Membrane Separation Technology has added a new dimension in modern separation technology. The recent novel development in membrane processes have made it possible to use various different purposes at eco-nomical rates with additional flexibility and improved efficiencies. Feed spacers can provide higher shear rates at the membrane surface, which, promote the mixing between the bulk of the fluid and the fluid ele-ment adjacent to the membrane surface. As a result concentration polarization and membrane fouling can be reduced. The present work is devoted to investigate the hydrodynamics in two dimensional spacer filled channels. Three different configurations of the cylindrical spacers are investigated with different channel Reynolds number and different meshlength. Different size and shape of formation of recirculation region, upstream and downstream of the spacers are closely observed. This recirculation regions have an important role in enhancing the mass transfer in the reattachment region.
This study aims to present the results obtained from the simulation of a flat plate photocatalytic reactor using CFD code FLUENT. For various turbulence models, the simulation results showed the computed flow features for inlet and outlet components of the flat plate reactor under different flow regimes.In addition the performance of the photocatalytic reactor for pollutant degradation was observed to depend on the reactor’s hydrodynamics. The results reported here suggest the importance of fluid mixing in the flat plate reactor since the reaction takes place only at the fluid-catalyst interface.The effect of inlet positions and roughness elements on the flow and mass transport of formic acid in the reactive module has been examined which provides significant insight for the efficient design of the flat plate reactor.
Urea prills are produced in the prilling tower, where a cooling-solidification-cooling process of the prills takes place. The ambient air is used as the cooling stream for this process. A case study of the urea prilling process is chosen due to in hot/humid days, the temperature of the product at the bottom of the prilling tower is hot and cannot be packed directly. In addition, the urea prills form lumps and cakes with each other on the scrubber at the bottom of the prilling tower that affects the quality of the product. A mathematical model based on the particle kinematics,and, heat and mass transfer between the urea prills and the cooling air is developed. This is followed by using a numerical technique with an explicit scheme to solve the model. The model numerical results are validated with Scanning Electronic Microscope (SEM) observation of urea particles. Moreover,to investigate the effect of the urea prilling tower configuration parameters on the above urea product problems, the hydrodynamic of air flow inside the tower is analyzed using Computational Fluid Dynamics (CFD) simulation software.
Higher energy consumption and storage loss beyond permissible limit are the two most important problems in Indian potato cold stores, which have been hindering with the further growth of this industry. The problems of energy consumption and storage losses are interrelated in nature and have direct relation with the intricacy of the coupled transport phenomena of heat, mass and momentum transfer in bulk-stored potatoes. The heat and mass transfer processes within the bags of potato in a stack depend on product properties, and operating as well as geometric parameters of the cold store. All these parameters influence the mechanism of heat and mass transfer in the storage facility, which ultimately affect the temperature of the packed product and humidity around the product.Therefore, an in-depth analysis of the relative importance of these parameters on the mechanism of transport phenomena within the bulk-stored potatoes in a cold store helps to overcome the problems of higher energy consumption and storage losses beyond permissible limit.
1stchapter, a two dimensional MHD natural convection and mass transfer flow past an inclined semi infinite vertical plate in the presence of heat generation and porous medium was discussed 2ndchapter, a free convective flow of viscous incompressible fluid of small electrical conductivity through a porous medium bounded by an oscillating infinite porous plate in slip flow regime. 3rdchapter, an analysis carried out to study the nonlinear MHD flow with heat and mass transfer characteristics of an incompressible, viscous, electrically conducting Boussinesq fluid over a vertical oscillating porous permeable plate embedded in a porous medium. 4thchapter, a theoretical analysis of influence of radiation effect on a two dimensional MHD convection and mass transfer flow of an electrically conducting fluid past an inclined semi-infinite vertical porous plate embedded in a porous medium. 5thchapter, a theoretical analysis of free convective two dimensional unsteady flow of a visco-elastic incompressible fluid through a porous medium bounded by an infinite vertical porous plate subjected to a uniform suction was presented under the influence of a uniform transverse magnetic field.
FLOW PROBLEMS WITH HEAT AND MASS TRANSFER. In this Dissertation, investigations are carried out on Natural convection flow of fluid between two infinite vertical parallel plates for different physical situations as well as different fluid properties. The different thermal conditions considered in this dissertation include symmetric and asymmetric heating of the boundaries, periodic temperature variation on the boundaries, viscous dissipation heating as well as the role of Non- Fourier energy equation on convective heat transfer. The dissertation also investigated the influence of heat generation or absorption and mass leakage (suction/injection) through the channel boundaries. Closed form solutions are obtained for momentum, energy and concentration equations for different physical situations. It is hoped that the result presented in this dissertation will be of use in validating Computer routines for numerical solutions of more complex natural convection fluid flows in the presence of heat and mass transfer and in stimulating needed experimental work in this area.
The performance of a reactor is greatly influenced by the hydrodynamics. Residence time distribution (RTD) is applied to characterize the flow in the reactor. The analysis of RTD data is very useful to study the flow pattern, determine the degree of mixing, and diagnose flow problems such as recirculation, channelling, short-circuiting or stagnation. RTD study of a reactor is generally performed by performing experiments. However, experiments for RTD are time consuming and error prone. The present study deals with avoiding the above problem. In current work, CFD code was developed for performing the RTD study of two different annular reactor configurations i.e. reactor with axial inlet and outlet, and reactor with radial inlet and outlet. It has been observed that the reactor with radial input and output can give better performance than reactor with axial input and output in case of surface reactions. However, flow channelling is observed in the reactor having radial input and output at high flow rate.
