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  Cooling Fan air Flow direction 
 
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I A Dec 19, 2010, 04:24pm EST Reply - Quote - Report Abuse
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Edited: Dec 19, 2010, 08:53pm EST

Replies: 15 - Views: 12659
Currently i am trying to work on designing and making my cooling pad for my 18 in laptop. I wanted to put 2 80mm fan on bottom for cpu and gpu and two 40mm at 45 degree pulling hot air from the bottom of the screen went and away. I am trying to get the air from the side wents for the bottom two fan, so when i have the laptop on my lap or any surface trying to block air from bottom, it will be able to pull air from side and up to the cpu and gpu cooling fans.
is there a fan i can use to pull air from side and send it up?. another idea i had was to use a fan and cut the side and pull air from side, but i don't know if this will work.
System
Toshiba Qosmio x505-q887
Here is a video on the laptop i am trying to make the pad for at 1:50 you will see the bottom view of the laptop to see what i am talking about
http://www.youtube.com/watch?v=PFRLhJDnTCM&feature=player_embedded#!

let me draw the pad so i can show different view of the part through flicker


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john albrich Dec 19, 2010, 04:50pm EST Reply - Quote - Report Abuse
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Edited: Dec 19, 2010, 04:54pm EST

 
>> Re: Cooling Fan air Flow direction
I A said:
...and two 40mm at 45 degree pulling hot air from the bottom of the screen went(sp = vent?) and away....


If I'm reading this right, you probably don't want to do that. In general, bottom vents are inlet vents for convection cooling on devices. Higher located vents are often used with lower vents to allow rising/hot air to escape through the top vents and draw cooler air in from the lower vents. Without knowing the exact configuration of your system, it seems you would be defeating the purpose of the lower vent by doing what you propose. Forced-air here in the possibly reversed direction might help, but then again it could hurt. It would depend on what electronics are positioned where, and the airflow you can achieve.

edit to add:
You might even consider the opposite approach, in which case a standard cage fan design is what you're looking for. This would "push" (presumably cooler) air into that lower vent.

john albrich Dec 19, 2010, 05:03pm EST Reply - Quote - Report Abuse
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Edited: Dec 19, 2010, 05:07pm EST

 
>> Re: Cooling Fan air Flow direction
I A said:
...another idea i had was to use a fan and cut the side and pull air from side, but i don't know if this will work....


Again, if I'm reading this part right, then yes that will work. But one design factor is to make sure there is enough clearance between the bottom of the box and the inlet perimeter of the horizontally mounted fan ("Vertical Inlet Distance"). You'd have to experiment to find the optimum Vertical Inlet Distance for a given fan. It will also be dependent on how wide you make the side vent inlet port.

^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ outlet airflow up to laptop
===================
Fan Fan Fan Fan Fan
===================-------------------------------top of side vent inlet port
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ inlet airflow into fan
|
|
| = Vertical Inlet Distance
|
|
----------------------------------------------------- bottom of box

I A Dec 19, 2010, 06:18pm EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction
i am wanting to make the pad about 1 in thick and use a 80x80x25 mm fan on bottom link
http://www.newegg.com/Product/Product.aspx?Item=N82E16835150007.
and then cutting the side to allow air in from the side
--------------------- -^ -^ -^-^ -^ -^--^ -^ -^- ---------- ----
>>>>>>>>>>>FAN FAN FAN FAN|||||||||||||||| 25mm 1in
---------------------------------------------------------------- ----
80mm

I A Dec 19, 2010, 06:44pm EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction
So should i just use two fans at the bottom pushing cool air up
i will try to post a picture of my current design as soon as i get the part touched up
Is there a way to post pictures in this forum

john albrich Dec 19, 2010, 07:37pm EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction

People use a photo sharing web-site and then just post the link here.

Some of the more recent threads have some examples...just look for the links.

john albrich Dec 19, 2010, 09:04pm EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction

By the way, you might want to try a quick model using cardboard with the 2 fans before you commit to a more ambitious project. Use a system/temp/gpu temp monitoring program (or just an IR thermometer (~$20)) pointed at the system air outlets to see how much difference there is. To assume best case, you don't even have to model the side-port design...just put 2 fans underneath that models the upper part of your "box" and gives them the best case of unimpeded air inlet.

Some laptops just don't get cooled very well by typical bottom-fan laptop coolers. I've got a Compaq 16" laptop that cools by a maximum of only 2C (anywhere/anyway I measure it) using a Targus 2x80cm fan cooler with the cooler powered by external adapter. Note that if you use internal USB port 5Volt-powered fans you're adding a couple watts of additional heat from the PSU inside the computer. Your fan choices are also more limited. I modified my Targus to use 12V fans and although a lot noisier it decreased the temp by only another 1C...and even that gain could be due to measurement resolution and error.

