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.

The W-shaped flame boiler with closed middle storage pulverizing system is designed to burn low volatile lean coal and anthracite. Blending coal with high proportion of bituminous coal is able to improve the adaptability of fuel and the flexibility of the boiler. It is necessary to solve the technical problems such as explosion prevention of the pulverizing system, anti-burning of pulverized coal pipes and prevention of serious slagging in the furnace. Therefore, an inert explosion-proof pulverizing technology, in which low temperature flue gas is used for temperature adjustment, is proposed. This method solves the problem of explosion prevention of coal pulverizing system effectively. By increasing the capacity of cooling air from primary fan to reduce the temperature of hot primary air conveying pulverized coal and the adaptability of the burners to blended bituminous, the safety of the primary air pipes and the burners will be guaranteed. With the optimization of refractory belt arrangement and combustion adjustment, this method not only controls the slagging, but also improves the performance of combustion in the furnace effectively. By these integrated technologies presented above, the goal of co-firing 70% bituminous coal safely and economically in the W-shaped flame boiler with closed ball mill medium storage pulverizing system is achieved.

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.

The dynamic model of lithium-ion batteries has typical nonlinearities and uncertainties, the estimation accuracy of the state of charge (SOC) of the lithium-ion batteries directly affects the effect of the monitoring and controlling in battery management system (BMS). To enhance the estimation accuracy of the SOC of the lithium-ion batteries, an adaptive sliding mode observer, which based on a variable gain for lithium-ion battery SOC estimating model is proposed. By using the robustness of the sliding mode observer and based on the second-order RC equivalent circuit model, an integral term is introduced in conventional sliding mode surface to improve the robustness on sliding mode surface, and a gradient descent rule is adopted to achieve gain adaptation to reduce the chattering of observer and improve prediction accuracy and robustness. Simultaneously, the stability of the proposed method is proved using Lyapunov theory. Finally, the proposed method is validated and compared with the sliding mode observe (SMO) method under dynamic stress test (DST) and Federal urban driving schedule (FUDS) conditions. The proposed method has less chattering in estimation with higher estimation accuracy and good robustness.

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.

In the context of achieving “dual-carbon” goals, power units function as adaptable power sources for integrating new energy sources, posing significant challenges to their power generation flexibility. The dry-wet joint cooling system plays a pivotal role in ensuring the safe and stable operation of power units. Therefore, there is an urgent need to optimize the operational strategy of the dry-wet joint cooling system to enhance its flexibility and economic efficiency. Focusing on the dry-wet joint cooling system of a 660 MW generator set, a multi-layer perceptron (MLP) neural network model has been established to predict the outlet temperature of the cooling water. A mixed integer nonlinear programming (MINLP) model is formulated and linearized based on actual operating condition constraints. By solving the MLP-MINLP optimization model, the optimal operation strategy for variable-frequency fans in each operating condition of dry-wet joint cooling system is determined, successfully reducing its power consumption. The results indicate that, after optimizing the configuration of variable-frequency fans, there is a significant reduction in total power by approximately 11.16%, and implementing different frequency operations for variable-frequency fans can reduce total power by about 3.62%~5.38% in a limited manner. The MLP-MINLP optimization model can achieve precise and low-power operation of dry-wet joint cooling system, offering a viable solution for optimizing dry-wet joint cooling systems.

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.

Solid oxide fuel cell (SOFC) is a promising energy conversion device. It has the advantages of non-pollution, high energy utilization rate, and good fuel adaptability. However, SOFC often needs to be operated under variable load conditions, which leads to the problems of shorten service life and performance degradation. The study of the relationship between the variable load characteristics of SOFC and its operating conditions is helpful to improve the output performance of the stack, extend its service life, and formulate a reasonable control strategy. A 100 W SOFC short stack testing system was developed to experimentally investigate the variable load characteristics of the SOFC stack under multiple operating conditions. The results show that, increasing the operating temperature can reduce the ohmic resistance and total polarization resistance of the fuel cell stack, thereby enhancing the stack’s steady-state output performance and dynamic response performance. Increasing the hydrogen flow rate in the medium to high current range can reduce the concentration polarization resistance, thereby effectively enhancing the stack’s peak output performance and dynamic response performance. Increasing the air flow rate has a smaller effect on the performance improvement of the stack. Under the constant flow utilization strategy, the response voltage immediately falls within the range of ±5% of the final voltage. By varying the load with constant voltage, the response current can smoothly reach a stable value. Compared with the constant flow strategy and constant current load variation method, the stack shows better dynamic response performance under the constant flow utilization strategy and constant voltage load variation method.

As a key component of air source heat pump, the thermodynamic performance of scroll compressor has an important influence on the heat pump system. A three-dimensional transient simulation model of the scroll compressor is established, and the accuracy of the model is verified through experiments. Based on computational fluid dynamics method, the non-uniformly distributed flow characteristics of internal flow field of the scroll compressor under the influence of tangential leakage flow are investigated. The influence of different operating conditions on thermodynamic performance of the scroll compressor is explored. The sensitivity analysis method is used to discuss the sensitivity of thermodynamic performance of the scroll compressor under different operating conditions. The results show that, with the increase of pressure ratio, the isentropic efficiency increases at first and then decreases, the heat production decreases, the maximum increase in time-averaged exhaust temperature is 11.26 K. When the suction temperature increases to 311.65 K, the isentropic efficiency grows by 16.72 percentage points. The increase of rotational speed will weaken the phenomenon of reflux and reduce the exhaust temperature, when the rotational speed rises to 4 500 r/min, the volumetric and isentropic efficiencies increase to 86.61% and 46.86%, respectively.