Numerical Simulation of Flow Field and Flow State Division in Thin-Film Evaporators

Abstract

The flow field and flow state of thin-film evaporators are complex, and it is significant to effectively divide and quantify the flow field and flow state, as well as to study the internal flow field distribution and material mixing characteristics to improve the efficiency of thin-film evaporators. By using computational fluid dynamics(CFD) numerical simulation, the distribution pattern of the highviscosity fluid flow field in the thin-film evaporators was obtained. It was found that the staggered interrupted blades could greatly promote material mixing and transportation, and impact the film formation of high-viscosity materials on the evaporator wall. Furthermore, a flow field state recognition method based on radial volume fraction statistics was proposed, and could quantitatively describe the internal flow field of thin-film evaporators. The method divides the high-viscosity materials in the thin-film evaporators into three flow states, the liquid film state, the exchange state and the liquid mass state. The three states of materials could be quantitatively described. The results show that the materials in the exchange state can connect the liquid film and the liquid mass, complete the material mixing and exchange, renew the liquid film, and maintain continuous and efficient liquid film evaporation.

Keywords

flow state division / material mixing / thin-film evaporator / numerical simulation

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Funding

National Natural Science Foundation of China(51905089)

National Natural Science Foundation of China(52075093)

Special Fund for Basic Research and Operating Costs of Central Colleges and Universities, China(22320D-31)

Open Fund for National Key Laboratory of Tribology of Tsinghua University, China(SKLTKF20B05)