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Old   March 17, 2003, 17:13
Default Can CFD do this?
  #1
Srinivas Kothy
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Can CFD simulate the refrigerant flow in a heat pump set up? The refrigerant flows through evaporator and condenser thus phase changes.
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Old   March 18, 2003, 03:18
Default Re: Can CFD do this?
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Helge
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1) In general I would say yes. 2) But I suggest it it is very hard to obtain good results for predictive purposes. 3) The flow is a two-pahse one with phase change. So you need a code which can handle this type of flow. A code with an Euler/Euler multiphase model plus a phase change model can handle such flows. 4) The problem is the interfacial shear which limits the maximum heat flux a heat pipe can transfer. At a certain heat flux level the momentum transfered from the gas phase to the liquid phase is high enough to hinder the liquid flowing from the condenser to the evaporator. And this operation point is very distinct. 5) In an Euler/Euler model momentum exchange is handled via equations which in general are empirical ones. You can choose between several ones which are valid for individual flow types. 6) That rises the problem of what equation to choose and the validity of it for your certain geometry and fluid. I suppose that there is little material in literature for it. You may search for the key word flooding. 7) A solution might be to adapt the empirical coefficients in the momentum exchange equation so that your simulation follows your experimental data. But I suppose if your coefficients fit for one geometry and fluid it will fail for a slightly different geometry. 8) Conclusion: In general yes, in particular no or with lots of difficult problems to solve.
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Old   March 18, 2003, 06:31
Default Re: Can CFD do this?
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Boris
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Helge,

Please give your comments on Heat Pump not heat Pipe. Thanks.
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Old   March 18, 2003, 08:12
Default Re: Can CFD do this?
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Helge
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O.K. I misunderstood or did not read the first question carefully.

1) In general I think that you can simulate that flow 2) It only depends on the boiling and condensation models you have 3) May it is a good idea to not simulate the whole cycle in 3D but to split it into evaporator, condenser and piping. It is also possible to connect evaporator and condenser via boundary conditions to get rid of the piping which may not be very interesting 4) If you are not interested in flow details you may set up the whole cycle in a 1D model in which the functionality of every component is modeled
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Old   March 18, 2003, 10:35
Default Helge...Can CFD-ACE do it?
  #5
Srinivas Kothy
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Hi Thanks a lot for your response. Can CFD-ACE do it? Do we have the option of selecting various refrigerants in there?
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Old   March 19, 2003, 08:24
Default Re: Helge...Can CFD-ACE do it?
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Helge
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I do not know what CFD-ACE is capable of
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