To improve the separation performance of a spiral pipe separator，a novel two‑stage cyclone separator using a spiral pipe assembly as the feed channel was developed.The structural parameters of the device were optimized through orthogonal experiments，and the optimal structure was determined as follows：the spiral pipe has one turn，the ratio of the curvature radius to the cyclone body radius is 0.76，and the outlet of the spiral pipe is located one pipe diameter below the interface between the cylindrical and conical sections of the separator.The separation performance before and after optimization was compared using numerical simulation methods，and validation experiments were conducted on the optimized structure.The results show that after optimization，the pressure distribution in the central region of the device becomes more uniform，the negative pressure region shrinks significantly，and the pressure loss is reduced.The swirling velocity increases，the centrifugal force is enhanced，promoting particle movement toward the wall，thereby strengthening liquid-solid separation.With the radial position r/R=0.5 as the boundary，the average solid phase concentration on the side near the wall increases by 5.1%，while the average concentration in the central region of the separator decreases by 28%.The residence time of solid particles inside the cyclone is shortened，and the number of particles escaping from the overflow port is reduced.The optimization of the spiral pipe structural parameters enhances the flow near the wall in the secondary cyclone region while reducing the disturbance to the central fluid，which is beneficial for the liquid-solid separation process in the two‑stage cyclone separator.This study can provide a reference for the engineering design and application of two‑stage cyclone separators.

Aiming at the problems of limited accuracy，high cost and poor real‑time performance of traditional centrifugal pump test systems，an automated test system based on Siemens S7-1500 PLC and the .NET platform was designed.The system employed high‑precision sensors and PID closed‑loop control，Breaking through the middleware limitations of traditional commercial configuration software，the system utilizes an underlying asynchronous Socket mechanism based on TCP/IP to directly interact with the PLC for lightweight data exchange，achieving a communication delay of ≤50 ms.Taking a centrifugal pump with a rated speed of 894 r/min，rated flow of 1 090 m³/h，and rated power of 221 kW as an example，the system underwent experimental validation.The results demonstrate that measurement uncertainties of all key performance parameters of the system meet Class 1 accuracy in GB/T 3216—2016.The measurement uncertainties for flow rate，head，power，rotational speed，and efficiency are ±1.06%，±1.20%，±0.91%，±0.19%，and ±1.79% respectively，all falling below their permissible limits （±2.0%，±1.5%，±1.5%，±0.5%，±2.9%）.Leveraging the .NET open‑source ecosystem and modular design，it significantly reduces development and maintenance costs Furthermore，through a dependency injection （DI） decoupled design，it provides underlying architectural support for intelligent expansions，such as the native integration of ML.NET machine learning algorithms.This system combines the advantages of high precision，low latency，low cost，ease of operation，and strong scalability.This research offers a reliable integrated solution for high‑precision，low‑cost automated test of industrial pumps.

Aiming at the prominent problems including hump characteristics and poor operation stability of nuclear reactor charging pumps under off‑design low‑flow conditions，this paper adopts numerical simulation combined with experimental tests to explore the effects of balance chamber flow passages on the hydraulic external performance and internal flow field of the charging pump，and optimizes the internal flow state by improving impeller structural parameters.Single‑stage model pump experiments and numerical results reveal that the leakage flow rate of the balance drum accounts for merely 3%~6% of the rated design flow.Such leakage exerts a marginal effect on pump head prediction and cannot change the qualitative law of hydraulic hump characteristic prediction；hence，a simplified numerical model ignoring the balance chamber flow passage is applicable for hydraulic performance optimization.Comparative tests on pump hydraulic performance with different blade lean angles （θ=0°，3°，4°，5°） under low‑flow hump working conditions verify that the blade lean design is an efficient method to restrain the hydraulic hump.Specifically，the hydraulic hump phenomenon of the pump is completely eliminated within the full operating flow range when the blade lean angle is set to 5°.Adopting the combined optimization scheme with tapered convergent flow passage and 5° blade lean toward the blade pressure side，the proposed design not only restrains the hump characteristic of the charging pump under low‑flow conditions，but also optimizes the internal flow field of the impeller.Meanwhile，the generation of internal low‑speed flow zones and flow vortices is weakened，which further improves the cavitation resistance and operational stability of the pump.This study can provide technical support and theoretical references for the optimal hydraulic design of nuclear reactor charging pumps.

