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The features of working fluids which enable synchronously high solar thermal conversion within broadband wavelength ranges and high heat transport are extremely vital for direct volumetric solar receivers. By making use of unique different spectral absorption behaviors of unitary nanofluids, in this paper, we study feasibility of binary nanofluids with enhanced solar thermal conversion and thermal conduction. The binary nanofluid contains multi-wall carbon nanotubes (MWCNTs) and silica/silver (SiO 2 /Ag) plamonic nanoparticles. Instead of the limited absorption property of unitary nanofluids, by mixing different types of nanofluids with different spectrally absorptive features in proper manners, the spectral absorptance of binary nanofluids can be adjusted by controlling the ratio of two components. Since MWCNTs have high absorption in infrared spectra while SiO 2 /Ag nanoparticles have strong absorption peaks within visible spectra, the mixed nanofluid get higher absorption within wider solar spectra. Meanwhile, the existence of MWCNTs in the working fluid remarkably improves energy transport of the binary nanofluid. Specifically, MWCNT with the volume fraction of 0.1% can enhance the thermal conductivity of about 7%. The favorable light absorption and heat transfer performance can lead to the higher light absorption efficiency. This work provides a new strategy to improve the solar energy harvesting efficiency of nanofluids being used for volumetric solar collectors. [ABSTRACT FROM AUTHOR]

The CaCO 3 /CaO based thermochemical system has great potential in Concentrating Solar Power (CSP) plants. However, the CaCO 3 suffers from high sintering speed, poor thermal conductivity, and weak light absorption, which is not conducive to being directly driven by solar energy. Herein, The Mn and Cr elements were doped into CaCO 3 through the sol-gel method. The synergistic effect between the two elements can maintain the storage density at 1057.3 kJ/kg after 20 cycles at 800 °C. The light absorption under AM 1.5G spectrum was obviously improved to 64.5% and reached 73.3% after 20 cycles. To further improve the thermal conductivity of the composite, the tetrapod-shaped zinc oxide whiskers (TZnO) were directly mixed into the composite. The TZnO acts as the thermal conductance bridge in the composites and can retain its original morphology at high temperatures without reacting with CaCO 3. When 5% mole ratio of TZnO was added to the Cr/Mn doped CaCO 3 , the thermal conductivity increased by 17.8%. Through the non-isothermal analysis of the reaction kinetics, it is found that the addition of TZnO can effectively accelerate the reaction, especially at a higher heating rate, which is very beneficial to direct solar-driven applications. The optimized composites showed excellent properties in light absorption, sintering resistance, thermal conductivity, and reaction kinetics, which can guide the direct photothermal utilization of CaCO 3. • Thermophysical properties of solar driven CaCO 3 -based composites are studied. • Tetrapod-shaped ZnO whiskers can serve as the thermal transport networks for CaCO 3. • The thermal conductivity increased by 17.8% after 5% mole ratio of TZnO was added. • The high thermal transfer network formed by TZnO accelerates the reaction kinetics. [ABSTRACT FROM AUTHOR]

Abstract: We develop a novel type of functional fluid-magnetic microencapsulated phase change material (MMPCM) suspension which incorporates the advantages of microencapsulated phase change material (MPCM) suspension and magnetic fluid (MF) for controllable and efficient energy transport processes. The specific heat capacity and thermal conductivity of this type of functional fluid are experimentally investigated, respectively. The effects of the mass fraction of components in the MMPCM on the thermal properties of the fluid are discussed. In addition, the effect of an eternal magnetic field on the thermal conductivity of the fluid is discussed. [Copyright &y& Elsevier]

