Study on internal circulation patterns and heat transfer characteristics of gas-liquid Taylor flow in a gradually expanding microchannel

The internal circulation within the gas-liquid Taylor flow slug promotes radial fluid mixing, which is a key factor in enhancing heat and mass transfer rates. The present study investigates numerically the internal circulation patterns of gas-liquid Taylor flow slugs in a gradually expanding microchannel and their effect on heat transfer characteristics. The flow field structure and heat transfer performance of slugs in straight and gradually expanding channels under different flow velocity conditions are compared and analyzed. The results show that secondary vortices within the slug significantly enhance the mixing in the liquid phase, thus improving local heat transfer efficiency. In the expanding channel, the gradual increase in hydraulic diameter promotes the formation and development of secondary vortices, leading to the further intensification of heat transfer. Under these conditions, the secondary circulation zone significantly impacts the main circulation zone, and its contribution to strengthening heat transfer cannot be ignored. This study provides a theoretical basis for optimizing the design of microchannel heat sinks with broad engineering applications, particularly in device cooling and efficient heat dissipation.