With the rapid global industrialization and urbanization, ensuring continuous water supply and comprehensive water quality management has become a major challenge. Power plant cooling water consumption is significant, and to achieve zero discharge, many plants have adopted desalination measures to increase concentration ratios and enable water reuse. However, existing treatment technologies face high energy consumption, system complexity, and secondary pollution issues. To solve these problems, the application of electrochemical coupling pilot-scale equipment in cooling water treatment is experimentally studied, and the effects of electrochemical coupling pilot-scale equipment on scale removal, corrosion prevention and wastewater resource utilization are analyzed. The results show that, the equipment removes hardness and alkalinity significantly, and reduces conductivity and chloride ion content efficiently. Under conditions with voltage of 3.2 V and current of 240 A, the hardness removal rate reached the highest (5.15% and 55.77%, respectively), and under conditions with current of 250 A and voltage of 3.2 V, the alkalinity removal rate reached the highest (36.96% and 91.41%, respectively). The electrochemical coupling technology offers clear economic advantages compared with the conventional methods, providing an efficient, eco-friendly, and cost-effective solution for cooling water treatment with broad application prospects.

Under the background of “dual-carbon” goal, the combined heat and power units with once through boilers are required to have the ability to quickly change load. To address this need, a strategy based on linear time-varying model predictive control (LTV-MPC) for coordinating electricity and heat to change unit load is proposed, which can simultaneously utilize boiler heat storage and heat network heat storage to improve the rate of variable load. Firstly, the deviation of the heat load signal is integrated to establish an equivalent heat load model, which is used as one of the controlled variables in the prediction model. Then, by taking rapid load tracking, stable unit operation, and timely compensation for heating as the objective of MPC rolling optimization, the optimal control law for each moment is solved online, and then it is applied to the unit. In addition, the operational constraints of the unit are explicitly addressed to ensure that changes in the heating extraction flow rate do not affect the operational stability of the low-pressure cylinder. Finally, simulation verification is conducted on a 350 MW unit, and the results show that this strategy can accurately track the 5%Pe/min variable load command. Furthermore, the heat load recovery time is reduced by 26% compared with that of the electric heating coordinated variable load strategy based on PID. The simulation results have verified the superiority of the proposed strategy in improving the fast load changing capacity of heating units.

The development of efficient energy storage technologies is critical as global energy demand rises and environmental issues become increasingly serious. Large eddy simulation is employed to model the phase change heat storage process in a packed bed system consisting of a double-layer cascade capsule-stacked structure based on the pore scale. The temperature, streamlines, and vortex distributions of phase change materials (PCMs) with various melting points and physical properties are investigated within the structure. The thermal characteristics of the capsule-type stacked structure are analyzed at different entrance velocities, and the simulation results are validated by experimental data. The simulation results demonstrate that, the interstitial flow and vorticity fields of the stacked structure exhibit significant dynamic characteristics during heat storage. At the pore scale, the phase transition induces streamline bending, vortex formation, and the increase of local velocity. After the phase transition, the flow field and vorticity tends to stabilize, with low-vorticity regions occupying most of the area. Eventually, the vortex structure is analyzed by the Q-criterion, revealing that the high-intensity vortices are primarily concentrated near the tank wall.

To address the electricity consumption challenges in remote regions beyond the reach of power grid, a novel off-grid microgrid system integrating wind and solar energy with flywheel storage technology is introduced. Research is conducted on the optimal capacity configuration of distributed power sources, and power output models are developed for wind turbines, photovoltaic arrays, energy storage flywheels, and diesel generators. With economic and reliability indicators as objective functions, and environmental protection indicators as constraints, a capacity optimization simulation for the microgrid system is conducted. By employing the improved NSGA-II algorithm, a multi-objective bi-level coordinated optimization of the microgrid system is performed, resulting in a Pareto optimal solution through multi-objective optimization. The TOPSIS method is utilized for decision-making, ultimately identifying the optimal solution tailored for the microgrid system. The data and conclusions obtained from this study have reference value for engineering applications in related fields.

It is of great significance to carry out health condition assessment and fault early warning of auxiliary equipment for safe operation of thermal power units in new power system. By taking the forced draft fan of a supercritical 660 MW thermal power unit as the research object, a method to construct dynamic memory matrix based on multiple characteristic parameters is proposed. The application shows that the proposed method can improve calculating speed of model effectively while ensuring the accuracy of calculated results. This work also presents a calculation method of weighted coefficients to modify the multivariate state estimation technique (MSET). The global similarity and parameter similarity indexes are introduced for fault early warning and recognition. An early fault warning model based on dynamic matrix and weighted MSET is utilized to simulate faults of forced draft fan. The results indicate that the weighted MSET model can not only improve the prediction accuracy of abnormal parameters under fault conditions effectively, but also reduce the influence of abnormal parameters on the predicted results of normal parameters. Consequently, the model proposed can realize both early warning of forced draft fan faults and recognition of abnormal parameters.