Abstract: Experimental investigations are carried out to measure the viscosity and the thermal conductivity of the aqueous magnetic fluids in either the absence or the presence of the external magnetic field. The effects of the volume fraction of the suspended magnetic particles, concentration of surfactants and the external magnetic field strength as well as its orientation on the transport properties of the magnetic fluid are analyzed. The experimental results show that the viscosity of the sample magnetic fluids increases with the percentages of the suspended magnetic particles and the surfactants. The viscosity first increases with the magnetic field and finally approaches a constant as the magnetization of the magnetic fluid arrives at a saturation state. For the same magnetic fluid, the viscosity in the magnetic field being perpendicular to the flow direction is bigger than that in the parallel field under the same magnetic field. The thermal conductivity of the sample magnetic fluids is larger than that of pure fluids in both the absence and presence of the external magnetic field. Almost no change in the thermal conductivity of the sample magnetic fluid is found in the magnetic field perpendicular to the temperature gradient. The thermal conductivity of the magnetic fluid increases with the strength of the applied magnetic field being parallel to the temperature gradient. [Copyright &y& Elsevier]

A response from the authors of the article "Aggregation structure and thermal conductivity of nanofluids" that was published in the 2003 issue is presented.

Abstract Phase change materials have been introduced into the concentrated photovoltaic-thermoelectric hybrid system to control its operating temperature. As the poor thermal conductivity of phase change materials (paraffin in this paper), the expanded graphite and copper foam are respectively added into the paraffin to decrease its thermal resistance. An experimental platform containing three concentrated photovoltaic-phase change material-thermoelectric hybrid subsystems is established. Experimental comparisons of performances among the concentrated photovoltaic system, the conventional concentrated photovoltaic-thermoelectric hybrid system, and the concentrated photovoltaic-phase change material-thermoelectric hybrid system are firstly carried out. Then, a series of comparative experiments are conducted to reveal the effects of thermal resistances on the hybrid system performance. The results demonstrate that the improved phase change material can well maintain the photovoltaic-thermoelectric hybrid system at the desired temperature and generate more electricity. The temperature of the photovoltaic cell in the concentrated photovoltaic-phase change material-thermoelectric hybrid system is nearly 50 °C while the one in the concentrated photovoltaic-thermoelectric hybrid system reaches about 80 °C. The average output power of the concentrated photovoltaic-phase change material-thermoelectric hybrid system increases by 23.52% compared with the concentrated photovoltaic-thermoelectric coupling system. The expanded graphite and copper foam both can decrease the thermal resistance of paraffin, and the expanded graphite has a better effect. The thermal resistance of the cooling system has little effect on the operating conditions of the photovoltaic cell and phase change material but greatly affects the performance of the thermoelectric generator. Highlights • Feasibility of photovoltaic-phase change material-thermoelectric system is studied. • Effects of thermal resistances on the hybrid system are discussed. • Two improved phase change materials are compared with pure paraffin. • Paraffin/expanded graphite composite is proved to be the best for the hybrid system. • Cooling system shows little effect on the PV cell owing to the phase change material. [ABSTRACT FROM AUTHOR]

