Microfluidics Measurement of Surface Tensions and Viscosities for Two-Phase Flow

Two-phase heat transfer, pressure drop and critical heat flux (CHF) are believed to be dependent on the surface tension in conjunction with the forces due to viscous shear. The critical physical properties are sensitive to environment parameter changes during two phase low and evaporation. Therefore, it is important to carry out the online experiment on the surface tension and viscosity measurement in microfluidic systems. This paper presents a novel and fast analytical tool for surface tension and viscosity measurement at the microsale. Based on the hydrodynamics of Taylor flow and the theoretical relationship between liquid film thickness and the critical physical properties, we carried out the surface tension and viscosity for refrigerant FC-72 as well as the liquid mixture of water/ethanol. This investigation indicated that the proposed method is capable of accurately and simply measuring both surface tension and viscosity at the microscale. It offers opportunities for online investigations in quality control and manufacturing where rapid and repeated measurements need to be made with small volume consumption.