An exploration of the gas CO

2

absorbed into liquid ethanol accompanied with Rayleigh convection is performed by analyzing the mass entransy dissipation; this new statistical quantity is introduced to describe the irreversibility of mass transfer potential capacity. Based on the general advection-diffusion differential equation for an unsteady mass transfer process

the variation of the included angle between the velocity vector and concentration gradient fields is investigated to reveal the underlying mechanism of interfacial convection enhancing mass transfer. Results show some identical characteristics with the qualitative analyses of the synergy effects generated by the concentration and velocity fields after interfacial convection occurring for a boundary condition of fixed surface concentration. And the equivalent mass resistance for convective mass transfer process presents the similar variation with the reciprocal of instantaneous mass transfer coefficient. Accordingly

it is reasonable to be seen that mass transfer dissipation rate could be provided to assess the convection strength and explain fundamentally how Rayleigh convection

improves mass transfer performance through establishing a close relationship between the mass transfer capacity and field synergy principle from the view of mass transfer theory.