Effects of gas phase and additive properties on Marangoni instability for absorption process in a horizontal fluid layer

The objectives of this study are to investigate theoretically the effect of additive on the onset of Marangoni convection and to find the meaningful relationships between the important parameters. The propagation theory in which the penetration depth is chosen as the length scale and the scaling analysis are adapted in the present study. It is found that the combined absorbate Marangoni number MB is linearly related to the modified Biot number Bi^* and there is a critical Biot number Bi to cause the most unstable state of liquid layer. It is concluded that it is not always advantageous to increase the mass transfer coefficient in the gas phase in order to enhance the absorption rate. It is interesting that the additive Marangoni number Ma_A and the relative surface diffusivity of additive R_A which represent the additive properties act as the stabilizer and the destabilizer respectively for the onset of Marangoni convection.