Latent heat thermal energy storage (LHTES) technology can well alleviate the imbalance between intermittent energy supply and demand. However, the low thermal conductivity and poor shape stability of phase change materials (PCMs) seriously limit their practical applications. Here, sugarcane-derived biomimetic SiC ceramics are proposed for fast and efficient thermal energy storage. After loading paraffin, the composite phase change materials (CPCMs) demonstrate a high thermal conductivity of 10.34 W/mK and a high energy density of 151.20 kJ/kg at a porosity of 85%, outperforming state-of-the-art ceramics-based CPCMs. This benefits from continuous SiC skeletons composed of tightly stacked grains, so that both boundary and contact thermal resistances are reduced even at a high porosity. No prominent decay of thermal conductivity and energy storage density after 500 charging-discharging cycles, as well as good leakage resistance, confirm the good cyclic stability of proposed CPCMs. High-performance CPCMs are further packed into a fixed-bed LHTES device and investigated both experimentally and numerically. The melting time of LHTES device is prominently reduced by 44.3% benefiting from synergy of high thermal conductivity and non-coaxial arrangement of packed CPCMs cells. This work opens a new route for rapid thermal energy storage based on sugarcane-derived biomimetic materials. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have been widely used for thermal energy storage in overcoming the intermittence of renewable energy and passive thermal management. However, low thermal conductivity, leakage, inherent brittleness, and lack of responses under multiple stimuli preclude their widespread applications. Here, we report a flexible and form-stable solid-solid/solid-liquid biphasic phase change composites to achieve efficient solar/electro-thermal energy conversion and storage as well as thermal management of high-power devices simultaneously. Proposed biphasic polyurethane–stearic acid/expanded graphite (PU–SA/EG) composites demonstrate state-of-the-art performances with a high energy storage density of 117.4–137.3 J/g and high thermal conductivity of 10.98–37.80 W/(m⋅K) simultaneously at an EG loading ratio of 10–30 wt %, benefiting from the formation of continuous thermal transport network provided by expanded graphite nanosheets. PU–SA/EG maintains high flexibility and good thermal reliability over more than 500 melting/solidification cycles. High solar- and electro-thermal conversion and storage efficiencies of up to 90.5% and 88.7% are achieved, respectively. When applied in thermal management of flexible electronic devices, PU–SA/EG film demonstrates a superior cooling performance by reducing device temperature prominently by 32 °C under a DC 5A discharging power supply. This work provides an effective way for harvesting and storing multiple energy sources like solar energy and electricity, as well as thermal management of high-power electronic devices. • A flexible dual-phase change energy storage material with a high 37.80 W/(m⋅K) thermal conductivity is proposed. • The photothermal/electrothermal conversion efficiency of PU-SA/EG PCM films can reach 90.5% and 88.7%, respectively. • After 500 cycles, the sample has no leakage and its shape, thermal conductivity, and photothermal conversion energy storage performance are stable. • PU-SA/EG phase change thin films can effectively reduce the surface temperature of curved electronic devices by 32 °C. [ABSTRACT FROM AUTHOR]

• Sea urchin skeleton-inspired TPMS based MFPCM is prepared for fast LHS. • The mechanism for enhancing the effective thermal conductivity can be explained. • MFPCM with the positive gradient in porosity has the fastest melting rate. The latent heat storage technology has been widely applied in various thermal management fields, but its extensive deployment is limited due to the poor thermal conductivity of phase change material. Here, inspired by the microstructure and functions of sea urchin skeleton, four different metal foam skeletons based on triply periodic minimal surface (TPMS) are introduced to enhance latent heat thermal energy storage performances, which are evaluated by both experiment and numerical simulation. The metal foam-PCM (MFPCM) based on the Primitive structure has the fastest thermal energy storage rate with melting time prominently reduced by 20% compared to the traditional structure (Lattice). The underlying mechanism can be attributed to a more continuous and compact internal structure of TPMS compared with traditional MFPCM by thermal resistance analysis. In addition, the effect of gradient porosity is investigated as well, and the positive gradient in porosity has the fastest melting rate. The present study provides a new idea to design high-performance MFPCM and promotes the application of bionics in accelerating latent heat thermal energy storage. [ABSTRACT FROM AUTHOR]

Solar thermal energy storage based on phase change materials (PCMs) plays a significant role in overcoming the intermittent and fluctuating nature of solar irradiation. However, the weak solar absorptance, intrinsic low thermal conductivity, and leakage problems preclude efficient solar energy storage harvesting and storage. Herein, eco-friendly, anisotropic, large porosity wood-derived SiC ceramics is proposed to overcome the above bottleneck problems and achieve rapid solar thermal energy storage. We report a synergetic strategy to fabricate composite phase change materials (CPCMs) with high thermal conductivity and large energy storage density by partially removing the interwoven lignin and hemicellulose from natural wood. The porosity of the porous wood-derived SiC ceramics can be increased from 55% to 80%, beyond the porosity limitation of conventional wood. Vertically aligned channels and compact SiC grains serve as thermal transport highways and enable resultant CPCMs to exhibit a high thermal conductivity of 31.2 W/mK even at a porosity of up to 80%. The solar absorptance of proposed composites (89%) is significantly higher than that of pure PCMs, enabling them to capture solar energy effectively. This work provides a synergetic strategy for achieving efficient solar energy harvesting, fast conversion, and high-density storage simultaneously via proposed eco-friendly and large porosity wood-derived SiC ceramics-based phase change composites. [Display omitted] • Efficient solar energy harvesting, conversion, and storage are achieved simultaneously. • The porosity of eco-ceramics increases greatly from 55% to 80% beyond the porosity limitation of conventional wood. • The thermal conductivity of proposed phase change composites is 31.2 W/mK even at a porosity of up to 80%. [ABSTRACT FROM AUTHOR]

