All-solid-state sodium batteries are considered a promising technology for large-scale energy storage owing to their intrinsic safety and the natural abundance of sodium resources. Although high ionic conductivity is exhibited by sulfide-based systems such as Na3SbS4, challenges in achieving a balance between ionic transport and electrochemical stability remain. In this study, a synergistic cation-anion co-doping strategy is proposed to overcome the intrinsic trade-off of single-element doping. By using first-principles density functional theory combined with ab initio molecular dynamics, the structural, ionic, and electronic properties of Na3SbS4 co-doped with M6+ (M = W, Mo) and X- (X = F, Cl, Br, I) are systematically investigated. Based on comprehensive analysis, the WCl and WBr co-doped systems are found to exhibit the most balanced performance among all candidates. In these systems, wide electronic band gaps are maintained, ensuring excellent electronic insulation. Simultaneously, competitive room-temperature ionic conductivities, associated with low activation energies, are also achieved. This optimal balance is attributed to co-doping-induced lattice distortions. Through these distortions Na+ migration pathways are reconstructed into highly connected diffusion networks, while structural integrity and electronic stability are preserved. In addition to bulk transport properties, first-principles interface calculations reveal favorable interfacial compatibility between Na metal and WCl/WBr-co-doped Na3SbS4, characterized by stable interfacial adhesion and localized charge redistribution, highlighting their practical applicability in all-solid-state sodium batteries. In contrast, Mo-based and F/I-containing systems are characterized by either narrower band gaps or excessive migration barriers at the current 6% doping concentration. However, improved performance may be exhibited at lower concentrations, which can be attributed to reduced defect interaction and impurity-derived states overlap. Overall, the intrinsic structure-property relationships among lattice distortion, migration dimensionality, and electronic structure in co-doped Na3SbS4 are elucidated in this work. It is demonstrated that synergistic anion-cation co-doping is an effective strategy to achieve concurrent enhancement of ionic conductivity and electrochemical stability. Through these findings, theoretical guidance is provided for the rational design of next-generation high-performance sulfide solid-state electrolytes.

Lithium-ion batteries (LIBs) are increasingly being adopted for applications requiring high energy density, such as energy storage power stations and electric vehicles. However, their thermal safety remains a significant concern, particularly due to the risks of thermal runaway (TR) and battery fires. Efficient battery thermal management systems (BTMS), particularly those based on phase change materials (PCMs), have emerged as a promising solution to address these issues. PCM-based BTMS offer advantages such as effective heat dissipation, temperature uniformity, and low energy consumption. However, the inherent flammability of PCMs poses additional risks, highlighting the need for advancements in their flame-retardant properties and overall thermal stability. Research into PCM-based BTMS has focused on enhancing the thermophysical properties of modified PCMs, including their thermal response rate, latent heat, and flame retardancy. The use of carbon-based, metallic-based, nanomaterial-based and polymer-based additives has been shown to improve the thermal response rate property of PCMs, making them more suitable for demanding applications. Additionally, the development of structure-enhanced PCM-based BTMS, which incorporates design elements aimed at mitigating thermal hazards, has been explored to further improve safety and performance. Despite these advancements, challenges remain in optimizing heat dissipation and improving TR propagation suppression in PCM-based BTMS. Future research directions should prioritize the development of flame-retardant PCMs that can effectively manage both regular operation and extreme conditions, such as TR events. This comprehensive approach is essential for building resilient, self-safety BTMS that ensure the reliability and longevity of LIBs in high-energy applications. By addressing these challenges, future designs can better safeguard against thermal hazards, contributing to the broader adoption of LIBs in various industries.

