As a typical kind of air pollutants, VOCs has hazardous effects on both the gas environment and impair human health. Abatement of VOCs is the major requirement of China’s ecological environment. Simultaneously, it is the significant content of China’s 14th five-year plan. Based on the economic development, emission source of VOCs in China has been illustrated. Furthermore, the national, local and industrial regulations of VOCs emissions have been concluded. Abatement techniques of VOCs have been compared and analyzed, including various recovery and destruction techniques. The multi-technique characteristics has been concluded. Finally, the dominant abatement technique in the future was prospected.

The straight-through labyrinth seal is an effective and simple sealing technology which is widely used in gas turbines. In this paper, the effect of rotation on the flow heat transfer in a straight-through labyrinth sealing structure is investigated using numerical simulations. All results are obtained at Reynolds numbers of 6000, 10000 and 15000. The results show that the increase in rotational speed reduces the vortex losses and throttling losses in the labyrinth seal channel, which leads to the increase in the discharge coefficient. With the increase of rotational speed, the heat transfer at the tip wall is enhanced while the heat transfer at the tooth cavity is weakened.

A total three-dimensional method for calculating mixing loss is proposed in response to the problem that existing methods for evaluating the mixing loss of film cooling cannot accurately calculate the loss between mainstream and coolant in the area affected by passage secondary flow. Film holes with different compound angles are set in the suction surface based on HS1A turbine guide vane. Under the premise of meeting the requirements from film cooling effectiveness, the loss mechanism is analyzed by controlling the mainstream and coolant parameters. Different models are analyzed by using the entropy creation of mixing as the basis for loss evaluation. The results show that film cooling effectiveness is improved by arranging subregional compound angle holes with entropy creation of mixing increasing. And the loss of film deflection caused by passage secondary flow and film detachment can be reduced by setting compound angles.

In this paper, a new solar photovoltaic/thermal system with parabolic trough concentrator and indium tin oxide/ethylene glycol nano-fluid beam splitting is proposed. Indium tin oxide/ethylene glycol nano-fluid is prepared and tested. The results show that the absorptivity and transmittance of the indium tin oxide nano-fluid are 30.9% and 69.1% in the full wavelength range. The optical behavior of the photovoltaic/thermal system is studied and the overall optical efficiency of the system is 89.38%. When the sun tracking error is less than 0.2 ̊, the photovoltaic/thermal system can have an overall optical efficiency which is greater than 84.14%. The operation performance analysis reveal that the photoelectric efficiency of the photovoltaic subsystem is 29.1%, and the overall photoelectric conversion and thermal efficiencies of the photovoltaic/thermal system are 19.1% and 19%. The thermal efficiency of the system can be improved by increasing the inlet indium tin oxide nano-fluid velocity, or by reducing the inlet indium tin oxide nano-fluid temperature and external convectional heat transfer coefficient.

Integrating the existing coal-fired, solar, wind power plants, and high-temperature thermal energy storage can simultaneously increase the portion of renewables and enhance the flexibility of electricity supply in a power grid. In this paper, a four-tank cascade heat storage scheme based on the combination of solar salt and Hitec salt is proposed under protective gas, a techno-economical analysis is performed. The results show that the unit energy cost of the proposed cascade heat storage with four tanks accounts 49% of that of traditional two-tank solar salt storage system. At a charging price of 3 cents/kWh, the levelized cost of electricity of the four-tank cascade heat storage scheme is about 2.2 cents/kWh less than the traditional two tanks of solar salt scheme. The levelized cost of electricity of the proposed cascaded system is significantly lower than systems integrated with other energy storage technologies with discharging duration is less than 9 hours, due to the reduction in initial investment utilizing existing infrastructures of coal-fired power plants. After investigating the distribution of wind, photovoltaic, and coal-fired power plants in China, Inner Mongolia, Gansu, and Shandong provinces are suitable to push the integrated systems. Taking Inner Mongolia as am example, Ordos and Ulanqab cities are particularly fit for the scheme implementation.

