Organic Rankine cycle (ORC) power systems can convert low-temperature (<150 ℃) thermal energy into mechanical energy to generate electricity. To improve the performance of small-scale ORC power systems, an ORC test-rig was built, which has a scroll expander directly connected to the generator. With a 24 kW variable-temperature heat source and the work fluid R245fa, the effects of the variations of load resistance (50~200 Ω) and the heat source temperatures (75~95 ℃) on the performance of the ORC test-rig were explored. The results indicate that, both the output shaft work and the thermal efficiency initially increase and then decrease with rising the load resistance. An optimal load resistance exists to maximize either the output shaft work or thermal efficiency, and this value varies with the heat source temperature. When the heat source temperature is 95 ℃, the output shaft work and thermal efficiency both reach the maximum at 100 Ω load resistance value, which is 722 W and 2.30%. When the heat source temperature is 75 ℃, the output shaft work reaches the maximum at 200 Ω load resistance, which is 532 W, but the thermal efficiency reaches the maximum at 150 Ω load resistance, which is 1.7%. The variation of the resistive load or the heat source temperature can change the scroll expander rotation speed and thus affect system flow rate. Therefore, the simultaneous changes of the resistance load and the heat source temperature have a synergistic effect on the system performance. The results highlight the importance of matching the resistance load and the heat source temperature. The experimental data also provide a direction for optimizing the ORC power systems.

The growing share of renewable energy leads to increased load volatility and uncertainty in power system, necessitating greater flexibility in cogeneration systems. The utilization of molten salt thermal storage equipment can enhance the performance of cogeneration systems. Against the main-pipeline cogeneration system consisting of four boilers and two steam turbines which is integrated with a coupled molten salt thermal storage equipment, the EBSILON simulation software is used to establish mechanism model for power supply and heating. The influence of molten salt heat storage equipment on combined heat and power system performance is analyzed, and the optimization scheduling methods for coupled systems are also investigated. The results show that, the coupling of molten salt thermal storage equipment in cogeneration systems can increase the system’s peak shaving capacity, expand the system’s operating range, and broaden the unit’s operating area. After estimation, the amount of coal saved in one day can be about 4.16 tons, the carbon emissions can be reduced by about 8.25 tons, and the pollutant emissions can be decreased by about 1.76 kg. The molten salt thermal storage equipment has improved the system’s economy and environmental friendliness.

Overdue service of thermal power units has become a trend, but fatigue crack of turbine rotor steel seriously affects the operation safety of steam turbine units. Due to the lack of the fatigue crack growth (FCG) test data of rotor steel, and large computation cost for stochastic model modeling and solution, the estimation of fatigue crack remaining useful life (RUL) is currently insufficient. On the basis of fatigue crack growth tests and analysis on its random models, a modified Gaussian membership information expanded (GMIE) sample domain method is proposed to generate virtual samples based on mega trend diffusion (MTD). Meanwhile, an extreme machine learning (ELM) neural network combined with the expective regression (ER) model is used to predict the RUL of fatigue crack propagation. The RUL of fatigue crack propagation under a specific cycle is calculated. By comparing the results with the RUL probability density function (PDF) curve and fatigue crack propagation curve of the existing numerical analysis methods, it shows that mean absolute percentage error (δ_MAPE) is 2.78%, which verifies the effectiveness of the proposed method and provides robust support for safe operation of the turbine rotor systems.

The influence of main-auxiliary combined indirect air-cooling tower at different ambient wind speeds and with different directions on flow heat transfer characteristics of the unit under normal working conditions in summer is investigated via numerical simulation. The results show that, as the ambient wind speed increases from 4 m/s to 16 m/s, the pressure in windward fan section of the main-auxiliary combined indirect air-cooling tower will increase, while the pressure on both sides of the fan section will decrease. The pressure on the inner side of the back fan section will increase and high-temperature zones which will decrease in quantity when the wind speed exceeds 8 m/s will form. The pressure on the outer side will decrease, and the pressure change in the upwind and backwind sections will be greater than that on both sides of the fan section. The total heat transfer in the main fan section will continue to decrease, while the auxiliary fan section will continue to increase slowly and be less affected by environmental wind. In different environmental wind directions, when the wind direction angle is 0° or 180°, the heat transfer of the blocked tower will increase significantly. When the wind direction angle is 45° or 135°, some fan sections between the two towers will be blocked, and the heat transfer of the blocked tower will decrease slightly. The maximum heat transfer of the main fan section occurs in the direction where the environmental wind is completely blocked, and the maximum heat transfer of the auxiliary fan section occurs at a 90° environmental wind direction angle, which is directly facing the auxiliary fan section.

