This paper provides a comprehensive review of the research progress in lignocellulosic biomass pyrolysis technology. The pyrolysis mechanism of various biomass raw materials are summarized, the composition and properties of the products are analyzed, and the regulation, modification and application of the products are reviewed with emphasis. The results indicate that future research directions should focus on the following aspects: technological improvement, committed to improving biomass pyrolysis technology, enhancing energy conversion efficiency and product selectivity; diversification of products, in addition to the main energy products generated by biomass pyrolysis, such as biochar, bio-oil, and biogas, developing high-value chemicals and materials, including bio based chemicals, special chemicals, and high-performance materials should also be focused on; integration with other energy conversion technologies to establish a multi-energy co-supply system by combining biomass pyrolysis with the processes like biomass fermentation, photocatalysis, electrolysis, and energy storage technologies.

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 order to study the changes in levelized cost of energy and cost of electricity supply after the carbon capture, utilization and storage (CCUS) retrofit of a coal-fired power station, the current development trend of the electricity-carbon market was summarized and analyzed, and a simulation model was built to show the cost and benefit of CCUS application for 660 MW coal-fired power station. A sensitivity analysis was carried out using the cost of carbon capture cost and carbon trading price as variables. Results show that the predicted levelized cost of energy of the thermal power units after CCUS retrofit will fall to the range of 20% upward fluctuation of the regional coal trading benchmark price between 2034 and 2035. After 2039, the change rate of levelized cost of energy before and after the transformation will be negative, which means that the levelized cost of energy after transformation will be lower than the target of levelized cost of energy before transformation. In addition, although the carbon capture cost and carbon trading price will have more or less impacts on levelized cost of energy and power supply cost, the coupling effect of carbon capture cost and carbon trading price still has good economic results in the future for the CCUS retrofit projects of the thermal power units.

An integrated energy system based on source side of thermal power plant was proposed,which takes thermal power units as the core, couples multiple renewable energy inputs such as biomass gasification, garbage gasification and dried sludge at the input end of the system, and supplies multiple energy products such as colding, heating, steam and electricity at the output end. By coupling the thermal balance model of the power plant with the renewable energy model and cooling/heating system model, an optimization configuration method was established with efficiency and economy as the objectives. The following two types of optimization logics, input optimization and output optimization, were adopted to analyze the impact of the main operating parameters of the integrated energy system on the economy and efficiency optimization goals from the input and output ends of the system. Results show that integrated energy transformation has positive significance for current thermal power plants.

During chemical looping combustion, oxygen carrier plays a crucial role as the carriers of oxygen and heat. Design of oxygen carrier has always been the emphasis and difficulty in chemical looping technology research. Chemical looping combustion usually occurs in a fluidized bed reactor. Since the chemical stress caused by chemical reactions has the greatest contribution rate to the abrasion of oxygen carrier, the life of oxygen carrier is significantly shortened and the effective components run away. From the perspective of oxygen carrier structure design, the anti-abrasion mechanism of different composite oxygen carriers was qualitatively evaluated. The core-shell structure inhibits the phase separation of the active components and avoids the deactivation of oxygen carrier caused by surface abrasion of the active components. The addition of Al₂O₃ fiber and "rivet" inhibits crack growth and slows down the abrasion of the material. The addition of fuel ash improves the skeleton strength of the composite oxygen carriers, and the resistance to abrasion and slagging aggregation of oxygen carriers. The synergistic effect of the composite oxygen carrier increases the reactivity and slows down the sintering agglomeration phenomenon. From the perspective of abrasion dynamics and service life, the abrasion conditions of different oxygen carriers were quantitatively compared. By logarithmically fitting of the Gwyn abrasion dynamics equation, fitting parameters K and n of different oxygen carriers were calculated, which reflects the abrasion mechanism and abrasion patterns.

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.

