Can somebody please guide me for a CFD simulation in Ansys Fluent for the following case?
The case is simple with hot pressurized oil running through a steel pipe which itself (the pipe) is submersed in a cooling tank containing water at normal atmospheric conditions .
The hot oil flow in turbulent with temperature above saturation temperature of the outside (cooling) water. The flow at inlet is pressurized and their is no boiling inside the tube.
Thank You.
https://www.sciencedirect.com/search?qs=Water%20cooled%20Heat%20exchanger&show=25&sortBy=relevance
But there will most likely be wall boiling on the water side of the tube, in particular because the oil temperature is above saturation temperature of the water and because the oil heat capacity is larger than that of water. A wall boiling model would be necessary to be applied on the water side of the tube and CHT has to be applied for the tube material, so that the CFD simulation can account for the heat conduction through the tube material (oil --> tube material --> boiling or convectively heated water). CFX has all ingredients to setup such a flow simulation without the need of customization.
Thomas Frank , Sir Can you please elaborate more on this part: ' (oil --> tube material --> boiling or convectively heated water) ' ?
I have defined four different materials- steel for tube, water vapor, water liquid and the oil.
However, the main problem is, I don't know how to assign these materials to the respective cell zones through Cell Zones Condition panel.
Ok. Essentially your simulation needs to consist of three cell zones - 1 flow domain for the oil flow inside the tube, 1 solid zone for the heat conduction from the oil to the water side of the tube through the steel material (so the space of the tube occupied by the steel material needs to be meshed as well and the conjugate heat transfer problem / thermal energy equation needs to be solved in this domain), 1 flow domain for the water flow in the outer surrounding of the steel tube.
For the water flow I would suggest to use IAPWS IF97 water/steam properties with a defined homogeneous binary mixture. In a first modeling setup for the water/steam flow a bubbly flow can be assumed with a fixed set steam bubble diameter of e.g. 0.1mm and using the thermal phase change model. But if phase change of the water on the outer side of tube really occurs, i.e. if the water boils due to the heat transfer from the oil flow, than this is a wall boiling process and simple thermal phase change model will predict the onset of boiling too late. In this case the wall modeling needs to be enhanced by a wall boiling model on the outside of the tube.
Bonjour;
oui mais donner moi une figure de domaine qui tua etudier
Merci
Dear Dr. Thomas Frank ,
IAPWSIF97 is the key point here.
So would you suggest me Ansys CFX insead of Ansys Fluent to incorporate
IAPWSIF97?
@ Soumitra Vadnerkar : Yes, for your complex heat exchanger project I would recommend you the use of ANSYS CFX instead of Fluent. IAPWS data are readily available and the boiling / phase change models in ANSYS CFX are much more reliable and better validated in comparison to Fluent (where the implementation of phase change and wall boiling gives reason to some doubts and where convergence of the solver for complex multiphase flow applications is frequently a larger challenge).
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