Biohydrogen production technologies such as photolysis of water, photo fermentation, dark fermentation, and coupled dark-photo-fermentation were mainly reviewed. The hydrogen production mechanism, technological advantages and disadvantages, influencing factors and research status of each method were analyzed. At the same time, the types and characteristics of biohydrogen production reactors were compared. The results show that biohydrogen production has great potential in low-grade energy treatment and advanced energy production. Finally, some suggestions on the development of biohydrogen production technology were given.

Considering the characteristics of high efficiency and zero carbon emissions of the semi-closed CO₂ cycle, and based on the semi-closed CO₂ power generation system integrated with liquefied natural gas (LNG) cold energy at present, an efficient utilization way of LNG cold energy was proposed. Results show that, for the base case, the energy consumptions of the air separation and compression processes are reduced by 70.4 and 75 MW, respectively, and with a net system efficiency of 63.76%, which is 9.48 percentage points higher than the conventional cycle. Furthermore, with optimization measures such as improving the system parameters and matching the heat capacities of regenerators, the net efficiency of the optimized case is further increased to 72.22%, and the exergy efficiency is 51.27%. Compared with the reference system Ⅱ of only integrating LNG cold energy within the power cycle, the exergy efficiency of cold energy utilization is improved by 28 percentage points.

In response to the challenges faced in the digital and intelligent operation and maintenance (O&M) of wind turbines, such as data overload of multiple units, information redundancy, low efficiency in maintenance knowledge retrieval and insufficient reasoning of life-cycle maintenance knowledge, a knowledge graph construction method for wind turbine operation and maintenance data was proposed. Firstly, important information such as faulty components and causes could be extracted using text data such as wind turbine equipment maintenance work orders, so as to provide the knowledge graph construction process for wind turbine operation and maintenance data.Subsequently, during the construction process, modeling analysis was conducted specifically for fault entities, attribute extraction and relationship extraction. Results show that the wind turbine O&M knowledge graph helps O&M personnel to accurately grasp the root causes of failures, efficiently implement maintenance measures, and ensure the repair capabilities of wind turbines under the conditions of informatization and intelligence. Moreover, compared to relational databases, the proposed design method offers better performance in terms of query precision and time.

Heavy-duty gas turbine is a kind of efficient thermo-mechanical conversion equipment so far, with the combined cycle efficiency higher than 60%. As gas turbines have excellent peak shaving capability, they will play an increasingly important role in the new power network based on new energy. An overview of the working characteristics, the structural features and main technical parameters of heavy-duty gas turbine compressors were introduced. The development and technical progress of typical gas turbine compressors from major international original equipment manufacturers were reviewed. The research progress of compressor design system was summarized. Considering the development of advanced heavy-duty gas turbine technology, key technology development directions were proposed, including aerodynamic layout optimization, high performance airfoil, full 3D design of transonic stages and highly integrated design system, based on the development status of heavy-duty gas turbines in China.

The effect of channel height on the thermal-hydraulic performance of airfoil fin printed circuit heat exchangers(PCHEs) was investigated by numerical method based on the impact of channel geometry. Results show that channel height significantly affects the compactness, resistance, and heat transfer performance of PCHE. Under the same Reynolds number (Re=6 000-14 000), the Fanning friction factor f first decreases and then increasesas with the channel height H decreases (i.e., the ratio of channel height to transverse pitch H/S_T=0.12-0.60), with the lowest f observed at H/S_T=0.24. The Colburn-j factor j shows no significant change for airfoil fin channels with H/S_T=0.24-0.60, while an increase in j is observed at H/S_T=0.12. The ratio j/f is suitable for evaluating the comprehensive performance of airfoil fin channels with different heights. When using j/f as the comprehensive performance evaluation indicator, the airfoil fin channel with H/S_T=0.24 exhibits the best overall performance.

A covert attack method based on a symbiotic organism search(SOS) algorithm to optimize long short-term memory (LSTM) neural network was proposed to solve the problem of obtaining a high-precision estimation model of the attacked target for covert attacks. The output and input signals of the feedback controller of the attack target were taken as the data set of the LSTM. The estimation model of the attacked area was obtained through training, and was used to design the covert attacker to impose attack signals on the attacked object.In addition, the SOS algorithm was applied to optimize the parameters of the LSTM to improve the performance of the covert attacker.The simulation results of covert attack on the primary circuit control system of nuclear power plant show that the attack method has high concealment performance while realizing preset attack behavior on the output signal of the target control system.