Extreme weather events become more frequent because of climate change, posing a threat to the security and stability of the electricity system. Current researches about strategic reserve generation units mainly focus on policy evaluations or modelling simulations from the perspective of unit costs and power sale income, which do not adequately account for the economic and social effects they can bring. In order to comprehensively analyze the economics of strategic reserve generation units, a cost-benefit analysis model was established from the perspective of the whole society, considering the benefits including the guarantees for the economic production, health benefits for residents and labor force level, and the costs of strategic reserve generation unit investment and operation, and Sichuan power restriction event was taken as a case study for analysis. Results show that the benefit for 1 kW·h electricity that can be brought by the strategic reserve generation units is 4.77 yuan/(kW·h) and the required costs for 1 kW·h electricity generated by building new strategic backup units and using units that are close to retirement were about 1.91 yuan/(kW·h) and 0.47 yuan/(kW·h), respectively. Thus it is economically feasible to build and operate the strategic reserve generation units from the whole society perspective. At the same time, the operating hours are the most critical factor affecting the cost of strategic reserve generation units, and if the operating hours are less than 89 hours in a year, the unit's cost of electricity will be higher than its social benefits.

In order to optimize the ignition delay time and CO mole fraction, a new optimization mechanism for methane oxygen-enriched combustion based on artificial-neural-network (ANN-OMOC) was proposed by simplification and optimization for the detailed methane oxygen-enriched combustion mechanism USC mech2.0, using the directed relational graph with error propagation, full species sensitivity analysis and artificial neural network (ANN). The results of simulation calculation and comparative analysis for methane oxygen-enriched combustion show that the prediction errors of ignition delay time and laminar flame velocity are reduced from 2.53%, 24.38% to 0.50%, 14.41% by use of ANN-OMOC, compared with the prediction error of the simplified mechanism FSSA for methane oxygen-enriched combustion. Meanwhile, compared with the simplified mechanisms DRGEP and FSSA for methane oxygen-enriched combustion, the optimized mechanism ANN-OMOC has the best prediction results for ignition delay time, peak mole fraction of OH and peak mole fraction of CO, with relative errors of less than 10%.

A cooperative control strategy of deep deterministic policy gradient (DDPG) and proportion integration differentiation(PID) based on multidimensional state information and segmental reward function optimization was proposed for the selective catalytic reduction(SCR) denitrification system with large inertia and multi-disturbance. Addressing the problem of low strategy learning efficiency of the DDPG algorithm caused by the partially observable Markov decision process (POMDP) in the SCR denitrification system, the multidimensional state information of the SCR denitrification system was designed firstly. Secondly, the segmented reward function of the SCR denitrification system was designed. Finally, a DDPG-PID cooperative control strategy was designed to achieve the control of SCR denitrification system. Results show that the designed DDPG-PID cooperative control strategy improves the strategy learning efficiency of the DDPG algorithm and the control effect of PID. Meanwhile, the designed cooperative control strategy has strong set value tracking capability, anti-interference capability and robustness.

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.

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.

To explore the effect of biomass components such as cellulose, hemicellulose and lignin on physical properties of pellets, cotton stalk and wood sawdust were mixed with their components at different mass ratios to prepare the pellets. The apparent density and compressive strength of pellets were analyzed by electronic universal material testing machine. The biomass molecular structure before and after briquetting was analyzed by X-ray photoelectron spectroscopy. Results show that the compressive strength of pellets is directly affected by cellulose, meanwhile hemicellulose and lignin mainly act as binders to improve the compressive strength of pellets indirectly. The addition of cellulose or hemicellulose to cotton stalk significantly increases the C—OH functional group in its pellets, and C＝C functional group is formed, which are conducive to form the intermolecular force and increase the stability of molecular structure. They can enhance the physical properties of pellets.

