Molten salt based nanofluids have emerged as promising working fluids for concentrated solar power (CSP) applications due to their enhanced properties as heat transfer fluid and thermal energy storage. In CSP systems, however, molten salt is inevitably exposed to electric fields from various system components and operations, such as the receiver that generates photoelectric effects, dust removal shields, electric heaters and electromagnetic equipment. The effects of electric fields on their thermal storage properties must be considered. In this study, the specific heat capacity of KNK (KNO3-NaNO2-KNO2) molten salt and its doping with Al2O3 and SiO2 nanoparticles under uniform electric field was investigated using molecular dynamics simulations. The results show that the addition of electric field leads to the reduced specific heat capacity of both KNK and its nanofluid. Notably, for the nanofluid without an electric field, Al2O3 nanofluid exhibits a higher specific heat than SiO2, but this trend reverses under the electric field. Mechanistic analysis reveals that the reduction in specific heat of KNK is caused by the attenuation of Na⁺-Na⁺ and Na⁺-K⁺ interactions, leading to a less uniform and more disordered ionic state. In contrast, for the nanofluids, ionic interactions do not play a decisive role. Instead, the electric-field-induced decrease in specific heat capacity of the nanofluids is attributed to a looser interfacial layer structure, and a smaller interfacial thermal resistance between the base fluid and nanoparticles. Furthermore, the reversal of specific heat capacity between Al2O3 and SiO2 nanofluids is found to be associated with the negative contribution of Coulomb energy fluctuation. These findings enhance the mechanistic understanding of electric field effects on thermal energy storage, and offer guidance for design of molten salt-based nanofluid under electric field.

The optimization of thermo-hydraulic characteristics in heat transfer tubes serves as an effective strategy for achieving high energy utilization efficiency. Therefore, this study develops a novel configuration that integrates an outward helical corrugated tube with an inserted twisted tape to enhance the thermal performance of heat transfer tubes. The investigation focuses on the relative rotational direction between the corrugated tube and twisted tape, namely co-rotating and anti-rotating, and the relative corrugation heights. Under a constant heat transfer area, numerical simulations are carried out for Reynolds numbers ranging from 3000 to 12000. The findings demonstrate that the enhanced combined effect of corrugation-induced flow disturbances and twisted tape induced helical flow intensifies fluid mixing and elevates heat transfer efficiency. Among all configurations examined, the anti-rotating corrugated tube with twisted tape at a relative corrugation height of 0.104 achieves optimal heat transfer improvement, with Nu being 276.94% greater than the smooth tube value at Re = 3000. A peak thermal performance factor of 1.93 is attained by this configuration, corresponding to a 93% enhancement relative to the smooth tube. The results provide some crucial information for crafting super-effective heat exchange tubes and underscore the importance of rotational direction and geometric optimization in enhancing energy efficiency.

As a core component of magnetic confinement fusion devices, the divertor must withstand steady-state heat fluxes of 10–20 MW/m2 and extreme transient thermal loads, making efficient cooling a critical challenge for its engineering application. To enhance the heat transfer capacity of the divertor, this study proposes a systematic design methodology that integrates multi-objective topology optimization with three-dimensional parametric analysis. Firstly, multi-objective topology optimization was performed on models with six different design domain heights H to clarify the evolution law of topological structures with vertical design freedom, and the optimal topological structure (MMCHS-TO) was screened out. Subsequently, the three-dimensional numerical simulations were conducted to systematically analyze the influence of microchannel width W on the flow and heat transfer performance of MMCHS-TO. The three-dimensional structure with the best performance was determined based on the Figure of Merit (FOM). The influence of vertical design freedom on the optimization outcome can be divided into four stages (H ≤ 1 mm, 2 ≤ H ≤ 3 mm, 3 ≤ H ≤ 5 mm, H ≥ 6 mm). With the increase of vertical design freedom, the number of trunk channels, the number of central fins, the arrangement of central fins, and the size of fins in the design domain evolve sequentially. As H increases, the pressure drop of the optimized structure decreases while its thermal resistance increases, with a performance plateau observed between H = 2–4 mm where changes are minimal (ΔR ≈ 0.00052 K/W). The structure at H = 4 mm is selected as optimal. The topology of MMCHS-TO transitions through five stages with increasing weight factor of thermal objective ω₁. In the balanced stage (ω₁ = 0.5–0.7), the heat transfer rate changes almost linearly with the energy dissipation of the flow. Within the investigated ranges of W = 0.5–1.5 mm and Re = 6000–11,000 under a heat flux of 15 MW/m2, MMCHS-TO exhibits a higher average heat transfer coefficient and a lower total thermal resistance than non-optimized structure (MMCHS-U). All FOM values remain greater than 1. The maximum FOM is approximately 1.392 at Re = 6000 and W = 0.5 mm. This work provides a systematic framework for the design of divertor microchannels with high heat dissipation efficiency.

