Inrow cooling system Data Center

[adhemartiya]

hi. I am doing CFD simulation for In-row cooling data center. the CRAC has 5000 m3/h with T supply 20 C and the heat per cabinet is 3kw and ups 1 kw. I set the cabinet as internal fan with 1200 me/h of flowrate. the problem is when I set the gravity to earth 0,0,0 the cool aisle has a diffrent temp so the CRAC can not flow out the cool air to all space of cool aisle. but when I set the gravity to 0,0,-1 the velocity vector show like the flow is absorbed by the wall even I set the iteration more than 1000. I am a beginner of this. please help me or explain to me. that's very helping . thanks a lot

[karol.suchon]

Hello, please attach the simulation file in zip format, I will look into it.
BR
Karol

[adhemartiya]

hi. the files is too large so I upload in this link. https://drive.google.com/drive/folders/10_Ulinwp3PTv0OwnAz6StG8asNiprrhU?usp=sharing

Thank you

[adhemartiya]

the first trial, I did not put the boundary condition of volume flowrate. because the result is not good enough so I tried to put. but it's still same

[karol.suchon · Accepted solution]

The issue here is connected to the lack of the pressure field( it is equal to 0 at every place), without it the velocity could not e calculated, and that is why you get that weird plot. Probably the volume flow rate did not match, so the heat exchanger pump had more flow in the region than the internal fans took out. the temperature field is generated by pure conduction in that situation.
Please look into the tutorial, and compute the proper balance between the fans./heat exchanger and if that does not help, create some air gap between the fans and the solid body.
BR
Karol

[adhemartiya]

I just follow the specification of CRAC from their manual book

[adhemartiya]

So, for the flowrate, that means I need to reduce the flowrate cabinet and increase the crac flowrate? I am sorry. I just begin this case so i am still learning

[karol.suchon · Accepted solution]

Ok, I will try to give you a better explanation.
We have outside and inside chambers. Internal Fans pump air from the inside chamber to the outside. There are 18 fan bodies, and each has 1200 m3/h so it gives us 21600 m3/h.
You have 4 air conditioners, which each has 5000 m3/h so, in summary, it gives us 20000 m3/h. the values do not match so we are not able to get the results, which generates the problem with the pressure field and velocity distribution.
There are a few things which we could do, I think that the most important one could determine the volume flow rate in the pressure difference function for the fans. In reality, not all CRAC unit has the same value of the air which goes thru it and not all of them has exactly the same temperature, the value depends on the pressure difference. 
I you have fixed VFR and heat generation you could easily get the temperature value from the excel file. 
BR
Karol

[adhemartiya]

Thanks a lot karol. I will try to apply it first.