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).

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.

In the context of global energy transition towards cleaner, more efficient, and sustainable energy sources, nuclear power is recognized as a critical base-load power source that serves as a substitute for fossil fuels, playing a pivotal role in transformation of energy structure. Key advancements in integration of large-scale energy storage technologies with nuclear power are introduced, with an emphasis on analyzing the coupling modes of thermal storage, mechanical energy storage, and electrochemical energy storage with nuclear power, as well as their potential to enhance the performance of nuclear power stations. Various methods of coupling energy storage technologies with nuclear power stations are explored, encompassing thermal, mechanical, and electrical coupling, and the effects of these methods on operation of nuclear power plants are discussed. Additionally, solutions for the integration of energy storage systems are presented, such as the redundant design of turbines and the design of heat exchanger-based energy storage. The research points out that, the development of energy storage technologies will offer a broader array of flexible technological options for nuclear power stations, aiding nuclear power in playing an even more critical role in the global energy transition.

The online monitoring methods for carbon emissions of domestic coal-fired power units in the short and medium term are still mainly based on accounting methods, and the online monitoring methods for carbon emissions are not yet fully developed. An online carbon emission accounting method for large coal-fired power plants is explored based on routine monitoring data from the units’ fuel management system, leading to the formation of a rapid carbon emission accounting method. Additionally, five direct online monitoring approaches for carbon emissions are designed to measure volume fraction, flow velocity and humidity of CO₂. Building upon the rapid accounting method, the calculation deviations of different carbon emission calculation methods within different calculation periods are compared. The results show that, as the time span of the calculation period increases, the calculation deviations for carbon emissions tend to stabilize. Results from a 60-day monitoring period indicate that the computational deviations for the system method, monitoring method, modified monitoring method, oxygen balance method, modified oxygen balance method, and calorific value method are –11.5%, 7.7%, 4.6%, 9.7%, 7.1%, and 17.0%, respectively. After long-term comparative corrections, all these methods are viable for online monitoring of carbon emissions from coal-fired power plants, providing support for managing and controlling carbon emissions and carbon asset management within these facilities.

To address issues such as data information security and difficulty in centralized management and control of data assets, a prototype system for data lifecycle security protection in power plant scenarios is designed. Firstly, the particularity and existing problems of the current field of power plant data protection scenarios are analyzed in detailed. Secondly, in response to the pain point of the lack of industry standards for data classification and grading in power plants, an automated classification and grading method is proposed to standardize the grading and classification of power plant data. Finally, in terms of system development, based on the analysis of the scope of power plant data protection and functional requirements, the functional architecture design and technical architecture design of the prototype system are completed. This system provides specific work steps from data asset sorting, automated classification and grading, full lifecycle management, security assessment, and other aspects, providing a complete solution for data security protection in power plants, and providing a basis for effectively achieving full lifecycle security of power plant data in the future.

The conventional heating method in thermal power plants has low energy utilization efficiency. To deeply explore the energy-saving potential of cogeneration units, a source load coordination load optimization allocation model for cogeneration units is proposed, which comprehensively considers the heat load side and heat source side. A modified outdoor temperature-heat load prediction model is established considering meteorological disturbances on the load side, and an energy efficiency variation model for cogeneration units is established on the heat source side. An optimal scheduling model considering source-load coordination is constructed with the goal of minimizing the coal consumption rate of all heating units. Finally, simulation experiment is carried out based on the heat network composed of six units and two heaters. The results show that, the load optimization distribution method considering source-load coordination based on the predicted value of heat load can effectively reduce the total coal consumption of the units during the heating period. Compared with the conventional distribution method, the coal consumption of the thermal power plant can be reduced by 214.56 tons in one day during the typical peak heating period, which is helpful to improve the operation economy of the thermal power plant. This load optimization distribution method has certain practical application value.