How difficult is it to model a parrafin wax phase change?
 

Hello,

I'm new to CFD and would like to know how difficult it would be to simulate a heat exchanger with water flow on one side and paraffin wax on the other. I'm about to start my post grad dissertation for which I've chosen to build a latent thermal heat store which will be connected to an air source heat pump in my flat.

It would be extremely advantageous to observe the heat transfer characteristics of different heat exchanger designs, for example shell and tube, flat plate, encapsulated ball etc. before I build it. However I am unsure of how large a task I will be taking on trying to simulate them using openfoam? I have about 2 and a half months before I need to begin building the heat store, I have a bit of programming knowledge through arduino projects (3d printer) and a few friends that would be willing to help me with C++. I have studied basic fluid dynamics (relevant to hydro turbine design) and understand basic thermodynamic fundamentals (entropy, specific heat, enthalpy, thermal conductance etc.). I also have basic 3D CAD skills in autocad and solidworks (plenty to build what I'm thinking of building)

Is it feasible to build 2D or maybe basic 3D models that will give me a better idea of which exchanger design to go for and maybe smaller details such as how far away plates in a plate heat exchanger should be to melt 95% of the wax in a given time etc. ?

Kind Regards,
Jim

Depends mainly on the complexity of your geometry I think.

Thanks for the reply, should be fairly simple geometry so I'm gunna go for it.

I don't suppose you know which solvers would be suited to modelling a phase change in wax?

In the mean time I guess I'll start working through the tutorials. Do you think it would be beneficial to have the newer version of openfoam and paraview? I'm not sure what will be easier, to follow the tutorials with the same version they were written for or to get the newest version and try to piece stuff together from the tutorials?

Cheers

I would get the newest version. Solvers to look at are buoyant?impleFoam and chtMultiRegonFoam. You also want to get to know solidificationMeltingSource of fvOptions. Perhaps you want to write your own code, as the melting source models the phase change as a porous medium, whereas for a wax you may want to tweak viscosity instead.