摘要:

Dry air density, moisNre content and thermal mass are the three independent variables used to produce a relevant physical description of heat, mass and momentum tranfer that occur in a capillary porous medium during drying processes. This choice leads to a conservative set of equations. This strongly coupled and highly non-linear system is solved numerically by focusing on the accuracy of the solution and on a time step procedure to enable faster processing time.

ISSN:0737-3937    

DOI:10.1080/07373939508916973

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

ABSTRACTA numerical model of isothermal drying of deformable substances is proposed. The model is applied in a uni-directional case to analysis of water transport in a sphere of agar ge. The simulation program makes it possible to calculate the water content fields and def rmations and stresses in the sphere during drying. Validation of the water content profile results is proposed by the experimental study of the dehydration of gel spheres in a sugar solution. The sensitivity of internal stresses to drying conditions is then analysed.

ISSN:0737-3937    

DOI:10.1080/07373939508916974

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The mathematical model proposed enables the description of mass and energy transfers during convection drying of granular materials. It shows evolution of the water content of the material in time and space, air and grain temperature, relative humidity of intergranular air, settling of the layer. mass energy and mass power input.

ISSN:0737-3937    

DOI:10.1080/07373939508916975

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A two-dimensional finite element model is developed for kiln-drying of refractory concrete. Using this model simulations are carried out for refractory concrete castings of different thicknesses to investigate the effects of drying schedules on pore steam pressure and moisture removal. Simulation results from both one- and two-dimensional models are compared and discussed. On the basis of the simulation results new realistic drying schedules are suggested.

ISSN:0737-3937    

DOI:10.1080/07373939508916976

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Drying plays an important role in many industries as diverse as cement production to the manufacture of foodstuffs. In order to understand the fundamental physics of the drying operation it is necessary to study the movement of moisture, in both the liquid and gaseous phases, throughout the capillary-porous body. The insight gained from the study can lead, not only to a greater understanding of the phenomena which arise during drying, but also, to an increase in the efficiency and productivity level of the kiln. Experimental methods enable drying practitioners to gain only a limited insight, whereas, mathematical models have been shown and proven to give a more detailed analysis of the drying process. This paper presents a novel application of the control volume finite element numerical technique to simulate the high temperature drying of spruce. The numerical treatment of this problem has been studied extensively in the past, however, the basic drawback with previous numerical analyses is that they have been limited t o astructured fixed mesh. During drying, timber twists and distorts and to accurately model the drying procedure, it is essential that this behaviour is taken into consideration. The control volume finite element method enables a structured or unstructured mesh to be employed without alteration to the formulation, and lays the foundation far the simulation of the timber deformation.

ISSN:0737-3937    

DOI:10.1080/07373939508916977

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper proposes a suitable method for calculating drying stresses. This is an application of the finite element method (FE) and the so-called control volume (CV) method. The latter has been chosen because most of coupled heat and mass transfer codes are based on CV.

ISSN:0737-3937    

DOI:10.1080/07373939508916978

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this paper, we study numerically two-dimensional heat and mass transfer during convective drying in porous media. The set of macroscopic equations is very comprehensive and takes into account the effect of gaseous pressure. A numerical code has been established. This code has allowed us to determine t.he space-time evolution of the temperature, the total pressure and the moisture content.

ISSN:0737-3937    

DOI:10.1080/07373939508916979

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This study is devoted to investigating the heat and mass transfer phenomena that occur during the convective drying of wood at high temperatures. A comparison will be made between an existing two-dimensional computer code known asTranspore. which was developed by Perre inFrance, and another two-dimensional code which was developed independently by Turner inAustralia. Both numerical codes use a comprehensive set of macroscopic equations to describe the drying process, and most importantly treat the anisotropic behaviour of the wood. The porous medium is defined by three state variables: temperature, moisture content and gaseous pressure and the numerical simulation codes allow the evolution of the distributions of these state variables to be analysed throughout the drying process. The numerical investigation presented in this research work will compare the results obtained from both simulation codes and comments will be made on their consistencies. The influence that the drying air characteristics (moist air and super-heated stream) have on the overall drying kinetics, together with the effect that varying the mesh structure or changing the relative permeability curves have on the results will be throughly scrutinised.

ISSN:0737-3937    

DOI:10.1080/07373939508916980

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Mathematical tools for studying panicle transpon in rotary drying and cooling processes are developed in this paper. In contrast to conventional approaches aimed at deriving empirical or xmi-empirical correlations, a rigorous mathematical analysis which employs dilferential calculus and analytical geometry is emphasis4 in the current research. These developments allow accurale computations of solid flowrate, retention time and particle holdup in rotary dryers with arbilrary flight configurations. Consequently, optimal dryer configuration design in terms of drum dimension, flight number and geometry can be achieved through a better understanding of the mathematical insight of rotary drum performance.

ISSN:0737-3937    

DOI:10.1080/07373939508916981

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Impinging stream contactors provide a novel configuration for drying and/or gas/solid chemical reactions involving particulates. pastes or suspensions which can be dispersed in a flowing gas stream. Essentially they consist of one or more highly turbulent “ impingement ” zones formed by normal collision of two confined opposing jets in a channel or duct. Little information exists in the current literature on the flow and thermal characteristics of such flows. The objective of this paper is to present computational fluid dynamic predictions for confined two-dimensional opposing turbulent jets over a range of nozzle-to-nozzle separations and jet Reynolds numbers and superheated steam drying of panicles in such contactors. The standard k-E model is used to close the governing conservation equations. Some results on the prediction of single particle trajectories and drying in such flows are presented. Predictions are performed in two distinct pans. In the first part a hybrid. finite volume method based on the “SIMPLEC” algorithm is used to solve the momentum and energy equations and in the

ISSN:0737-3937    

DOI:10.1080/07373939508916982

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor