Simulation of thermophysical flow in axisymmetric nozzle with expansion chamber

Axisymmetric nozzle flows with a free‐jet expansion are simulated considering several substances and several flow conditions, and the thermophysical properties in the nozzle and the free‐jet region are predicted. The present numerical method is based on the preconditioning method developed by Yamamoto and the mathematical models of thermophysical properties of the substances. As numerical examples show, gas flows of carbon dioxide, water, and nitrogen under a subcritical pressure condition are first calculated. Calculated distances to the Mach disk are compared with the experimental results, and also the density distributions are compared among these three substances. Second, carbon dioxide flows while changing the pressure from subcritical to supercritical values are calculated and the effect of pressure on the flow field is investigated. Third, flows of water vapor with and without nonequilibrium condensation are calculated and the effect of condensation on the flow field is investigated. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Evaluation of Barros and Wolf Efficiency Correlations for Conventional and Extractive Distillation Columns in Bioethanol Production Process

In view of the increasing environmental concern, the use of renewable and less pollutant energy sources has been encouraged. In this context, bioethanol has been used as fuel in the anhydrous form, blended with gasoline. In this work, simulations of the extractive distillation process in anhydrous bioethanol production were carried out in Aspen Plus® using nonequilibrium stage model and equilibrium stage model with Barros and Wolf efficiency correlations for plate and component. Equilibrium stage model with plate efficiency determined through Barros and Wolf efficiency correlation showed a satisfactory agreement with results predicted by the nonequilibrium stage model for anhydrous bioethanol production process.     

Transport Properties of Inhomogeneous Fluid Mixtures

Explicit expressions for the transport coefficients of mixtures of dense, strongly inhomogeneous fluids are derived in terms of the equilibrium structure factors of such mixtures, in the framework of the nonequilibrium statistical mechanical theory suggested by the authors. Particular attention is paid to the diffusion coefficients of multicomponent inhomogeneous fluids. The case of binary diffusion in inhomogeneous fluids is considered in detail.     

MOMENTUM INTEGRAL METHOD FOR FORCED CONVECTION IN THERMAL NONEQUILIBRIUM POWER-LAW FLUID-SATURATED POROUS MEDIA

Forced convection heat transfer for power-law fluid flow in porous media was studied analytically. The analytical solutions were obtained based on the Brinkman-extended Darcy model for fluid flow and the two-equation model for forced convection heat transfer. As a closed-form exact velocity profile is unobtainable for the general power-law index, an approximate velocity profile based on the parabolic model is proposed by subscribing to the momentum boundary layer integral method. Heat transfer analysis is based on the two-equation model by considering local thermal nonequilibrium between fluid and solid phases and constant heat flux boundary conditions. The velocity and temperature distributions obtained based on the parabolic model were verified to be reasonably accurate and improvement is justified compared to the linear model. The expression for the overall Nusselt number was derived based on the proposed parabolic model. The effects of the governing parameters of engineering importance such as Darcy number, power-law index, nondimensional interfacial heat transfer coefficient, and effective thermal conductivity ratio on the convective heat transfer characteristics of non-Newtonian fluids in porous media are analyzed and discussed.     

热电器件中的汤姆孙热

应用非平衡态热力学理论，求出热电器件吸热和放热端与热源交换的热流。进而讨论汤姆孙热对电器件性能的影响。结果表明，在热电器件中常被忽视的汤姆孙热是不容忽视的。     

用荧光法研究分子非平衡化学过程对湍流参数的影响

用荧光法测量了激波管接触面内的当地湍流参数,给出了密度脉动自相关函数和频谱曲线以及它们与流动介质内分子非平衡化学过程的关系。     

High-temperature effects in hypersonic flows

The hypersonic (M=25) flow past a 10° right circular cone at 0° angle of attack has been computed using an implicit, noniterative, finite-difference scheme for the Parabolized Navier-Stokes (PNS) equations. Three different gas models have been considered in the study — (1) ideal gas (γ = constant), (2) equilibrium air, and (3) five species (N₂, O₂, NO, N, O) chemical nonequilibrium air. For the nonequilibrium air case, three different models have been considered — (a) one in which the constituent species have no internal structure (i.e., species are ideal gases), (b) one in which the constituent species have internal structure (i.e., species are thermally perfect gases), and (c) one in which the species have internal structure and their thermodynamic properties have been obtained from quantum mechanical and spectroscopic calculations.     

Measurement of transport properties of liquids with equilibrium and nonequilibrium Rayleigh scattering

We have developed an experimental arrangement for measuring Rayleigh scattering in liquids and liquid mixtures that are either in thermal equilibrium or in thermal nonequilibrium states. As an illustrative example we report experimental values for the thermal dilfusivity, the mass diffusion coefficient, the Rayleigh-factor ratio, and the Suret coefficient of an equimolar mixture of liquid toluene andn-hexane.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994 Boulder Colorado U S A     

氮氧化物在等离子体中的分解与转化

利用非平衡态等离子体技术处理燃烧烟气中的氮氧化物（NOx）是目前最有吸引力和发展前途的方法，它是利用非平衡态等离子体产生的微放电通道提供给电子、离子的能量，激发、分解和电离分子和原子，使燃烧污染物分子在条件下得以分解和转化。本文结合催化原理，研究了NOx在Al2O3催化剂条件下的分解和转化，得到了脱除率达到95％以上的效果，并探讨了基于Al2O3催化剂条件下的催化转化原理。     

Effects of thermal nonequilibrium and non-uniform temperature gradients on the onset of convection in a heterogeneous porous medium

The simultaneous effect of local thermal nonequilibrium (LTNE), vertical heterogeneity of permeability, and non-uniform basic temperature gradient on the criterion for the onset of Darcy-Benard convection is studied. The eigenvalue problem is solved numerically using the Galerkin method. The interaction of various types of permeability heterogeneity and non-uniform basic temperature gradient functions on the stability characteristics of the system is analyzed. It is observed that the linear variation (about the mean) of the permeability and the basic temperature gradient with depth has no added effect on the criterion for the onset of convection. However, the concurrent variation in heterogeneous permeability and non-uniform basic temperature gradient functions has more stabilizing effect on the system, while opposite is the trend when the effect of non-uniform basic temperature gradient alone is present.