Problem with CHT on a cooling device

rideway · February 6, 2012, 09:32

Hello everybody.

First of all, saying that this forum is great. I have been using it for weeks to get started into CFX. Now im doing my first project with it and i am already having trouble.

System is a simple cooling water pipe with several cupper pipes across it who deliver heat (lets say 1000w for the sake of the problem). I tried to follow the CFX-5 tutorial "Conjugate Heat Transfer in a Heating Coil" but it doesnt work. The hot pipes get inifinitely warm (10 million Celsius degrees!!) and cooling water doesnt change temperature.

I applied the 1000w heat to the subdomain, like in the tutorial, but when I tried applying this heat to the fluid walls in contact with the hot pipes it worked! But the thing is that I want to know which ΔT there is between cooling and hot pipes, so I need to know where my mistake is.

Can anyone give me a hint to solve this problem? Connectivity problems? Bad modelling?

Thank you very very very much!!!
Regards

ghorrocks · February 6, 2012, 20:12

Sounds like you did not apply the interface between the solid and fluid domains.

rideway · February 7, 2012, 04:46

Thanks a lot, you are right. The thing is that i still dont know why in the tutorial that Interface is not being defined... Anyway, it works perfectly!
Thanks Glenn

ghorrocks · February 7, 2012, 17:18

Because the interface is automatically detected from the two coincident faces. For some reason your faces were not detected as coincident, or you turned this checking off.

February 6, 2012, 09:32	Problem with CHT on a cooling device	#1
rideway New Member Anonymous Join Date: Feb 2012 Location: Germany Posts: 13 Rep Power: 14	Hello everybody. First of all, saying that this forum is great. I have been using it for weeks to get started into CFX. Now im doing my first project with it and i am already having trouble. System is a simple cooling water pipe with several cupper pipes across it who deliver heat (lets say 1000w for the sake of the problem). I tried to follow the CFX-5 tutorial "Conjugate Heat Transfer in a Heating Coil" but it doesnt work. The hot pipes get inifinitely warm (10 million Celsius degrees!!) and cooling water doesnt change temperature. I applied the 1000w heat to the subdomain, like in the tutorial, but when I tried applying this heat to the fluid walls in contact with the hot pipes it worked! But the thing is that I want to know which ΔT there is between cooling and hot pipes, so I need to know where my mistake is. Can anyone give me a hint to solve this problem? Connectivity problems? Bad modelling? Thank you very very very much!!! Regards

February 6, 2012, 20:12		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Sounds like you did not apply the interface between the solid and fluid domains. rideway likes this.

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February 7, 2012, 04:46		#3
rideway New Member Anonymous Join Date: Feb 2012 Location: Germany Posts: 13 Rep Power: 14	Thanks a lot, you are right. The thing is that i still dont know why in the tutorial that Interface is not being defined... Anyway, it works perfectly! Thanks Glenn

February 7, 2012, 17:18		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Because the interface is automatically detected from the two coincident faces. For some reason your faces were not detected as coincident, or you turned this checking off.