The Pt-based catalysts are quite promising for ethylene glycol oxidation reaction (EGOR) due to their superior catalytic activity and their high cost, low reserves and poor stability of precious metals greatly limit the further large-scale application. Developing low-Pt and high-performance anode electrocatalysts is urgent to direct ethylene glycol fuel cells. At present, a high-entropy alloy (HEA) of PtPdNiCoBi/C has been developed for EGOR, and its catalytic performance has been verified by electrochemical and physical methods. Notably, the EGOR peak current density on PtPdNiCoBi/C (0.782 A mg−1PtPd) reaches 3.54 times of Pt/C (0.221 A mg−1Pt), and the residual current on PtPdNiCoBi/C (0.092 A mg−1PtPd) is superior to that of Pt/C (0.076 A mg−1Pt) after 3000 s. Moreover, the current density retention (84.0

Adsorption and separation technologies based on physical adsorbents have the advantages of simple operation, low heat of adsorption and easy regeneration. They have received much attention for the capture of CO2 and PM from flue gases. However, the inherent "trade-off" between adsorption capacity and adsorption selectivity, as well as the high gas permeation resistance after powder processing and shaping, severely limit the prospects for industrial applications. Here, acyl functional groups were strategically introduced into polymer frameworks to successfully synthesize monolithic adsorbents (AC-CMPs) with a hierarchical pore structure for PM capture and CO2/N2 selective adsorption. The three-dimensional network structure composed of aligned hollow nanotubes effectively enhances the dispersion and mass transfer of gas flow per unit volume. Based on the porous media, multiphase flow model and discrete phase model, the gas flow process of PM trapped by AC-CMPs was simulated using Fluent. The simulation dynamically revealed the relationship between permeability resistance and filtration efficiency. The highly delocalized 7C-7C conjugated porous skeleton linked by continuous covalent bonds endowed AC-CMPs with good stability, which prevented them from degrading in humid and high-temperature environments, thus keeping the adsorption capacity unchanged. The high polarity environment generated by the open oxygen atoms within the AC-CMPs framework, along with a high micro/mesopore ratio, enable it to achieve a CO2 adsorption capacity of 2.07 mmol/g at 273 K and 1 bar. Ideal adsorption solution theory calculations (IAST) and CO2/N2 column breakthrough experiments confirmed the excellent CO2 selectivity of ACCMPs under realistic carbon capture conditions.

In this work, a new model to analyse the dynamic characteristic coefficient of the S-CO2 dry gas seal was reported. Taking into account that the flow within the S-CO2 dry gas seal is close to adiabatic flow, the impact of the temperature change on the dynamic characteristic coefficient of the gas film cannot be ignored. To address this issue, a complete variable perturbation model (CVPM) under the adiabatic flow process was established using the frequency perturbation method while considering multiple complex effects. Then, the finite difference method was used to solve the CVPM. The gas film’s dynamic stiffness and damping coefficients were calculated and analysed for different conditions, operating parameters, and frequency ratios. From our analysis, it was demonstrated that the dynamic coefficient of the gas film exhibited frequency dependence. The turbulence coefficient perturbation had the most remarkable influence on the gas film’s dynamic coefficient, compared to the temperature, viscosity, and centrifugal inertia force perturbations. The isothermal flow, adiabatic flow, inlet pressure, and inlet temperature also affected the magnitude of the dynamic characteristic coefficient of the gas film. However, no significant impact on their tendency to vary with the frequency ratio was found. Our work provides new theoretical support for the dynamic analysis of S-CO2 dry gas seals, which is of great importance for future applications.

The Pt-based alloys catalysts with special morphology attract great attention. Herein, a flocculent-structured high-entropy-alloy (HEA) (named as F-PtBiCuCoMo/C) electrocatalyst is prepared by co-reduction, which can greatly improve the overall catalytic performance and reduce Pt-usage. In ethylene glycol oxidation reaction (EGOR), it has mass activity of 1.08Amg-1Pt, which also has a good durability with high residual current density (0.27Amg-1Pt after 3000s). Notably, the power density reached 17.9mWcm-2 in as-assembled direct ethylene glycol fuel cells (DEGFC), which exceeded commercial Pt/C references by 2.4 times. Thence, this F-PtBiCuCoMo/C electrocatalyst would be a good option for the advancement of DEGFC technology.