To address the shortcomings of traditional vapor‑compression refrigeration technology in terms of volume，energy efficiency，and operational reliability，thermoelectric refrigeration technology has attracted widespread attention due to its high efficiency，environmental friendliness，and high reliability.This paper reviews the latest research progress in thermoelectric refrigeration technology，with a focus on the current status of thermoelectric materials，numerical modeling methods for thermoelectric cooling，and their application scenarios.First，the development history of thermoelectric materials is introduced，and the major achievements are summarized.Second，to improve the performance of thermoelectric cooling systems，models of thermoelectric elements and thermoelectric coolers at different dimensions are compared and analyzed，and the results show that 3D models can more comprehensively describe the microscopic mechanisms during the actual operation of thermoelectric modules.Finally，the application status of thermoelectric refrigeration is summarized from the aspects of electronic cooling，medical equipment，and automotive air conditioning，and it is pointed out that the key to future development lies in improving the intrinsic properties of thermoelectric materials，optimizing the heat dissipation path on the hot side of thermoelectric devices，and further enhancing the system COP，thereby achieving collaborative design of materials，devices，and systems.This study can provide a theoretical reference for the design optimization and engineering application of thermoelectric cooling systems.

To address the problem of excessive time cost when adopting fluid-structure interaction CFD simulations to study the effect of low‑temperature characteristics of boil‑off gas （BOG） on screw compressor efficiency，this study establishes a numerical model of a twin‑screw compressor using MATLAB.The PDE toolbox is employed to calculate the temperature distribution and thermal deformation of the screw rotors.The new clearance caused by rotor deformation is then incorporated into the numerical model to obtain the compressor efficiency considering rotor deformation.The computation time of this process is approximately 1/100 of that required for CFD simulations，greatly reducing the time cost.The numerical results were compared with those from an experimentally validated CFD model，and the errors in volumetric efficiency and isentropic efficiency were both within 3%.Furthermore，a low‑temperature intake test rig was constructed to measure volumetric efficiency at different intake temperatures.The maximum error between the measured data and the numerical results was within 5%，thereby verifying the reliability of the model.Based on the model，the influence of rotational speed on compressor performance was analyzed.The results show that as the rotational speed increases from 4 000 r/min to 10 000 r/min，the volumetric efficiency rises from 55.1% to 73.2%.The isentropic efficiency first increases and then decreases with rotational speed，reaching a maximum value of 62.2% at 8 000 r/min.This model can quickly and accurately predict the performance of the BOG twin‑screw compressor under various operating conditions，providing a reference for the efficiency design and optimization of high‑speed twin‑screw compressors.

To address the issues of repetitive design，high cost，and optimization difficulties in the series development of blower volutes caused by a single design process and limited software functionality，an adjustable partition plate is adopted to achieve serialized structural design of the volute.By optimizing the width and height of the partition plate to adapt to the flow channel cross‑section requirements of different volutes，the maximum sharing of volute components across blower units is realized.Combined with CFD calculations and flow field analysis，the performance quality and operating condition adaptability of the serialized products are ensured，and the reliability of the numerical simulation is verified through experiments.The results show that when using the adjustable partition plate for volute serialization design，the optimal range for the partition plate height D₄/D₂ is 1.65~1.72；when the partition plate width is greater than 5 mm，optimizing its structure can improve the flow field performance of the serialized volute.The blower units adopting the serialized volute structure have a wide operating range，with relative variability efficiencies of each unit all exceeding 82.5%，and total pressure ratios greater than 1.8，and they have been well applied in wastewater treatment energy‑saving projects.This study can provide a reference for the serialized design of blower volutes.

