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Need help to simulate R22 Evaporation-Condensation Simulation...

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Old   June 29, 2012, 00:48
Default Need help to simulate R22 Evaporation-Condensation Simulation...
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Niaz Ali Ahmed
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Hello everyone. I am using Star-CCM+ v 7.02.011 for simulating Condenser of a Refrigration Unit.

Problem Statement :

Make superheated R22 Gas enter the pipe (10m length and .00615m diameter) and observe a drop of 8C temperature drop along with phase change from R22 Gas to R22 Fluid

Inputs Used :

Material Used :
I have created a custom .mdb( Material Database File ), containing density and specific heat as polynomial data from REFPROP Database for both R22 Gas and R22 Liquid.

Boundary Condition :
Negative Heat Flux applied at wall of pipe to make the fluid loose the enthalpy. Using corelation it is around 6.4W spread at a surface area of approximately 0.19m2.

Model for Evaporation/Condensation:

VOF Phase Interaction Model along with Evaporation/Condensation model.

Simulation

The simulation runs and converges easily and residuals show no wiggles and converges easily.

Problem Faced

The phase change doesnt happen, and the temperature remains constant throughout the domain.

I have gradually tried to apply more negative heat flux at the walls, but no luck.

Note : I have checked the Solver Frozen node in energy equation but the solver is enabled. Still have trouble making the termperature drop in fluid.

"Please help me in solving the temperature drop and phase change problem."
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Old   July 16, 2012, 08:37
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Aga
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Can you use the model of Vof with evaporation and condersation at ver.7.02?
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Old   July 16, 2012, 08:48
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Ryne Whitehill
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Don't think this will solve the problem at hand, but make sure your properties transferred up from your material. I.e. go up to your Physics Continua, expand Models, expand Gas, and then your entry. Make sure the specific heat is set to same values you set below. I was having this issue recently
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Old   July 16, 2012, 10:04
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I try to use this model, but disaply error message.
The message is
ConditionManager: get(T): condition not found: class peciesSpecification.
Who could help me to solve this problem?
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Old   July 24, 2012, 01:00
Default Evaporation-Condensation
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Niaz Ali Ahmed
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@rwryne

I have noticed that problem here too. I have been doing a lot of work since I posted my query. I have defined two R22 phases now.

Density is now entered as a field function expressed as a function of Pressure and Temperature.

Specific Heat as Polynomial in T.

Saturation Pressure also as a Polynomial in T.

Enthalpy is set to specific heat method.

Sorted :

Density is as indicated in p-h diagram

Enthalpy is also accurate.

To be sorted :

Single phase simulation runs fine, but multiphase problem show divide by zero. Its probably due to some junk data or curve overlap of some field function.


@Icweng :

Yeah Evaporation-Condensation is available in 7.02.xxx

"ConditionManager: get(T): condition not found: class peciesSpecification"
Check whether the multiphase physics node has the Energy model selected.

Sometimes I get this error. Only way to sort it out is start a fresh simulation.
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Old   June 24, 2013, 01:39
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Kevin Wang
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Hi, niaz.

I've tried to simulate water vapor condensation outside a tube through CCM+7.02. After I setted the parameters in Evaporation and Condensation model, and run the simulation, an error occured:

SaturationPressure::getMaterialProperty(): property missing

Have you faced with a problem like this? Do you know what's the reason?

Waiting for your response.

Thank you in advance!
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