionally, infrared thermal imaging was performed to investigate the heat dissipation of cooling modules with and without the ultra-thin vapour chamber. The maximum heat transfer capacity of the ultra-thin vapour chamber in the horizontal state was 4.50 W, and the temperature difference was 4.75 °C. The experimentally measured values were very close to the theoretical capillary limit. Under normal and reverse gravities, the maximum heat transfer capacity changed by less than 11%. The effective thermal conductivity of the ultra-thin vapour chamber was 12000 W/(m·K), which is 30 times higher than that of pure copper. The cooling module with the ultra-thin vapour chamber exhibited better heat dissipation, thermal uniformity and thermal response properties. When the heating input power was 6 W, the heating block temperature, maximum surface temperature difference and equilibrium time of the cooling module with the ultra-thin vapour chamber were 8%, 54% and 32% lower, respectively, than those of the module without the ultra-thin vapour chamber. The proposed cooling solution is promising for heat dissipation problems in high-power portable electronic devices. [ABSTRACT FROM AUTHOR]

In this study, Ni/Mg hybrid foams were fabricated by depositing electroless Ni-P coatings on open-cell Mg foams. The microstructure, composition and phases of Ni-P coatings were observed and analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The compressive properties of the Ni/Mg hybrid foams were evaluated by compressive tests. The results show that the compressive strength, specific strength and energy absorption capacity of open-cell Mg foams are improved by electroless plating. However, compared with open-cell Mg foams, the Ni/Mg hybrid foams exhibit more brittleness characteristics. It was found that the different compressive properties between the Mg foams and Ni/Mg hybrid foams were attributed to the diverse failure mechanisms confirmed by fractography observation. [ABSTRACT FROM AUTHOR]

l Inspired by nature, the vertical-horizontal double gradient pore structure was proposed. l Excellent comprehensive performance was obtained due to the graded pores and nanoparticle additives. l The effective thermal conductivity has been greatly improved by 333%. To speed up the thermal response rate of the latent heat storage system, this research draws on the ideas of bionics and proposes two methods to enhance the performance of heat storage and heat transfer during phase change process. First, a biomimetic, double-gradient porous ceramic was applied to assemble phase change material (PCM) D-mannitol. The optimized gradient pore structure ensures that the composite possesses higher effective thermal conductivity, and better uniformity of phase interface evolution, with reasonable heat storage density. Numerical simulation predicts a 226 % increase in effective thermal conductivity comparing with the pure D-mannitol. Then, two kinds of carbon-based nanoparticles were added to further reinforce the heat transfer performance. Results found that graphite nanoparticles provide the most significant enhancement in the effective thermal conductivity of the composite material under the premise of ensuring a higher heat storage density. In conclusion, the effective thermal conductivity of the final composite achieves 3.33-fold increase due to the collaboration of the double gradient pore framework and the additive graphite nanoparticles. Accordingly, the overall heat transfer rate could be raised by 4.2 times, comparing with the pure PCM sample. This work demonstrates that the bidirectional gradient pore skeleton has significant advantages in heat storage and transfer over the single pore and unidirectional gradient pore. [ABSTRACT FROM AUTHOR]

The present study based on the numerical investigation of a hybrid nanocomposite phase change material (HNCPCM) filled heat sink for passive cooling of electronic devices. The combination of graphene oxide (GO) and silver (Ag) hybrid nanoparticles are added inside the RT-28HC to enhance thermal performance. The volume fraction ratios of Ag:GO are varied from 0:0, 0:4, 1:3, 2:2, 3:1 and 4:0. Four different shape factor values of 3.7, 4.9, 5.7 and 16.1 of Ag-GO are varied. The transient simulations are carried out to solve the governing equations using the finite volume method scheme. The results depicted that employing HNCPCM has better heat transfer enhancement compared to the pure PCM because of the addition of nanoparticles. The results showed that adding the Ag-GO inside the RT-28HC improved the thermal conductivity and uniformity in the melting process compared to the RT-28HC based heat sink. With the addition of Ag-GO, melting time of HNCPCM filled heat sink is reduced and heat transfer rate in increased. The optimum ratio of 1:3 of Ag:GO nanoparticles and shape factor value of 16.1 show the higher thermal conductivity of 0.348 W/m.K, 12.93% reduction in melting time, 8.65% enhancement in heat storage capacity and rate of heat transfer. [ABSTRACT FROM AUTHOR]