In order to reduce the influence of solar energy fluctuation on the performances of the solar-coal complementary power generation system, a new type of solar-coal complementary power generation system was proposed. Models of key devices and subsystems were developed and verified, and the thermal and techno-economic performances of the new solar-coal complementary power generation system were studied. Results show that the thermal performance of the system decreases with the operation load, and increases firstly and then decreases with the increase of direct normal irradiance. The average annual output power of the system is 699 MW, the average annual coal saving rate is 7.506 g/(kW·h), and the average annual solar-to-power efficiency is 10.82%. When the heat storage capacity duration is 10 h, the system has the best techno-economic performances, with the life-cycle net present value of 4.18×10⁸ yuan, the internal return rate of 11.81% and the dynamic payback period of 12.6 years. The levelized cost of electricity is 0.402 yuan/(kW·h), and the profitability is good.

To solve the issue of un-stable operation of thermal power units caused by severe fluctuations in the power grid, a secondary frequency regulation control strategy assisted by flywheel energy storage considering the operation stability of thermal power plant was proposed. Firstly, a secondary frequency regulation control model for ultra-supercritical thermal power units integrated with the flywheel energy storage was developed. Then, a non-linear decomposition method for AGC instructions based on constraints of multi-layer variable gain rates was proposed. Finally, a fitness function was designed based on the unit stability and the AGC performance of the system, and the whale optimization algorithm (WOA) was used to obtain the optimal parameters of limiting algorithm. Based on the above method, a collaborative control strategy of secondary frequency regulation was designed for the integrated system of thermal power unit and energy storage. A simulation verification was conducted on the integrated system with a 1 000 MW thermal power unit and flywheel energy storage as an example. The results show that the proposed control strategy can effectively respond to high-frequency commands of the integrated system without affecting the frequency regulation performance, reduce the action amplitude of thermal power unit, and improve the stability of power unit operation.

Optimization research was conducted on supercritical carbon dioxide recompression cycle system applied to the fourth generation gas-cooled reactor. By establishing a comprehensive thermodynamic and exergoeconomic model, and introducing spatial compactness indicators based on the demand for nuclear power modularization, a study was conducted on supercritical carbon dioxide recompression cycle system from multiple dimensions such as thermodynamic performance, spatial compactness, and exergoeconomic performance. Impact of key parameters on the performance of supercritical carbon dioxide recompression cycle system was analyzed, and further multi-objective optimization was carried out to improve the applicability of the system. Results show that through multi-objective optimization, the comprehensive performance of the cycle is improved, and the optimal exergy efficiency, unit power cost rate, and required heat exchange area per unit output power are 71.5%, 3.11 cent/(kW·h), and 0.191 m²/kW, respectively.

Ammonia-coal co-firing involves complex chemical reaction processes, and it is highly concerned that whether co-firing exacerbates the generation of nitrogen oxides. Using the method of chemical reaction kinetics calculation, the reaction pathways of NO generation and reduction in the gas-phase reaction of ammonia-coal co-firing were studied, as well as the effects of different factors on NO generation. Results show that compared to pure coal combustion, the NO volume fraction at the outlet of the reactor can be reduced by 96.5% with the ammonia co-firing ratio of 0.3 at temperature (T) of 1 300 ℃ and excess air coefficient (α) of 0.84. Since ammonia decomposition generates a large number of free radicals such as NH₂ and NH, which leads to a faster reduction reaction rate and the conversion of N-containing elements into N₂ under co-firing working condition. At T=1 300 ℃, an ammonia co-firing ratio of 0.3 is suitable, since the volume fractions of NO and NH₃ at the reactor outlet are both low. Small ammonia co-firing ratio will increase the rate of NO generation and NH₃ decomposition, leading to an increase in NO volume fractions at the reactor outlet. The higher the temperature is, the more obvious this phenomenon is. Reducing atmosphere (α<1) and a lower temperature (T≤ 1 300 ℃) can effectively reduce NO emissions.

By dividing the incident solar spectrum into bands, an integrated photovoltaic (PV) and photothermal (PT) driven organic Rankine cycle (ORC) was established. Thermodynamic analysis of the system was conducted under the temperature limit of 100 ℃ for the cooling panel, to identify suitable working fluids for the ORC system and optimize the evaporation temperature. Results show that isobutene as the cooling fluid for the photovoltaic system and the working fluid for the ORC system, the highest system efficiency can be achieved. Frequency division technology transfers the heat dissipation load of the cooling panel to the collector, which can reduce the cooling demand of the photovoltaic panel and thus reduce the mass flow rate of the working fluid. It has a positive effect on improving the system's power generation capacity, and can enhance the efficiency of pure photovoltaic electricity generation by 9%. Additionally, frequency division efficiency and the absorption band of solar cells significantly impact the overall efficiency of the integrated power supply system.