In the realm of large-scale power system energy storage, sodium-based batteries represent a cost-effective post-lithium energy storage technology, making inorganic solid-state sodium batteries (ISSSB) a critical branch of this development. Inorganic solid-state electrolytes (ISSEs) are the core components of sodium batteries; however, they face significant challenges such as insufficient ionic conductivity, interfacial instability, and dendrite growth, all of which severely hinder practical application. This review critically assesses experimental protocols and theoretical frameworks related to mainstream ISSEs and systematizes optimization strategies aimed at overcoming these challenges. Leveraging integrated insights from both experimental and computational studies, the review first categorizes and summarizes the primary types of ISSEs, namely oxide-, sulfide-, and halide-based electrolytes. It then details interfacial optimization strategies focused on addressing three core interfacial issues: ion transport barriers resulting from mechanical incompatibility, side reactions stemming from electrochemical mismatch, and dendrite formation. Finally, the review advocates prioritizing in-depth research that integrates experimental and theoretical approaches to establish a closed-loop methodology encompassing predictive design, multiscale investigation, mechanistic exploration, and high-throughput automated experimentation, with feedback-driven refinement. This work serves as a comprehensive reference and systematic roadmap for future research on solid-state electrolytes (SSEs).

Compared to the recuperative and non-recuperative supercritical carbon dioxide (sCO2) pumped thermal electricity storage (PTES), the recompression Brayton cycle PTES system exhibits significant thermo-economic advantages. To further explore the potential for improving system round-trip efficiency, two recompression cycle variants, the intercooling recompression cycle and the reheating recompression cycle, have been proposed. Currently, while intercooling and reheating modification measures enhance thermal efficiency, they also lead to a decrease in the coefficient of performance (COP) in heat pump cycle. Therefore, a detailed thermo-economic analysis is necessary to clarify the variation trends in round-trip efficiency and the levelized cost of storage (LCOS). Based on the thermodynamic model and economic model of these three PTES systems (basic recompression system, reheating system and intercooling system), the impacts of key parameters on the thermoeconomic performance indicators in each system are investigated. Furthermore, a multi-objective optimization study is performed on three PTES systems with a net power output of 12.5 MW and an 8-equivalent-hour charge/ discharge time. The optimization results reveal that the round-trip efficiency of the reheating system and intercooling system can reach 70.05% and 70.81%, respectively, with LCOS of 0.124 $/kWh and 0.119 $/kWh, respectively. The round-trip efficiency of the intercooling system is 2.17% higher than that of recompression system, while its LCOS increases by 1.71%. Moreover, the system exergy investigation indicates that turbomachinery is the primary source of exergy losses in the three systems, accounting for 47.4% of the total exergy loss in the recompression system, 43.4% of that in the reheating system, and 46.2% of that in the intercooling system. Compared with the recompression system, the turbomachinery exergy losses of the reheating system and intercooling system are reduced by 0.395 MW and 0.324 MW, respectively. Additionally, the total exergy loss of regenerators in the intercooling system is reduced by 0.130 MW compared to the recompression system. This study provides theoretical foundations for the configuration selection and performance improvement of sCO2 PTES systems.

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 interfacial incompatibility between sodium anodes and sulfide/selenide solid-state electrolytes (SSEs) remains a central bottleneck for all-solid-state sodium batteries (ASSBs). Representative Na3PS4 (NPS), Na3SbS4 (NSS), Na3PSe4 (NPSe), and Na3SbSe4 (NSSe) electrolytes were coupled with Na, Na-Sb, Na-Sn, and Na-K anodes to establish baseline interface energetics, followed by W/Mo/Cr and B/O/F/Cl/Br/I co-doping to generate 304 interfaces. Candidate interfaces were prioritized using tree-based ensemble machine learning with compositional, structural, and low-cost density functional theory (DFT) descriptors. Controlled ablation was used to determine whether the single-point descriptors added information beyond composition and structure. Under grouped validation, modest ranking ability was retained by the formation energy model within the chemical space represented in the training data, whereas the migration model was used primarily for candidate prioritization. Cr/halogen-doped NSS/Na interfaces were prioritized through the integrated ranking for explicit first-principles assessment. The prioritized Cr/halogen-doped NSS/Na interfaces exhibited more negative relaxed formation energies than undoped NSS/Na, while subsequent Dimer searches along predefined directions yielded lower local Na migration barriers. Within the enumerated phase set, complete reduction of both undoped NSS and the CrX candidates was predicted by the Na-rich grand-potential analysis, showing that favorable contact-formation energetics do not imply equilibrium electrochemical stability. Frozen-ion single-point calculations required only approximately 1/248 of the computational cost of full interface relaxation. The cost of candidate prioritization is reduced by the workflow, while the range in which the models can be applied is clearly defined. Final assessments were based on relaxed DFT, Dimer, and grand-potential calculations.