You might get far superior cooling simply by manually adjusting the internal fan speeds to maximum (if possible on your model) and making sure the air inlets are clean and aren't blocked. The downside of this of course, is that it increases wear and tear on the internal fans, which can be difficult and/or expensive to replace when they fail (or become intolerably noisy) due to bearing failure.

I A Dec 20, 2010, 11:52pm EST Reply - Quote - Report Abuse
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Edited: Dec 21, 2010, 12:20am EST

 
>> Re: Cooling Fan air Flow direction
currently i am using CPU Temp to view my laptop temperature.
While watching video it is in mid 60
using high graphics programs (autocad, inventor,...) it is in mid 70
and playing games about 95
just surfing or not high activity it is in mid 50
and i have tested this once or couple of times using a fan (house fan) the temp can drop to low 40 or even 30
at the moment right now core 0 -- temp high low and almost nothing is running other than
64 54 anti virus program and other
core 1---- 70 59 background activity
and i will be using other power source than usb to connect with the laptop
TOSHIBA Qosmio X505-Q892 NoteBook Intel Core i5 460M(2.53GHz) 18.4" 4GB Memory DDR3 1066 500GB HDD 7200rpm DVD Super Multi NVIDIA GeForce GTX 460M
and a bottom view of my laptop if you don't want to watch a video
http://www.flickr.com/photos/57357285@N08/5279591544/

john albrich Dec 21, 2010, 04:07am EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction
I A said:
...and i have tested this once or couple of times using a fan (house fan) the temp can drop to low 40 or even 30...


My opinion, but I believe using a house fan (or other large fan) isn't a suitable model. Not only is the mass flow rate likely much higher from a house/room fan, but there will be air flowing perpendicularly past the edges of the laptop in much higher volume and almost certainly affecting any heat-sink radiator(s) usually mounted on the back of the laptop more than would two 40cm bottom-mounted fans. Generally speaking, the bottom-mounted fans of laptop coolers don't direct any significant volume of air over the heat-sink radiators. The house fan would almost certainly be much more effective at lowering temps.

I A Dec 21, 2010, 04:55pm EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction
Any ideas on what type of fan i should use to pull air from side. my idea was to use a normal 80mm cooling fan and cut one of the sides to pull air from the side but don't know if it will work because of the direction the blades are spinning and the blades type. at the same time the bottom will be blocked only way to pull air in would be side and exit from top
sorry i am taking to long to draw a pad but i will have couple of pictures posed soon, so you can get a better idea of what i am talking about because i am unable to give you good explanation and idea of what i am wanting to do

Dr. Peaceful Dec 22, 2010, 01:52am EST Reply - Quote - Report Abuse
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Edited: Dec 22, 2010, 02:16am EST

 
>> Re: Cooling Fan air Flow direction
I A said:
is there a fan i can use to pull air from side and send it up?

If I am understanding correctly, you are looking for a fan that can basically "bend" air flow 90 degrees. You probably can not use a regular case fan for that purpose. You need a special fan blade design (curvature) to do the 90 degree direction change and a housing to guide the air.

Here is one that may do the job for you. It's designed originally for PCI video card cooling. In fact, due to the low profile of laptops, manufacturers do use similar kind of fan for cooling laptop CPU or GPU.

This one sucks air in vertically then exhaust it horizontally. http://www.newegg.com/Product/Product.aspx?Item=N82E16835888309

It's hard to find ones that does it in opposite direction, i.e. sucks air in horizontally then blows vertically, which fits your description more closely.

Edit: Found it finally, I know I saw it before... ;) It brings air horizontally (side) then turns it vertically (up). Exactly what you wanted. Newegg sold out all of them, but perhaps you can find it else where. http://www.newegg.com/Product/Product.aspx?Item=N82E16835209016

john albrich Dec 22, 2010, 02:49am EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction

As long as there's sufficient Vertical Inlet Distance, as mentioned in my earlier post, a normal "case" type fan will work fine. I'd start the "VID" at 20mm and tweak it in or out from there. One can even use 80mm fans as thin as 10mm or so to help reduce the total vertical size of the box, although when at a comparable price those tend to be less powerful than the 25mm versions.

But it is correct that the blade pitch, number of blades, etc. can make a difference. They directly affect the speed, mass-flow rate, turbulence, and that's why some experimentation is needed to find that optimum distance for a given fan. Some laptop coolers I've seen do in fact use normal "case" type fans and they move a good deal of air...they've just done their development work. Some implemented a p**s-poor design, not leaving sufficient space and/or not providing a large enough inlet aperture. They of course looked "sleek" but had horrible air-flow efficiencies. Anytime you change the direction of the air-flow you will lose some efficiency...the goal is to minimize the losses, even with "cage" fans.

