Experimental and numerical investigations of bubble formation in a flow-focusing device with temperature difference between gas and liquid phases

In this paper, the bubble formation with temperature difference between the gas and liquid phases is investigated through experimental and numerical methods. A flow-focusing device is employed to generate the bubbles. Different from previous studies with the same temperature of the gas and liquid phases, a temperature difference is introduced in this work, which could change relevant physical properties and therefore impact the hydrodynamics of the micro-flow. Thus, a coupled Level-set (LS)/Volume of Fluid (VOF) method (CLSVOF) is employed to precisely calculate the bubble formation involving heat transfer. The experimental and numerical results of the bubble lengths as a function of the temperature ratio of the liquid to gas phases are shown to be consistent. Further, a power-law function, which involves the temperature ratio of the gas and the liquid phases, is proposed for the first time to calculate the bubble length. Meanwhile, the bubble formation is accelerated by the relatively higher temperature, especially in the expansion stage of the bubble formation. The results of this work are helpful in designing microreactors with temperature difference between the continuous and dispersed phases. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This paper investigates the bubble formation with temperature difference between the gas and liquid phases through experimental and numerical methods. The results show that the temperature ratio of the liquid to gas phases has an impact on the bubble length, and a new method for calculating the bubble length is proposed. The findings are important for designing microreactors with temperature difference between the continuous and dispersed phases.