Solar desalination systems commonly suffer from intermittent freshwater production due to the transient nature of solar radiation and the absence of effective thermal buffering during low- or off-sunshine periods. This study develops and optimizes a hybrid solar desalination system integrating flat-plate solar collectors, a packed-bed latent heat thermal energy storage (TES) tank filled with encapsulated RT65 phase-change material, and a four-effect solar still. A transient numerical framework is developed to describe the coupled thermal interaction among the collector loop, PCM storage tank, heat exchanger, and multi-effect still. The heat-transfer fluid flow is divided between direct heating of the solar still and TES charging, creating a trade-off between immediate freshwater production and delayed thermal supply. Response surface methodology is employed to optimize the total system flow rate Qsys and the TES flow fraction γ. The optimum operating conditions are obtained at Qsys=0.87 m3/h and γ=11%, yielding a distilled water production of 53.30 kg/day. Compared with the optimized conventional system under the same solar radiation profile, collector area, still geometry, and operating duration, the PCM-assisted configuration increases freshwater productivity by 21.97%. The solar-to-evaporation thermal efficiency increases from 50.68% to 62.20%, corresponding to a 22.73% relative improvement. The results demonstrate that optimized latent heat storage can stabilize thermal delivery, extend desalination operation, and improve freshwater productivity in solar-driven multi-effect desalination systems.

Although the introduction of organic molecules into electrolytes effectively suppresses dendrite formation, its adverse impact on ionic conductivity poses a critical challenge for implementing extreme fast charging technologies of aqueous zinc-ion batteries. The effects of addition of N, N-dimethylacetamide (DMA) or methanol (MeOH) on ionic conductivity of ZnSO4 aqueous electrolyte are studied using molecular dynamics simulations. The results show that both DMA and MeOH reduce ionic conductivity of electrolyte, and the reduction is more obvious in DMA systems compared with MeOH systems. The insights into ion conduction proposed mostly in organic electrolyte, such as viscosity, ion states, solvation structures and coordination stability are evaluated for aqueous electrolyte. It is found that the reduced ionic conductivity is related to the increased electrolyte viscosity and the reduced diffusion coefficient of the most abundant ion state. However, the amount of ion states, the size of solvation structures and the coordination stability has no effect on ionic conductivity. New insights into ion conduction are given from the perspective of molecular and ionic motions. A correlation between the reduced ionic conductivity and the weakened electrolyte disturbance, which stems from suppressed rotational and translational motion of additives, is highlighted. This study advances the understanding of ion conduction mechanisms in organic additive electrolytes while offering practical guidance for the selection of additives in electrolyte design.

A solar-driven energy system integrating photovoltaic/thermal (PV/T) collector and heat pumps is investigated to achieve further decarbonization and near-zero emissions in buildings. The capacity configuration and thermalelectrical dynamic operation characteristics for PV/T heat pump system are analyzed through multi-objective optimization. By transient heat current method, dynamic model is established for PV/T heat pump system, primarily powered by solar energy. Under the premise of satisfying user loads and enabling long-term system operation, multi-objective optimization framework is established for capacity configuration and analyzing the impact of PV/T collector quantity, heat source side tank capacity, user side tank capacity and compressor speed on energy, economic and environment performance. Critical thresholds were identified on study data context: PV/T collectors below 75 units show near-linear positive correlation with primary energy ratio and CO2 emission reduction rate, with diminishing returns beyond this point; heat source side tanks require exceeding 10 m3 for continuous operation, with performance gains plateauing above 13 m3; user side tanks exhibit strong cost sensitivity within variation from 2 to 8 m3. Lower compressor speed is optimal for energy-economic balance. Dynamic simulations demonstrated 82.4% domestic hot water demand coverage with 43.9% PV curtailment on optimal design point. The system operational characteristics are analyzed on supply gaps during low-irradiance and high-load demand peaks and suggested possible improvement recommendations. The optimization result emphasizes ensuring thermal energy storage capacity to mitigate solar periodic and intermittency, providing optimal configuration methodology for solar-dominated energy systems.

