Heat Transfer Characteristics of Liquid-Liquid Taylor Flows in Flat Mini Channels

Abstract Taylor flows in mini or micro channels have been investigated for a long time due to the wide application of this kind of flow patterns in thermal management, heat exchangers, microfluidics, coating, and micro chemical reactions. The characteristics of Taylor flows in flat mini channels have not been studied in detail, even though these types of tubes are commonly used in many industrial fields. In this paper, water was used as the dispersed phase, and Hexadecane was used as the continuous phase. A circular tube with an inner diameter of 2 mm was chosen as the reference geometry, while 4 flat mini channels with the same perimeter as the circular tube were considered, with aspect ratios ranging from 0.5 to 2. The numerical results of liquid-liquid Taylor flows in circular tubes agreed well with the experimental data in the open literature. The liquid-liquid interfaces and heat transfer coefficients of these channels were obtained and compared. The results showed that axisymmetric liquid-liquid interfaces are obtained in circular tubes, while nonaxisymmetric interfaces are formed in flat channels due to the confinement effect of flat walls. The thinnest liquid film is obtained near the junction of circular and flat walls in flat channels. The heat transfer coefficient of a circular tube is lower than that of flat channels. The heat transfer coefficient increases with increasing aspect ratios of the flat channels. A maximum heat transfer enhancement of 32% is obtained for the flat tube with an aspect ratio of 2 compared to the circular tube.