Double-layered thermal barrier coatings (DL-TBCs), which combine a top layer (with low thermal conductivity and high-temperature stability) and a bottom layer (with high fracture toughness), offer superior thermal insulation potential compared to single-layer coatings. This advantage stems from the functional synergy between the two layers. However, the introduction of a new heterogeneous interface often leads to interfacial stress concentration, which becomes a critical bottleneck limiting the coating's service life. To resolve the conflicting structural requirements-where the ceramic layer near the bond coat must be dense to resist cracking, while the interface between the two ceramic layers requires porosity to relieve stress. This study proposes a design approach based on multiscale strain partitioning and gradient porosity regulation. The design uses high-entropy rare-earth zirconate (HEFO) as the top layer (for low thermal conductivity and high-temperature stability) and yttria-stabilized zirconia (YSZ) as the bottom layer (for stress buffering). Through integrated optimization of materials, structure, and processing, a functionally graded pore structure was achieved across different regions. The region near the bond coat was densified, with a porosity of approximately 7.3%. In contrast, the double ceramic layers exhibited a gradual increase in porosity along the thickness direction: from 7.3% to 17.3%. Meanwhile, the proportion of unmelted regions increased from 5.8% to 34.2%, forming a continuously transitional microstructure. The lifespan of the DL-TBCs under this design is approximately 1.7 times longer than that of the conventional DL-TBCs. Further investigation into the structural evolution during high-temperature service revealed that the graded pore structure can effectively mitigate interfacial thermal expansion mismatch, reduce stress concentration at the interface, and enhance the bonding strength of heterogeneous interfaces, thereby delaying the process of interfacial cracking. The "structure-stress-life" relationship established in this study offers a new paradigm for designing DL-TBCs.

NiCrBSi-CrB2 composite powders and coatings, with varying CrB2 mass fractions, were successfully prepared using spray granulation and high-velocity oxygen-fuel (HVOF) spraying. This study systematically investigated their hot corrosion behavior and underlying mechanisms in KCl-NaCl-Na2SO4 molten salt at 600 degrees C. The results showed that the composite powder consisted of gamma-Ni, CrB2, CrB, CrSi2, Ni2B, and Ni3B phases. The phases within the coatings were similar to those in the powder, with the additional identification of Ni2Si and Ni3Si2 phases in coatings containing 30% and 40% CrB2. Crucially, the hot corrosion weight gain and kinetic constant of the coatings initially decreased and then increased with increasing CrB2 content. The coating with 20% CrB2 demonstrated optimal corrosion resistance, exhibiting the lowest corrosion weight gain (12.42 mg/cm2) and kinetic constant (0.80 mg2/(cm4 & sdot;h)). The superior corrosion resistance is primarily attributed to grain refinement, which increases the short-range diffusion channels centered on grain boundaries and dislocations in the coating. The nano-crystalline and amorphous forms of Cr2O3 and SiO2 oxide scale on the coated surface effectively hinder the rapid diffusion of corrosive media, thereby reducing the corrosion rate.

LaCrO3 coatings hold great potential for the thermal protection of ultrahigh-temperature components such as rocket engine nozzles. However, they suffer from inherent limitations, including low emissivity and insufficient durability under operating conditions of 1000–1300 °C. This study overcomes these challenges through a dual-scale “composition–structure” codesign approach: Si‒Ca codoping induces Cr³⁺ impurity energy levels and narrows the bandgap to enhance infrared absorption. The plasma spraying injection mode was controlled to create a porous structure with approximately 20% porosity, reducing the elastic modulus and inducing crack deflection/forking to increase toughness. The resulting coating achieved a stable emissivity of >0.94 and demonstrated durability through 15 thermal cycles at 1200 °C.

