Numerical Study Of The Flow And Heat-transfer Of Falling Film Evaporation In A Vertical Wavy Wall Tube

In this paper, in order to describe the corrugated tube falling film evaporation process involved in multi-scale flow and heat transfer phenomena ,then accurate prediction heat transfer efficiency, we preliminary study of some questions that are the local micro-flow, the mechanism of gas-liquid and the macroscopic gas-liquid distribution in the corrugated tube falling film evaporation process.This paper use VOF method to set up a two-dimensional gas - liquid two-phase stratified flow in CFD model and bring forward two important momentum source term that affect the flow of liquid film: surface tension and interface shear stress. According to simulation results,we discussed the parameters such as the wall structure and the physical properties of liquid-phase affect the liquid film flow. Simulation results show enhancing the interface fluctuations (using corrugated wall structure), can effectively enhance the effect of falling film heat transfer. At the same time, analyzing swirl near the wall liquid film formation mechanism, discussing influence of the swirl on the liquid film flow and heat transfer, set up multi-scale correlation calculating heat transfer model. Considing the liquid flow, heat transfer temperature difference, evaporation temperature, liquid viscosity and other parameters on the heat transfer effect, according to simulation results give a corrugated tube falling film evaporator of the reference operation range, fitting a mathematical calculation and bring forward a viscosity correction factor to make simulation results closer to experimental data.In this paper, the method will probably only set up with giving gas-liquid parameters and wall structure,then more accurate estimates the corrugated tube falling film evaporation of the heat transfer efficiency. So, provides a method and means to desig structural of evaporation equipment, and process optimization.