To address the issue of power fluctuations caused by disturbances and parameter variations in the pitch control of wind turbines，a pitch angle control strategy based on the fusion of an improved genetic algorithm and predictive control （PID+ImGA+MPC） is proposed.This method introduces a Cauchy-uniform distribution hybrid crossover and adaptive mutation mechanism to enhance global search capability，and combines ARIMA wind speed prediction with model predictive control to achieve feedforward adjustment of the pitch angle. By deeply integrating the improved genetic algorithm，ARIMA wind speed prediction，and MPC，an integrated "prediction-optimization-feedforward" pitch control framework is formed，which compensates for the shortcomings of existing strategies，such as insufficient utilization of predictive information and reliance on offline optimization for parameter tuning.Hardware‑in‑the‑loop verification is conducted using a pitch control system intelligent loading test bench based on Bladed.The results show that the error between simulation and measured results is controlled within ±3%，verifying the engineering feasibility and real‑time performance of the strategy.In simulations on a 1.5 mW doubly‑fed wind turbine model，under step wind conditions，the proposed strategy reduces the power overshoot from 4.025% to 0.69% and shortens the settling time from 3.66 s to 2.2 s；under turbulent wind conditions，the standard deviation of output power is reduced by 12.40% compared with conventional PID.This study can provide a theoretical basis and engineering reference for the stable control of wind turbines under high wind power penetration conditions.

To improve the atomization effect of multiple nozzles in snowmaking machines，a 3D transient multiphase flow model was constructed using the discrete phase model （DPM） and the Taylor analogy breakup （TAB） model.Combined with experimental validation，the variation laws of atomization characteristics under linear，circular，right triangular，and equilateral triangular nozzle arrangements were systematically analyzed.Meanwhile，the regulatory effects of installation height and spacing differences on atomization characteristics were investigated.The results indicate that on the same plane，the equilateral triangular and circular arrangements exhibit good and similar distribution uniformity.Among them，the equilateral triangular arrangement has a larger sauter mean diameter SMD （94.31 μm） and better atomization effect.For the right triangular arrangement，the proportion of large‑sized droplets in the far‑field region reaches 72%，showing a stronger droplet coalescence effect.The linear arrangement has the smallest SMD （92.8 μm），achieving the best droplet breakup effect.Meanwhile，differences in nozzle installation height and spacing have a limited impact on the overall atomization characteristics but can effectively regulate atomization interference behavior.The research results reveal the influence mechanism of nozzle geometric layout on the synergistic atomization characteristics of multiple nozzles，providing a reference for the layout design of snowmaking machine nozzles.

To enhance the separation performance of a hydrocyclone for coal slurry classification，this paper proposes a volute‑type inlet structure，aiming to strengthen particle prealignment during the entry process.A downward structure is designed to reduce inlet turbulence，with both features working together to improve the separation accuracy of the hydrocyclone.This paper employs laboratory experiments to investigate the influence of volute structure parameters on the separation performance.The results indicate that as the volute angle increases，the treatment capacity of the hydrocyclone is enhanced with higher yield and concentration of overflow.The highest separation efficiency is achieved at a volute angle of 180°，where the classification efficiency reaches 88.80% for particles smaller than 15 μm.The separation performance of the hydrocyclone tends to increase at first and then decrease with increasing downward depth，showing the optimal separation effect at a downward depth of 47.5 mm.Industrial verification demonstrates that，compared to the involute inlet hydrocyclone，the volute entrance hydrocyclone exhibit a significant improvement to the particle mismatch in the separation products.The research can provide references for the optimal design and application promotion of the volute entrance hydrocyclone.

To address the issue of uneven refrigerant flow distribution in conventional venturi type liquid separators under low evaporation temperature conditions，as well as the resulting technical bottlenecks in transport refrigeration units operating in freezing mode，such as insufficient cooling capacity and excessively high discharge temperature，a liquid separation device with gas‑liquid separation functionality was designed.This device replaced the original venturi type liquid separator in the unit.A performance test bench was constructed，and experimental tests were conducted under both refrigeration mode and freezing mode.The experimental results indicate that compared with the original unit using the venturi type liquid separator，the unit equipped with the new liquid separator exhibited a significant increase in cooling capacity with increasing bypass regulating valve opening，while the discharge temperature first increased and then decreased.At a bypass regulating valve opening of 20%，the cooling capacity in refrigeration mode increased by 30.6% accompanied by a discharge temperature rise of approximately 6 ℃，while in freezing mode the cooling capacity increased by 38.6% accompanied by a discharge temperature rise of approximately 4 ℃.At a bypass regulating valve opening of 40%，the cooling capacity in refrigeration mode increased by 21.0% with a discharge temperature decrease of approximately 11 ℃，while in freezing mode the cooling capacity increased by 16.0% with a discharge temperature decrease of approximately 10 ℃.This study provides a technical solution for the efficient and stable operation of transport refrigeration units.