Experimental Study On Gas-liquid Two Phase Flow In Serpentine Channels With Different Y-type Junction

Serpentine microchannel is a special form of miniature pipe, showing the unique charm in many industrial applications, which is widespread in the field of biological engineering,chemistry, energy and and other projects. There are a lot of elbow structers, which can achieve long distance transport on a limited area and are especially important for the small space of the micro miniature chemical equipments such as micro fuel cell, micro reactor, micro evaporator and condenser. The flow pattern is the basis of the study of two phase flow behavior and different flow modes will make the position distribution of gas and liquid phase different at the horizontal section and upstream or downstream corners. These have a certain effect on the different side wall of micro heat exchanger, which is an important point that distinguishs from straight microchannel. It is necessary to discuss the mechanism of flow.In this work, visualization experiments were carried out in serpentine micro channels with different Y-type microfluidic junctions using a high-speed camera. The characteristics and phase distribution of gas-liquid two-phase flow were studied with air and deionized water used as working fluids. Some parameters, shape and causes of special flow patterns, which are different from the conventional channels, were collected and analyzed. The effects of Y type angles and gas-liquid mixing modes on the pattern generation and the fluid phase distribution are compared.Compared with straight channels, great changes occurred in the bubble flow and slug flow in the serpentine microchannels. And there appearances were influenced by flow velocity,surface tension and turbulent flow. The processes of gas slug and the transition ways of gas halberd in arc induced slug flow and hastate slug flow were directly affected by the elbows. The head or tail of gas phase also differed from the traditional shape of gas slug and change in length was closely related to the apparent velocity of gas and liquid phase. In addition, the nonlinear model and drift model to predict void fraction of halberd-shaped slug flow showed advantages.Two kinds of gas and liquid mixing modes with contrary injection sequences have some influence on the formation of flow patterns, which is further indicated that the important status of various forces, such as gravity, inertia force, surface tension and so on, will be reconfigured.