This study investigates the salt spray removal characteristics of Venturi ejectors through experimental testing and computational fluid dynamics （CFD） simulations to enhance their performance. The air suction variation under different inlet water flow rates was analyzed，and a modified Venturi ejector integrated with a helical mixer was proposed to improve gas‑liquid mass transfer efficiency. Results show that the salt spray removal efficiency decreases with increasing gas‑liquid ratio （GLR），declining from 83% to 52% as GLR rises from 0.25 to 1.25. Phase stratification at high GLR reduces gas⁃liquid interfacial area by 12.5%，significantly degrading removal performance. The helical mixer‑integrated ejector maintains higher interfacial area and volumetric mass transfer coefficients under high GLR conditions. Despite a 43% reduction in air suction and a 9% increase in pressure drop after mixer integration，the mass transfer rate improves by 90%，indicating superior salt spray capture capability. These findings provide critical insights for optimizing Venturi ejector designs in desalination applications.

In view of a low temperature turbine expansion machine with excessive axial load and the insufficient performance study of the gap，firstly，the pneumatic design designed the pneumatic structure of the main structure of the gap，and then simulate the numerical simulation based on the simulation results.The results show that the presence of the impeller gap will change the flow field distribution within the roof gap，the impeller and the depth ratio of the gap，the impeller efficiency and power are reduced，and the axial force decreases.When the gap depth ratio of the gap is 0.3，the equal entropy efficiency decreases by 2.9% compared with 2.4% and the power，and the axial force is reduced by 38.1%.Meet the performance index.This study provides theoretical reference for the application of impeller with gap in low temperature turbine expander.

To address the cylinder fracture issue in 90 MPa diaphragm compressors for hydrogen refueling stations，a thermo‑mechanical coupling model of the high‑pressure stage membrane head was established using Ansys Workbench finite element analysis software. The cylinder strength was analyzed，and an improved through‑hole bolt cylinder connection structure was proposed and verified. Results show that when the cylinder bottom fillet radius is 0.5 mm，the local stress reaches 1 665 MPa，exceeding the material yield strength and causing stress concentration，leading to fatigue failure under cyclic alternating loads. Increasing the fillet radius to 3 mm reduces the maximum stress to 793 MPa，meeting strength requirements. The improved through‑hole bolt structure reduces the maximum stress by 17% for cylinders with the same fillet radius. At a 3 mm fillet radius，the optimized structure achieves a maximum stress of 649 MPa，satisfying design specifications. This study provides reference for structural design of 90 MPa diaphragm compressor cylinders.

To address the leakage and diffusion issues in light hydrocarbon pipelines，this study establishes a conceptual model of the leakage diffusion process，dividing it into four stages and conducting theoretical analysis with formula derivation.A numerical model of atmosphere‑pipeline‑soil leakage diffusion was developed using CFD to analyze the entire leakage process，focusing on the diffusion range variations of different hydrocarbon components and comparing multi‑component versus single‑component leakage characteristics.Simulation results show that light hydrocarbon leakage occurs in three phases：rapid diffusion in the initial phase，stabilization during the middle phase，and full stabilization after 800 s in the final phase.C3 exhibits the largest gaseous diffusion range，while C5 shows the largest liquid diffusion range.Single‑component C2~C4 demonstrate broader diffusion ranges，whereas multi‑component C5~C8 exhibit larger diffusion extents.In multi‑component leakage，sequential vaporization and diffusion suppress the diffusion of heavy gaseous components，resulting in smaller ranges compared to single components，while liquid components expand their diffusion due to gas‑phase entrainment.This study provides theoretical foundations and technical support for emergency management of light hydrocarbon pipeline leaks.

To investigate the influence of different spool structures on the internal flow field of sliding valves during dynamic motion，unsteady simulations based on the overset mesh method were conducted to analyze the dynamic characteristics of the flow field in sliding valves with three spool types （standard spool，dual‑curve spool，and turbine‑blade spool，corresponding to outlet jet angles of 90°，45°，and 30°）. The spool and valve chamber domains were defined in the foreground and background meshes respectively，enabling dynamic fluid domain variation during spool movement to simulate valve opening/closing. Results indicate that under a 1 MPa inlet‑outlet pressure difference，the maximum flow velocity reaches 50 m/s，generating lateral hydraulic forces up to 100 N. Dynamic changes in spool displacement significantly affect velocity，pressure，and turbulence distributions. Curved spools （dual‑curve and turbine‑blade） effectively reduce maximum turbulent kinetic energy （TKE） and outlet negative pressure backflow. The standard spool exhibits flow oscillation and negative pressure backflow during bidirectional regulation，causing flow instability with maximum TKE≈400 J/kg. The symmetric dual‑curve spool shows smaller directional dependence in flow fluctuations （maximum TKE≈330 J/kg）. The turbine‑blade spool demonstrates superior flow regulation，pressure distribution，and turbulence suppression due to its enlarged inflow boundary. These results provide theoretical foundations and design guidelines for high‑precision sliding valves.