The dynamic integration of Solid Oxide Fuel Cell (SOFC) systems with power electronics presents significant challenges due to the disparate time scales of thermo-electrochemical processes and electronic control systems. This manuscript develops a unified standard thermal resistance-impedance-circuit approach for grid-connected SOFC systems. This approach provides a comprehensive cross-scale dynamic model, coupling the standard thermal impedance (STI) method for SOFC modeling with power regulation circuit for converter and inverter, which constructs the overall system topology and characterizes the transmission and coupling characteristics of various physical parameters within different components, integrating the multi-physical processes, cross-timescale dynamics and inter-disciplined areas to facilitate real-time simulation and control. On this basis, we analyze the dynamic response processes of power electronics equipment, and SOFC systems under varying load conditions. The results show that the power electronics respond in sub-second time frames (0.15-0.5 s), Balance of Plant (BOP) components have intermediate response times (7-9 min), and SOFC stack exhibit slow response times (25-39 min) when the load changes. This unified model visualizes the transfer and coupling properties of physical parameters within different components, highlights the interactions between the slow thermal-electrochemical dynamics and the fast-switching power electronics, then emphasizes the topology's capacity to handle transient states and ensure robust performance. The proposed framework provides a pathway for enhancing computational efficiency, improving power quality, and ensuring operational stability in distributed energy systems.

Improving the cooling effectiveness of turbine blade squealer tip regions under high thermal loads remains a challenge in designing of gas turbines. This study numerically investigates the cooling performance of a novel protrusion-V-rib composite structure applied to the internal U-channel near the blade squealer tip. Eight configurations, including holed/hole free designs and combinations of V-ribs, protrusions and vanes, are evaluated at Re = 10,000-50,000. Key findings show that holed structures enhance heat transfer near holes due to accelerated fluid velocity and increased turbulence, resulting in higher Nusselt number. However, hole free configurations exhibit superior downstream heat transfer (up to 4.14 % improvement) by maintaining coolant mass flow. Complex geometries, particularly the V-Convex design, significantly suppress flow separation and reduce vortex size by promoting fluid disturbance and turbulence. The V-convex structure exhibits the highest Nusselt number and comprehensive thermal performance factor under both constant temperature and constant heat flux boundary conditions, confirming its robustness. The results highlight the trade-off between local heat transfer enhancement (holed structures) and downstream cooling effectiveness (hole-free designs), emphasizing the importance of geometric optimization for blade squealer tip cooling. This work helps understand the composite cooling structures and provides insights for efficient thermal management in applications of hightemperature turbines.

The tips of turbine rotor blades are among the most prone to failure due to the complex flow and heat transfer within the tip clearance in gas turbines. This paper proposes a novel and pragmatic film cooling structure in blade tips: a V-shaped groove with different film cooling hole arrangements. Compared with the conventional squealer tip, the V-shaped groove effectively expands the film coverage. Numerical simulations are conducted to investigate the flow and heat transfer characteristics of the V-shaped groove and conventional squealer tips at blowing ratios from 0.5 to 2.0. Results indicate that through its unique geometric structure, the V-shaped groove causes coolant jets to attach obliquely to the tip surface, significantly enhancing lateral spreading capability and coverage continuity of the cooling film. All V-shaped grooved tips except the pressure-side hole arrangement show improved film cooling effectiveness compared to the conventional squealer tip, with improvement increases with blowing ratio. Hole arrangement significantly affects cooling performance. The case with holes arranged along the camber line achieves the greatest improvement, with the film cooling effectiveness increased by 24.13% to 40.00% compared to the conventional squealer tip within the blowing ratios. Furthermore, the coefficient of temperature variation effectively reflects the film spreading on the surface and is an evaluation metric for film cooling performance. Although the V-shaped groove has slightly higher leakage than conventional squealer tips due to weaker cavity vortices, its improved cooling performance and good machinability provide a new approach for the optimal design of turbine rotor blade tips.