A novel solar energy driven CO₂ and H₂O conversion system based on concentrated spectral splitting technology is proposed for liquid hydrocarbon fuels production. Concentrated solar energy is divided into two parts via spectral splitting technology. The short-wave segment is utilized for photovoltaic power generation to drive a proton exchange membrane cell, by which water can be split into hydrogen and oxygen, providing the reactant necessary for CO₂ hydrogenation into methanol. While, the rest part is converted into heat and stored in heat transfer fluid, and can be used in gaseous reactant preheating, water desalination, and/or direct air carbon dioxide capture, etc. Then, the mathematical theoretical model for this solar energy utilization system is built, and its thermodynamic performance is also investigated. It is found that the system achieves its maximum exergy efficiency of about 23.40%, when the temperature of gallium arsenide photovoltaic panel reaches 105°C, along with a corresponding hydrogen production rate of 2.84 L·min⁻¹. Employing an exhaust gas recirculation reaction mode, the CO₂ hydrogenation reactor achieves a hydrogen conversion rate of 68.19%, methanol product selectivity of 97.90%, and methanol yield of 0.91 g·min⁻¹, at reaction pressure of 5 MPa, reaction temperature of 220°C, and a carbon-hydrogen ratio of 1 : 3. The solar energy-to-methanol fuel efficiency of this system is calculated to be 6.08%. This work offers a viable approach for leveraging solar energy to mitigate carbon emissions and advance carbon neutralization technologies.

The thermal conductivity of soil is a vital parameter in describing its heat transfer properties. Accurate prediction and sensitivity analysis of this parameter can aid in assessing the thermal response in geotechnical engineering and prevent deformation and damage in projects. Based on thermal conductivity experiments by Kersten’s team, we analyzed the factors influencing this parameter. we considered introducing a temperature variable into the traditional empirical formula and conducted validation, resulting in an improved formula with good applicability to clay. Using artificial intelligence algorithms, we established a prediction model for thermal conductivity. The model uses soil type, dry density, water content, and temperature as input variables. Our analysis showed that the Random Forest model, Radial Basis Function Neural Network (RBFNN), and Whale Optimization Algorithm Backpropagation Neural Network (WOA-BP) could all accurately predict thermal conductivity. Among these, the WOA-BP model demonstrated the best performance, followed by Random Forest and RBFNN.We tested the prediction model using a new sample set and found that the model still performed well, indicating a certain level of generalization ability. We employed a Monte Carlo simulation for parameter sensitivity analysis of the improved empirical formula. With the Random Forest model, we ranked feature importance to evaluate the impact of different input variables on model output. Finally, we calculated the sensitivity of influencing factors using a weighted product method combined with WOA-BP. The results from all three methods were consistent. They indicated that the sensitivity of thermal conductivity to changes decreases in the order of water content, dry density, temperature, and soil type.

This article compares three compression heat recovery methods in cryogenic air separation units, including organic Rankine–assisted air compression heat recovery system (ORC-ACS), organic Rankine-electric driven vapor compression-assisted air compression heat recovery system (ORC-VCR-ACS), and organic Rankine-driven vapor compression-assisted compression heat recovery system (ORVC-ACS). The calculation results show that among the three systems, ORVC-ACS has the highest energy-saving efficiency and economic benefits. The system power saving of the ORVC-ACS reaches 1723 kW, which saves about 15.1 GWh/a, and accounts for about 7.5% of the total power consumption of the air compressors. The ORC-VCR-ACS is next, and its highest system power saving is about 1268 kW, while that of the ORC-ACS is about 783 kW. The highest net present value of the ORVC-ACS is about 99 million CNY with an average discounted payback time less than 3.2 years, indicating great economic potential. The maximum net present value and maximum discounted payback periods of the ORC-VCR-ACS and ORC-ACS are approximately 97 million CNY, 3.4 years and 44 million CNY, 4.8 years, respectively. In addition, the three systems can save up to 10.8, 11.4 and 4.9 million tons of carbon dioxide per year, respectively, showing great environmental potential.