• Ceramic NPs on latent heat TES properties of LiNO 3 /NaCl is evaluated from material to system level. • Concurrent enhancement of C p by 32.3% and solidus thermal conductivity by 63.5% is enabled by MgO NPs. • Natural convection considering viscosity is as important as thermal conductivity during melting. • The optimal concentration of MgO NPs is 4 wt% to achieve best thermal energy storage performances. Focusing on the development of the next generation latent heat thermal energy storage (TES), molten salt is one of the most promising candidates, while it suffers from small thermal charging rate and low energy storage density. Adding ceramic nanoparticles (NPs) with high thermal conductivity and high chemical stabilities has been proposed to alleviate above problems. However, it's very challenging to enhance both thermal conductivity and specific heat capacity (C p) simultaneously. Besides, induced viscosity increment by NPs will instead reduce the thermal charging rate of TES system, due to suppressed natural convection of molten salts. Herein, concurrent enhancement in solidus thermal conductivity and C p is demonstrated by doping MgO NPs into LiNO 3 /NaCl, which are improved by 63.5 % and 32.3 % at 4 wt%, respectively. The underlying mechanism is attributed to very low interfacial thermal resistance (R b = 2.424 × 10−9 K·m2·W−1) between MgO and LiNO 3 /NaCl. Benefiting from enhanced C p , the total energy storage density increases from 662.9 J·g−1 to 671.7 J·g−1 for temperature range of 50–300 °C despite decreased phase change enthalpy. The viscosity has a sharp increase from 4.2 cP to 22.4 cP when NPs concentration rises from 0 wt% to 10 wt% at 360 °C. When being applied in TES system, the optimal concentration of MgO NPs is found to be 4 wt%. The thermal charging rate of TES system is suppressed when NPs concentration is too low or too high due to limited thermal conduction and inhibited natural convection, respectively. Viscosity is verified as important as thermal conductivity in system level evaluation. This work helps to guide the design of high-performance molten salts in TES system, so as to achieve both faster thermal charging rate and higher energy storage density. [ABSTRACT FROM AUTHOR]

• Starch-derived porous ceramics-based phase change devices are proposed for high-performance thermal energy storage and thermal management. • Thermal conductivity of starch-derived porous SiC ceramics reaches 30 W/m-K even at a high porosity of 80%. • The temperature of high-power chip is 10 ℃ lower when replacing pure copper via porous SiC/paraffin for thermal management. • The thermal conductivity and enthalpy of starch-derived porous SiC ceramic loaded with LiOH-LiF eutectics is as high as 24.27 W/-K and 331.56 kJ/kg, respectively. Low thermal conductivity and leakage of phase change materials (PCMs) have severely limited their applications in thermal energy storage and thermal management of electronic devices. Here, we propose starch-derived porous SiC ceramics to achieve high thermal conductivity and prevent leakage of PCMs simultaneously. Porous SiC ceramics with high thermal conductivity of 30 W/m-K at high porosity of 80% are obtained, benefiting from directional pore structures and dense grains enabled via facile directional freeze-drying of starch combined with liquid silicon infiltration technology. Thermal conductivity and thermal energy storage density of SiC/paraffin composite PCMs (CPCMs) attenuated only slightly by 2.75% and 2.80% after 500 repeated heating-cooling cycles, respectively, confirming their longevity and good stability. The phase change enthalpy achieves 331.56 J/g with high thermal conductivity of 24.27 W/m-K maintained by replacing paraffin with LiOH-LiF eutectics. When applying into transient cooling of high-power chips, the chip temperature is 10 ℃ lower if replacing traditional copper by porous SiC/paraffin CPCMs as a cooling medium. Our work demonstrates a promising route to realize efficient thermal energy storage and thermal management of high-power electronics via starch-derived porous ceramics-based phase change devices. [Display omitted] [ABSTRACT FROM AUTHOR]

