[shields]

Hi all,

I'm pretty new to Ansys and i'm trying to model fluid flow and heat exchange between two pipes as shown in the attachment.

The large pipe is a plastic pipe - orientated horizontally - partially filled with water ( red ) and the rest of pipe is area. The smaller orange pipe represents a copper pipe fully filled with colder water flowing in the opposite direction to the larger pipe.

I'm having problems creating the geometry correctly. I draw small circel - extrude, draw second larger circle the extrude. The problem is when i try to label the different inlets, i cant label the inlet and outlet for the smaller copper pipe.

I can only label:
Inlet Big Pipe
Outlet Big Pipe
Outter Surface Big Pipe
Outter surface small pipe

I need to be able to input flows for both pipes.

I hope this makes sense. I'm trying to model how much heat cant be taken by conduction into the smaller copper pipe from the warm waster water in the larger pipe.

Thanks in advance
Peter


Untitled.jpg

2.jpg

[PSYMN]

As is often the case, you first need to consider what you are modeling...

In your first image, you have 4 zones. The outer shell (which you didn't model at all), the outer flow volume (your big extruded circle), the small pipe wall (Again, not modeled) and your inner flow.

Do you need that small pipe wall? If so, model it (I probably would have).

Assuming you didn't model it on purpose, then your biggest problem is that you used the small circle only to "Cut Material" from the first pipe. You need to follow that with a 3rd extrusion (second on the small circle sketch). But since you don't want it to immediately join with the first pipe, you must choose the option for "Add Frozen".

In my screen shot, you can see that sketch1 is the big circle, Extrude1 makes the big pipe. Then Sketch2 is the small circle. Extrude 2 cuts the hole out of the big pipe. Then Extrude3 also uses sketch2, but with "Add Frozen" to put in the second part. In this case, it thinks the outer pipe is solid, but you can always change that by clicking on the part...

Shields_Pipes.jpg

There are other ways you could do it (model the two circles as thin wall pipes and then cap the ends to capture flow volumes, or do boolean subtraction, etc.), I just think this is the easiest. Have fun.

[shields]

Hi,


Thanks very much, yes i agree it is always important to think about your problem before you begin to model it, i got excited. I was getting close to getting it configured last night but I didn't understand the "add frozen" command. Thanks.

I am trying to model model the heat transfer between the two liquids in the pipes, hot fluid from large pipe which will transfer heat enrgy to cold fluid in small pipe. This will occur by conduction through the wall of the small pipe. I do not fully understand what you mean when you say i'm not moddeling the wall of the small pipe. How do I do this. I presumed i would be able to model this in Fluent as it usually picks up walls automatically.


I've done this so far.

Pipe10.jpg


Thanks for you advice :-)

[shields]

Hi i see what you mean, the fluent program is only picking up the wall of the large pipe, i need to model the wall of the small pipe as this is the boundary (of my interest) upon which the heat transfer is occuring.

fluent picture.jpg

[PSYMN]

Right, so you could just use a named selection to pic that outer surface of the small pipe and do a zero thickness interface of some sort. Or your could model the thickness of the pipe as a third body, then do conjugate heat transfer between the fluids and the solid pipe...

Did you figure out the "add frozen". In my image, that option is visible in the details panel on the left.

[baba]

Hi,
Iam new to ansys.
i am modelling a heat exchanger problem.
co2 flows inside a pipe and air is in the surrounding environment.
i think i have done the geometry part correctly.
but while using the set up an error comes that 'Model information is not compatible with mesh.'
Please suggest something

[PSYMN]

It means that you are applying cell zone or boundary condition information to a part that doesn't have the right mesh to support it...

I can't tell any more without images or more info...

[baba]

thanks for replying

i started by extruding the pipe.
then for the inside flow region for c02 i did the 'add frozen ' thing as was suggested by you.
then i used named selection to mark the regions which are

1.this one shows the pipe with inside region as add frozen.
my aim was to make co2 enter the inside region while air flows outside

.

2.this one shows that i have taken made the add frozen region to be the auxiliary fluid c02 region and also i did the add frozen thing throughout.i have taken the faces of this region to be the inlet and outlet also.


3. this one shows the region of primary fluid that is air the faces are taken as inlet and outlet.



this one shows the mesh.
i adopted the automatic methid and the grain are coarse.
i also tried with fine but it wont work.



please tell me what to do or if my approach to the problem is correct or not.


Thanks

[baba]

hi

i was simulating a heat exchanger problem in which c02 passes through a pipe and air flows around.
so i enclosed the pipe in air using 'enclosure'.
defined inlets and outlets for primary and auxiliary fluid.
in the solutions part my solution ain't converging and also the mass flow rate at the outlets are coming to be negative.
what is the problem.
what should i do.
please help.



baba

[M_H215]

Hi all,

I'm pretty new to Ansys and i'm trying to model fluid flow in pipe with grooves.

My question is...
How can I create grooves in pipe with design-modeler?

My attached file maybe explain better for you , what I mean.

Thank you

[harry8227]

hi mohammad,

1)you can draw thses grooves in sketching.
2) you can create a body in modelling and then can use the pattern option to copy the grooves.

[M_H215]

Hi all,
Thanks harry
How can i create the grooves in sketching?
And also..
How can i use the pattern option?
Can you explain more it for me?
(I'm a new member of ansys-fluent software)
Thank you

[k.vedprakash]

Hello guys,

i am trying to design a heat pipe in ansys fluent.
temperatures at evaporator and condensor are 50degree and 25 degree respectively.
liquid fillinf ratio is 70%.

so here are the conditions i gave in my simulation.
i chose double precision, transient pressure based solver.

model- multiphase-volume of fluid with energy equation on.

In phase interaction - mass - number of transfer mechanisms - 1
Evaporation-condensation with both 0.1 frequency
and saturation temperature of 320K.
Surface tension of 0.072 n\m with wall Adhesion.

Boundary Conditions - Evaporator as Pressure inlet
Guage pressure: 0
Initial Guage Pressure: 0
Temp: 350K

Condensor as Pressure outlet
Guage pressure: 0
Back flow temperature: 0

Adiabatic as Wall
No slip wall
contact Angle: 70


I am not getting any proper result with these conditions. Rest all are kept default values.

Please Anyone of you guys are familiar with the design, it would be great if you could help me

[mhm_dabbagh]

Hi there,
Actually I'm new in Fluent and was wondering if anyone can help me! Basically, I'm trying to model air-gap inside a wall and mesh it; and does not know how to do it! My model is attached. Fluent (19.1) Just shows me the solid walls in geometry and I'm not sure how to define and mesh air existing inside the wall, as natural convection inside the wall really matters to me.

I really appreciate your help.

Sincerely,