To enhance the quality of biomass gasification products, briquettes of eucalyptus bark and corn stalk were used as the typical feedstocks for the fluidized bed gasification experiments. Rice husks and sawdust were selected for comparison. Gasification experiments were conducted on a pilot-scale fluidized bed to obtain the optimal air equivalence ratio values for rice husks, sawdust, and the briquettes of eucalyptus bark and corn stalk. The causes of slagging during biomass briquettes gasification were analyzed. Results show that the optimal air equivalence ratio value for briquettes of eucalyptus bark, rice husks and sawdust is 0.20, and the gas heating values of the three biomass are 5.5 MJ/m³, 5.5 MJ/m³ and 6 MJ/m³ respectively, the corresponding gasification efficiencies are 60%, 45% and 52%. While the optimal air equivalence ratio value of corn stalk briquette is 0.24, which means requiring more air due to the high ash content and low heating value. The gas heating value of corn stalk briquettes is 4 MJ/m³, and the gasification efficiency is 35%. The increase in gasification temperature promotes the gasification reaction of various biomass. Biomass briquettes with high concentration of alkali and alkaline earth metals are more susceptible to slagging during gasification.

Aiming at the serious impact of wake effects between wind turbines on the power generation efficiency of wind turbines, a calculation method for safe yaw constraints of wind turbines, a mixed semi mechanism modeling method for wake characteristics, and a multi-objective collaborative optimization scheduling method for wind turbine groups were proposed. Based on the FAST.FARM platform, the dynamic interaction and integration simulation environment between multi degree of freedom controllable units and wake was improved, and compared and analyzed the collaborative operation optimization performance of two units arranged in tandem and seven units arranged in an offshore wind farm in East China. Results show that the established integrated simulation model can reasonably characterize the multi domain dynamic interaction characteristics between wind turbine groups and air flow fields. The proposed method can effectively improve the power generation efficiency of wind turbine groups and promote balanced optimization of economic benefits, resource utilization and cost control.

Deflected yaw control is beneficial to reduce the wake effect of wind turbines, and the power generation of wind farm can be maximized by reducing wake loss through yaw optimization at field-level. The FLORIS wake surrogate model was used to optimize the yaw angles of all turbines to reach the maximum total power of wind farm. The sensitivity of yaw optimization to wake loss and power increase was compared and analyzed in terms of different spacing distance of turbines, number of turbines, turbulence intensity, incoming wind speed and wind direction. Results show that yaw control of wind farm has the best effect on wake optimization when the turbine distance is less than 5D, there are more than 3 turbines at line, and only the first 5 rows need to be optimized, the angle between turbine-connect-line direction and main-frequency wind direction is less than 15°, the wind turbulence is less than 0.1 and wind speed is within the range of "cut-in+2 m/s" and "rated+2 m/s". If only single-turbine yaw control system is used, the yaw error of 3°~5° is beneficial to the overall wind farm power generation.

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.

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.

Large-scale grate furnaces have been widely used in the energy conversion of biomass and municipal solid wastes (MSW). However, due to the fact that design and operation of grate furnaces are still in the stage of engineering exploration, in the actual operation process, there are still problems such as high excessive air rate, poor combustion efficiency in both gas and solid phase, and high initial NO_x emissions. In response to the complex layered combustion process of grate furnaces, a large-particle conversion model and a multi-component parallel particle combustion model were constructed to achieve fine numerical simulation of actual grate furnace combustion processes. The accuracy of this model was verified by comparing with experimental results. Using numerical simulation methods, real-furnace analysis and optimization were carried out for large-scale grate furnaces burning MSW and agricultural straw. Based on the surface- and bottom-ignition modes, on-site adjustments were made. Results show that for the middle-arch SW incinerator, localized high temperature and high NO_x emission are mainly caused by the departure of component distribution, combustion and reduction reactions from design, which are clearly improved by the operation adjustment. According to numerical modeling calculation, a further optimization in its structure can reduce NO_x emission to 26.8 mg/m³. For the vibrating grate boiler for straw, low combustion efficiency in gas and solid phase is mainly caused by the convective cooling of large primary air and the "chimney-like flow" in furnace. After optimization, its emission is hugely reduced, and power-generation load remarkably rises.