The prospective demand for carbon reduction requires gas turbine combustion chambers to control NO_x emissions, improve power regulation range and fuel adaptability while outlet temperatures are continuously increasing. To address the above challenges, gas turbine manufacturers are developing axial staged combustion technology. This paper firstly introduced the principle of axial staged combustion and analyzed the effects of axial staged parameters, jet-in-crossflow flame morphology, nozzle geometry and fuel type on pollutant emissions and combustion instability. Existing studies show that reducing the equivalence ratio of the primary combustion chamber and enhancing the mixing uniformity of the secondary stage primary combustion chamber can reduce pollutant emissions. The thermoacoustic oscillation of axial staged combustion chambers is complex, and could be inhibited by a reasonable selection of stage parameters. The emission reduction benefits and part-load flexibility of axial staged combustion chambers have been verified in commercial operation. Based on the current research status, key issues and future research directions of axial staged combustion technology are proposed.

Due to the complexity of turbulent flow problems for film cooling, the traditional Reynolds average Navier-Stokes (RANS) method tends to underestimate the intensity of turbulent thermal diffusion, leading to inaccurate prediction of cooling effectiveness. A framework based on physics-informed neural network (PINN) was therefore proposed, and a data-driven neural network model of turbulent Prandtl number was built based on RANS flow data and large eddy simulation(LES) temperature data. After implementing this model into a RANS solver, the intensity of turbulent thermal diffusion could be adjusted dynamically and a temperature distribution highly consistent with LES results was obtained. Results show that PINN is an effective method to build a data-driven turbulence model and modeling of turbulent Prandtl number can effectively improve the accuracy of RANS temperature prediction.

In order to realize stable, efficient and environmentally friendly coordination of waste incinerator power generation units, multi-objective optimization was conducted for combustion process of the incinerator. A dynamic modeling method combining extreme learning machine (ELM) and nonlinear autoregressive moving average model with exogenous inputs (NARMAX) was proposed, and the parameters of the model are optimized by improved sparrow algorithm (ISSA). The dynamic models of steam flow, boiler efficiency and first flue temperature of the incinerator were established respectively. The ISSA-ELM-NARMAX model was compared with the traditional BP neural network model, ELM-NARMAX model and SSA-ELM-NARMAX model. Finally, multi-objective optimization of the combustion process was carried out to find the optimal operating parameters of the incinerator based on the improved non-dominated sorting genetic algorithm (NSGA-II). Results show that the dynamic model of combustion process of the incinerator based on ISSA-ELM-NARMAX is more accurate and effective, and the proposed control strategy can provide operational guidance for the incinerator operators.

In order to alleviate the extensive energy consumption of amine-based carbon capture, nanoscale aluminum oxyhydroxide was applied as the catalyst to reduce the heat duty of amine regeneration. The desorption process was divided into a heating-up stage and an isothermal stage based on the basic heat transfer theory. An energy consumption assessment model for calculating the heat input during different stages was established, and the real-time heat duty variation curves were obtained. This model was more precise than conventional methods, and was beneficial for determining the optimal operation conditions to reach the lowest energy consumption. Based on this method, the best desorption temperatures to achieve the lowest heat duty with and without catalyst were investigated. Results show that moderate temperatures can bring the lowest energy consumption. Besides, through the analysis of the overall reaction kinetics during the regeneration process, it is found that the reaction order model is most suitable for describing the reaction rate of ethanolamine solution. The parameters of the reaction order model prove that the catalyst saves the energy consumption of regeneration by reducing the activation energy of the desorption reaction.

Vacuum gas nitriding process was applied to strengthen the surface of the SP-700 titanium alloy at different temperatures. The surface morphology, cross-sectional morphology, hardness, abrasion resistance and electrochemical corrosion performance of the newly formed gas-nitrided layers were investigated using scanning electron microscope (SEM), optical microscope (OM), micro-Vickers hardness tester, reciprocating friction and warm damage tester, white light interference three-dimensional surface profiler and electrochemical workstation, respectively. The corrosion behavior of the gas-nitrided layers was determined by immersion corrosion method in HF solution. Results show that, the microstructural morphologies of the gas-nitrided layers are significantly influenced by the processing temperatures. With the increase of temperature, the amount of nitride increases and the nitride layer becomes denser. The hardness of the high-temperature gas-nitrided layer was about 1.9 times higher than that of the matrix, and the relative abrasion resistance can reach 51.34. All samples can be passivated spontaneously in 3.5% NaCl solution, indicating their good electrochemical corrosion resistance. The samples with gas-nitrided layer perform better in HF corrosion solution, and the higher the processing temperature, the better the corrosion resistance of the samples.

