Marangoni enhancement factor

Abstract The mass transferred from one phase to the adjacent phase must diffuse through the interface and subsequently may produce interfacial effect. In this chapter, two kinds of important interfacial effects are discussed Marangoni effect and Rayleigh effect. The theoretical background and method of computation are described including origin of interfacial convection, mathematical expression, observation, theoretical analysis (interface instability, on-set condition), experimental and theoretical study on enhancement factor of mass transfer. The details of interfacial effects are simulated by using CMT differential equations. 

As stated in previous section, the mass transfer process can be enhanced by the presence of Marangoni convection. Xiao analyzed the mass transfer condition under Ma > Ma r to find the enhancement factor as follows [12]. 

Sun [13, 14] performed the experiment of CO2 absorption by methanol, toluene, and chlorobenzene in a horizontal liquid-gas contactor at different liquid thickness h as shown in Fig. 8.16 for investigating the progress of Marangoni effect. The development of enhancement factor F with time of the unsteady absorption is given in Fig. 8.15. 

As shown in Fig. 8.16, the F increases with increasing liquid thickness because the higher the liquid thickness the more intense Rayleigh effect. It demonstrates that the coupling effect of Rayleigh and Marangoni makes greater increase in the enhancement factor. 

Under the condition of existing Marangoni convection, the enhancement factor F can be expressed as follows ... 

To determine the mass transfer enhancement factor R it is advisable to define the Marangoni number by equation (4) using Eq. (7). The critical Marangoni number has to be considercxl as a fonctiem only of the gas - liquid phase resistance ratio B. 

The action of the lipase, its stability and rate of reaction are influenced by many factors, including temperature, pH, type of solvent, water activity and whether it is in an immobilized or free form (Valivety et al., 1994 Soumanou et al., 1999 Ma et al., 2002, Rousseau and Marangoni, 2002). Liquid butteroil by itself can act as a solvent as well as a substrate and interesterification is enhanced in the presence of an organic solvent such as hexane (Lee and Swaisgood, 1997). 

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