工业纯铝阳极氧化工艺

采用正交实验法设计了铝的阳极氧化工艺配方实验 ,通过对样品的电化学性能如极化电阻、自腐蚀电位及耐蚀等级等的测试结果进行了分析 ,得到了优良的阳极氧化工艺配方。     

热浸锌–钛合金镀层钢板的电化学行为

在纯锌浴中添加钛,制得锌–钛合金镀层含硅钢板。通过塔菲尔极化及电化学阻抗测量,研究了其在w=5%的NaCl水溶液中的腐蚀电化学行为,并与热浸纯锌镀层钢板进行了对比。结果表明,锌–钛合金镀层钢板的极化电阻和交流阻抗增大,腐蚀电流密度减小,耐蚀性能得到提高。     

化学镀镍-磷合金机理的研究

通过对化学镀Ni—P合金过程中线性极化电阻及沉积速度的测量,得出极化电阻的倒数1/Rp与电流密度i呈线性关系。用阳极极化曲线的方法,较详细地研究了次磷酸钠在镍电极上的氧化过程。提出了化学镀Ni—P合金是按电化学机理进行的。     

热浸锌-钛合金镀层钢板的电化学行为

在纯锌浴中添加钛,制得锌-钛合金镀层含硅钢板.通过塔菲尔极化及电化学阻抗测量,研究了其在w=5%的NaCl水溶液中的腐蚀电化学行为,并与热浸纯锌镀层钢板进行了对比.结果表明,锌-钛合金镀层钢板的极化电阻和交流阻抗增大,腐蚀电流密度减小,耐蚀性能得到提高.     

AC5/CP5-2交流阻抗测试系统

一、技术简介:电化学交流阻抗技术是交流信号对电化学体系进行激励观察电化学体系对激励信号的响应。响应信号中包含了电化学体系的极化电阻(Rp、Ra)、双电层电容(Cd)、溶液电阻(Rs)等电化学信息。电化学交流阻抗技术是对同一电极进行阳极和阴极交替微小极化,即使测量信号作用于电解池时间较长,对电极的影响也比较小。     

AC5／CP5—2交流阻抗测试系统

一、技术简介： 电化学交流阻抗技术是交流信号对电化学体系进行激励观察电化学体系对激励信号的响应。响应信号中包含了电化学体系的极化电阻（Rp、Ra）、双电层电容（Cd）、溶液电阻（Rs）等电化学信息。电化学交流阻抗技术是对同一电极进行阳极和阴极交替微小极化．即使测量信号作用于电解池时间较长,对电极的影响也比较小。     

La0.8Sr0.2MnO3涂覆液浓度对La0.8Sr0.2FeO3电极电化学性能的影响（英文）

研究了0.005、0.010、0.020、0.035和0.040 mol/L 5种不同浓度的La0.8Sr0.2MnO3(LSM)溶液涂覆La0.8Sr0.2FeO3(LSF)电极后,其电化学性能的变化。X射线衍射结果表明:LSM和LSF化学相容性好。扫描电子显微镜观察可见:电极的晶粒尺寸和涂层厚度随着涂覆液浓度的增加而增加。电化学阻抗谱表明:在阳极极化条件下,经过0.010 mol/L LSM溶液涂覆处理后的LSF电极表现为最佳的电化学性能,其极化电阻在800℃仅为0.3.cm2。而且无论在阳极极化还是阴极极化处理后,涂覆LSM后的LSF电极的极化电阻,1200s内都呈现下降的趋势,LSM涂覆后的LSF电极具有一定的抗阳极极化的能力,归因于LSM涂层的良好催化特性。因此,0.010mol/LLSM溶液涂覆处理后的LSF可以作为固体氧化物电解池的阳极材料。     

工业纯铝阳极氧化工艺

采用正交实验法设计了铝的阳极氧化工艺配方实验，通过对样品的电化学性能如极化电阻，自腐蚀电位及耐蚀等级等的测试结果进行了分析，得到了优良的阳性氧化工艺配方。     

La0.8Sr0.2MnO3涂覆液浓度对La0.8Sr0.2FeO3电极电化学性能的影响

研究了0.005、0.010、0.020、0.035和0.040 mol/L5种不同浓度的La0.8Sr0.2MnO3 (LSM)溶液涂覆La0.8Sr0.2FeO3 (LSF)电极后,其电化学性能的变化.X射线衍射结果表明:LSM和LSF化学相容性好.扫描电子显微镜观察可见:电极的晶粒尺寸和涂层厚度随着涂覆液浓度的增加而增加.电化学阻抗谱表明:在阳极极化条件下,经过0.010 mol/L LSM溶液涂覆处理后的LSF电极表现为最佳的电化学性能,其极化电阻在800℃仅为0.3Ω·cm2.而且无论在阳极极化还是阴极极化处理后,涂覆LSM后的LSF电极的极化电阻,1200 s内都呈现下降的趋势,LSM涂覆后的LSF电极具有一定的抗阳极极化的能力,归因于LSM涂层的良好催化特性.因此,0.010 mol/L LSM溶液涂覆处理后的LSF可以作为固体氧化物电解池的阳极材料.     