In order to accurately analyze the ash accumulation on photovoltaic panels, a photovoltaic dust visualization experimental platform was built, and the average grayscale value was introduced to numerically analyze the photovoltaic panel images. The clear correspondence between the average grayscale value of photovoltaic panel images and the dust density of photovoltaic panels was verified. On this basis, five fusion methods were used to fuse the visible light images and infrared images collected from the dual spectral image fusion experimental platform. The five types of fusion images were combined with visible light images and infrared images to form an image dataset. These seven types of images were identified and analyzed. The results showed that, the recognition effect of infrared images on the degree of ash accumulation on photovoltaic panels was the least affected by irradiance, with the highest accuracy, and the most significant change in the degree of ash accumulation was reflected. This conclusion can provide a theoretical basis for the study of ash accumulation rules and is of great significance for the recognition of the degree of ash accumulation on photovoltaic panels.

Superheated steam temperature is crucial for safety and economy of coal-fired power units. However, the large inertia and strong uncertainty of superheated steam temperature system make it difficult to control. To solve these difficulties, a cascade control structure based on modified active disturbance rejection control is proposed. The inner loop uses a conventional PI controller and the outer loop uses a modified active disturbance rejection controller. An engineering tuning method for modified active disturbance rejection control is provided, and a response curve to optimize the compensation time constant is designed to address the difficulty of obtaining the compensation time constant. Finally, the advantages of the proposed control strategy in tracking and disturbance rejection performance under large-scale variable loads are verified through comparative simulations and practical engineering applications. The operational data of engineering applications shows that the proposed method can ensure smaller maximum positive and negative deviations, average absolute deviation, and deviation standard deviation, which has significant advantages and potential for engineering applications.

Aiming at the problem of wind turbine off-grid due to lack of high voltage ride through (HVRT) capability of wind power, the internal mechanism of wind turbine off-grid due to voltage increase of junction point caused by DC fault is elaborated. The dynamic reactive power response characteristics of energy storage system and static var generator (SVG) during HVRT are analyzed. Through real-time monitoring of the voltage of the junction point, the priority of the control strategy during HVRT crossing is divided into reactive power regulation inside the wind farm (cooperative control of energy storage system and doubly fed induction generator (DFIG)) and SVG reactive power regulation. On this basis, a collaborative control strategy of energy storage system, DFIG and SVG is proposed to improve the HVRT capability of wind farms. At the same time, the voltage reference value for adverse situations after fault removal is reset to avoid unnecessary reactive power flow. Finally, a simulation model is built based on MATLAB/Simulink platform to verify the correctness and effectiveness of the theoretical analysis and control strategy. The research results provide new ideas for fully exploring the reactive power regulation capability of wind farms and greatly reducing the burden of SVG reactive power compensation.

Carbon capture and storage is an important way to achieve the “dual-carbon” goal. The exhaust gas of the supercritical water-coal to hydrogen coupled CO₂/H₂O mixed working medium thermal power generation system is low pressure and low-temperature CO₂/H₂O mixed gas. In order to achieve zero carbon emission and heat recovery, condensation separation of CO₂/H₂O is a necessary way. Fluent is used to simulate the condensing heat transfer characteristics of CO₂/H₂O mixture outside the horizontal bifurcation tube bundle. The volume of fluid (VOF) model, the component transport model, and the phase transition model written by the user-defined functions (UDF) are employed to load the mass, energy, and component source terms of the two-phase flow. The formation and development process of the liquid film on the wall surface, and the distribution of streamlines, velocity vectors, and liquid-phase volume fractions in the vicinity of droplets, as well as the effects of velocity, vapor superheat, and noncondensable gas content on the heat transfer coefficients and the thermal resistance of the diffusion layer, are investigated. The results show that, the simulation results are in agreement with the experimental data, and the liquid film thermal resistance hardly varies with the steam superheat but decreases with the increase of CO₂ content, inlet flow rate and total pressure. The thermal resistance of the mixed gas diffusion layer increases with the CO₂ content and steam superheat, and decreases with the increase of inlet flow rate. The total heat transfer coefficient increases with the steam superheat, inlet flow rate and pressure, and decreases with the CO₂ content, and the local condensation heat transfer coefficient is negatively correlated with the liquid film thickness. A new dimensionless correlation formula for heat and mass transfer of condensation is proposed for low pressure CO₂/H₂O condensation process.

An axial tangentially swirl low nitrogen burner is designed based on flue gas internal circulation and staged combustion, and the effects of the burner’s load, fuel staging, and recycled high-temperature flue gas on combustion and NO_x emission characteristics are studied through industrial experiments and numerical simulations. The results indicate that, the loads and fuel staging ratios have a synergistic effect on NO_x generation. Under medium and low load conditions, the NO_x emissions increase monotonically with the secondary fuel ratio, large amount of NO_x generates in the secondary flame zone. At full load, there exists an optimal primary to secondary fuel ratio (88:12), which minimizes the NO_x emissions. When the secondary fuel ratio falls below 12%, the primary flame zone becomes dominant in NO_x production. The length of the primary fuel mixing pipe can alter the fuel and air mixing process, thereby affecting NO_x generation. When the relative length of primary fuel mixing pipe is shortened to 0.74, the main combustion zone moves upstream in the furnace, and the main flame is anchored in the middle of the furnace, resulting in a more uniform temperature distribution at the rear of the furnace. The NO_x emission mass concentration decreases by 10%~20% across all loads, all below 30 mg/m³ (with O₂ volume fraction of 3.5%, the NO_x is calculated as NO₂).