Supercritical carbon dioxide (S-CO₂) power generation technology offers better flexibility, and its substitution for steam power generation technology in the field of thermal power generation is of significant strategic importance for constructing a new type of power system, establishing a modern energy system, and achieving the “dual carbon” goal. Through numerical simulation and experiment, the flow and heat transfer characteristics of S-CO₂ boilers within the actual operating range are analyzed, and the influence of working fluid flow states and physical properties on heat transfer and resistance performance is also investigated. The results show that, the heat transfer coefficient of CO₂ decreases with the thermal conductivity under the same flow conditions. This is because the thermal resistance of the fluid boundary layer increases as the thermal conductivity decreases. Under the same thermal conductivity conditions, the heat transfer coefficient of CO₂ increases with the Reynolds number (Re). The reason is that the fluid boundary layer becomes thinner as Re increases, reducing the boundary layer thermal resistance. For CO₂ working fluid inside the pipe with pressures ranging from 3 MPa to 30 MPa, enthalpy values of 500~1 150 kJ/kg, and Re between 1.1×10⁵ and 2.1×10⁶, a correlation formula for heat transfer considering boundary layer property corrections is derived. The average deviations are 3.33%, demonstrating it has high precision. The research lays a solid foundation for the design and research of subsequent S-CO₂ boilers.

In order to solve the problems of difficult, high cost and poor accuracy of state-of-charge (SOC) estimation for vanadium redox flow batteries (VFB), a joint SOC estimation method is proposed, based on forgetting factor recursive least squares (FFRLS) and multiple innovation unscented Kalman filter (MIUKF). The FFRLS algorithm is used to identify the equivalent circuit model parameters of vanadium redox flow batteries online, and the MIUKF algorithm is used for SOC estimation, so as to achieve the purpose of accurately estimating the SOC of vanadium redox flow batteries. Finally, a 5 kW/30 kW·h vanadium redox flow battery is taken as experimental platform to verify the method. The experimental results show that, compared with the RLS-UKF algorithm and FFRLS-UKF algorithm, the FFRLS-MIUKF algorithm has lower mean square error and root mean square error in the charging and discharging phases, which are 0.003 7, 0.060 9 and 0.001 3, 0.036 3.

It is a common problem that the direct air-cooled unit cannot be fully charged during the high temperature period in summer, and the widely used solution is to install a sprinkler device in the air-cooled unit for humidification and cooling. Through analysis on the air flow field in the cooling unit, it is found that the air flow field in the silo is non-uniform due to the influence of fans and bridges. The method of non-uniform arrangement of nozzles in the air flow field is used to evenly mix the air and spray water, and the high-pressure spray is used to achieve a uniform temperature drop in the overall air field to minimize the temperature of the cooling air. This method effectively solves the problem of cooling and improves the efficiency of air-cooled units in summer, and is of great significance for peak operation of thermal power units in summer.

At present, foreign brands almost occupy the entire fan lubrication market share, and domestic oil products lack opportunities to enter the market. To demonstrate the feasibility of domestic substitution of lubricating oil for wind turbine gearboxes, the testing and analysis database for domestic gearbox lubricating oil and foreign competitors is established by adopting laboratory analysis to test the physical and chemical performance indicators (including kinematic viscosity, viscosity index, flash point, pour point, moisture, acid value, demulsibility, foam characteristics, liquid phase corrosion, and copper corrosion), tribological performance indicators (sucn as maximum seizure free load, sintering load, friction coefficient, wear spot diameter, comprehensive wear), and other lubricating oil performance indicators (like antioxidant performance, ferrography, infrared spectroscopy, and PQ index). The comprehensive performance of domestic gearbox lubricating oil products is systematically evaluated, and the feasibility study of domestic substitution of wind turbine lubricating oil is completed. The results indicate that there is not much difference in the basic performance indicators between domestic brand fan gearbox lubricating oil products and imported brands, and the substitution is feasible.

To achieve simulation validation for the control software and hardware platform of a gas turbine control system, the co-simulation method based on real-time and virtual environments is studied. A real-time simulation hardware platform is built using a real-time simulator, signal conditioning devices, and fault injection devices. Additionally, a detailed simulation model of the gas turbine and fuel system is developed based on multi-domain physical modeling methods, taking into account dynamic factors such as thermal soak effects, volume effects, and rotational inertia. A virtual simulation environment is constructed using a virtual controller for the control system, and logic modeling methods are used to create simulation models for auxiliary systems such as the lubrication and electrical systems. Signal interaction between the real-time simulation platform, virtual simulation platform, and control system hardware platform is achieved through hardwiring and communication methods, enabling integrated co-simulation operation. The results show that, the co-simulation method, combining real-time and virtual environments, not only provides a lightweight simulation environment for the gas turbine control software, encompassing all critical link elements, but also allows for functional and performance testing of the control logic. Moreover, it offers a validation environment for the control system hardware platform under various gas turbine operating conditions, enabling functional and performance testing of the hardware in multiple operational scenarios. This research can be applied for integrated validation of both software and hardware in gas turbine control systems, supporting the development of domestic gas turbine control systems and the retrofitting of control systems in existing units for domestic applications.