In the face of the increasingly urgent need for the reduction of carbon emission and energy consumption, the development of efficient advanced thermal cycles with low carbon emission is becoming more and more important. A natural gas fueled semi-closed supercritical CO₂ cycle was proposed with zero carbon emission, and the semi-closed cycle was split into an open cycle and a closed cycle through working fluid splitting to further clarify the thermal to power conversion process. Furthermore, the cycle splitting method was applied to the complex modified cycle, which was split into several simple cycles to formulate the thermodynamic evaluation models of the different process modification measures and intuitively reveal the energy-saving mechanism of different cycle configurations. Through parameter sensitivity analysis, the optimum parameters of process modification measures were obtained. Results show that the cycle efficiency can be effectively improved by various cycle layout modification measures such as reheating, recompression, intermediate cooling and partial cooling, which can contribute to the efficiency improvement of 1.79~5.59 percentage points. After the integration and optimization of various process modification measures, the net power generation efficiency of the system is increased by 10.18 percentage points compared with the basic cycle.

To explore the deep peak shaving capacity of coal-fired boilers, the hydrodynamic force and wall temperature characteristics of the water-cooled wall of a supercritical 630 MW boiler were studied. Mathematical models of the hydrodynamic force and wall temperature characteristics were established, and water-cooled wall pressure drop, flow distribution, outlet working substance temperature and wall temperature distribution along the furnace height between 20% and 30% boiler maximum continuous rating (BMCR) loads were analyzed. Results show that, the helical tube sections of the water-cooled wall exhibit small thermal deviation and uniform heat load distribution under 20% and 30% BMCR loads. The outlet steam temperature deviation of the vertical tube sections of the water-cooled wall is large, and the over-temperature is more likely to occur in this area. Under 30% BMCR load, the boiler could operate safely in dry state condition. Under 28.8% BMCR load, the inlet water temperature of the water-cooled wall is 280.0 ℃, and the maximum wall temperature of the water-cooled wall in dry state condition exceeds 450.0 ℃. Under 27.3% BMCR load, the maximum wall temperature of the water-cooled wall in dry state condition exceeds 500.0 ℃, and the boiler should operate in wet state condition or the wall temperature should be reduced by adjusting the inlet water temperature.

A fault warning method based on the improved whale algorithm to optimize the hyperparameters of Transformer network (IWOA-Transformer) was proposed. The method improved the whale optimization algorithm (WOA) by utilizing nonlinear convergence coefficients and Gaussian variation to improve its convergence speed and avoided falling into local optimum. Then, the hyperparameters of Transformer were optimized with the improved whale optimization algorithm (IWOA) to establish a fault warning model of coal mill, and the adaptive threshold was determined by the similarity function of predicted and actual values. Combined with the expert system, the fault type was judged and solutions were proposed,and coal mill fault early warning was achieved. Finally, A fault warning test was conducted using a 350 MW cogeneration unit medium-speed coal mill as an example. Results show that the IWOA-Transformer model can significantly improve the speed and accuracy of early warning, and has practical engineering value.

To further improve the aerodynamic performance of airfoils, a bionic curved flap was proposed based on the trail fin profile of mako sharks. The aerodynamic performance and internal flow of the bionic airfoil were simulated using the SST k-ω turbulence model, and the effects of relative position and installation angle of the bionic flap were analyzed to obtain the optimal bionic flap airfoil with the best aerodynamics, which was compared to the Gurney flaps. Results show that after installing a bionic flap, its lift-drag ratio is significantly higher than the baseline; when the relative flap height remains unchanged, reducing the installation angle and increasing the distance between the flap and the trailing edge lead to an early airfoil stall onset. The aerodynamic performance of the bionic flap airfoil with reverse installation angle of 45° at the trailing edge is the best, and the lift coefficient is 5.9% higher than the Gurney flap airfoil before the stall. After arranging the bionic flap, the flow field tends to be complicated, and the position, quantity and size of vortices change.

In order to optimize the overall power output and fatigue load of the wind farm, an optimization method of wind turbine yaw angle group was proposed. A neural network judgment model for wind turbine wake interference was established, and the relative coordinates of the wind turbine and the incoming wind speed were taken as characteristic values, to determine whether there was wake interference between the fans. The connected component decomposition algorithm was introduced to divide the wind farm into multiple aerodynamic decoupling groups without wake interference. With the goal of increasing power and suppressing load, the improved adaptive evaluation particle swarm algorithm was used to optimize all swarms in parallel. Results show that compared with the greedy algorithm and the overall optimization method, the group optimization method has better effects on power improvement and load suppression, and its stability is better.