Aiming at the problems of poor adjustment effect and difficult parameter setting of traditional linear active disturbance rejection control (LADRC) for high-order plus time delay (HOPTD) systems, a high-order time delay-linear active disturbance rejection control (HTD-LADRC) was proposed. On the basis of first-order LADRC, a high-order feedforward compensator was connected in series to solve the problem of asynchronicity between feedforward signal and feedback signal of the linear extended state observer (LESO) and the accuracy of state observation of the system was improved. On this basis, the objective approximation legal quantization parameter setting formula was used, and the adjustable interval of parameters was derived to realize single parameter λ adjustment of controller parameters and simplify parameter setting. Furthermore, the frequency domain analysis method was used to verify the effectiveness of the tuning method, and the relationship between the parameters and the system robustness was determined. Finally, in the simulation experiment of selective catalytic reduction (SCR) denitration control system, the proposed controller was compared with other controllers to verify its superiority. Results show that the proposed high-order linear active disturbance rejection control with time delay has obvious advantages in fixed value following, disturbance resistance and robustness, and has great engineering application potential.

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.

Machine learning methods have demonstrated promising applications in biomass gasification modeling. However, machine learning models primarily rely on experimental data and do not consider the reaction mechanisms in gasification. In situations that data samples are insufficient, there can be significant deviations between the actual correlation characteristics exhibited by the model and the mechanistic laws. Thus a method for predicting biomass gasification product distribution based on physics-informed neural networks (PINN) was proposed. This method seamlessly integrated real experimental data with prior mechanistic knowledge, embedding boundary constraints and monotonic relationships among key parameters into the artificial neural network(ANN) model. Automatic differentiation techniques were used to assist optimization, enabling efficient model training. Results show that the PINN model achieves a coefficient of determination greater than 0.89 and a root mean square error less than 4%, the overall prediction accuracy is superior compared to the three models which are purely fitting based on machine learning: random forest (RF), support vector machine (SVM) and ANN. Furthermore, the PINN model strictly adheres to boundary constraints and prior mechanistic monotonic relationship, exhibiting better interpretability and generalization capabilities.

A three-dimensional temperature distribution reconstruction algorithm based on Tucker decomposition and acoustic temperature measurement was proposed. In the algorithm, numerical computation was used to establish a priori dataset, the main characteristics of the boiler temperature field were extracted using Tucker decomposition, and acoustic temperature measurement was combined with two-dimensional temperature field interpolation to reconstruct the three-dimensional temperature field. The algorithm could improve the reconstruction accuracy of complex temperature fields and have a fast reconstruction speed. Results show that the method can reconstruct complex three-dimensional temperature fields in about 10 seconds, and reduce reconstruction errors by more than 10% compared to traditional acoustic temperature measurement. It also has strong applicability for temperature fields outside priori operating conditions, and has some guiding significance for combustion optimization and load adjustment in coal-fired power plants.

A coordinated torque-pitch control strategy based on improved model free adaptive control was proposed to overcome the difficulties in modeling floating offshore wind turbines and the serious fatigue damage caused by frequent pitch action. This strategy didn't rely on the mathematical model of the floating offshore wind turbine. The model free adaptive control method was improved by integrating the iterative learning control strategy; a multi input and multi output controller with the generator torque and pitch angle as control variables was designed for coordinated control; allow the wind turbine to be used as kinetic energy buffer under the non-zero pitch angle, and the amount of pitch action was reduced while the output power was smoothed. To demonstrate the effectiveness of the designed strategy, comparative experiments were conducted with methods such as gain scheduling PI control in various wind scenarios. Results show that the proposed control strategy enables the floating offshore wind turbine to meet the stability of power generation while reducing the pitch motion of the floating platform, which can significantly reduce the fatigue damage of the floating offshore wind turbine.

Based on the technology of desulfurization, self-denitrification and selective non-catalytic reduction (SNCR) denitrification in circulating fluidized bed (CFB), the emission of air pollutants from CFB units was studied. The combustion model, the pollutant generation and removal model in CFB units were established, and the key state variables affecting the emission of pollutants were analyzed. Results show that the established models of SO₂ and NO_x emission of CFB units can fit the actual operation data well, and have certain prediction effect and strong model universality. The combustion of carbon affects the reduction atmosphere in the furnace, which significantly affects the reduction of NO_x. The amount of active limestone and furnace temperature is the main factors affecting the curing reaction between SO₂ and active limestone, while relatively high furnace temperature and less active limestone stock will both increase the concentration of SO₂ emission, but the higher the temperature is, the lower the level of NO_x emission is.