• Highly efficient solar-driven CRM is demonstrated by reactors with heat recovery. • An ultrahigh and stable light-to-fuel efficiency of 36.51 % is achieved over 28 h. • The high thermal conductivity of Ni foam improves temperature uniformity. • The carbon deposition rates of foam reactors are reduced by 88%. • Heat recovery improves CO 2 reforming of CH 4 rates by 23.8%. By converting two greenhouse gases into fuels, CO 2 reforming of CH 4 via free and clean solar energy is a promising solution to the energy shortage and global warming problems simultaneously. However, serious challenges such as limited light-to-fuel efficiency, severe catalyst aggregation, and deactivation still exist for reactors employing traditional catalyst powders. Here, Ni/MgAlO x -LDH catalysts loaded Ni foam reactor with heat recovery is proposed for highly efficient and stable CO 2 reforming under direct concentrated solar irradiation. The temperature nonuniformity is reduced by 84.3% compared to powdered systems, which benefits from the high thermal conductivity of nickel foams. Overheating is also prevented, which leads to much less carbon deposition and relieved active sites aggregation. Ultrahigh light-to-fuel efficiency of 36.51% is achieved, which is much higher than that of traditional powdered systems (23.87%). Numerical simulation results have an excellent agreement with experiments and demonstrate that heat recovery can greatly improve CRM rates by 23.8%. This work opens new routes to achieve highly efficient, stable, and scalable solar-driven CO 2 reforming via Ni/MgAlO x -LDH catalysts loaded Ni foam reactors with heat recovery. [ABSTRACT FROM AUTHOR]

· Fast and stable solar/thermal energy storage is achieved via gradient SiC foam-based phase change composite. · No obvious leakage is observed over 1000 cycles enabled by strong capillary force via gradient pore structures. · Thermal conductivity is enhanced to be 760% as high as that of paraffin PCMs through interconnected SiC skeletons. · Efficient solar-thermal charging is achieved due to high volumetric solar absorptance and high thermal conductivity. Phase change materials with high latent heat can bridge the gap between constant energy demand and intermittent supply. However, the intrinsically low thermal conductivity and leakage problems severely limit the charging/discharging rate and cyclic stability in practical applications. Here, a leakage-proof phase change composite strategy based on gradient SiC foam is proposed to achieve fast and stable latent heat storage. The thermal conductivity of composites achieves 1.9 W·m−1·K−1, which is 760% as high as that of paraffin wax, while the latent heat (120 J·g−1) still maintains 85.7% of paraffin wax. Excellent leakage-proof property is demonstrated with nearly unchanged latent heat over 1000 cycles, due to the enhanced capillary interaction provided by the gradient pore structures. The influence of volume fraction, input power, and thermal conductivity on the melting behavior are systematically investigated, demonstrating fast thermal charging performance of gradient SiC foams. Efficient and rapid solar-thermal charging performance are also achieved benefitting from high volumetric solar absorptance and high thermal conductivity. This work guides the design of ceramic based phase change composites for rapid, stable, and efficient solar/thermal energy storage. [ABSTRACT FROM AUTHOR]