用交流阻抗谱研究活性砂浆胶结材料的电化学行为

海水环境潮差浪溅区钢筋混凝土结构易腐蚀破损,可采用锌网阳极与活性砂浆组成的牺牲阳极阴极保护系统进行修复保护.用交流阻抗谱方法对活性砂浆胶结材料的电化学性能进行了研究,并采用等效电路对阻抗谱进行拟合解析.结果表明:砂浆中掺入活性组分后,砂浆电阻显著降低,极化电阻与扩散阻抗系数也随活性组分的掺入大幅度降低；活性砂浆中阳极表面膜层不再是致密钝化的状态,表面易于进行阴极反应；活性组分同等掺量条件下,溴化锂更利于提高砂浆的电化学活性.     

埋地高含硫天然气管道泄漏扩散数值研究

针对输送高含硫天然气埋地管道在发生穿孔泄漏后的扩散过程进行系统分析,建立了埋地天然气管道泄漏扩散控制方程,根据输送高含硫天然气管道在不同工况下的泄漏过程数值模拟,得出天然气中主要成分甲烷及高浓度硫化氢的扩散规律,研究高含硫天然气管道埋地后穿孔泄漏扩散规律的差异,为埋地高含硫天然气管道泄漏后避免意外事故发生及进一步研究有毒气体扩散机理提供一定的理论基础。     

Gas self-ignition in a plane vortex chamber

This paper describes the numerical modeling of gas flow in a plane vortex chamber by using the Navier–Stokes equations. The model is based on the laws of conservation of mass, momentum, and energy for nonstationary two-dimensional compressible gas flow in the case of axial symmetry with a tangential component of the gas velocity. The processes of viscosity, thermal conductivity, and turbulence are accounted for. It is shown that the transition of the kinetic energy of gas into thermal energy as a result of transfer processes leads to the formation of hot spots in the boundary layers near the walls of the chamber. The gas temperature at these hot spots can exceed the gas combustion temperature, while the gas remains rather cold in the neighboring regions. This could be the reason for the cold gas self-ignition observed in the experiments. The turbulence of the flow and the processes of mixing and diffusion of the components make a significant contribution to the capacity of gas self-ignition.     

Consolidated theory of fluid thermodiffusion

We present the Onsager–Stefan–Maxwell thermodiffusion equations, which account for the Soret and Dufour effects in multicomponent fluids. Unlike transport laws derived from kinetic theory, this framework preserves the structure of the isothermal Stefan–Maxwell equations, separating the thermodynamic forces that drive diffusion from the force that drives heat flow. The Onsager–Stefan–Maxwell transport-coefficient matrix is symmetric, and the second law of thermodynamics imbues it with simple spectral characteristics. This new approach allows for heat to be considered as a pseudo-species and proves equivalent to both the intuitive extension of Fick's law and the generalized Stefan–Maxwell equations popularized by Bird, Stewart, and Lightfoot. A general inversion process facilitates the unique formulation of flux-explicit transport equations relative to any choice of convective reference velocity. Stefan–Maxwell diffusivities and thermal diffusion factors are tabulated for gaseous mixtures containing helium, argon, neon, krypton, and xenon. The framework is deployed to perform numerical simulations of steady three-dimensional thermodiffusion in a ternary gas.     

Higher order heat and mass transfer equations and their justification in extended irreversible thermodynamics

Three models leading to higher order heat conduction and diffusion equations are considered. A thermodynamic substantiation is suggested for constitutive equations in the framework of extended irreversible thermodynamics. Expressions for generalized temperature and generalized chemical potentials are presented, which are determined by the form of the constitutive laws describing the heat conduction and diffusion processes.     