Spectral beam splitting technology offers a potential solution for limited solar conversion efficiency and local overheating of photovoltaic panels in centralized photovoltaic/thermal (CPV/T) system. In this work, an Ag@Al2O3 core-shell nanofluid-based spectral splitter is integrated into a thermally decoupled system equipped with a compound parabolic concentrator to address spectral mismatch and overheating in CPV/T. A numerical framework is constructed that couple finite-difference time-domain simulation for predicting the optical properties of nanoparticles, a radiative transfer model for the transmittance of nanofluids, and a three-dimensional conjugate heat transfer model coupled with photovoltaic electrical performance. With the spectral matching factor as the objective, a multi-parameter co-optimization is performed over the silver core diameter, shell thickness, particle mass fraction, and optical path length. The optimal nanofluid is selected, and its combined thermal and electrical performance is evaluated under 4 suns. Results indicate that the silver core diameter governs localized surface plasmon resonance, with absorption dominates below 40 nm, while scattering increases with rise of the diameter, accompanied by higher-order modes. The Al2O3 shell redshifts the resonance peak and provides chemical protection. Multi-parameter optimization yields an optimal design with 30 nm of silver core diameter, 5 nm shell thickness, 66 ppm mass fraction of nanofluid, and 19 mm optical path, yielding a spectral matching factor of 0.3916, achieving electrical efficiency of 12.82%, thermal efficiency of 67.76%, and total exergy efficiency of 17.76%. This work provides a systematic design framework for spectrally tunable, nanofluidbased CPV/T systems.

Photovoltaic thermal heat pump systems can simultaneously provide electricity and heat, but their thermal performance may decrease under low ambient temperature conditions. However, many existing planning and operational studies describe device performance using fixed conversion coefficients or fitted curves, which provide limited insight into how the outlet temperature affects system performance under varying ambient and irradiance conditions. To address this issue, this study develops a physics-based model of a photovoltaic thermal heat pump system and applies it to outlet temperature setpoint analysis and optimization. A proportional integral derivative controller is used to track the prescribed outlet temperature setpoint, and a quantum-inspired particle swarm optimization algorithm is applied to identify the optimal setpoint without requiring gradient information. The results show that the outlet temperature has a distinct optimum rather than a monotonic effect on system performance. This optimum arises from the trade off among increased heat loss at high outlet temperatures, reduced heat pump cycle efficiency at low source temperatures, and pumping power consumption. Compared with a fixed high outlet temperature baseline, the optimized setpoint increases the mean pointwise electrical efficiency by 0.68% to 2.14% and the mean pointwise thermal efficiency by up to 43.7%, with larger thermal gains under cold conditions. The proposed framework provides a physically interpretable method for determining outlet temperature setpoints and improving the operation of photovoltaic thermal heat pump systems.

