[shields]

Hi all, i've been struggling with this masters project for a few months now and have only really being getting into it now, so any help would be appreciated as i'm quite new to CFD analysis.

the background to the problem is that I'm trying to analyse heat transfer between two fluids (water) which are being carried inside separate pipes. one fluid hotter than the other. Its basically a heat exchanger prototype. The attached picture is a cross section of the proposal.

cfd.jpg

I want to measure how much of the heat energy will be transfer from the red hot water via conduction through the surroundings of the small copper pipe into the the cold blue water.

I will have to use a VOF analysis for the red fluid but this i not of immediate concern.

I need advice on how to model the geometry initially in either design modeler or gambit, with a view to either using a shell conduction technique of conjugate heat transfer as i can get neither of them to work correctly after much effort.

I've modeled the setup in various ways using design modeler but i don't no how to bring these to together with a heat transfer model for conduction in fluent. I will attach photos of the various geometries I've completed in design modeler.

pipe1.jpg

pipe2.JPG

In the first i tries to model 3 bodies, the large hot fluid, the small copper pipe wall and the small cold fluid. with a view to conjugate heat transfer model.

in the second i model the large fluid and the smaller fluid. wit a view to using some sort of shell conduction the the walls are quite thin.

I cant get either to work correctly in fluent. I'd like someone else plan of attack on this problem as i think its quite simple i'm just trying to solve it the wrong way i think.

If any can point me to a better way of doing it please i'd be delighted.

Thanks Again.

[kola77]

copy/paste from my thread:

Thanks for your help, but I have managed to solve the problem by now. The solution was to mesh the solid domain using the ansys mechanical method, and the fluid domain using any other method (tetrahedral, even the outdated cfx-mesh method, etc) and joining them later on.

As for your problem, I am using CFX to run the analysis. I don't know if this is really an option for you, but it shouldn't be much more different than it is with FLUENT.

Anyway, here's how it goes:
First I have created three domains, one for the solid, and two for the fluids, hot and cold obviously. As you could see from my files, I have prepared some regions in advance, especially pay attention to the interface regions, which, later on, are used to connect both sides of the pipe wall with corresponding fluids. The results I have obtained using this strategy seem promising and realistic.

Unfortunately I have no idea how to use FLUENT, since my university only supplies me with a CFX license, but I imagine it shouldn't be much of a problem.

Thanks for the help once again, and I hope my thoughts on your problem help you at least a bit!
Cheers!

[shields]

Thats good that you got a solution. Yes i'm trying to connect the fluid and solids regions. this is where I am having difficulty. My problems geometry is simpler than yours as I do not have the narrow inlet and outlet.

Would you be able to upload your cfx files, as I should be able to compare your methods then and possibly transfer them to fluent. I have a licence for CFX but I have not used it before, I should be able to follow the basics.

Thanks in advance, if this is not possible, no worries.

[kola77]

Sure, not a problem at all, the files are about 100MB though and this will take a completely random amount of time, depending on the mood of Portuguese internet. Check this thread in about an hour or so...

[shields]

Portuguese internet is similar to the Irish internet...


Thanks.

[kola77]

Worked faster than expected, here it is: https://rapidshare.com/files/194554856/pizdarija.rar

Please note that the files attached are not an actual heat exchanger, only a bullshit example (which is even suggested by the filename in my native language hehe) to test if my new meshing method and domain connection works. I couldn't be bothered with the actual run yet.

Anyway, what you should pay attention to in CFX-Pre (marked "setup" in the workbench) are the tabs Solid models and Fluid models of each domain where I have stated if I want to compute only thermal energy or total energy, the latter obviously applying only to fluid domains. Also important are the interfaces. If you have any additional questions feel free to post here and I'll try to help to the best of my abilities.

[shields]

Thanks I look forward to working through it.

[mithun80]

Hi Kola77,

CAn you please reattach the files?

I also need some help regarding the same.

Thanks
Mithun

Originally Posted by kola77

Worked faster than expected, here it is: https://rapidshare.com/files/194554856/pizdarija.rar

Please note that the files attached are not an actual heat exchanger, only a bullshit example (which is even suggested by the filename in my native language hehe) to test if my new meshing method and domain connection works. I couldn't be bothered with the actual run yet.

Anyway, what you should pay attention to in CFX-Pre (marked "setup" in the workbench) are the tabs Solid models and Fluid models of each domain where I have stated if I want to compute only thermal energy or total energy, the latter obviously applying only to fluid domains. Also important are the interfaces. If you have any additional questions feel free to post here and I'll try to help to the best of my abilities.

[kola77]

Sure, here you go. The files are not the same, since I've deleted them a while ago, but the same logic applies here and you should be able to work your way through your problem using these.
http://www.megaupload.com/?d=IKZT9MUK

[mithun80]

Thank you very much my friend.. It was really nice of you.

[mithun80]

Hi,

I was wondering if any of you ever did an ansys workbench simulation on compression springs. I was trying to simulate the spring compression, but the spring always interferes with both the contact plates during simulation. I know this could be done as I have seen the animation of the spring in youtube when it compresses. But I am just not able to figure it out. Any help is really appreciated.

Thank you
Mithun

[krishnateja]

hi shields

even i've been facing the same problem of heat transfer. my geometry is similar to urs . can you please upload you solved fluent files which would be helpful for me in my project plzzzz

[Turtle]

As i also don't know how to couple the interfaces correctly (for a similar heat exchange-conduction problem), I would also like to see the file!
It would be great if you could upload it again since megaupload is blocked nowadays.

greetings
Turtle

[jobito_2012]

Originally Posted by kola77

Worked faster than expected, here it is: https://rapidshare.com/files/194554856/pizdarija.rar

Please note that the files attached are not an actual heat exchanger, only a bullshit example (which is even suggested by the filename in my native language hehe) to test if my new meshing method and domain connection works. I couldn't be bothered with the actual run yet.

Anyway, what you should pay attention to in CFX-Pre (marked "setup" in the workbench) are the tabs Solid models and Fluid models of each domain where I have stated if I want to compute only thermal energy or total energy, the latter obviously applying only to fluid domains. Also important are the interfaces. If you have any additional questions feel free to post here and I'll try to help to the best of my abilities.

Can you please reattach the files?

I also need some help regarding the same, please...thanks a lot!!

[rupjyoti]

Hi kola77
Even i m facing the same problem..and the oulet condition of water is same as inlet water temperature, but steam temperature is decreased..can you plz suggest me how to solve the problem. i m taking 3 regions viz. steam, pipe and water. also how to mesh the solid part differently in meshing? plz help me..i would be very thankful to u..