Porous media play a key role in the fields of energy conversion, thermal management and energy storage due to their outstanding advantages such as large surface area, light weight and complex channels. In this paper, the homogeneous porosity and gradient porosity W type porous structure (porosity ε=0.3∼0.5, hydraulic diameter dh=1.33∼3.86 mm) were customized based on the triply periodic minimal surface (TPMS) method. A computational model of combustion reaction of porous media was established to investigate the range of flame stabilization within the W type porous structure and the SC-BCC cubic lattice structure, and the results showed that the flame blowout of W type structure limitation is higher (equivalence ratio φ=0.65 and inlet velocity V_in=0.6∼2.2 m·s⁻¹). Furthermore, the regulation of combustion and heat transfer processes by the W type porous structure with continuous gradient porosity was investigated, and the results showed that the continuous gradient porous structure would significantly broaden the range of flame stabilization by adaptively modifying the heat rejection rate. 

The water and thermal management strategies in the proton exchange membrane fuel cell stack are closely related to the structure and size of the stack. Computer-aided design simulation tools can be included in the development process. A two-dimensional model of the rapid prototyping stack based on COMSOL software is developed in the present study. In the model, the components of the entire are considered. The interactions among the transport processes of air, water, heat, and electricity within the membrane electrode assembly, bipolar plates, and cooling water channels are computed. A pair of inlet and outlet headers are added to the model to realistically simulate the gas flow distribution of the entire stack. The geometric dimensions and the number of unit cells in the model are parameterized, which can be quickly modeled and simulated according to the design requirements. A preliminary design scheme for the stack can be provided before more detailed 3D simulations are carried out. A 2D fuel cell stack model with 10 unit cells connected in series is presented as an example. This model solves a complete set of mass, momentum, composition, and temperature conservation equations for heat transfer in gas flow channels, porous media, electrode coupling surfaces, and solid fluids. With the U-shaped configuration, the oxygen velocity, mass fraction and current density distribution characteristics of the electrode coupling surface of the battery stack are analyzed. Based on the stack model, the effects of parameters such as voltage,PEM conductivity, and air intake velocity on the stack moisture distribution are studied. The simulation results show that high voltage operation, larger conductivity of the proton exchange membrane, and larger air flow rate will improve the stack performance. By optimizing the existing model structure, a more uniform distribution of water and gas in the stack is obtained, providing a reference for the further fuel cell stack design.

The compressor is the core component of an air conditioner, and its vibration characteristics play a key role in improving the reliability of the compressor. In order to clarify the effect of the fixing method of air conditioner external pipeline on the compressor’s vibration characteristics, this paper carried out some experimental research on it. Two variable factors, including the location of the constraints and the number of constraints on the air conditioner external pipeline, were taken into account; the vibration acceleration in different directions at each test point of the compressor was recorded during the test at an operating frequency of 30 Hz∼90 Hz. The results of the test show that a moderate increase in the distance between the restraining position and the outdoor unit can lead to a better realization of compressor vibration reduction; Increasing the number of constraints achieves little vibration reduction in the axial direction at the compressor position, but will increases the radial vibration acceleration at the motor position considerably.

Large eddy simulations (LESs) were conducted to investigate the effects of wall heat transfer on the transition process within separated shear layers over two highly loaded compressor blades (adiabatic and isothermal cooled wall conditions) at a Reynolds number (Re) of 1.5×10⁵. Results showed that wall cooling reduced the flow kinematic viscosity of the near-wall flow, which weakened the relative role of turbulent energy dissipation in suppressing the rapid amplification of amplifications. For the compressor blade IET-ULF1, the separated shear layers were more prone to being destabilized, and the transition process was accelerated. However, for the compressor blade IET-ULF2 with a higher loading level, the positive effect of wall cooling on promoting the transition process was much weaker. It was found that the reverse flow mixing, breakdown of large-scale threedimensional hairpin vortices, and the ejection-sweeping process of the near-wall flow determined the generation of turbulent fluctuations and the resulting loss. Compared with the adiabatic wall, the vortex dynamics on the cooled wall were weakened, and the generation rate of turbulent fluctuations declined. Thus, the growth rate of boundary layers was decreased, and the profile losses of the IET-ULF1 and IET-ULF2 were reduced by 18.2% and 22.1%, respectively.