The scarcity of freshwater in arid regions necessitates reliable and sustainable desalination methods. While traditional solar-powered stills offer a viable solution, their performance is inherently limited by daily solar intensity, leading to inconsistent freshwater production. This study introduces an innovative integrated system that couples a solar still with a latent/sensible heat packed bed thermal energy storage unit. This novel design aims to achieve stable, continuous freshwater production throughout both day and night. This research addresses a research gap in the existing literature by providing a comprehensive analysis of this integrated system under realistic solar conditions. A numerical model has been developed, coupling differential equations for a solar still and solar collector with a dispersion concentric model for a packed bed storage system. The system's performance has been assessed under Sinai Desert solar conditions and validated against existing literature. Various phase change materials (PCMs), sensible heat storage materials, and geometric parameters were analyzed. Results showed that RT65, as a PCM, delivered the best performance with 40.94 % thermal efficiency and 26.17 kg/day freshwater output. Among sensible heat materials, quartzite rock performed optimally, achieving 34.31 % efficiency and 21.90 kg/day water production. Further analysis revealed that smaller storage capsules (20 mm diameter) and lower bed porosity (0.22) enhanced distilled water yield to 27.04 kg/day with 42.29 % system efficiency. The geometric optimization of the solar still resulted in maximum freshwater production of 29.51 kg per day when using a length of 6.75 m with a first effect water depth of 0.04 m and subsequent effect depths of 0.06 m, demonstrating how staged water depth variations significantly improve system performance. Additionally, various correlations have been developed to predict accumulated distillate output and system efficiency, aiding in system performance estimation. These findings provide critical insights for designing efficient integrated thermal storage and desalination systems in arid regions.

The utilization of hydrogen could help reduce carbon emissions in the energy industry and achieve carbon neutrality. In this paper, the conventional hydrogen-oxygen combined cycle (HOCC) is first analyzed, and then the novel HOCC for combined heat and power is proposed and analyzed. Afterwards, two integrated systems based on the novel HOCC are proposed with the corresponding operation strategies. In integrated system 1, the proton exchange membrane electrolyzer is used for hydrogen production utilizing the wind power during nighttime, while the hydrogen is used for driving the novel HOCC for heating and power output along with air source heat pump during daytime. In integrated system 2, multi-stage flash desalination is added for producing freshwater, compared with integrated system 1. The thermodynamic and economic performances of integrated systems 1 and 2 are evaluated through a case study. Thermodynamic analysis shows that: the heating output is higher and the power output is lower in integrated system 1. While the heating output is lower and the power output is higher in integrated system 2. The average exergy efficiency of integrated system 1 on the four typical days are 36.55 %, 38.10 %, 37.25 %, and 37.48 %, those of integrated system 2 are 36.89 %, 35.29 %, 34.43 %, and 36.48 %. Economic analysis suggests integrated system 1 outperforms integrated system 2: the dynamic payback periods for integrated systems 1 and 2 are 11.68 and 12.97 years, with the corresponding net present values being 14.12 and 12.26 million USD.

In the cold-end system of indirect dry cooling power plants, circulating water acts as the heat transfer medium, which absorbs waste heat from turbine exhaust steam in the condenser and releases heat to ambient air via air-cooled heat exchanger. To improve the overall heat transfer efficiency under windy conditions, it is essential to regulate the circulating water flow in each cooling sector to match the local air-side heat dissipation capacity. Accordingly, this study proposes an circulating water flow regulation strategy based on the principle of uniform water outlet temperature. Practically, a pipe network resistance model is further coupled with the proposed strategy to achieve accurate power consumption calculation of circulating water pumps, where the sector-level circulating water flow rate is adopted as the intermediate coupling parameter bridging the water-side and air-side heat transfer processes. The operating performance of the adjusted strategy is comprehensively compared with the conventional uniform circulating water flow distribution scheme, and the pump power consumption characteristics under various ambient conditions are quantitatively analyzed. The simulation results demonstrate that the regulation effect is enhanced with increasing ambient wind speed and weakened as the ambient temperature rises. Furthermore, the proposed strategy reduces the total circulating water flow rate under fixed heat load conditions. A maximum circulating water pump power saving of 0.597 MW is achieved at an ambient temperature of 287.15 K and a wind speed of 10 m/s. This work provides a feasible optimization scheme for the energy-efficient operation of indirect dry cooling power plants.