In order to solve the problems of instability and utilization of renewable energy, a combined cooling, heating, and power (CCHP) system was proposed that integrated solar photovoltaic/thermal, water electrolysis for hydrogen production, and biomass gasification and methanation. Aiming at the capacity matching problem of the CCHP system under high dimensional target, an improved beluga whale (MOBWO) algorithm was proposed and verified. The proposed algorithm improved the distribution of solutions and the convergence rate. A case study based on this method shows that compared with the individual systems, the fossil fuel consumption is reduced by 56.8%, the CO₂ emission is reduced by 53.1%, and the flexibility reaches 51.6%, although the annual total cost of the optimal capacity allocation scheme is increased by 19.8%. In this case model, the MOBWO algorithm has better solving performance than non-dominated sorting genetic algorithm-II (NSGA-2) and multi-objective particle swarm optimization (MOPSO) algorithm.

To solve the problems of inadequate cyclic stability, low thermal conductivity, and insufficient light absorption in CaO/CaCO₃ energy storage system, discussions were conducted on improvement methods for the performance of calcium-based materials from the aspects of the selection of calcium-based raw materials, addition of doping elements in composite materials, and adjustment of operating conditions. Results show that inert oxides are formed within materials through the addition of elements such as Al, Mn, and Ti, which can inhibit sintering and further improve the cyclic stability of materials. The thermal conductivity of materials can be enhanced by the doping of materials with high thermal conductivity, such as Al₂O₃, MgO, SiO₂, and ZnO. Additionally, the spectral absorption of materials can be improved by the doping of elements such as Mn, Cu, Fe, Co, and Cr. Corresponding summaries may provide a reference for the design of materials for thermochemical energy storage.

A composite supercritical carbon dioxide-organic Rankine combined cycle was used for waste heat recovery from the gas turbine, comprehensive thermodynamic and exergy economic model was established, and the impact of key parameters on the performance of the combined cycle system was explored. A study has been carried out on the combined cycle system from multiple purposes such as thermodynamic performance, space compactness and exergy economic performance, so as to conduct the multi-objective optimization on the combined cycle. Results show that the combined cycle efficiency in the optimal state can reach 54.56%, which is 4.2% higher than that of the conventional gas turbine-steam combined cycle. The required heat exchange area per unit power output is 0.117 8 m²/kW, which is 21.41% lower than that of the conventional gas turbine-steam combined cycle.

Severe ash deposition and slagging issues have occurred during the combustion utilization of Xinjiang coal, and adding kaolin additives is an effective way to address these issues. With the sedimentation furnace ash accumulation experiments and the fixed-bed sintering experiments, the performances and mechanism for prevention and control of kaolin with different particle sizes were studied. Results show that kaolin changes the ash-forming characteristics of Xinjiang coal through its dilution and interaction with minerals in coal, which in turn affects the ash accumulation behaviors and sintering characteristics. Although fine kaolin can effectively inhibit the vapor deposition of alkaline substances through interaction, the dilution of the additives leads to a smaller ash particle size. Therefore, it is easier to form ash deposition in the initial stage. Under the combined effect of above two aspects, fine kaolin and coarse kaolin have similar prevention and control effects on the growth of ash accumulation in the initial stage. In addition, the smaller ash size distribution after the addition of fine kaolin promotes the development of ash sintering degree, which is not conducive to the soot blowing and removal of sediments.

