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| Thread ID: 65503 | 2006-01-20 06:36:00 | Case Fan - suck or blow? | Tony (4941) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 422794 | 2006-01-20 22:33:00 | This thread has got me thinking, are my fans ok?I would have thought your main problem would be making sure everything was properly bolted down to stop it blowing away in the gale. :) | Tony (4941) | ||
| 422795 | 2006-01-20 22:44:00 | I would have thought your main problem would be making sure everything was properly bolted down to stop it blowing away in the gale. :):lol: I made sure everyting was screwed in tight enough when I built it :) | The_End_Of_Reality (334) | ||
| 422796 | 2006-01-20 23:25:00 | Have you considered a top fan between the PSU and cdrom drives that sucks up and out?? might as well get as many fans as you can! :lol: how did you get 4 fans in the front??? I sure would like to know what case you used |
Agent_24 (57) | ||
| 422797 | 2006-01-20 23:34:00 | edited by me - have PM'd :cool: | Jester (13) | ||
| 422798 | 2006-01-21 00:15:00 | That reminds me of 2 400w PSU I bought from DSE. The 2 fans on them were both sucking in air. Took em back and got a refund. Trevor :) But that's how the manufacturer designed it. They make power supplies, not computers. They naturally arrange the air flow so the PSU gets the first go at the cool air from outside the case. Why should it bother with air that's been past a few KW of CPO and video cards? :D |
Graham L (2) | ||
| 422799 | 2006-01-21 00:40:00 | You should have laminair flow through the case by allowing air to be inserted (blowing in) through the front of the case over the hdds, and then another fan educting ( blowing out) of the case from the rear. I'm going to do a Graham and be pedantic. Laminar flow is the last thing you want or will get inside a case. The air flow will be turbulent, and the convective heat transfer coefficient in turbulent flow is higher than for laminar flow (streamline viscous flow) |
Terry Porritt (14) | ||
| 422800 | 2006-01-21 05:44:00 | I'm going to do a Graham and be pedantic . Laminar flow is the last thing you want or will get inside a case . The air flow will be turbulent, and the convective heat transfer coefficient in turbulent flow is higher than for laminar flow (streamline viscous flow) Uh . . . . not! Laminaire flow is actually just air flow that is zoned . It makes little sense to send heated air all over the case after it has picked up btu's on the HDDS . Turbulence is good if true molecular impact and expansive values are ignored, but it impedes the heat removal if the air arriving at . . . say . . . . . the CHA is already much above ambient because it took on the heat from a hot device like the HDDS . Enermax worked out a really fine case with a tunnel effect that started at the front intake fans, sent the air over/thru the HDDS and then proceeded to keep the flow straight out the back of the case via exhaust fans . The idea was simply intelligent . The rest of the case got it's air from a side fan that sent non-preheated air to the motherboard and the residual of that went out the PSU's eductors . They advertised that the cooling effect was at least 20%-25% better than just allowing the air to flop around inside the case and get battered about striking ribbon cables, expansion cards and other objects thereby generating dead air pockets and slow flow over critical components . I tend to believe that those numbers were pretty close to truth . . . we had to also make large gen-sets run in very cramped quarters in a boiler room in which I worked . At first they used just "generally indirect" turbulated air to cool the very close areas . The manifolds and the fields and generator cases ran very hot and would blister the dielectrics all the time . We replaced many sets of windings yearly . After switching to a more "tunnel-ram" effect and keeping the manifolds airflow seperated from the general cooling airflow, the gen-sets never had any dielectric failures again . I vote for laminaire flow . . . I've seen it work much better than sloppy and non-directed air . True, with the smallness of the internals of the towers and the obstructions inside, laminaire flow is difficult to achieve . Any attempts to keep pre-heated air from being used to cool another hot object is a good idea . Heated air has less effectiveness in removing heat from an object on a parabolic scale as the latent heat level rises; much more air (higher flow-rates) will become less effective as the temperature increases exponentially . At some point, no matter how fast the airflow is, it will not be able to remove enough heat to assist in cooling at all, turbulated or laminaire . Stratification of the airmass will increase to where the impact and transfer of energy via molecular conduction will cease as the heat load coefficient is reached . We could go into thermodynamics of superheating here, but that is too OT for a computer tower in someone's home/office . |
SurferJoe46 (51) | ||
| 422801 | 2006-01-21 05:52:00 | Sorry, but uh.... yes. Laminar flow means streamline flow, but the air from a typical 120mm fan is turbulent, the Reynolds number based on average air speed is about 30,000, that is, about 15 times that for the onset of turbulence. If the flow was laminar there would be hardly any flow at all. It's basic physics. |
Terry Porritt (14) | ||
| 422802 | 2006-01-21 08:57:00 | Before I go to bed, I'll just add I fully agree with you Joe about directing the air flow intelligently as per Enermax example, but being pedantic as I said originally, that flow will be turbulent not laminar :) You can have a turbulent directed flow, as for example turbulent flow in a duct. |
Terry Porritt (14) | ||
| 422803 | 2006-01-22 20:25:00 | This thread has got me thinking, are my fans ok? 4 blowing in from the front (added after built) 1 blowing in from the side window (standard) 2 sucking out from the back (standard) 2 PSU sucking out (standard) 1 CPU (side window blows directly on to it) (standard) 1 GPU (standard), most likely going to add a dual fan PCI card to blow more onto GPU (add after build) 1 Northbridge fan (standard) A total of 12 fans :lol: How does all that look? Thanks all :), Thanks Tony for letting me use your thread :) I wondered why my lights have dimmed ;) |
dolby digital (5073) | ||
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