A power generation system with pre-combustion CO₂ capture based on staged coal gasification and chemical recuperation was proposed to achieve high-efficiency and low-carbon power generation from coal. The system decoupled the coal gasification process into two stages: a pyrolysis stage at 600 ℃ and a gasification stage producing syngas at 1 400 ℃. The exhaust heat from gas turbines was used to drive pyrolysis, and in addition, the sensible heat of syngas was used to drive pyrolysis gas reforming. The thermodynamic performance of the present system was compared with the reference system, and the effect of different key parameters on the system performance was analyzed. Results show that at the carbon capture ratio of 90%, the net power generation efficiency, exergy efficiency and CO₂ emissions per kW·h of the present system are 39.97%, 38.94% and 85.27 g/(kW·h), respectively, which are 2.33%, 2.34% higher and 5.27 g/(kW·h) lower than the reference system. The superior performance of the present system comes mainly from the significant reduction in the irreversible losses of its gasification process, which is 62.13% of the reference system. The analysis further indicates that the system net power generation efficiency reaches an optimal 41.3% under the steam-to-carbon ratio of 1.4 and the carbon capture ratio of 80% at the gasification temperature of 1 200 ℃. As the carbon capture ratio increases, the net power generation efficiency and CO₂ emissions per kW·h both decrease, the latter with a minimum of 51.1 g/(kW·h).

An integrated energy system using solid oxide fuel cell (SOFC)/gas turbine (GT) as power generation device and hydrogen-doped natural gas as the fuel was proposed. The mathematical models of various types of energy utilization equipment, such as wind power generation, solar power generation, hydrogen production equipment, SOFC/GT system, energy conversion and storage equipment for electricity, heat, and cooling, carbon capture equipment, etc, were established. The performance and economy of the integrated energy system were studied considering various load balance constraints, equipment operation constraints and aiding in achieving the "dual carbon" targets. Results show that the power generation efficiency of SOFC/GT system increases from 60.36% to 64.79%, and the comprehensive energy utilization rate increases from 87.80% to 90.80% with the increase of fuel hydrogen blending ratio. When the system used renewable energy sources to produce hydrogen, the carbon emissions are the lowest, although carbon trading gains are considered, the high cost of hydrogen production leads to the highest operating costs.

To explore the application potential of sound-assisted combustion technology in W-shaped flame boilers, the combustion characteristics of a W-shaped flame boiler with real-time load of 315 MW under acoustic excitation were experimentally studied. Twelve and four acoustic excitation devices were staggered in the main combustion area and the burning area of the boiler, respectively, and they were put into operation in a group of three devices in a circular manner. The frequency of the motor driving the acoustic excitation device was 35 Hz, and the corresponding intake pressure was maintained at 0.35-0.47 MPa. In the test, the changes of the NO_x mass concentration at the inlet of the A and B sides of the denitration tower, the SO_x mass concentration at the inlet of the desulfurization unit, and the coal consumption of the unit were recorded through the distributed control system (DCS) of the centralized control room of the power plant. Results showed that, after the acoustic excitation was put into the denitrification tower, the mass concentration of NO_x at the inlet of the A and B sides of the denitration tower is decreased by 6.08% and 5.47%, respectively, the SO_x mass concentration is decreased by 1.24%, and the average coal consumption of the unit is decreased by 1.5 g/(kW·h). In addition, based on the ash sampling analysis of the economizer and air preheater outlet, it is found that the carbon mass fraction of fly ash is decreased by 1.64% and 1.70% respectively, compared with the case without acoustic excitation. Sound-assisted combustion technology can effectively improve the thermal efficiency of W-shaped flame boilers and reduce pollutant emissions.

To control plumes and save water resources, a hot test system for high level water collection mechanical cooling tower was established for comparative analysis of the plume abatement, water saving and thermal performance of the external cooling module (dry-wet hybrid cooling tower) and the internal condensation module (condensation plume cooling tower). The impact of the ambient temperature, inlet circulating water temperature and circulating water flow rate on the performance of cooling towers was studied. Results show that dry-wet hybrid cooling tower and condensation plume cooling tower have plume abatement and water saving capabilities, which are achieved at the cost of cooling performance reduction of the cooling tower. Compared with the original tower, the circulating water temperature drop of dry-wet hybrid cooling tower and condensation plume cooling tower decreases by about 1.5 K. The plume abatement and water saving performance of the dry-wet hybrid cooling tower and the condensation plume cooling tower is greatly affected by the operating parameters, and the water saving amount and water saving rate of the condensation plume cooling tower are higher than those of the dry-wet hybrid cooling tower.