When zero-carbon units represented by clean energy power generation were integrated into the grid on a large scale, frequency fluctuations caused by intermittency and uncertainty became more prominent. Aiming at the problems of insufficient flexibility in frequency modulation and unsatisfactory effect in charge state maintenance of thermal power units assisted by battery energy storage, an energy storage assisted secondary frequency modulation control strategy based on adaptive decomposition of frequency modulation signals was proposed. Firstly, the switching time criterion of regional adjustment demand signal and regional control error signal was given by synthesizing sensitivity, energy storage charge state and frequency deviation state. Considering the climb rate limit of thermal power units and the state limit of stored energy, an adaptive frequency modulation signal decomposition strategy was proposed, and the rule between return gain and state of charge was constructed as the adjustment reference value. Frequency deviation was used to correct the reference value. Finally, the state consistency detection module was used to judge the output of return gain, so as to realize the complementary advantages of the two frequency modulation resources. Effectiveness of the proposed strategy was verified by the simulation of the single-region system frequency response model. Results show that the strategy can improve the flexibility of the system and make each frequency modulation resource form a complementary relationship.

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.

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 order to study the SO₃ generation characteristics of SCR system during low temperature operation, the effects of flue gas temperature, SO₂ mass concentration and ammonia injection on the catalytic SO₃ generation characteristics were analyzed on a pilot test bench. Results show that temperature is the main factor affecting the SO₃ generation rate. SO₃ generation rate decreases as the flue gas temperature decreases,which is also influenced by SO₂ mass concentration. However, the effect of SO₂ mass concentration on SO₃ generation rate becomes very little when the inlet flue gas SO₂ concentration is in the range of 700 to 1 150 mg/m³ and temperature is below 260 °C. Compared with the un-injected ammonia condition, both the outlet SO₃ mass concentration and SO₃ generation rate decrease under ammonia injection condition. At the same time, the probability of low-temperature corrosion decreases, and the probability of ammonium bisulfate generation increases. Since SO₃ generation rate in the SCR system decreases at low temperature, the harm to the low-temperature heating surface is reflected in the low-temperature corrosion and blockage under the synergistic effect of H₂SO₄ and ammonium bisulfate.

Heat generated during the incineration of hazardous waste is usually used to produce saturated steam to supply steam, heat and other needs for industrial parks, which can also be used for low-temperature power generation. The thermodynamic performance of the saturated steam-driven organic Rankine cycle (ORC) system was analyzed. Based on thermal matching analysis of the steam latent heat source and the ORC system under the basic working condition, three optimization measures were proposed, and the thermodynamic performances of the system with single optimization or combined optimization measures under different working conditions were studied. Results show that the combined optimization method can make the system achieve better performance, and the maximum net output work is 3 193.81 kW, which is increased by 170.46% compared with the basic working condition. Accordingly, the thermal efficiency is 23.34% with an increase of 30.25%, and the total exergy efficiency is 66.25% with an increase of 41.80%.

Aiming at the measurement problem of gland seal leakage of high pressure (HP) and intermedia (IP) combined turbine, a method of determining the gland seal leakage by introducing intermediate variable was proposed. And a calculation method was derived through theoretical analysis. The total amount of gland seal leakage of HP and the component of IP side gland seal leakage at different conditions were calculated by taking the leakage of IP balance piping of gland leakage as an intermediate variable. Taking a subcritical 600 MW steam turbine as an example, the calculation results were compared with the design conditions. Results show that the relative error of gland seal leakage is within 1%. Compared with the calculated values by the variable steam temperature method, the relative error of the IP side gland seal leakage is within 5%. Research results prove that the proposed method is reliable in theory and has high accuracy in calculation, also simple in operation and feasibility.

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.

The characteristics of pulverized coal combustion, CO₂ enrichment and NO_x generation during the oxygen-enriched combustion were analyzed. The synergistic control of CO₂ enrichment and NO_x generation was simulated. Results show that compared with air combustion, the negative synergistic effect between CO₂ enrichment and NO_x volume fraction distribution during the oxygen-enriched combustion can be observed. Under different O₂/CO₂ volume fractions, as the oxygen volume fraction increases, the volume fractions of both CO₂ and NO_x at the furnace outlet increase to the maximum firstly and then decrease slightly, showing the positive synergistic effect, but the turning point of the oxygen volume fraction is different. When enriched CO₂ volume fraction exceeds a certain value, it can effectively inhibit the NO_x generation. Under enriched oxygen conditions, a synergistic control technology can be achieved for high CO₂ enrichment and low NO_x generation at the furnace outlet.