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thermaltake ducting mod

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March 14, 2003 2:41:59 AM

This is a very interesting idea that I think could work. It's a tube that goes above the hsf and attached is an extra 80x80 fan. Now, this could be cool, and of course it would increase air flow, but wouldn't it be better if the tube connected to one of the case's intake fans, therefore drawing outide air that would be cooler? I remember seeing a product like this but I can't find it again. You could probably make one yourself using that tubing that heat vents are made of, but it'd be a pain in the rear to seal it and make it fit.

If anyone knows of a product like this, please let me know. It could be a great mod! Thanks to all who respond.

<Brendini>
March 14, 2003 4:07:58 AM

It's not an extra fan... it just moves the fan away from the heatsink.

We already decided, in another thread, that it's just a way of separating you from your money.

As for making a duct to connect to a remote fan... don't forget that every bend, corner, and crinkle adds resistence and reduces airflow. It's probably smarter to stay with standard heatsink and fan combos and increase the airflow through your case.



--->It ain't better if it don't work<---
March 14, 2003 5:12:21 PM

Don't place 2 fans in serie with eachother as that will mean that the last fan will get lots of front-pressure and the first a lot of back-pressure.

The only time a duct will work is when you make it totally without bends and use cones on the back of the fan to guide the air. It is a pain in the ass designing that and it wont help much... if any.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
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March 15, 2003 5:35:26 AM

Ya is no good... Dell does it to compensate for garbage HSF combos they use... don't bother.. concentrate on good case airflow...

To err is human... to really screw things up you need a computer!
Anonymous
a b K Overclocking
March 18, 2003 12:14:45 AM

"Don't place 2 fans in serie with eachother as that will mean that the last fan will get lots of front-pressure and the first a lot of back-pressure."

I've been imagining that a counter-rotating set of fans in series, with apropriately reshaped fan blades on the one turning in the oddball direction, might have some airflow benefits. I don't believe that a setup like that would necessarily have the problems you mentioned, in fact to me it seems that overall fan efficiency would be increased. The catcher is, I can't find any commercially available fans that could be used this way to test it out.

An opportunity it seems fan companies would be taking advantage of, especially considering what we overclockers might potentially be willing to pay for such a device. Maybe I'm overlooking something...
March 18, 2003 4:00:45 PM

I can't really follow you... but I do know that Delta has special 3-fans-in-one fans.
You can also use 2 fans if the second fan is twice as stron as the first... that way you will compensate for the extra pressure. But if you have any gain with this...

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
Anonymous
a b K Overclocking
March 18, 2003 6:55:44 PM

yes, that was a bit confusing, i see that now.

Basically, I was describing 2 fans in series, where one rotates clockwise the other rotates counterclockwise. It would require one to have fan blades in an opposite pitch than they are on fans sold currently. I this configuration, I am imagining that the two fans would work together to increase efficiency of both fans.
March 18, 2003 8:02:59 PM

Or, at the very minimum, use twice as much power.

2 25cm fans in series will still only move 25cm... you can't get more air out than you put in.


--->It ain't better if it don't work<---
Anonymous
a b K Overclocking
March 18, 2003 9:41:01 PM

Remember: being in series wasn't my only qualifier, the more important part of my qualification that you forgot to mention was the counterrotating fans part.

You said:
"Or, at the very minimum, use twice as much power."

Similar to the half egg idea this is an effort to improve air flow/noise, which by definition would reduce power draw/CFM. If you think about it, a setup like ive described would push/pull the other fan it's proper running direction, so power would be less than with the 2 fans standing alone since each has part of it's work being done by the other. When both fans of this configuration are powered up there is load sharing.

As you can imagine air coming from a fan is not flowing from the fan in a direction parallel to the axis of rotation (which the fan blades spin around). I'm guessing the pattern would be more like a whirlpool effect. With an ideal (non-existent, and perfect) fan the air would flow parallel to the axis of rotation, and the fan blades would not interfere with its path. My belief is that the counter rotating assembly would help to rectify these issues I've pointed out. The issues in this paragraph are the reasons to argue for this fan configuration.

you said:
"2 25cm fans in series will still only move 25cm... you can't get more air out than you put in."

While it is certainly true that you will never get more out than goes in, you could make each fan push more air by making it operate more efficiently. If something you are doing by putting them in series is allowing them to run more efficiently, then you WILL get increased airflow through both of them. I'm not even saying that putting 2 REGULAR fans in series will incrwease airflow, but my SPECIAL set of fans would (if I am correct).

I just wish I had the money to do a prototype so I could prove/disprove my hypothesis.
March 18, 2003 10:34:56 PM

I still can't see how you'd more than one fan's worth of airflow out of it...

By way of analogy:

In electrical theory (and fact) the current flowing in a series circuit is the same in all parts of the series circuit. 2 resistors in series will have exactly the same current flowing through them. If the resistors are of identical values, they will have the same voltage. If they are of differing values they will have different voltages across them but the same current will flow through each.

In a Parallell circuit the current is the sum of the current in all parts of the circuit. Two parallell resistors will have the same voltage across them. If they are of the same value you will get the same current through each. If they are different values, you get the same voltage across each but different currents through them.

I rather think the fan thing will work the same way... two fans in series, counterrotating or not cannot produce more airflow than the least capable of the two fans. To get double airflow you would have to put the fans side by side (in parallell) and blow them into some kind of Y adaptor.

The other thing is noise... fans emit air in a spiralling pattern that follows the rotation of the blades. Spinning the second fan in a reverse direction would chop rather seriously as it had to reverse the rotation of the air from the first fan and that's going to make a lot of noise.

Still... it would be an interresting experiment...





--->It ain't better if it don't work<---
Anonymous
a b K Overclocking
March 18, 2003 11:35:25 PM

"I still can't see how you'd more than one fan's worth of airflow out of it..."

Same way you might expect to see better airflow by attatching a half egg or ping pong ball: by reducing overall drag.

Since I have no actual proof all I can do at this point is defend my hypothesis with applicable logic. My goal is to find and post link/s which are supporting or denying my claim. At the moment I am not finding anything really applicable.

My logic refuting your last post follows:

1.I never claimed this would double airflow, my only claim is that it could possibly increase the airflow of both fans over and above what they could flow alone (i don't think I mentioned this earlier, but I think the fans should be matched but opposite to optimise the effect).

2.Hydraulic theory tends to be analogous to electrical theory, unfortunately pneumatic theory does notdo as well. Therefore electrons in a electrical circuit act much differently than air molecules in a fan circuit. So the resistor analogy is bogus.

Please don't get me started on the noise claim I think my plate is full already with this whole increased efficiency of flow claim.
Anonymous
a b K Overclocking
March 18, 2003 11:40:42 PM

For all the genius lurkers out there: come on, be cool, and help us out here.
March 18, 2003 11:49:30 PM

Well, I guess ultimately one of us has to try it...

But, it is fun and challenging debating this... :smile:



--->It ain't better if it don't work<---
Anonymous
a b K Overclocking
March 18, 2003 11:51:47 PM

Totally!
Anonymous
a b K Overclocking
March 18, 2003 11:57:08 PM

Although....

You could try to run through the math once.

I know I wouldn't want to try that one.
March 19, 2003 1:21:02 PM

And how about the fact that the additional air pressure delivered by the first fan can damage the second fan?

But your theory is already used by Delta. They made a triple blade fan this way: first one clockwise, then one standing still followed by a counter-clockwise one.
<A HREF="http://www.deltaww.com/products/dcfans/pdf/GFB120120762..." target="_new">http://www.deltaww.com/products/dcfans/pdf/GFB120120762...;/A>

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
!