With the continuous growing demand for heat dissipation of high-power devices such as chips, the development of high-performance thermal interface materials has become increasingly urgent. Carbon fibers possess excellent potential for high thermal conductivity applications, whereas their internal heat transfer mechanisms remain unclear so far. In this study, a numerical model based on the random sequential adsorption (RSA) algorithm is developed to investigate the thermal conduction mechanisms of polymer-based thermal interface materials reinforced with a hybrid filler system comprising carbon fibers (CFs) and alumina (Al2O3) particles of different sizes. The results indicate that small-sized Al2O3 particles can fill the gaps between CFs and large-sized Al2O3 particles, thereby enhancing the connectivity of the thermal network, whereas large-sized Al2O3 particles provide more efficient phonon transport pathways. A size-dependent trade-off exists between these two effects. When the volume ratio of large- to small-sized Al2O3 particles is 60:40, a synergistic and efficient three-dimensional thermal conduction network is established. This study not only elucidates the synergistic thermal conduction mechanism between aligned carbon fibers and multi-scale alumina, but also provides crucial theoretical guidance for the design of high-performance thermal interface materials, showing great application potential in the thermal management of high-power power electronic devices.

To meet the demands for high thrust-to-weight ratios and reusability, rocket engines require thermal barrier coatings (TBCs) capable of withstand 1800 u00B0C for prolonged durations. This study presents a novel quaternary rare earth-stabilized cubic zirconia (RSZ) material and systematically optimizes double-ceramic-layer (DCL) RSZ/yttria-stabilized zirconia (YSZ) coating architectures. The optimized structureu2014with a total thickness of 350 u03BCm and a YSZ-to-RSZ thickness ratio of 1 : 1u2014exhibits outstanding thermal shock resistance at 1800u202Fu00B0C, achieving a lifespan of 15 cycles and thereby satisfying the performance benchmark for rocket engines under such extreme conditions. In this optimized configuration, failure proceeds through sintering-induced localized spallation, a comparatively gradual process that contributes to prolonged coating durability. These findings highlight the strong potential of RSZ/YSZ coatings for application in next-generation rocket engines operating at 1800u202Fu00B0C.

The development of flexible phase change composites (PCCs) with high latent heat, low leakage, and reliable performance in harsh environments remains a great challenge. This study presents a novel PCC by employing acrylonitrile butadiene rubber (NBR) as a flexible matrix, palmitic acid (PA) as the phase change material, and polydopamine-modified montmorillonite (DMMT) as a barrier filler. NBR grade with 26% acrylonitrile content exhibited optimal compatibility with PA, driven by a close match in dispersion surface energy components. The DMMT, uniformly dispersed and exfoliated within NBR, constructed a tortuous labyrinth, which worked with the NBR crosslinking network to encapsulate the PA. This endowed the PCC with a high latent heat of 118.6 J g-1 and low leakage rate (1.1% after 8 h at 80 degrees C). Furthermore, the PCC demonstrated outstanding cyclic stability and remarkable performance retention in transformer oil. This work provides profound insights into the compatibility mechanism and an effective preparation strategy for high-performance PCCs, demonstrating great potential for thermal management applications in harsh conditions.

High-temperature sodium heat pipes with a large length-to-diameter ratio(L/D) are core heat transfer components of heat pipe-cooled reactors (HPCRs). A three-dimensional model was developed by integrating the Volume of Fluid (VOF) multiphase flow model, Lee phase-change model, and user-defined functions (UDFs). This integrated approach enables dynamic tracking of the vapor-liquid interface and coupled simulation of the evaporation and condensation processes. A systematic analysis was conducted to evaluate the effects of heat flux, heating methods, and structural parameters on the thermal performance of heat pipes. The results indicate that while increasing the heat flux (from 45 to 90 kW/m2) reduces the effective thermal resistance, it also exacerbates the wall temperature fluctuation; Non-uniform heating, such as a cosine distribution, increases thermal resistance by 67% compared to uniform heating; Localized heating on half of the evaporation section leads to a higher temperature gradient, a 47% increase in thermal resistance, and an increased risk of reaching the capillary limit. Structural optimization shows that the heat transfer performance is optimal when the porosity is 0.7; increasing the bending angle to 45 degrees increases the thermal resistance by 39%; the thermal resistance is the lowest when the filling ratio is 100%, which is 11.52% lower than that at 80% filling ratio, the lower filling ratio induces a steeper temperature gradient, indicating potential dry-out. An increase in the L/D can readily trigger the capillary limit, leading to a degradation of the heat pipe's heat transfer performance. This study provides valuable insights and theoretical support for the design and performance optimization of HPCRs in extreme environments.