In order to explore the influence of the blade arrangement mode on the vibration characteristics of the self‑priming jet impellers，a combination of experimental and numerical methods was adopted. A comparative analysis was conducted on the fluid flow characteristics and mixing power consumption in stirred tanks with co‑directional（SJI） and staggered（PSJI） blade configurations，along with an evaluation of vibration differences under static and prestressed modal conditions. The results show that the staggered blade arrangement generates upward and downward jet flows，increasing fluid flow complexity. Under power‑law fluid conditions，compared to SJI，the viscosity and mixing power consumption around PSJI blades decreased by 1.2% and 4.0%，respectively，while the maximum stress of PSJI increased by 8.86%. Modal analysis revealed the largest vibration mode differences between the 1^st/2^nd‑order static and prestressed modes，with PSJI vibration amplitudes exceeding SJI by 14%~18% due to blade arrangement effects. Analysis of the 6^th‑order modes showed that the liquid-solid coupling had less influence on PSJI vibration modes than on SJI，with maximum vibration amplitudes occurring at the jet outlet. The staggered configuration enhanced bottom fluid flow，intensified shear-thinning effects on power‑law fluids，and reduced power consumption. This study provides insights for the optimal design and application of stirred impellers.

This study investigates the thermal performance of diffusion‑bonded hybrid heat exchangers through wind tunnel experiments and numerical simulations. Comparative analysis was conducted on the adaptability of heat transfer and friction factor correlations obtained by different methods for stainless steel plain fins. Results indicate that the thermal load of the heat exchanger increases with rising air‑side velocity，while the pressure loss grows more significantly. When air velocity increases from 8.1 m/s to 28.2 m/s，the thermal load increases by 2.9 times，and the pressure loss escalates by 9.82 times. Within the air‑side Reynolds number range of 2 440≤Re≤8 502，the theoretical thermal load calculated using statistically derived Colburn factor correlations deviates by 0.34%~16.55% from numerical and experimental results. Theoretical pressure loss predictions show less than 3% deviation from measured values. The study verifies the accuracy of the heat transfer/friction factor correlations and numerical models，providing practical guidance for thermal design of single‑phase diffusion‑bonded hybrid heat exchangers.

This study investigates the dehumidification and heating performance of a dual‑evaporator heat pump system for electric vehicles，which operates in two modes：Single‑evaporator mode （SEM） and dual-evaporator mode （DEM）.Experimental evaluations were conducted under varying operating conditions to compare system characteristics.Results demonstrate that at 60%~90% inlet air humidity and 4 000 r/min compressor speed，SEM achieves 26.2%~62.8% higher dehumidification rates and 25.7%~43.9% greater D_SMER than DEM. Conversely，DEM exhibits 26.6%~67.6% superior effective heating capacity and 11.2%~50.0% higher COP compared to SEM.When maintaining equivalent dehumidification performance，DEM delivers 43% higher outlet air temperature and 28% improved COP over SEM. These findings provide critical insights for expanding application scenarios of electric vehicle heat pump systems and advancing their technological development.

To address restart challenges in heavy oil‑water ring pipelines caused by water ring instability，an experimental study was conducted using a laboratory‑scale restart loop system with four conventional heavy oils. The research investigated flow pattern evolution and pressure drop characteristics during pipeline restart under constant water velocity，analyzing effects of oil holdup （H_o），oil viscosity （μ_o），shutdown duration （t_st），and water velocity （U_cl）. An exponential decay model was established to describe time‑dependent restart pressure drop. Results reveal four distinct flow pattern phases during constant‑flow restart： water shear stripping of oil layer，oil droplet/cluster migration，wall‑adherent film formation and film detachment. The pressure drop exhibits initial peak followed by decay and equilibrium stages，with model predictions showing excellent agreement （goodness‑of‑fit values approaching 1）.Within tested ranges （H_o=0.26~0.76，μ_o=1.055 3~3.02 Pa·s，t_st=0.5~1.0 h，U_cl=0.25~1.01 m/s），maximum restart pressure drop increases with H_o，μ_o，t_st，and U_cl （up to 30.38 kPa），while restart duration extends with H_o，μ_o，and t_st but shortens with U_cl （up to 3 616.78 s）.This study provides theoretical and practical guidance for optimizing pipeline restart operations.

This study investigates the feasibility of applying CO₂ systems to thermal management in temperature-controlled rail transport vehicles. A transcritical CO₂ refrigeration heat pump system for thermostatic transport vehicles was developed based on a multiphysics simulation platform，with simulation results validated through experimental testing. Further research was conducted on system discharge pressure and charge amount under varying operating conditions. Results indicate that optimal discharge pressure increases with rising ambient temperature and indoor heat exchanger inlet air temperature. A predictive correlation for optimal discharge pressure，using ambient temperature and inlet air temperature as independent variables，was established through data simulation. Both ambient and inlet air temperatures significantly influence the system's refrigerant charge amount，with an optimal charging range of 3.2~6.1 kg across all operating conditions. The well-designed transcritical CO₂ system demonstrates excellent performance over a wide temperature range，particularly achieving heating COPs above 3.2. The optimized thermal management system maintained stable temperature control with only two start-stop cycles within 300 000 seconds. These findings provide theoretical support for promoting transcritical CO₂ thermal management technology in thermostatic transport vehicles.