Carnot battery (CB) is a novel electricity storage technology which could realize electricity storage and waste heat recovery simultaneously. The thermal integrated CB (TI-CB) only utilizes the waste heat energy during the charging process in previous study. The waste heat energy utilization is insufficient. A CB with thermal integration during charging and discharging process (DTI-CB) is proposed in this paper. The waste heat energy is effectively integrated with DTI-CB in all periods through being coupled to the Organic Rankine cycle (ORC). A thermo-economic evaluation of the proposed DTI-CB is conducted. Compared with TI-CB, the power output capacity could be increased 95.67% and the Levelized cost of storage could be reduced 30.90%. The thermoeconomic performance of the proposed DTI-CB performs better than those of the single ORC and CB under the conditions with relatively higher heat utilization load. 

Flash steam is an efficient and rapid phase change process with great engineering applications. In this paper, a pressure-driven Lee phase transition model with variable saturation temperature is established for the flash evaporation process accompanied with flow, and a numerical simulation and mechanism analysis of pure water flash evaporation with inlet superheat of 3∼6 K and initial liquid level height of 0.3∼0.8 m are carried out by combination with the VOF model. The results show that the intense phase change steam generation at the inlet area improves the gas-liquid and temperature distribution in the flash chamber, which is an important factor to increase the steam generation rate and the degree of conversion of water. Within the study scope, an increase in the inlet superheat and a decrease in the initial level height can reduce the non-equilibrium fraction of outlet water by about 55% and 35%, respectively, and an increase in the inlet superheat and the initial level height can increase the steam generation rate by about 292% and 191%, respectively. 

Open microchannels have advantages such as promoting vapor-liquid separation, stabilizing two-phase flow, and improving heat transfer performance. However, with the increasing demands for thermal management of electronic devices, enhancing the flow boiling heat transfer capacity of open microchannels has become a research focus. In this study, low-surface-tension fluid SF-33 is used as the working fluid to experimentally compare the flow boiling characteristics in smooth surface open microchannels (SSOMC) and multi-stage enhanced open microchannels (MEOMC). High-speed visualization is employed to observe bubble behavior and flow regime transitions in both types of microchannels, analyzing the effect of micro/nano structures on flow boiling heat transfer mechanisms. The results show that under high heat flux, a plug-stratified flow is observed in SSOMC, while a new flow regime, termed plug-dispersed flow, is observed in MEOMC. The multi-stage enhanced structures significantly improve the flow boiling heat transfer performance of open microchannels, with a more pronounced improvement during subcooled flow boiling. Additionally, due to the strong capillary wicking effect of the micro/nano structures, the two-phase pressure drop in MEOMC is consistently lower than that in SSOMC.

The application, screening, evaluation and funding of National Natural Science Foundation of China programs in Engineering Thermophysics and Energy Utilization Discipline in 2024 are summarized and statistically analyzed. The strategic research, funding proposals in the field of energy and power under the carbon peaking and carbon neutrality goals are introduced. The outstanding achievements funded by the discipline in 2024 and future work in 2025 are introduced as well.

As a very competitive hydrogen production technology, supercritical water gasification technology has important practical significance in exploring the combination route with hydrogen metallurgy under the carbon peaking and carbon neutrality goals. This paper presents a new technical route: supercritical water gasification for hydrogen production complete the reduction of metal oxide in the same reactor, simplifying the metallurgical process. The feasibility of this technology was verified from thermodynamics and experiment, and Fe₃O₄, Cu and MoO₂ powders could be rapidly reduced to prepare in supercritical water gasification atmosphere with glycerol mass concentrations of 2%, 5% and 10%. Under the mass concentration of formic acid 50%, 60% and 70%, blue tungsten oxide and violet tungsten oxide can be obtained by supercritical water gasification, and under the mass concentration of 50%, the needle structure is obvious and less agglomeration.

In this paper, the combustion process of ammonia pre-chamber jet ignition is visualized using high-speed photography. The experimental results show that: a larger pre-chamber volume can provide a larger ignition energy, leading to a reduction in the ignition delay and combustion duration; the pre-chamber volume is the most influential factor for the ignition position of the mixture in the main combustion chamber, and the larger the pre-chamber volume is, the closer the ignition position is to the pre-chamber. Under good combustion conditions, a pre-chamber with a small aperture has better combustion characteristics, and despite the prolonged ignition delay, the combustion duration can be significantly shortened, especially in high-temperature environments.