Integrated solar thermal conversion and latent heat storage based on phase change materials (PCMs) has emerged as a promising way for improving solar thermal utilization by avoiding redundant energy transport processes. However, the poor solar absorptance and low thermal conductivity of PCMs prohibit achieving high solar thermal energy storage efficiency. Here, bamboo-derived silicon carbide (BSiC) eco-ceramics based phase change composites are proposed to realize efficient, rapid, and compact solar thermal energy storage. BSiC/paraffin demonstrates a high thermal conductivity of 40 W m−1 K−1 at the porosity of 66%, where 96% pores are filled with paraffin and no prominent deterioration is observed after 2500 cycles. By further loading TiN nanoparticles on BSiC skeletons, an ultrahigh solar absorptance of 96.23% is obtained due to exciting broadband plasmonic resonances. Subsequently, the solar-thermal energy storage efficiency achieves as high as 91.1% at 1.62 W cm−2. The high-performance solar thermal energy storage benefits from continuous thermal conductive channels and excellent solar absorptance of BSiC/PCMs composites. For high temperature applications, BSiC/LiOH–LiF composites are developed and possess high thermal conductivity of 35.0 W m−1·K−1 and large latent heat of 309 kJ kg−1 simultaneously, but corrosion problems need to be tackled before long-time utilization. This work paves the way for applying BSiC eco-ceramics in high-performance solar thermal energy conversion and storage. • Bamboo derived SiC-PCMs is proposed for high performance solar thermal energy storage. • BSiC-paraffin demonstrates a high thermal conductivity of 40 W m−1 K−1 at large porosity of 66%. • Solar absorptance of 96.23% and solar thermal energy storage efficiency of 91.1% are demonstrated. • BSiC/LiOH–LiF shows thermal conductivity of 35 W/m-K and energy density of 309 kJ kg−1. [ABSTRACT FROM AUTHOR]

• Concurrent enhancement of C p , thermal conductivity, and optical absorption are demonstrated. • C p and thermal conductivity are enhanced by 4.86% and 159% compared with pure PCMs respectively. • C p enhancement is attributed to weak interaction between SiO 2 nanoparticles and PCMs. • Rapid thermal and solar charging rate are demonstrated. Phase change materials (PCMs) based thermal energy storage techniques are promising to bridge the gap between thermal energy demand and intermittent supply. However, the low specific heat capacity (C p) and thermal conductivity of PCMs preclude the simultaneous realization of high energy density and high power density thermal charging/discharging. Here, concurrent enhancement of C p and thermal conductivity are demonstrated to be possible based on SiO 2 nanoparticles decorated LiNO 3 /NaCl eutectics inlaid in three-dimensional (3D) hierarchical ultralight silicon carbide (SiC) foams. The average C p is 4.86% higher than that of pure PCMs due to the high surface energy and interfacial thermal resistance induced by weak interaction between SiO 2 nanoparticles and eutectics, as confirmed by molecular dynamics (MD) simulations. The thermal conductivity of composites achieves an ultrahigh value of 2.78 W·m−1·K−1, which is 259% of LiNO 3 /NaCl, accompanied with a large phase change enthalpy of 331.9 kJ/kg. Continuous heat transport paths provided by ultralight SiC foams have dominant contributions to the enhancement of thermal conductivity, although the presence of SiO 2 nanoparticles deteriorates it slightly. In addition, the full-spectrum solar absorptance is enhanced from 25.2% to 76.3%. Rapid thermal transport and enhanced solar absorptance of composites enable heat charging rate to rise by 150% compared with SiO 2 nanoparticles decorated eutectics. This work provides a strategy for the realization of high energy density and power density compatible thermal energy storage technology. [ABSTRACT FROM AUTHOR]

Directly absorbing sunlight and on-site storing thermal energy via phase change processes are promising to achieve efficient and fast solar-to-thermal energy storage. However, the performance is severely inhibited by intrinsically low thermal conductivity and poor optical absorption capability of phase change materials (PCMs). We propose a strategy to achieve integrated efficient solar-to-thermal conversion and ultrafast energy storage by developing nacre-like ceramics embedded with titanium nitride (TiN) nanoparticles (NPs) contained PCMs. A high thermal conductivity of 25.63 W m−1 K−1 compatible with large phase change enthalpy of 157.93 kJ/kg are demonstrated. The excellent performance is attributed to ordered arrangement of silicon carbide ceramics and erythritol PCMs, just like microstructure of natural nacre. Meanwhile, the solar absorptance is improved by exciting localized plasmon resonances of TiN NPs in a broad band. Combination of high thermally conductive biomimetic skeletons with volumetric absorptive PCMs leads to a prominent enhancement of solar-to-thermal energy storage rate by 864%. This work paves a way for the application of ceramics in rapid and efficient solar energy harvesting and thermal energy storage. [Display omitted] • Nacre-like ceramics-based phase change composites are designed for solar thermal conversion and storage. • The thermal conductivity is 25.63 W/m-K due to ordered arrangement of SiC ceramics and PCMs. • Large phase change enthalpy of 157.93 kJ/kg are demonstrated with good leakage-proof properties. • High solar absorptance is enabled by decorating TiN nanoparticles on SiC skeletons. • Solar-to-thermal energy storage rate of biomimetic composites is successfully enhanced by 864%. [ABSTRACT FROM AUTHOR]

