Combined heat and mass transfer

Mass transfer may be influenced by gradients in variables other than concentration and pressure. In the pharmaceutical sciences, gradients in electrical potential and in temperature are two important examples of these other driving forces. Section IV.B.l describes the effect of electrical potential gradients on the transport of ions, and Section IV.B.2 discusses mass transport in the presence of temperature gradients, known as combined heat and mass transfer. 

Problems involving combined heat and mass transfer provide a final example of multiple driving forces but differ in important ways from the previous examples. In those examples, all the gradients involved (concentration, pressure, electrical potential) were directly responsible for driving mass transfer. In combined heat and mass transfer, however, both heat and mass are being transported. The transfer of heat may drive mass transfer indirectly, as in the loss of a volatile solvent from a beaker when it is heated by evaporation. Thus, problems in heat and mass... 

Various formulations and methodologies have been suggested for describing combined heat and mass transfer problems, such as the integral transform technique, in the development of general solutions. In this chapter, cross phenomena or coupled heat and mass transfer are discussed using the linear nonequilibrium thermodynamics theory. 

Merrill, T. L., and Perez-Bianco, H. (1997) Combined Heat and Mass Transfer During Bubble Absorption in Binary Solutions, International Journal of Heat and Mass Transfer, Vol. 40(3), pp. 589-603. 

Kang, Y. T., and Christensen, R. N. (1995) Combined Heat and Mass Transfer Analysis for Absorption in a Eluted Tube with a Porous Medium in Confined Cross Plow, Proceedings of the 1995 ASME/JSME Thermal Engineering Joint Conference. Part 1 (of 4), Mar 19-24 1995, Maui, HI, USA, Vol. 1, ASME, New York, NY, USA, pp. 251-260. 

Lewis number Le Sc D = Pr Ratio of molecular thermal and mass diffusivities Combined heat and mass transfer... 

G. Ackermann, Combined Heat and Mass Transfer in the Same Field at High Temperature and Partial Pressure Differences, Forsch. Ingenieurwes, 8(382), pp. 1-16,1937. 

Combined heat and mass transfer to a horizontal plale... 

The Lewis number appears in double diffusive problems of combined heat and mass transfer. From Table 3.5.2 it can be seen that in gases all the transport effects are of the same order, but in liquids conduction heat transfer is the controlling mechanism on a large scale. 

I.L. Maclaine-Cross, A Theory of Combined Heat and Mass Transfer in Regenerators, Ph.D. Thesis, Monash University, Australia, 1974. 

This chapter discusses the very complex phenomenon of combined heat and mass transfer. In some cases, these two transfer operations may take place in opposite directions across the interface between phases. At dmes, the mass transfer may involve more than one component. Methods for design of such columns will be developed despite the absence of rigorous theory for many of these engineering applications. This chapter deals with these complicated situations through empirical adjustments to heat transfer coefficients, based upon extensive practical experience. 

Lykov number (Luikov number) Adimensionless number, Lu, that combines heat and mass transfer as the ratio of mass diffusivity, D, to thermal diffusivity, a ... 

COMBINED HEAT AND MASS TRANSFER IN TAPERED CAPILLARIES WITH BUBBLES UNDER THE ACTION OF A TEMPERATURE GRADIENT... 

FIGURE 3.23 Combined heat and mass transfer in a tapered capillary of the length L. Radius of the capillary at cross section x is r x) = Tq + x-tana, imposed temperature... 

Combined heat and mass transfer in porous media is of great interest in a number of areas. Porous space inside any porous material has a sophisticated structure and is difficult to model even using computer simulations. It is even more difficult to model a combined heat and mass transfer in such complicated structures. In the following text we investigate a mass transfer of oils in a model porous system, which is a tapered capillary. The mass transfer takes place between two menisci of oil at jc = 0 and x = L under the action of an imposed constant temperature gradient (Figure 3.23). 

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