To realize reasonable control of the water injection parameters for a single-screw steam compressor, a three-dimensional single screw groove model was established, the numerical simulation of the wall-approaching film formation process of injected water along the wet compression process was carried out, the coverage area of the effective water film formed by the injected cooling water inside the compression channel, as well as the influence laws of the key parameters such as water injection mass flow rate, velocity, angle, and screw rotor rotational speed were analyzed. The results indicate that the injection mass flow rate has the greatest impact on the coverage area of the effective water film with a maximum increase of 6.77×10⁻⁴ m². Within the selected parameter range in the study, the respective increases in the coverage area of the effective water film caused by these factors are 59.85%、50.68% and 47.79% compared to the increase caused by the injection mass flow rate. 

The ignition delay times of ammonia/methanol mixtures were measured by a shock tube at different equivalence ratios, high temperature and medium-low pressure. A new combined simplification model (NH₃-M) was proposed and it can well predict the experimental ignition delay times of ammonia/methanol mixtures, Chemkin-PRO software was used to analyze the chemical reaction kinetics based on NH₃-M model. The results show that adding a small amount of methanol can significantly shorten the IDTs of ammonia/methanol mixtures. The ignition delay time satisfies the Arrhenius relation, it is mainly affected by small radicals such as OH, O, HO₂ and H. The initial consumption of ammonia and methanol mixtures begins with H-abstraction, R224 is the most sensitive ignition-promoting reaction, it is not R466 and R467 that directly promote ignition but the active substances generated from the intermediates produced by R466 and R467 that facilitate the entire reactions.

The thermal properties of ZnO with different crystal orientations were characterized by the time-domain thermoreflectance method combined with a diamond anvil cell and a heating stage in 0∼8 GPa and 300∼873 K. It is found that the thermal conductivity of wurtzite ZnO is anisotropic under both high pressure and high temperature conditions. Meanwhile, the pressure dependence of the thermal conductivity is non-monotonic, while the temperature dependence of the thermal conductivity is monotonic. This research can provide useful insights into the internal heat transport mechanism of wide band-gap semiconductors under high pressure and high temperature, and give ideas for searching for materials with high thermoelectric figure of merit.

In this paper, the in-cylinder combustion characteristics and soot generation processes of diesel blended polyoxymethylene dimethyl ethers (PODE)-gasoline reactivity controlled compression ignition mode were collected on an optical engine using high-speed imaging combined with the two-color method for clean fuel replacement of conventional fuels. The test results showed that with the increase of PODE blending at the same premixed ratio, the peak in-cylinder pressure, peak heat release rate and pressure rise rate were reduced, the ignition delay was extended, the combustion duration was increased, the combustion phase was shifted back and the combustion tended to be gentle. At a premixed ratio of 50%, the total heat release volumes from single cycle combustion of P20D80 and P50D50 as direct injection fuel was 97.89% and 95.39% of the total heat release volumes of direct injected P0D100 respectively, the total soot generation from single cycle was 55.22% and 36.55% of that of direct injected P0D100 respectively, the high temperature region of soot was reduced by 52.9% and 73.32% respectively, the stable values of soot average temperature were reduced by 6.65 K and 20.25 K respectively, and the stable values of soot average KL factors were reduced by 10.35% and 16.12% respectively. In contrast, P50D50 as a direct injection fuel ensured high combustion thermal efficiency and effectively suppress the generation of soot.

Supercritical carbon dioxide (sCO₂) power cycle has a more compact structure and higher efficiency. However, dramatic variations in thermophysical properties of working fluid and the coupling of multiple nonlinear physical processes such as fluid transport process and energy transfer process make conventional modelling and solving methods more difficult to simulate the cycle accurately and efficiently. This study constructs the heat current model of the sCO₂ power cycle and proposes an efficient solution algorithm based on the generalized Benders decomposition. The proposed algorithm categorizes system governing equations according to their linear or (explicit/implicit) nonlinear mathematical properties,and variables’ gradient information is used to update unknown variables iteratively. Compared to conventional algorithms, the new solution method owns better robustness and has a 48% larger convergence range regarding the deviation of initial values. Besides, the proposed algorithm is more efficient when the initial value deviation is small.

Oxy-fuel technology has strong economic and technical advantages in CO₂ capture during the combustion process. Oxy-fuel combustion in circulating fluidized bed (Oxy-CFBC) combines the advantages of both the oxy-fuel technology and the circulating fluidized bed combustion, such as wide fuel adaptability, and excellent CO₂ enrichment in the flue gas which is easy to achieve CO₂ capture and storage. This paper reviewed the published literatures on the key aspects of Oxy-CFBC, including unit scale, hydrodynamics, combustion characteristics, pollutant formation and control, fuels, optimization of Oxy-CFBC power plants, the new generation of Oxy-CFBC technology, patent analysis, and discussed the challenges and interests for future in China.

The optimization of centrifugal compressors steps into data-driven pattern with the introduction of the surrogate model, while the optimization is still based on the quasi-three design method. However, the input parameters completely rely on experience of designer. It is necessary for centrifugal impeller design to establish data-driven optimized design method. Based on the quasithree design method, adopted all-over-controlled vortex method and combined k-fold cross validation method, the swirl distribution provided by the designer is optimized in full operation range. The numerical results indicate that the efficiency at design condition increases by 0.61%. Finally, the parameters sensitivity is analyzed by Sobol global sensitivity analysis method. The results show that the efficiency at design condition is more sensitive to the leading edge loading, while the trailing edge loading has more effects on the stall margin. This research is driven by data, and has a certain reference value to the design of a large flow coefficient centrifugal compressor. 

Chemical looping can achieve high product selectivity using lattice oxygen in oxygen carriers for partial oxidation of methane. Oxygen carrier La_1−xSr_xFe_0.8Al_0.2O₃ was prepared by sol-gel method for chemical looping dry reforming of methane. The reaction performance of the oxygen carrier doped with different proportions of Sr was tested by thermogravimetric and fixed bed reactor. The experimental results showed that the oxygen capacity of x=0.4 oxygen carrier in La_1−xSr_xFe_0.8Al_0.2O₃ is as high as 1.88 mmol·g⁻¹, with excellent reaction performance and less carbon deposition. The stability of the oxygen carrier La_0.6Sr_0.4Fe_0.8Al_0.2O₃ was further tested for 20 redox cycles. The oxygen carrier maintained excellent redox performance, achieving 61.2% methane conversion, 97.1% CO selectivity, and 1.81 H₂/CO. The material characterization results displayed that the morphology and crystal structure of the oxygen carrier were stable. The results show that La_0.6Sr_0.4Fe_0.8Al_0.2O₃ is an excellent oxygen carrier suitable for chemical looping dry reforming of methane.

Hollow fiber membrane dehumidification technology has been paid more and more attention in recent years, because it avoids the indoor environment pollution caused by gas-liquid entrainment. The hollow fiber membrane is prone to bend and deform under the combined action of liquid gravity and airflow erosion. The vibration and shape change of the membrane tube have effects on fluid flow and heat and mass transfer, but there are few studies on heat and mass transfer of the hollow fiber membrane tube under flow-induced vibration at present. In this study, an arbitrary Lagrange-Euler method is used to establish a two-way fluid-solid coupling heat and mass transfer model of flow-induced vibration, and the effects of the amplitude and frequency of pulsating flow on the heat and mass transfer performance of the hollow fiber membrane are studied. The results show that: When the amplitude of pulsating flow is increased, the vibration amplitude of the membrane in the upstream direction is higher than that in the vertical direction. Compared with the non-flow induced vibration state, the enhancement factors of heat and mass transfer can reach 81.4% and 86.7%. When the mean velocity of the pulsating flow is 1.5 m·s⁻¹ and the pulsating frequency is 10∼40 Hz, the flow-induced vibration can make the enhancement factors of heat and mass transfer up to 68.9% and 96.2%.

