Modelling the sublimation of dry ice

UPDATE: I previously posted about modeling the sublimation of dry ice, and I am now working on automating the process by introducing water into the tank through a perforated pipe to enhance sublimation. However, I am encountering the following error:

"Nonlinear solver: failed to converge, residual norm too large."

I am unsure how to resolve this issue and would appreciate any guidance on how to correct it.

[Yifeng Tang]

Hi @Kyle,

I couldn't run your model as it's missing the parameter definition. But by visual inspection, I believe you'll at least need a pipe or flow resistance between the two tanks. These ports from the tank will have the pressure inside the tank, and the model in its current form is forcing the pressure of the liquid to be the same. Tank (TL) is set up to be at atmosphere, and can be in conflict with the gas pressure in the Tank (G-TL).

[Kyle]

Hello @Yifeng Tang,

I have uploaded an updated version of the file with the missing parameters included. I also added a restriction and a pipe to the model, which helped it run for a slightly longer duration. However, I am still encountering the same issue where the water level in the tanks drops below the height of the inlets.

I kept the Tank (TL) pressure specification at atmospheric pressure since I am essentially modeling a bucket filled with water from which the pump can draw.

Let me know if you have any suggestions on how to address this issue. Thanks for your time!

[Yifeng Tang]

Quick fix: add a reservoir to the B port of the check valve.

The model will still run out of water (level below inlet). This is because CO2 is being added to the Tank, so the air pressure increases. The higher pressure will push the water out, into the atmospheric tank. Unless the pump adds enough water to offset that, you'll run out of water no matter what.

I don't know how to fix this in the model, because I don't know what the actual system is like. Does the CO2/air pressure increase in the actual system? Does that pressure push water out? How in real life the water is kept at a certain level?

Answer 1

[Yifeng Tang]

Hi @Kyle,

Interesting problem.

I would approach it from the angle of convervation of energy and mass.

Assuming the dry ice stays at a constant temperature, say 194.7 K, I can measure the heat flow into the dry ice mass. From that, I can use the PS domain to calculate melting rate, use a PS integrator to keep track of the total dry ice mass (set initial mass here). The dry ice mass, assuming perfect sphere, can be used to find a heat tranfer area, which can be fed to the convective heat transfer block after enabling the variable convection option. The melting rate will also provide the amount of CO2 gas to be released into the tank. See below and the attached model.

There are much details left out and some parameters I made up. But hopefully this shows my thought process.

[Kyle]

Thank you so much! This problem has been racking my brain for weeks! I'm so grateful for your help