Study on Enhancement Mechanism of Additive on the Absorption of Water Vapor by Aqueous LiBr

The surface tensions of aqueous lithium bromide（LiBr）with additive（2-ethyl-1-hexanol and 1-Octanol）have been measured by using a Wihelmy plate method，and the enhancement effect of the additives on the absorption of steam into aqueous LiBr in a static pool has been studied by a real-time type laser holographic visualization method. The experimental results show that both of liquid additive and vapor additive can decrease the surface tensions of aqueous LiBr significantly，vapor additive not only can trigger the Marangoni convection at the absorption interface just like the liquid additive，but can bring about better enhancement effect on the absorption performance than that liquid additive can. The enhancement mechanism of additive on absorption has been concluded that both liquid additive and vapor additive can be adsorbed by aqueous LiBr at the liquid-vapor-interface from the liquid side and the vapor side respectively，which result in surface tension gradient，and then cause Marangoni convection at the interface which enhances the heat and mass transfer performance during the absorption process.