Numerical Simulation on Enhanced Heat Transfer and Flow Characteristics in Direct-Contact Heat Exchanger: A Novel Kenics Static Mixer

Abstract

In this paper, a novel Kenics static mixer applied in a direct-contact heat exchanger (DCHE) was proposed in order to enhance the heat transfer efficiency. The computational fluid dynamics (CFD) simulation method was adopted to investigate the effect of the continuous phase and dispersed phase on direct-contact heat transfer (DCHT) in the Kenics static mixer. The perforation index (PI) was introduced to depict the performance of the Kenics static mixer, and the effect of different numbers of openings at three initial heat transfer temperature differences (at the inlet of the continuous and dispersed phases) was studied. The simulation results showed that under the same working conditions, a larger initial temperature difference would result in greater differences in the fluid uniformity index (UI), turbulence intensity, and time evolution of a gaseous working substance. The increase of hole numbers and decrease of hole diameters can optimize the DCHT. Under three initial temperature differences, the heat transfer efficiency for the 6-hole and 9-hole Kenics DCHEs was about 20% higher than the Kenics DCHE without holes.