The challenge in developing porous materials that significantly reduce energy consumption in industrial gas separation lies in striking a balance between adsorption capacity and permeability. Herein, the precise anchoring of polar oxygen adsorption sites in a robust porous conjugated backbone is achieved through the directed selfassembly of building blocks, resulting in the formation of oxygen-enriched conjugated microporous polymers (O-CMPs). O-CMPs serve as attractive porous hosts for the synergistic separation of CO2 and PM in exhaust gases emitted from point sources. As analyzed by surface electrostatic potential, the introduction of oxygen-doped pi-conjugated systems induced surface charge redistribution, enhancing the CO2 quadrupole-dipole effect within a widely distributed microporous network. The O-CMPs exhibited a high CO2 adsorption capacity of 125.84 mg/g at 273 K and 1.0 bar. The monolithic O-CMPs incorporate permanently integrated hierarchical pores with a high micropore ratio. This transport channel can enhance the transfer rate of gas flow while selectively intercepting CO2 and PM. The rigid conjugated molecular chains and hollow nanotube microstructure effectively prevent material densification, yielding a minimal gas permeation resistance of only 5 Pa. Additionally, O-CMPs also demonstrate outstanding stability and PM separation performance under humid and acid/ alkaline condition. The visual process simulations serve to further validate that aforementioned design strategy can optimize the trade-off between adsorption capacity and permeability.

In order to study pressure fluctuation characteristics of a centrifugal pump as turbine (PAT) in its start-up process, Fluent was used to do numerical simulation of the PAT start-up process. Time and frequency domain analyses were performed on the data acquired at different positions and different heads. The results show that a large number of low-pressure areas and strong vortexes are formed within the impeller at the initial time of start-up. With the increase in rotating speed, the vortexes rapidly decrease and are concentrated on the blade non-working face. The pressure fluctuation amplitude is the maximum at the start-up initial instant; with increase in rotating speed, it reduces rapidly at the volute spiral part. The pressure fluctuation number within one impeller rotation cycle is consistent with blade number, and the dominant frequency of pressure fluctuation is 6 times the impeller rotational frequency. The dominant frequency amplitude of radial pressure fluctuation increases with decrease in radial size in the volute. The pressure fluctuation in the impeller is much more intensive than that in the volute, and its maximum dominant frequency amplitude occurs in the middle of the impeller towards the inner edge. With the increase in head, the number of pressure fluctuation and the amplitude of dominant frequency increase at the same time during the start-up process.

Exploring efficient metal-nitrogen-doped carbon (M-N-C) catalyst is urgent to improve the performance of electrocatalytic CO2 reduction reaction (CO2RR). In this study, a series of dual-metal M-N-C electrocatalysts (Ni, Fe-N-C) under different calcination temperatures (at 950 degrees C, 1000 degrees C and 1050 degrees C) was prepared by a heattreatment process. The electrochemical results show that, in a flow cell, as-prepared optimal Ni, Fe-N-C (1000 degrees C) indicates the highest selectivity for CO (at 1.0 V), with a FECO of 92.37 % and CO partial current density of 13.76 mA cm (-2). Moreover, in 24 h stability test, the current densities of Ni, Fe-N-C (1000.C) always remains around 10 mA cm (-2), and the FECO remains above 86 %, indicating it has high efficiency and good long-term stability. This study is a promising and cost-effective exploration of the dual-metal M-N-C catalysts for CO2RR, would provide a valuable case for exploring the other M-N-C in future.

