Comparison of breakup and coalescence kernels in population balance model for modeling isothermal gas-liquid flow

Abstract

At present, combining the Eulerian-Eulerian approach and the population balance model (PBM) to describe the bubbles coalescence and breakup has attracted much attention for the gas–liquid flow of the nuclear energy industry. In this paper, the bubble size distribution, void fraction, interface area concentration, gas/liquid flow velocity with four breakup and coalescence kernels of the PBM were calculated and compared to experimental data for an isothermal bubbly flow. First, four kernels in PBM: model of Luo and Svendsen (1996) model of Lehr et al. (2002), model of Coulaloglou and Tavlarides (1977) and model of Prince and Blanch (1990) were proposed and used to calculate the isothermal gas–liquid two-phase flow inside the pipe. Second, related parameters in the inlet and exit section were analyzed and the calculation results especially in the position in the near wall were compared to the experimental data to evaluate the calculation accuracy of four models. The results indicate that the suitable breakup and coalescence kernels are crucial to ensure the calculation accuracy. In most cases, all models have high accuracy for the gas and liquid flow velocity inside the pipe (within 10%), while the calculation accuracy of interfacial area concentration is lower (within 55%). Model of Luo and Svendsen (1996) shows higher accuracy (relative error within 12%) and superiority in calculating the bubble size and reflect more accurately the bubble size distribution. This paper will be helpful to provide guidance for choosing breakup and coalescence kernels using PBM for simulating bubbly flows in nuclear installations.