A model-data joint prediction method was proposed. The object dynamic model was established through mechanism analysis, and the future solar radiation intensity and user load prediction data were introduced for immediate model prediction. The data prediction model was established through the convolution - short and long time memory hybrid neural network improved by attention mechanism, and the historical data was introduced for rolling data prediction. Then, Kalman filter was used to combine the output of the two prediction models to realize the joint prediction of energy storage. Results show that the combined prediction has the advantages of both methods, which can solve the problem of accumulated energy storage prediction errors over time and timely characterize the changes of energy storage when meteorological factors suddenly change and system operation mode changes. The proposed method has good prediction accuracy under various weather conditions.

This paper proposed an integrated system which includes a tower-type solar thermal power system and energy storage system, employing S-CO₂ and quartz as the storage media and a re-compressed S-CO₂ Brayton cycle as the power cycle. Based on the Gensystem platform, mathematical models of the power cycle, solar heat collection system, and S-CO₂ thermocline storage tank were developed to investigate the performance of the heat collection system and the dynamic characteristics of heat storage and release in the S-CO₂ thermocline storage tank. This foundation facilitated an analysis of the integrated system's thermodynamic and economic performance. Results show that after 13 cycles of heat storage and release, the temperature at the outlet of the thermocline storage tank tends to be stable. At the conclusion of heat release, the temperature of the thermal fluid exiting the tank is decreased by 63 K, while at the end of heat storage, the temperature of the cold fluid exiting is increased by 46 K. Compared with a dual storage tank tower solar thermal power system, the average daily power generation efficiency on the summer solstice and winter solstice is enhanced by 1.8% and 1.7%, respectively. The total system investment is reduced by 9.46%, the levelized cost of electricity is reduced by 9.45%, and the investment payback period is shortened by 1.8 years.

Due to the uneven distribution of combustion temperature field in the operation processes of thermal power plants, issues such as over-temperature, tube explosion and flue gas corridor of the furnace heating surfaces may occur. By evaluating the temperature field distribution of the boiler during operation processes, the combustion adjustment can be made to improve the safety, stability and economy of the boiler operation when the operation status can be examined timely. With the boiler of a 660 MW ultra-supercritical power plant as an example, the combustion optimization adjustment test and simulation were carried out. Temperature of heating surfaces and the wall temperature change at the burner were analyzed, and the wind speed and pulverized coal concentration deviations of powder pipes in the pulverizing system, internal and external secondary air volume and intensity of the burner, the adjustment of the direct current air volume, and the wall air in the furnace were measured. Results show that the factors, such as the combination operation modes of different coal mills and the modes of secondary air distribution have a great impact on the boiler operation. In particular, the wall over-temperature, the burner temperature and reducing atmosphere on the heating surface are influenced, which will affect the boiler economic operation. After adjustment, the wall over-temperature phenomenon of the screen superheater, high temperature superheater and high temperature reheater disappears, there is no burnout of burners, and the amount of NO_x generation is also within a reasonable range.

As the heart of the gas turbine, the central rod-fastened rotor operates under harsh conditions with frequent incidents, necessitating a rigorous exploration of its strength under complex contact states across multiple scales and loads to ensure the safe functioning of the disc structure. Employing a rough surface contact model and three-dimensional finite element methods, a thermo-mechanical coupling analysis model for the gas turbine disc's Hirth tooth contact interface was developed, incorporating microscale interface dimensions and surface roughness. Results show that the maximum equivalent stress of the end face teeth decreases with the increase of the root fillet radius and the decrease of the pressure angle; the maximum equivalent stress and average contact pressure of the end face teeth decrease with the increase of surface roughness.

In order to realize the simple and accurate measurement of carbon emissions of thermal power units and grasp the influence of operating factors on carbon emission intensity, basing on the emission factor method technology, referring to the traditional q-γ-τ matrix structure form, according to the needs of solving carbon emissions of thermal power units, and grasping the influence of operating parameters on carbon emission intensity of power generation, a general matrix model of carbon emissions and carbon sensitivity of thermal power units was established, and the matrix filling rules were determined. The accuracy of the model was verified by the heat balance method combined with the material balance algorithm, and the calculation results were compared with the emission factor method. The carbon emission of a thermal power unit for 24 h was calculated, and the disturbance ΔM_CO2 of carbon emission intensity of power generation was analyzed when the smoke oxygen, main steam temperature and pressure fluctuated. Results show that, compared with the emission factor method, the proposed model can shorten the time span of carbon emission accounting and improve the accuracy of carbon emission accounting. The carbon emission of the unit for 24 h is 5 780.644 t; When the smoke oxygen is reduced by 0.1%, ΔM_CO2 is 1.772 6 g/(kW·h); When the main steam temperature increases by 0.5 K, ΔM_CO2 is 3.020 6 g/(kW·h); When the main steam pressure increases by 0.2 MPa, ΔM_CO2 is 0.378 8 g/(kW·h).

