The main technical challenges for ultra-supercritical coal-fired power plants in low-load flexible operation are the long state conversion time between dry and wet state, and the unclear safety boundary for wet state operation. In this paper, a dynamic model of the wide-load operation of a ultra-supercritical coal-fired power generation unit and a water wall temperature analysis model were established. The dynamic response characteristics and the water wall temperature distribution after the boundary conditions change during wet state operation were discussed. The results show that when the water wall recirculation water flow increases by 20%, the economizer inlet water temperature will increase by 9.7°C, the under-enthalpy of the work medium entering the water wall will decrease, and the maximum wall temperature of the water wall will increase by 16.9°C. When the boiler fuel supply rate increases by 5.0%, the separator outlet temperature will increase by 4.2°C, the unit output power will increase by 4.1 MW, and the quality of the steam/water will increase. Under the limitation of wall overtemperature, the orderly utilization of heat storage in the recirculation system is conducive to achieving smooth, flexible, and safe state conversion during low-load operation.

Compressed Carbon Dioxide Energy Storage (CCES) technology has attracted much attention due to its advantages of large scale, environmental friendliness and easy coupling of carbon capture systems. In this paper, a new system for coupling compressed CO₂ energy storage and carbon capture coal-fired units is proposed. The system uses CO₂ captured by coal-fired units as the working fluid of CCES system, and realizes the deep coupling of carbon capture coal-fired units and CCES system through the comprehensive utilization of heat energy. In this paper, the thermodynamic model of the coupling system is built, and the thermodynamic characteristics of the system are analyzed to obtain the optimal coupling mode of the CCES system and the carbon capture coal-fired unit. The results show that compared with the carbon capture coal-fired unit, the thermal performance optimization effect of the coupling system increases with the increase of the energy storage and release time ratio. When the energy storage and release time ratio is 2.16, compared with the carbon capture coal-fired unit, the thermal efficiency and exergy efficiency of the coupling system increase by 0.45% and 0.37% respectively, and the coal consumption decreases by 24.9 g/kWh. The energy storage efficiency of the CCES system is 70.7%. This study is of great significance for the development of CO₂ energy storage technology and the realization of dual-carbon goals.

The low-temperature distillation separation technology utilizes the boiling point differences of various hydrocarbon components in associated gases to gradually condense and separate light hydrocarbons into products. This process is essentially a complex coupled phenomenon of fluid flow, heat transfer, and mass transfer, which becomes even more intricate when azeotropic phenomena are involved. This study employs molecular dynamics simulation to investigate the vapor-liquid interfacial characteristics of the CH₄-C₂H₆-CO₂ ternary mixture at low temperatures. Initially, different molecular force field models were used to construct the initial vapor-liquid interface, and the accuracy of the models was validated. Subsequently, the behavior of the ternary mixture at various temperatures was simulated to analyze the density distribution, stress distribution, and azeotropic phenomena at the vapor-liquid interface. The results indicate that C₂H₆-CO₂ forms a binary azeotropic mixture under specific conditions, and temperature variations significantly affect the structure and characteristics of the vapor-liquid interface. This research provides an important microscopic perspective for understanding vapor-liquid interfacial phenomena in low-temperature distillation and offers a theoretical basis for optimizing related separation processes. 

With the technological advancement of hydrogen trains around the world, the continuous breakthrough in the demand for long range has increased the difficulty of matching the design of hydrogen refueling stations. Mobile hydrogen refueling stations meet the operational requirements of trains well due to its maneuverability, but requiring the integration of all components within a specified enclosed space. Reducing the volume of the storage system is of importance for mobile hydrogen refueling stations to lower its cost, increase the hydrogen utilization rate, and decrease the footprint. In this work, the configuration modeling and analysis of the storage system for mobile hydrogen refueling stations oriented to trains are carried out. Firstly, the number of pressure divisions and switching points of the station storage system are optimized, and a 7-division average pressure multi-division strategy is proposed. A thermodynamic model is established from the station side to the vehicle side, then the refueling process of the proposed multi-division strategy is simulated under different number of refueling guns. The results show that: 1) with the increase of the number of pressure divisions, the volume of the storage system decreases, and the average pressure multi-division strategy corresponds to a smaller volume; 2) the mass flow rate increases with the number of refueling guns increases, leading to a shorter refueling duration, higher peak temperature and precooling peak power, lower refueling mass and precooling specific energy consumption. Considering the refueling time and precooling power consumption, the optimized configuration to meet the target refueling mass (500 kg) and duration (30 min) is a 7-division average pressure multi-division strategy with parallel refueling of 4-guns. This study provides an reference for the design of hydrogen refueling stations for trains.

With the growing penetration of renewable energy in power grids, enhancing operational flexibility of existing coal-fired units becomes crucial for grid stability. This study proposes a novel molten salt energy storage integration scheme using combined main steam and reheat steam extraction in a 315 MW subcritical coal-fired unit, developing three distinct thermal storage configurations: steam cycle return to condenser, low-pressure cylinder operation, and steam ejector-driven exhaust heat utilization. A comprehensive thermodynamic evaluation based on energy and exergy analysis reveals that the MR-C-a system (combined storage/release operation) achieves optimal performance with 16.19% peak-shaving depth, attaining 50.92% cycle efficiency and 482.198 g/kWh comprehensive coal consumption. Exergy analysis identifies the storage/release subsystem as the critical efficiency determinant, with MR-C-a demonstrating superior exergy efficiency of 37.866%. Parametric studies indicate that elevating the high-temperature storage tank (R1) operating temperature significantly enhances system exergy efficiency. Economic analysis shows a 9.22-year payback period, with peakshaving duration exhibiting greater impact on investment recovery than discount rate. This research provides theoretical foundations and engineering insights for deep peak-shaving retrofits in coal-fired power plants.