Prediction of Mixing Time for Miscible Liquids by CFD Simulation in Semi-Batch and Batch Reactors

Abstract

For a quantitative description of the measured dynamic mixing behavior of ethanol and glycerol, a computational fluid dynamics (CFD) simulation is carried out by using the ANSYS CFX-10 tool. An unstructured mesh with tetrahedral cells is generated by using ANSYS ICEM CFD 5.1. The newly modified algebraic slip model (MASM) which includes the ethanol droplets break-up as a function of time dp(t) by using a validated step function gives the real mixing behavior, i.e., viscosity as a function of time ηm(t) and mixing times (tm) in good agreement with the experimental results in semi-batch reactor (SBR) at different dosage times and in batch reactor (BR) at a total liquid height of 0.14 m. The modified model proposed in present paper which is based on the algebraic slip model (ASM) gives results closer to experimental results than its original model and the transport model (TRM). The prolongation of the mixing time by a factor of 1.5 caused by the pan cake effect is predicted by the MASM. The flow velocity and mixture viscosity fields of ethanol/glycerol as a function of time are calculated in a 3D BR.