In order to solve the corrosion problem of direct air cooling condensers, the independently developed dynamic corrosion simulation test device is used to simulate the actual operating conditions of the initial condensate, and the alkalizing agent and oxidant with low vapor-liquid distribution coefficient are selected for the flow accelerated corrosion test of carbon steel. The results show that, both alkalizing agent and oxidant can effectively inhibit the accelerated corrosion of direct air-cooled condenser. The rapid change of water flow direction has little effect on the accelerated corrosion rate of flow. Under the same conditions, the flow accelerated corrosion rate of carbon steel in oxidant environment is much lower than that in alkalizer environment. When oxidant is added to the direct air-cooled condenser for anticorrosion, the production cost of a single unit can be saved by 523 700 yuan per year.

Biomass contains a high content of alkali metal elements, which can cause serious slagging problems during the combustion process. Coal gangue is a kind of bulk solid waste, and its resource utilization is an urgent need. In order to solve the problem of biomass combustion slagging and coal gangue utilization, coal gangue was used as an additive and mixed with sunflower straw for combustion. Physical and chemical characterization of the burned ash samples were carried out using thermogravimetric analysis (TG-DTG), inductively coupled plasma spectrometry (ICP-AES), and ash melting point tester. The effects of temperature and ratio on the combustion performance and slagging of mixed fuels were also investigated. The research results show that, during the combustion of sunflower straw, the addition of a small amount of gangue significantly increased the alkali metal content in the ash. More of these metals were converted into high-melting-point silica-aluminates, which were fixed in the ash samples, while the gaseous alkali metal content decreased. As a result, the tendency for slagging during combustion was reduced. At the same time, the sunflower straw reduced the ignition point and burnout temperature of the gangue, thereby promoting its combustion. The synergistic effect was obvious. When the proportion of coal gangue was 20%, the flammability index of the fuel reached 9.36×10^–4%/(min·℃), and the comprehensive combustion characteristics index reached 42.6×10^–7%/(min²·℃³). The combustion performance was optimal, with a softening temperature of 1 470 ℃, and the tendency for slagging was significantly reduced.

The experimental data and simulation studies on ammonia co-combustion in coal-fired power plants in recent years are investigated, with a focus on the effect of ammonia fuel on NO_x generation. Through experimental observation, numerical simulation, and theoretical analysis, the spatial distribution of soot and polycyclic aromatic hydrocarbons (PAHs) during combustion is directly observed using high-speed cameras, laser-induced ignition (LII) method, and laser-induced fluorescence (PAH-LIF) method. It finds out that, the generation of NO_x during ammonia combustion is significantly higher than that of the conventional hydrocarbon fuels. Reasonable design of ammonia nozzles and selection of appropriate injection positions can significantly reduce the NO_x generation. The ammonia blending combustion technology provides a promising approach for achieving low-carbon transformation of coal-fired power plants. Although there are still challenges in the industrial application of large-scale ammonia blending combustion technology, the application prospects of ammonia fuel in coal-fired power plants are broad through continuous experimentation and technological optimization. Future research should continue to focus on the generation and emission of other pollutants during the process of ammonia combustion, and explore in depth the transformation behavior of minerals in coal in the combustion environment, providing theoretical and practical support for the industrialization of ammonia combustion technology.

In order to realize cascade utilization of energy in the heating system, in view of the problem that the heat load of industrial users does not completely match the heat consumption for activated carbon regeneration, the steam-air heater has been installed in flue gas desulpherization and denitration demonstration unit for No.2 coal-fired generation unit in a thermal power plant. Steam becomes primary heat source to realize activated carbon regeneration. Steam extracted from the turbine heats circulating hot air in the FGD unit firstly, then supplies remaining heat energy to different terminals outside the plant after desuperheating. Hereby this article thoroughly describes how to select control valve in steam supply system, so as to realize coupling control of heat energy between two different users. The rationality of this design has been verified during actual operation of the demonstration project, and it provides a reference for the selection of control valves in future engineering practices.

The power generation by co-firing of coal and biomass is the most economical and efficient technology for existing coal-fired power plants to achieve CO₂ emission reduction and large-scale efficient utilization of biomass. However, due to the significant alkali metal content in biomass, serious issues such as ash deposits, slagging, and corrosion arise during co-firing of coal and biomass, posing substantial threats to safe and economically viable operation of boiler equipment. Comparative analysis on slagging characteristics of heating surfaces in coal-fired boilers, biomass-fired boilers, and co-firing boilers of coal and biomass are conducted, with their influencing factors investigated. The slagging characteristic evaluating indicators for boilers firing different fuels and co-firing boilers are comprehensively discussed and evaluated. Furthermore, the applicability of these slagging evaluation indicators in specific boiler equipment is assessed. A comprehensive analysis reveals that the ash components in the fuel determine the physical and chemical properties of ash residues. The ash fusion characteristics reflect the tendency and temperature of solid-liquid transformation of ash residues, whereas ash viscosity relates to ash flowability and its propensity to deposit as slag on heating surfaces. A comprehensive consideration of these aspects enables a more accurate evaluation of boiler heating surface slagging characteristics.