Decarbonizing transportation requires approaches that embed renewable generation into existing infrastructure. Here we show that roadside photovoltaic deployment along China's roads and railways can be quantified using a geospatial framework that links segmented transport corridors to meteorological grids. The approach maps 480,019 km of transport infrastructure to 4,133 meteorological grids and provides a scalable alternative to coarse regional averaging. Across all deployment scenarios, roadside photovoltaic systems could support 40.91-202.84 GW of installed capacity and generate 56.6-239.2 TWh of electricity annually. Under the baseline scenario, annual generation reaches about 100.6 TWh, equivalent to about 50% of current transport-sector electricity demand. The resulting carbon reduction reaches 33.62-143.97 Mt CO2 annually. The results reveal strong regional heterogeneity, with North and Central China showing the highest near-term potential, while Northwest China could act as a generation-export region. These findings provide a basis for region-specific infrastructure planning and more coordinated transport-energy system integration.

To meet the demands for high thrust-to-weight ratios and reusability, rocket engines require thermal barrier coatings (TBCs) capable of withstand 1800 degrees C for prolonged durations. This study presents a novel quaternary rare earth-stabilized cubic zirconia (RSZ) material and systematically optimizes double-ceramic-layer (DCL) RSZ/yttria-stabilized zirconia (YSZ) coating architectures. The optimized structure-with a total thickness of 350 mu m and a YSZ-to-RSZ thickness ratio of 1 : 1-exhibits outstanding thermal shock resistance at 1800 degrees C, achieving a lifespan of 15 cycles and thereby satisfying the performance benchmark for rocket engines under such extreme conditions. In this optimized configuration, failure proceeds through sintering-induced localized spallation, a comparatively gradual process that contributes to prolonged coating durability. These findings highlight the strong potential of RSZ/YSZ coatings for application in next-generation rocket engines operating at 1800 degrees C.

In Vessel Retention (IVR) strategy is an important measure to prevent leakage of radioactive melt, and the key to achieve the IVR strategy is to maintain the heat load at the lower head of the pressure vessel below the critical heat flux (CHF). This study introduced the application of machine learning methods in the field of pool boiling, using multilayer perceptron (MLP) and convolutional neural network (CNN) models to identify boiling states (natural convection, nucleate boiling, film boiling) and predict the heat flux based on boiling images. The CNN model was found to be more accurate in boiling state identification with up to 100 % accuracy than that of MLP model. Image resolution and orientation angle had a coupling effect on boiling state identification, and the prediction accuracy increased with increasing orientation angle when the image resolution was 16 x 9 px. The MLP model could effectively predict the heat flux based on images, with an average absolute percentage deviation of less than 5 % for predicting test data at different orientation angles. The single model had certain limitations in predicting the full range heat flux. The segmental prediction model could achieve better prediction results, and the prediction results of the low heat flux region were better than those of the high heat flux region.

Efficient thermal management is indispensable for the rapid development of electronic devices and systems, especially when hot spots with ultra-high heat flux are encountered more frequently. By utilizing the high heat dissipation capacity of thin film phase-change, the integration of nanoporous membranes and parallel square microchannels (PSMC-NM) achieved heat flux higher than 600 W/cm2. To further enhance flow and thermal performance, two novel hybrid heat sinks, namely, snowflake square microchannel integrated with nanoporous membranes (SSMC-NM) and radial convergent microchannel integrated with nanoporous membranes (RCMCNM), were designed and numerical simulation evaluated. The unique designs of snowflake square microchannel and convergent microchannel show a prominent role in achieving stable liquid supply for liquid film. In comparison with PSMC-NM, SSMC-NM reduces pressure drop (Delta P) by 44% through shortened flow paths and enhanced flow uniformity. As for RCMC-NM, the convergent microchannel improves the uniformity of fluid supply for the nanoporous membrane, thereby preventing severe dry-out and overheating. Consequently, RCMCNM demonstrates excellent thermal performance, with total thermal resistance (Rt) accounting for about 66% and 60% of that of SSMC-NM and PSMC-NM, respectively. Based on the comparative analyses, multi-objective optimization was carried out to identify optimal geometric parameters for RCMC-NM. Four geometric parameters concerning both microchannel and the nanoporous membrane were chosen as design parameters. The optimization targeted simultaneous minimization of Delta P and Rt while maintaining heat source temperature inhomogeneity (dT) below 0.1. Sensitivity analysis revealed the effect of each geometric parameter on target parameters, and confirmed the inverse relationship between Delta P and Rt. Through NSGA-II optimization, a pareto optimal solution set comprising 532 combinations of Delta P and Rt was obtained. Multi-objective optimization of RCMC-NM further demonstrates an 80.8% reduction in Delta P at equivalent Rt, highlighting its exceptional thermalhydraulic performance. These findings provide scalable heat dissipation solutions for ultra-high heat flux, while the optimization methodology provides a blueprint for designing devices and systems with excellent thermalhydraulic performance.