The start-up process of a centrifugal pump as turbine (PAT) under gas–liquid two-phase conditions was simulated based on Fluent, and the evolution mechanism of the internal flow field and the variation law of force characteristics were studied in its start-up process under gas–liquid two-phase conditions. The results show that the area with high gas phase concentration corresponds to a strong vortex at the beginning of the start-up. The vortex intensity in the impeller gradually decreases with an increase in rotational speed. The gas volume fraction of the blade suction surface is more significant than that of the blade pressure surface. The higher the inlet gas volume fraction (IGVF) is, the more severely the blade load will fluctuate during the start-up process. As the rotational speed increases, the fluctuation of the blade load gradually weakens, and the maximum load is distributed near the inner edge of the blade after the rotational speed is stable. The periodic unbalanced radial force is produced in the start-up process. From the pure liquid conditions to the gas–liquid two-phase conditions with increasing IGVF, the dominant frequency amplitude of radial force shows a similar trend of decreasing first but then increasing. After the rotational speed tends to be stable, the dominant frequency of radial force is equal to the rotational frequency of the blade. With the increase in rotational speed, the dominant frequency amplitude of axial force decreases gradually. The higher the IGVF, the greater the dominant frequency amplitude of axial force at the same time.

为研究离心泵作透平(pump as turbine,PAT)启动过程中的瞬态特性,根据转动方程编写UDF程序,基于Fluent软件滑移网格的转速控制方法对PAT启动过程进行模拟计算,并与试验结果进行对比验证.结果 表明,启动初始时刻叶轮内形成了强烈的叶道涡,随着转速的增加,叶道涡的强度逐渐减小,压力呈梯度分布.启动初始时刻叶片载荷振荡分布,最大振幅出现在叶片中间位置,远高于稳态工况下的叶片载荷;径向力和轴向力都随着转速的增加急剧增大后振荡下降,当转速趋于稳定后,径向力和轴向力呈周期性振荡,轴向力脉动的幅值大于径向力的,每个振荡周期的脉动次数与叶片数一致.启动过程中转子做加速度逐渐减小的加速转动,来流压力越大,达到没计转速的时间越短,完成启动后的稳定转速越高;转动惯量越小,完成启动越快.

Fatigue life of a marine riser with different-size cracks under the action of internal pressure and wave force was calculated by using ANSYS,a finite element software,to analyze the variation of the fatigue life of a marine riser according to the geometric parameters of the crack.It is found that fatigue life of a marine riser gradually decreases with the increase of the angle between the two cracks with the depth a=5 mm;when the angle increases from 10°to 50°,the reduction of fatigue life of the marine riser slows down with the increase of the length of the cracks,in other words,the effects of the angle between two cracks on fatigue life of the marine riser is gradually weakened with the increase of the angle between cracks.

The wave force acting on marine riser was calculated based on the linear wave theory.The finite element model of marine riser with axial crack on outside surface was established,and then the fatigue life of marine riser with crack of different dimensions under combined action of internal pressure and wave force were calculated by the ANSYS finite element software.Variation of fatigue life of marine riser with geometry parameters of crack had been analyzed.The calculation and analysis results showed that:the fatigue life of marine riser reduced with the increase of crack length and crack depth,but the crack depth had much more effect on the fatigue life of marine riser than the crack length.When the crack depth was smaller,the fatigue life of marine riser decreased with the increase of crack depth more rapidly.For the same crack depth,crack ellipticity was the larger,the fatigue life of marine riser was the lager.In short,the fatigue life of marine riser mainly depended on the size of crack depth.

Through the study on fluid-solid coupling vibration of fluid-conveying pipes,the dynamic characteristics of marine riser under wave-current interaction was studied; and basing on the principle of Hamilton energy,the coupling vibration model for marine riser was built to derive its equation and then to have it solved through discrete method and Hermit interpolation method. By using ANSYS,the dynamic characteristics of the riser's coupling vibration was analyzed to obtain the first six-order vibration mode and natural frequency.Comparing the simulated natural frequency of marine riser with the result of theoretical analysis verifies the correctness of marine riser's coupling vibration model and shows that the marine riser's natural frequency can decrease with the increase of the internal flow velocity.