Improving electrochemical performance while maintaining thermally stable operation is a critical challenge in the design of flow fields for proton exchange membrane water electrolyzers (PEMWEs). In this paper, a hexagonal honeycomb-like geometric-gradient flow field (HLGFF) is proposed and numerically investigated as an evolution of the conventional honeycomb-like design. The proposed HLGFF is designed to mitigate under-rib mass transfer limitations and gas accumulation by redirecting part of the in-plane flow momentum toward the through-plane direction, thereby enhancing reactant supply and gas removal near the reaction interface. A three-dimensional, two-phase, non-isothermal multiphysics model is developed and experimentally validated using a parallel flow field configuration. Numerical results indicate that the HLGFF significantly enhances mass transport and electrochemical performance, achieving a maximum current density increase of 17.72% at the same operating voltage compared with conventional flow field designs. Despite operating at higher current densities and increased heat generation, the HLGFF maintains a well-controlled temperature distribution comparable to reference configurations, reflecting effective flow-field-induced heat redistribution. These results demonstrate that the proposed design achieves a favorable balance between electrochemical performance enhancement and thermal stability, offering a promising flow field strategy for high-performance PEMWE applications.

The cross-sectional contraction of internal cooling passages in gas turbine blades fundamentally impacts coolant delivery, a critical effect overlooked by constant-section models. This numerical study investigates how longitudinal channel contraction (contraction angles CA = 0 degrees, 7 degrees, 13 degrees) governs the downstream evolution of flat-plate film cooling performance. Using a validated Realizable k-epsilon model, we demonstrate that contraction angle critically alters the internal vortex dynamics, shifting the dominant flow structure from a central swirl vortex to wallhugging helical vortices. This restructuring induces strong spanwise asymmetry and changes the vortex structure of the downstream hole. Simultaneously, the cooling effectiveness is redistributed along the channel, a critical phenomena that remains undetected in uniform cross-sections. At a low mass flow ratio (MFR = 0.614 %), high contraction (CA = 13 degrees) triggers mainstream ingestion, nearly eliminating cooling from the most downstream hole. Conversely, at a moderate MFR (1.228 %), a CA of 13 degrees enhances lateral coverage for mid-channel holes. The discharge coefficient exhibits a complex, non-monotonic dependence on CA and MFR, increasing at high MFR due to separation suppression. However, this potential benefit is countered by a consistent rise in pressure loss with contraction angle. This research provides novel insights and essential design guidelines for optimizing internal cooling channels in real engine blades, where geometric contraction is inherent.

The operational efficacy of hydrogen-fueled gas turbines is constrained by severe thermal management challenges arising from the interplay between high-temperature, steam-rich combustion products and inherent flow non-uniformities generated by modern swirl combustors. This study systematically investigates the conjugate heat transfer characteristics of turbine vane film-cooling systems under such conditions through a rigorous computational framework implementing three canonical combustor-exit patterns (Uniform, Central Core, and Dual-Core Flow) on a flat-plate configuration. Our approach innovatively integrates entropy generation rate analysis with conventional thermal performance metrics to quantify both aerodynamic losses and cooling effectiveness under non-uniform steam concentration and temperature distributions. It is demonstrated that the Dual-Core Flow configuration achieves optimal cooling performance across all streamwise locations, with coupled cooling effectiveness increasing substantially at higher blowing ratios. Notably, the non-uniform inflow pattern asymmetrically modulates the heat transfer coefficient by altering the vortex structure in the shear layer. Meanwhile, the presence of steam suppresses irreversible thermal entropy generation while enhancing irreversible viscous entropy generation, particularly near wall boundaries where entropy production surpasses mixing-zone levels by significant margins. The maximum local irreversible heat transfer dissipation caused by water vapor reaches 8.4%. Furthermore, substrate temperature homogeneity proves most sensitive to Uniform Flow conditions, with ceramic top coat thickness exhibiting negligible influence on temperature uniformity. This work provides fundamental insights for advancing thermal barrier coating integration strategies in hydrogencombustion environments, establishing a critical foundation for optimizing next-generation turbine cooling architectures against complex thermo-fluid interactions characteristic of zero-carbon power systems.