Si-based environmental barrier coatings (EBCs) are indispensable for SiC composites. However, the service temperature of next-generation composites exceeds 1400 degrees C, leading to melting of the Si bond coat. To mitigate this issue, Yb2Si2O7 (YbDS) and mullite/YbDS coatings without Si bond coat were proposed. The results indicate that YbDS coatings can survive for 150 h at 1425 degrees C, while mullite/YbDS coatings experienced significant spallation during this period. Both SiO2 phase transition and interfacial holes cause spallation of the YbDS and mullite/YbDS coatings. This research provides valuable insights for designing next-generation EBCs.

With the Main Document advancement of market liberalization, energy storage, as a key technology for energy transition, has seen diversified investment entities. However, a significant unresolved issue in deregulated markets is how to assess the market power of energy storage, especially considering the diversity of ownership. This paper introduces a data-driven analysis framework to study the interaction between storage ownership and market behavior. The paper establishes a bi-level, agent-based model that effectively captures the dynamic relationship between strategic market behavior of storage and system operation. To enhance the scalability of the model, this paper designs a correlation analysis algorithm based on random forests, elucidating the relationship between different market boundary conditions and storage market behavior. Case study results demonstrate that energy storage exercises market power, particularly by creating flexibility scarcity, can obtain over 16% excess revenue by influencing inter-temporal electricity prices. Furthermore, the ownership of energy storage significantly impacts its market behavior and the transfer of social welfare, increasing approximately 11% excess revenue when collaborating with flexible units. It is hoped that the analysis framework proposed herein will offer valuable insights for the design of market mechanisms and policies pertaining to energy storage.

To meet the growing demand for high thrust-to-weight ratios and reusability, modern rocket engines require thermal barrier coatings (TBCs) capable of enduring temperatures up to 1600 degrees C for prolonged durations. However, samples coated with pure yttria-stabilized zirconia (YSZ) failed within just 90 s under such conditions. This study introduces YSZ/quaternary rare earth-stabilized zirconia (RSZ) double-ceramic-layer (DCL) TBCs to improve performance. Compared with both the pure YSZ and RSZ coatings, the RSZ/YSZ coatings exhibited substantially longer lifetimes during gradient thermal shock testing at 1600 degrees C. The primary failure mechanism identified was sintering within the RSZ layer. These results support the potential application of RSZ/YSZ DCL TBCs in rocket engines operating at temperatures up to 1600 degrees C.

Al2O3 is extensively utilized as an oxidant barrier in aeroengines and gas turbines at elevated temperatures, and small-angle grain boundaries significantly reduce its oxygen permeation. However, experimentally observing and regulating these small-angle grain boundaries poses considerable challenges. In this study, we search for these small-angle Al2O3 grain boundaries via first-principles calculations. We identify two families of ultralow-oxygen-diffusion grain boundaries, namely, Gb(xxx)/(001) and Gb(xxx)/(110), whose diffusion rates are 2 to 4 orders of magnitude lower than those of conventional grain boundaries. On the basis of these findings, we summarize and analyze the influence mechanisms and relative importance of various factors affecting grain boundary permeation. Our results indicate that, in addition to the grain boundary angle, the average bond length and band gap play primary roles in impeding oxidant transport. Finally, the [0001] selective nucleation growth of alumina was achieved by stepwise sintering, and ultralow-oxygen-diffusion Gb(104)/(110) was successfully prepared, which was consistent with the simulation results. These findings provide valuable insights for the design of ultralow-oxygen-diffusion Al2O3 grain boundaries, thereby significantly enhancing the oxidation resistance of aluminum-containing superalloys.