基于FLUENT的海上平台天然气储罐泄漏扩散研究

针对海上石油平台天然气储罐泄漏扩散问题,基于计算流体动力学软件FLUENT,参照某海洋平台,建立海上平台的二维模型。模拟得到不同风速、泄漏孔径和泄漏速度条件下天然气在海上平台的泄漏扩散分布规律,并根据天然气5%~15%的爆炸极限模拟出天然气泄漏后的危险区域。模拟结果表明不同风速、泄漏孔径和泄漏速度与天然气泄漏扩散之间的规律并以此预测天然气泄漏扩散危险区域。为此类事故的预防、控制以及海上平台人员应急逃生方面均提供了参考。     

PEMFC阴极扩散层结构特性对水淹影响的数值分析

建立质子交换膜燃料电池一维两相传递模型,通过达西定律和菲克定律的联立求解得到扩散层中的液体饱和度和氧气浓度分布。考察扩散层特性参数孔隙率、厚度、接触角、渗透率对阴极水淹的影响,结果表明扩散层表面憎水将有助于液态水移出,但当达到憎水条件后,增大接触角对液态水传输和氧气传质的影响逐渐变小。憎水条件下孔隙率和厚度对液态水传输的影响不是很明显,但孔隙率增大和扩散层厚度减小均有利于氧气传质,实际应用中孔隙率增大的同时,厚度也要适当增大,极限电流密度相差不大。模型计算结果与文献中不同PTFE含量条件下实验的Tafel斜率和极限电流密度比较,吻合较好。     

Modeling conventional drying of wood: Inclusion of a moving evaporation interface

A one-dimensional mathematical model is presented that accounts for a moving evaporation interface in simulating the coupled heat and mass transfer during convective drying of wood. In the model proposed, the only mechanism considered in water transport within wood is diffusion. Additionally, the transport of moisture is dominated by the gradient of the moisture content. The controlling equations were established from Whitaker’s volume averaging laws and solved numerically with the finite volume method. The simulation results for the density of vapor and the volume rate of evaporation indicate that the migrating moisture was mainly in the form of gas under conditions of lower moisture content. The evaporation interface moved at approximately constant speed and the evaporation rate of the interface decreased with time. Finally, the core temperature and average moisture content in wood were successfully simulated.     

Instability in Unsteady-State Evaporation of Binary Solutions into an Inert Gas

The critical time of transition to the convective mode of the unsteady-state evaporation of a horizontal layer of a binary solution into a stagnant gas is theoretically and experimentally determined. It is shown that the slow diffusion mode of evaporation can be destabilized and replaced by the convective mode if the molecular weight of one of the liquid components is higher than the molecular weight of the gas and the molecular weight of the other liquid components is lower than the molecular weight of the gas. The neutral stability curve of the diffusion mode is determined using the Navier-Stokes equation in the Boussinesq approximation, the continuity equation, and the convective diffusion equations of the evaporating components. The transition between the modes is faster than the molecular diffusion; therefore, the depth of penetration of the vapor of the light component into the gas in the diffusion mode can be taken as the linear scale of the phenomenon considered. By the Galerkin method, the neutral stability curve of the diffusion mode of evaporation is determined and the critical time of bifurcation of the mode is found as a function of the composition of an aqueous butanol solution. The theoretical and experimental data are in good agreement.     

Modeling of Diffusion in Capillary Porous Materials During the Drying Process

This paper presents a model of heterogenous diffusion in capillary porous materials during the process of drying. The governing heat and mass transfer equations have been established using the liquid as well as vapor flow. Two models have been presented. Model 1 does not consider the heat conduction while the model 2 has been established by considering the conduction. The developed models and the numerical solutions of the resulting differential equations can take into account the moisture and temperature dependent thermophysical properties of the product. All equations have been established in spherical coordinates but the programme written for the purpose of calculations can be used for other geometries also. Numerical calculations have been performed for gas concrete and tiles using model 1, while model 2 has been used for gas concrete only because of the lack of data for thermophysical properties of the tile. For gas concrete it was seen that conduction has only marginal effect on the drying process and the numerical predictions of the drying process were reasonably accurate.     

Anomalous transport phenomena in semihydrophobic fuel cell electrodes

The so-called bubbling and weeping effects observed with porous semihydrophobic fuel cell electrodes are discussed in terms of gas transport in porous media. It is shown that the bubbling of gas on the electrolyte side can be accounted for by transport equations valid in the intermediate region between ordinary and Knudsen diffusion. The anomalous transport of liquid toward the gas side is attributed to isothermal distillation proceeding in the electrode pores. A gradient of the partial pressure of water vapour in the pores is the principal cause for both effects.