## Fluids

#### Evaporation and the heat transfer trough the metal

• Katarína Pauerova
Subscriber

Hello everyone,

I am a self-learner in ansys. I would like to know if someone can recommend a material or any help of how to simulate heat transfer in metal, which is placed in the quartz tube with a high temperature and the subsequent evaporation of this metal. I ve tried for several times to set up conditions for evaporation but still did not get the wanted effect. I totally do not know if I shall use a function of multiphase, melting-solidification or species transport and how to set up all the function to do it right. The pic of the geometry is below the text.

Can some one give me of any recommendation, please?

• C N
Ansys Employee

Hello,

Could you explain in detail on what parameter or effect in terms of which quantity you are interested in?

Accordindly I can suggest what model you can use and also send you some videos and links for best practices to you.

Thanks

Chaitanya Natraj

• Katarína Pauerova
Subscriber

I will try to explain my problem in detail.

I ve got a quartz tube (inner diameter 20 mm, wall thickness 2 mm) placed in the furnace. Furnace is heated up at the temperature of 900 degrees. Into this tube a zinc rectangle (dimensions 25x10x5 mm) is being placed. All the tube is being blown by argon gas with flow rate of 150 mL/min. The argon and zinc temperature is ambient.

So, in this conditions I ve tried to simulate evaporation of zinc with respect to temperature, argon flow direction, velocity, laminar(turbulent) flow.

Within geometry, the quartz tube is of lenght 400 mm. This tube is placed all in the furnace, so the tube is heated at constant rate, the zinc heats up and changes its shape into a  rounded rectangle. As it is heatep up it starts to evaporate.

At this conditions of flow, it should be a laminar flow, but with respect to the zinc object, in its closed vicinity a turbulant flow should occur.

I used a fluid flow (fluent). I ve tried to set up conditions as follows:

gravity, transient state

energy on

I wasnt sure if I should use melting/solidification function or species transport.

I ve tried to use function of multiphase - volume of fluid, 3 eulerian phases, formulation implicit,type sharp, no other changes.

3 phases: 1 phase - argon, 2 phase - liquid zinc, 3 phase- vapour zinc

Number of heat mass transfer mechanism - 1, liquid to solid, mechanism evaporation/condensation, lee function - no changes, only the temperature to 900 celsius.

Inlet marked as inlet velocity, argon velocity 2.973e-6, temperature ambient

outlet marked as outlet pressure

wall - set up temperature at 900 degrees celsius

zinc object - not sure if to marked as inlet zinc with specific velocity or set up other way.

The features of zinc phases I marked as follow:

liquid zinc - density 6620 kg/m3, Cp 387 J/kg.K, thermal conductivity 164 W/m.K, viscosity 0.000373 kg/m.s

vapour zinc - density trough the polynomial function or just signed density 2.9 kg/m3, Cp 208 J/kg.K, thermal conductivity 0.024 W/m.K, viscosity 2.03e-5 kg/m.s.

I ve tried to watch a plenty of videos, but i was never successfull to set up simulation according my needs.

Thank you very much for your help in advance. I  really appreciate any kind of help.

• Rob
Ansys Employee

It'll be two phases, sort of, and species mixture. Zinc vapour & argon are the gas phase (easy bit). For the solid>liquid part it's a bit more complex. A "solid" zone in Fluent can't melt, but the solidification & melting model links to VOF so evaporation may be more difficult. Have a look at phase change and VOF to see why it's complicated.