• High thermal conductivity and high energy density compatible latent heat thermal energy storage are achieved via porous AlN ceramics-based phase change composites. • The thermal conductivity of composites is as high as 52.63 W/m-K enabled by continuous thermal transport channels of densified AlN skeletons. • The average solar absorptance of composites is enhanced from 70% to 90% after decorating plasmonic TiN nanoparticles on AlN surfaces. Ceramics embedded phase change materials (PCMs) composites are promising candidates for high-temperature thermal energy storage due to good chemical stability and high thermal shock resistance. However, the energy storage rate is severely restricted by the low thermal conductivity of composites. Here, we successfully achieve high thermal conductivity and high energy density compatible thermal energy storage based on porous AlN-eutectic NaCl/LiNO 3 composites. Designed composites possess a high thermal conductivity ranging from 31.8 to 52.63 W/m-K benefiting from continuous thermal transport channels of densified AlN skeletons. Meanwhile, the phase change enthalpy reaches 140 to 186 kJ/kg since about up to 92% of pores are filled with PCMs. Further decorating AlN skeletons with TiN nanoparticles can significantly increase the solar absorptance from 70% to 90%, enabling proposed composites to be applicable for direct solar thermal energy storage as well. This work provides new routes to achieve high thermal conductivity and energy density compatible thermal energy storage via porous AlN ceramics-based phase change composites. [Display omitted] [ABSTRACT FROM AUTHOR]

Inorganic salts can be used as phase change materials (PCMs) for high temperature (>200 °C) thermal energy storage. Advantages of such PCMs include a wide range of phase change temperatures, high energy density, excellent physical/chemical stability and low price. However, applications of above salts based PCMs are greatly limited due to their corrosion to container materials and low thermal conductivity. These problems can be resolved by integrating salts to a porous skeleton, forming the so-called shape-stabilized PCMs (ss-PCMs). The ss-PCMs typically consist of an inorganic salt and a porous skeleton with the former for thermal energy storage and the latter both as a shape stabilizer and a thermal conductivity enhancer. The porous skeleton, made from packing of skeleton materials, is shown to effectively prevent leakage of loaded salts due to capillary force and surface tension. The generated porous skeleton also improves the thermal conductivity of ss-PCMs by providing a high thermally conductive heat transfer path. This review therefore focuses on the skeleton materials for high temperature salts based ss-PCMs, covering selection principles, types and current status of skeleton materials, formation mechanisms of porous skeletons generated from skeleton materials, and effects of different porous skeletons on mechanical and thermophysical properties of ss-PCMs, such as mechanical strength, phase transition temperature, latent heat, thermal conductivity, and cycling stability. Fabrication methods and applications of the ss-PCMs have been also summarized. To the best of our knowledge, this is the first profound review of skeleton materials for salts based ss-PCMs for high temperature applications. Image 1 • High temperature salts are integrated into a porous skeleton to form ss-PCMs. • Skeleton materials prevent corrosion and enhance thermal conductivity of ss-PCMs. • Selection principles and types of skeleton materials for ss-PCMs are summarized. • Skeleton materials are shown to form flexible or rigid porous skeleton in ss-PCMs. • Porous skeleton greatly affects mechanical and thermophysical properties of ss-PCMs. [ABSTRACT FROM AUTHOR]