In chapter I,we have discussed the fundamental concept of heat and mass transfer. In this chapter we have shown some relation among the various parameters related to heat and mass transfer of fluid. In chapter II, we have discussed about forced convection. The temperature distributions in a forced parallel flow near the wall with constant temperature and constant heat flux have been discussed here.In chapter III, an attempt has been made to discuss the natural convection. The basic equations related to various free convective processes have been shown with the help of some nondimentional numbers. In chapter IV, the combine effects of forced and free convection in fluid have been taken into account. Here we have shown the convective boundary layer related to mixed convection. In chapter V, we have investigated the mass transfer of fluid. Here, we have discussed about mass transfer, forced and fluxes, diffusion equation. In chapter VI, we have discussed about some additional convective process. Various processes like melting, atmospheric convection, oceanic convection etc. have been taken here. In describing special types of convective flow we have considered porous medium.
High Performance Light Water Reactor is a reactor concept of the 4th generation which is cooled and moderated with water at supercritical pressure. Water as the working fluid is guided three times upward and downward through the core and finally heats up to 500°C.The fluid temperature at the outlet of the first upwards flow, the so-called “evaporator?. The presence of the wire inside the fuel assembly results in a strong flow mixing and sweeping effects among sub-channels. The values of the “wire factor” indicate that the wire spacer can improve the heat transfer at DHT conditions.
Compositional reservoir simulators are commonly used to estimate the potential incremental hydrocarbon recovery by gas injection processes. Successful design and implementation of these processes rely in part on the accuracy of available simulation tools. This manuscript presents the results of three main research projects related to fluid flow, mass transfer and sorption in the context of enhanced hydrocarbon recovery from conventional and unconventional resources. The results and analyses presented in this work significantly improve our understanding of enhanced oil/gas recovery processes and boost the predictive capabilities of compositional reservoir simulation.
In this research project a method has been analysed through CFD technique to obtain steady state heat transfer in nuclear fuel rod assembly and the local heat transfer coefficients of carbon dioxide at supercritical pressures in triangular channel under cooling conditions is presented through the numerical simulation. The CFD code Ansys CFX has been used to simulate the convective heat transfer coefficient of the triangular channel. Supercritical CO2 heat-transfer data were obtained at reactor-equivalent conditions at three pressures above the critical point (7.6, 8.4 and 8.8 MPa), mass fluxes from 840 to 3000 kg/m2s,heat fluxes up to 600 kW/m2 and inlet temperatures from 20 to 40?C. The effects of pressure, mass flux of supercritical CO2, rod diameter, and heat flux on heat transfer are investigated. The computational results showed that the sharply varying thermo physical properties of carbon dioxide have a significant role on the local heat transfer coefficient which varies significantly along the triangular channel and small tube when the CO2 bulk temperatures were within the near-critical region.
Gas–liquid–solid fluidized beds are used extensively in the refining, petrochemical, pharmaceutical, biotechnology, food and environmental industries. Some of these processes use solids whose densities are only slightly higher than the density of water. Because of the good heat and mass transfer characteristics, three-phase fluidized beds or slurry bubble columns have gained considerable importance in their application in physical, chemical, petrochemical, electrochemical and biochemical processing. The first part discusses about importance of gas-liquid-solid fluidized bed, their modes of operation, important hydrodynamic properties those have been studied either related to modeling or experimental analysis and applications of gas-liquid-solid fluidized bed. The second part gives an overview of the methodology used in CFD to solve problems relating mass, momentum and heat transfer. Also comparative study of various CFD related software is given in this section. Third part contains the details about problem description and approach used in FLUENT to get the solution. Finally results of simulation and comparison with experimental results are shown.
The fluid flow due to a stretching cylinder encounters in several industrial manufacturing processes. Such processes are fiber technology, drawing of plastic films, paper production, extrusion processes and of theoretical interest etc. Present study deals with the numerical solutions for mass transfer flow problems of Newtonian and Non-Newtonian fluids. The effect of mass transfer on axisymmetric laminar boundary layer flow along a continuously stretching cylinder immersed in a viscous and incompressible fluid is investigated. The boundary layer equations in cylindrical form are first transformed into a set of non-dimensional ordinary differential equations using dimensionless variables and then solved by Runge-Kutta method with Shooting Technique. The problem under consideration reduces to the flat plate case so that the curvature parameter is absent, and thus the results obtained can be examined.
Viscosity and thermal conductivity are two temperature dependent properties of matter. In most of the problems of fluid mechanics, the viscosity and thermal conductivity of the fluid were assumed to constant. However it is known that these physical properties can change significantly with temperature.When the effect of variable viscosity and thermal conductivity are taken in to account, the flow characteristics are substantially changed from that of constant cases. Most fluids however have temperature dependent properties, and under circumstances where large temperature gradients exist across the fluid medium, fluid properties often vary significantly. Under many conditions, ignoring such variations may cause serious in-accuracy in estimating heat transfer rates. So, here in this book we are considering some heat and mass transfer problems of fluid mechanics where the effects of variable viscosity and thermal conductivity are observed under different flow conditions. The book will be helpful for researchers working in the field of heat and mass transfer flow.
This book mainly deals with the dynamics of Newtonian and Non-Newtonian multiphase fluid flow inside the hellical coils, elbow, valve, straight pipe, orifice etc. Computational Fluid Dynamics was adopted as a tool to describe the flow phenomena and related incidents inside the geometry. The study was primarily concentrating on the hexagonal and tetrahedral grid generation followed by SIMPLE algorithm as a solver.