Influence of hole configuration including cylindrical, fan-shaped and laidback fan-shaped holes on effusion cooling performance under different pressure drops of cooling air was examined using infrared thermal imaging technology. Results show that due to the vortex impact effect, low local cooling efficiency areas appear on the wall surface, which are independent of the hole type. The change in hole type only affects the cooling effect of the wall surface. Increasing the pressure drop of the cooling air can improve the cooling effect, and the area of the low cooling effect zone also decreases accordingly. The difference between the cooling hole shape and the pressure drop of the cooling air causes the movement of the lowest cooling effectiveness position on the wall. As the velocity of cooling air increases, this point moves upstream. In terms of the uniformity, the minimum effectiveness of cylindrical holes is lower by 14.3% to 27.5% than the area-averaged one. The difference between the minimum cooling efficiency of the fan-shaped hole, the expansion hole and the average level is greater, and the uniformity of the cooling effect is worse. The comprehensive cooling efficiency of the expansion hole is the highest, but the uniformity is the worst.

For the supercritical carbon dioxide (S-CO₂) with heated flow in a horizontal tube, to research the influence of the buoyancy effect on flow and heat transfer characteristics, experiments were conducted on flowing and heating in optical and inner coiled wire tubes under the same condition. Investigations were carried out for the influence of the wall heat flux density and mass velocity on the buoyancy effect, while discussions were given for the influence of the inserted coiled wires on the wall temperature distribution, heat transfer mode, etc. Results show that the temperature stratification caused by the buoyancy effect occurs along the gravity direction during SO₂ horizontal flowing with heating, which leads to the severe wall temperature divergence at the top and bottom, with a maximum wall temperature difference of up to 48 K. The inserted coiled wires in tube can effectively inhibit the temperature stratification caused by the buoyancy effect, while the heat transfer coefficients at the bottom and top are increased by more than 60% and more than 140%, respectively. Based on the validation of experimental results with four heat transfer correlations, it is found that Bishop correlation has the best comprehensive performance.

Aiming to reduce carbon emissions for environmental sustainability, hydrogen-blended combustion has emerged as a pivotal advancement in gas turbine technology. Focusing on the hydrogen-blended natural gas combustion characteristics, comprehensive full-temperature, full-pressure, and full-scale combustion tests with a hydrogen-enriched ratio were conducted on an independently developed DeNO_x burner of F-class heavy-duty gas turbine. The burner's adaptability to hydrogen-blended combustion was analyzed based on performance parameters such as temperature, emissions, humming, and acceleration. Results show that within a hydrogen blending range of 30% to 40%, the NO_x emissions from this burner can be controlled below 30 mg/m³ across the base load range of 55% to 100%. As the hydrogen blending ratio increases, flame transition occurs at a lower load, which is conducive to stable load increases. Furthermore, the outlet temperature of the burner rises, but no flashback occurs.

A torsional vibration identification method for shafting of pumped storage unit based on hydraulic pulsation was proposed. The dynamic random torque signal was obtained by using strain measurement technology. Setting the trigger threshold, a group of sample signals was obtained by using the intersection point of the signal, the threshold and the points of a certain length. After averaging a sufficient number of sampled signals, the random response and positive/negative velocity impact response were averaged out, and the remaining signal was the amplitude impact response signal. The torsional natural frequency and damping could be obtained by fitting the impact response signal with exponential function. The method was applied to identify the torsional characteristics of a pumped storage unit. The test results show that the hydraulic fluctuation is larger under 25% load condition. The trigger threshold has little influence on the identification results. When the load increases, the torque pulsation decreases. The trigger threshold has little effect on the identified frequency, but it will affect the identified damping. This method does not need to apply torque excitation. It realizes the identification of torsional vibration characteristics under installation conditions, which has a good engineering application value.

To solve the problems of the high regenerationenergy consumption and the thermal degradation caused by prolonged high-temperature heating of absorber in CO₂ chemical absorption system, a new type of tubular falling film reboiler was proposed. By analyzing the flow characteristics of falling film, a research was conducted on structural optimization design of liquid distributors. To verify the heat and mass transfer performance of the falling film reboiler and find the optimal operating parameters, a systematic thermal experiment was conducted on a 200 m³/h flue gas CO₂ chemical absorption pilot platform. The experiment results of falling film flow reveal that the unevenness of the liquid distributor can be significantly reduced to 0.026 after optimizing the direct opening of the connecting tube and the aperture of the distribution slot. Results show that, with the increase of liquid phase flow velocity within the tubes and the transition between laminar and turbulent flow states, the overall heat transfer coefficient of the falling film reboiler initially decreases and then increases. Concurrently, as the mass flow rate of steam increasing from 60 kg/h to 70 kg/h and 80 kg/h, the regeneration rate can be increased from approximately 10% to approximately 20%, and with a peak of up to 24.7%, thereby promoting the secondary desorption of the amine solution. By increasing the steam flow rate and the inlet temperature of the amine solution, the heat flux of the falling film reboiler gradually increases, resulting in a gradual enhancement of the overall heat transfer performance and a subsequent increase in the overall heat transfer coefficient. The CO₂ chemical absorption tube-type falling film reboiler developed in this study has achieved a reduction in the residence time of the absorbent within the reboiler, while simultaneously can improve the heat transfer efficiency of the reboiler and the CO₂ regeneration rate of the amine solution. This is expected to significantly reduce the heat consumption for carbon capture.