The combination of spray flash and mixing evaporation (FME) was one of the most effective way to process wastewater with high aqueous salt concentration. In this paper, aqueous NaCl solution was selected as working fluid, a comprehensive calculation model for flow field of FME, including movement, evaporation and crystallization of droplets was set up on basis of previous experimental results. Numerical simulation was carried out with initial diameter of droplets between 20 and 200 μm, initial temperature between 100 and 120^◦C, initial mass fraction 0.26, initial speed 20 m·s⁻¹, and air speed of 15 m·s⁻¹, air temperature between 100∼300^◦C, and spray angle between 0 and 90◦ Results suggested that, during the increasing of spray angle from 0 to 90^◦ the main location of crystallization moved from the spray axis to the top of spray plume, making crystal easier to be separated. Besides, with the increasing of spray angle, superheat or air temperature, the average mass fraction of crystallization increased, but the average particle size and crystallization distance decreased. In order to measure the effect of crystallization within a given distance, complete crystallization efficiency was defined as the ratio of the mass flow rate of crystal salt of droplets to the mass flow rate of dissolved salt at inlet. Results suggested that this efficiency could be improved by increasing spray angle or air temperature. A semi-empirical formula for complete crystallization efficiency was proposed, and the main error between its calculated value and the simulated value was in ±35%. Above conclusion could provide technical support for design and operation of industrial desalination system.

A heat dissipation model using the electromagnetic vibration fan on a heated wall was setup to study the convective heat transfer performance of the heated wall. Based on the rectangular fan blade, nine types of serrated fan blades were constructed. The experiment and numerical simulation were used to study the heat dissipation effects of the blades. The results showed that the three-sided serrated blade with the highest number of serrations has the best heat dissipation performance in the present range. The average and maximum wall temperatures were decreased by 3.3°C and 5.2°C, respectively, in comparison with the rectangular blade. The numerical simulation results are in good agreement with the experimental results. The flow field analysis showed that the large scale vortex is broken by the saw tooth, and hence the convective heat transfer is enhanced. 

Entransy analytical model of heat transfer process in stacked porous medium is built, and a new utilization efficiency of Entransy is proposed, meanwhile wave function and field function characteristics of Entransy are found. Based on the model, coupling the cooling curve, surface temperature of cooling products in porous medium, internal temperature gradient, convective heat transfer coefficient along quick freezer, entransy dissipation rate during cooling process are predicted for the first time. Mesoscale characteristics of coupled heat transfer for conduction, convection and radiation in heat transfer process in porous medium have been found. Results show that, volume scale of internal heat transfer core and temperature gradient control heat flux and convective heat transfer coefficient on surface, and wavy characteristics of internal temperature difference decreasing rate affect tendency of heat flux convective heat transfer coefficient. Temperature change trend can be predicted accurately based on along heat transfer coefficient. Porous medium can enhance heat transfer, and scaling factor of heat transfer coefficient without and within porous medium is about 0.6, meanwhile radiation and convection have field synergy characteristics.

Supplying industrial steam can achieve combined heat and power generation, and it is an effective way to enhance the energy efficiency and economic performances of coal-fired power generation units. However, the high extraction temperature entering the industrial steam pipeline limits the operational flexibility, when the combined heat and power unit operates under low power load condition. To address this issue, a parameter sliding operation strategy by reducing the reheat steam temperature was proposed in this study. Then, the system performance analysis model under variable operating conditions was developed, and the flexibility and energy consumption characteristics of the system were analyzed with a 330 MW combined heat and power unit as the reference case. The results show that the maximum peak shaving capacity of the unit increases by about 14% with the operation mode of reheat steam temperature sliding, and the coal consumption rate of the unit can be reduced after the temperature of the reheated steam is reduced to a certain extent. Under typical heating conditions, the annual operating income of the operation mode of reheat steam temperature sliding is about 788400 CNY.

Delayed Detached Eddy Simulation (DDES) method based on the Spalart-Allmaras (SA) turbulence model, as a classical hybrid Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approach, has been widely applied in practical engineering. However, the DDES-SA model, while combining the advantages of RANS and LES methods, still exhibits certain limitations in achieving the desired prediction accuracy in the field of turbomachinery. In this study, helicity is introduced to modify the traditional DDES-SA model. By accurately identifying the streamwise vortex core using helicity, the excessive turbulent viscosity in the vortex core is reduced, leading to a significant improvement in the predictive capability of the DDES-SA model for tip leakage flow. Numerical simulations of simplified rotor tip leakage flow are performed using the original and helicity-based modified DDES-SA methods, with LES results serving as a benchmark, to assess the predictive performance of the modified DDES-SA method for leakage flow. The results demonstrate that the modified DDES-SA method provides predictions closer to the LES results, and it offers more accurate vortex core strength and unsteady characteristics, significantly enhancing its predictive capability for rotor tip leakage flow.