Latent heat thermal energy storage (LHTES) uses phase change materials (PCMs) to store and release heat, and can effectively address the mismatch between energy supply and demand. However, it suffers from low thermal conductivity and the leakage problem. One of the solutions is integrating porous supports and PCMs to fabricate shape-stabilized phase change materials (ss-PCMs). The phase change heat transfer in porous ss-PCMs is of fundamental importance for determining thermal-fluidic behaviours and evaluating LHTES system performance. This paper reviews the recent experimental and numerical investigations on phase change heat transfer in porous ss-PCMs. Materials, methods, apparatuses and significant outcomes are included in the section of experimental studies and it is found that paraffin and metal foam are the most used PCM and porous support respectively in the current researches. Numerical advances are reviewed from the aspect of different simulation methods. Compared to representative elementary volume (REV)-scale simulation, the pore-scale simulation can provide extra flow and heat transfer characteristics in pores, exhibiting great potential for the simulation of mesoporous, microporous and hierarchical porous materials. Moreover, there exists a research gap between phase change heat transfer and material preparation. Finally, this review outlooks the future research topics of phase change heat transfer in porous ss-PCMs. • The recent advances investigations in phase change heat transfer in porous ss-PCMs are reviewed. • Paraffin and metal foams are the mostly used PCM and porous support respectively in the experimental studies. • The pore-scale simulation can provide extra flow and heat transfer characteristics in pores. • There exists a research gap between phase change heat transfer and material preparation. [ABSTRACT FROM AUTHOR]

A novel shape-stabilized phase change material was successfully prepared using polyethylene glycol (PEG) as phase change material (PCM) and mesoporous carbon FDU-15 as support via the melting impregnation method. The structural and thermal properties of materials were measured by TEM, SEM, XRD, FT-IR, nitrogen adsorption-desorption isotherms and DSC, respectively. The maximum loading of PEG/FDU-15 reaches up to 75 wt%, and the corresponding crystallization ratio is 71%, which is superior to other mesoporous-based composite PCMs. Molecular dynamic (MD) analysis showed that some PEG adhered to the pore wall with an amorphous structure which failed to crystallize, ultimately resulting in a gap between the measured latent heat and the theoretical value. It was interesting that the filling of PEG could stimulate the frequency shift of atomic vibration in FDU-15, which then just fell in the dominant vibrational zone of PEG, despite the suppressed atomic vibration of PEG after compounding. Accordingly, the thermal conductivity of the composite is more than 60% higher compared to pure PEG, which relates to the reinforced matching of the atomic vibration between the skeleton and PCM material. FDU-15 was applied to pack PCM for the first time and delivered a better thermal performance compared with other mesopore-based composite PCMs. Image 1 • Mesoporous carbon FDU-15 was successfully applied to prepare a novel low temperature composite phase change material PEG/FDU-15. • The composite received a 63%-fold increase in thermal conductivity, and superior loading and crystallization behavior over other mesopore-based counterparts. • The molecular dynamic analysis pointed out a frequency shift of atom vibration in FDU-15 thus a better match with PEG. [ABSTRACT FROM AUTHOR]

Recently, the technology of mixing phase change materials with high thermal conductivity fillers was developed, which has allowed thermal energy storage to be implemented in a wide range of industrial technologies and processes. In the present study, a hierarchical bionic porous nano-composite was prepared, which efficiently merged the nanomaterial characteristics of magnetism and high thermal conductivity in order to form a magnetically-accelerated solar-thermal energy storage method. The morphology and thermo-physical properties of materials were analysed. The experimental outcomes of phase change heat transfer demonstrated that the maximum storage efficiency increases by 102.7% when the hierarchical bionic porous structure is used, and a further 27.1% improvement can be achieved with the magnetic field. At the same time, the heat transfer process of energy storage in hierarchical porous composites under external physical fields is explained by simulation. Therefore, this magnetically-accelerated method demonstrated the superior solar-thermal energy storage characteristics within a hierarchical bionic porous structure which is particularly beneficial for the utilisation of solar direct absorption collectors and energy storage technology. • A novel magnetically-accelerated solar-thermal energy storage method was developed. • The storage efficiency is increased by 102.7% when adding bionic porous nanoparticles. • Energy storage efficiency and capacity can be enhanced by the magnetic field. [ABSTRACT FROM AUTHOR]