In order to analyze the influence of inflow distortion on flutter characteristics of gas turbine compressors, an inlet total pressure model with radial distortion was established. Based on the influence coefficient method, the effects of radial inflow total pressure distortion with different phases and distortion intensities on the flow field characteristics and aeroelastic stability of compressors were studied. Results show that the radial inflow total pressure distortion with phase angles of 90° and 180° will increase the minimum value of aerodynamic damping under dangerous conditions, and the aeroelastic stability is improved. The radial inflow total pressure distortion with phase angle of 180° can improve the aeroelastic stability of the compressor at all inter blade phase angles. However, the radial inflow total pressure distortion with phase angles of 0° and 270° will increase the risk of compressor flutter,which should be avoided.

To improve the thermodynamic performance of the heavy duty gas turbine with bleed air, a novel gas turbine system with high effective utilization of bleed air energy was proposed, and the change of thermodynamic performance was researched. Taking the performance data of a traditional typical F-class gas turbine under different ambient temperature conditions as the comparison reference, for the novel gas turbine with high effective bleed air cooling, the changes of performance indicators of the total system were analyzed with different design parameters of cooling system by numerical simulation, while the thermodynamic performances under three operation modes were calculated and compared. Results show that the temperature of bleed air from compressor can be effectively decreased by adopting the novel gas turbine system with high effective utilization of bleed air cooling, and the thermodynamic performance of gas turbine is further improved. Under summer condition, when the inlet air temperature is cooled to 30, 20, and 15 ℃, respectively, the output power is increased by 25.92, 40.49, and 48.22 MW, and the efficiency of gas turbine is improved by 0.78, 1.19, and 1.40 percentage points.

Comprehensive analysis and research were carried out on the performance of large-scale steam ejectors for exhaust steam heat-supply. Based on the inherent characteristics of the steam injector, the performance of the ejector in the exhaust steam heat supply system of a 300 MW class unit under off-design conditions was experimentally studied. The performance curves of the steam ejector under different turbine back pressures, power steam pressures and outlet pressures were obtained. A solution method for full-operation-condition performance parameters of the steam ejector was established. Results show that the performance parameters are in good agreement with the experimental data.

A turbine with high cycle fatigue failure was used as the simulation model, the coupling method of three-dimensional unsteady flow field and solid vibration response analysis was adopted, the simulation of fault point was carried out. According to the different conditions of turbine expansion ratio and turbine reaction force, the law of aerodynamic load distribution and aerodynamic exciting force caused by aerodynamic state change was compared, at the same time, the relative variation trend of blade vibration stress was obtained. Results show that under unchanged intake conditions, the average exciting force, the amplitude of exciting force and the vibration stress of the blade increase obviously with the increase of the expansion ratio of the turbine. While the turbine reaction force increases, the average aerodynamic exciting force of the blade increases obviously, but the amplitude of the exciting force and the vibration stress have a downward trend.

Using numerical simulation methods, the thermodynamic and hydraulic parameters in the fuel bundle channel, especially downstream of the positioning grid, were calculated under different Reynolds number conditions. The effects of different punching models on the velocity and turbulence intensity in the downstream of the positioning grid were analyzed from the aspects of pressure drop, Nusselt number and comprehensive local heat transfer factor, and the optimal punching area within different Reynolds number ranges was calculated. Results show that when the Reynolds number is not less than 5 871, compared with the unperforated model, the perforated model can effectively reduce the pressure drop in the downstream section. When the Reynolds number is greater than 6 605, punching holes on the surface of the turbulent blade can reduce the longitudinal vorticity at the blade outlet, which leads to a decrease in the Nusselt number in the far field of the downstream flow field. When the Reynolds number is less than 7 339, the comprehensive heat transfer factor increases the most when the punching area ratio is 15%. However, when the Reynolds number is greater than 7 339, the local comprehensive heat transfer coefficient in the downstream far-field will gradually decrease with the increase of punching area.