Think of it like designing a plenum for an air circulation system...section distances, cross-sections, geometry, etc. all impact the final efficiency.

If you want to quickly observe the impact of changing the "VID", just use any case fan and a piece of cardboard that can cover the inlet area of the fan. Hold the cardboard about 20mm from the inlet side, and move it closer toward the fan. Even when you aren't closing off the inlet side and think there's plenty of space for air to get through to the fan, you'll feel a drop-off in the amount of air the fan moves through the outlet side...probably first noticeable to our senses at about 10mm. You'll also hear a distinct change in the "humm" of the fan. Again, the degree of effect will depend on the fan and the speed at which its running. A piece of paper or string suspended in front of the outlet might more easily show the effect at a greater distance. The goal would be to make the "VID" the point where moving the cardboard any farther away from the fan doesn't change the deflection in the paper/string.

I A Dec 27, 2010, 02:42pm EST Reply - Quote - Report Abuse
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>> Re: Cooling Fan air Flow direction
sorry for making you wait so long but i made a quick change to the pad after your replies i placed fans to the back instead 45 degree angle so hot air would enter a small chamber and then be pulled out using 40 mm fan this way it would not be directly in contact with the laptop
here is a link to the views of the pad with sectional and other views
http://www.flickr.com/search/?s=int&w=57616952%40N08&q=&m=text

I A Dec 27, 2010, 02:45pm EST Reply - Quote - Report Abuse
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Edited: Dec 27, 2010, 05:30pm EST

 
>> Re: Cooling Fan air Flow direction
i still have to go back and change the spot where the 80 mm fans go to system blowers, that is what they are called what you showed and new egg has them in stock so i will try to find better or buy two of those. thank you for your help you were very help full and is how would you know which way the fan is blowing or pulling air in from.
and don't forget to view the pictures of the pad, still have to make some changes
Thank you

Dr. Peaceful Dec 28, 2010, 01:07pm EST Reply - Quote - Report Abuse
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Edited: Dec 28, 2010, 01:11pm EST

 
>> Re: Cooling Fan air Flow direction
I A said:
i still have to go back and change the spot where the 80 mm fans go to system blowers, that is what they are called what you showed and new egg has them in stock so i will try to find better or buy two of those. thank you for your help you were very help full and is how would you know which way the fan is blowing or pulling air in from.
and don't forget to view the pictures of the pad, still have to make some changes
Thank you

Like I said before most blower fans out there are sucking air down to the fan, then vent it out the side vents. The Antec VCool is probably the only fan you can find that will pull air in from the side vent then blow air up. I actually looked at one of those in a store few years ago, so I am very sure the direction of air flow, plus I reconfirmed it by reading the specs. Here are the product links to the fan.
http://www.antec.com/Believe_it/product.php?id=ODQ=
http://www.antec.com/pdf/VGACooler.pdf (This one shows the detail dimensions)

Nice schematic diagrams for your cooling pad! I think it will probably work well for cooling your laptop. Just 3 notes, though.

1. Note that the VCool fan occupies two PCI slots (most blowers take only 1 slot), leaving sufficient vertical space for air to be supplied to the fan, precisely as what John mentioned above. The thickness as indicated in the diagram above is 38mm. So your cooling pad must be at least as thick to accommodate the fan.

2. Here are some support links to your laptop in case you need it.
http://tinyurl.com/23b49yp (Toshiba support site)
http://tinyurl.com/2cwste2 (Qosmio X500 series service manual)

From the service manual, it confirms your finding on the laptop air flow. Your laptop uses two blower fans inside (one for the CPU and one for the GPU). They suck air from the bottom of laptop, then blow the air across the heat pipes fins located on the back and push heat out the back of laptop. Just like you diagrammed above. As you can see the air flow is limited by how fast the internal blower fans can spin. The external intake and exhaust fans on your cooling pad design will definitely help improve the air flow actively, but still it's limited by how much air the inside fans can move. In another word, they are the bottlenecks of cooling.

3. Power to the fans?! The blower fans, the 4cm fans you will be getting are all desktop PC case fans. You can certainly test them by using a standalone desktop PSU (with a quick tweak of shorting two pins), if you have a spare one that is. But unless you want to keep the ugly contraption of a PSU on the outside of your cooling pad... you may want to do some wire work and make them power by your laptop's USB ports (may be a little too much power draw though), or by an external AC adapter. You want to keep this in mind in your design. Wire works is a little beyond my expertise, but I am sure John or other tech heads here can help you.

(Note: I have no financial benefit from any of the manufacturers or retailers mentioned above. I am merely a freelance computer geek. ;) )

I A Dec 29, 2010, 04:13pm EST Reply - Quote - Report Abuse
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Edited: Dec 29, 2010, 10:20pm EST

 
>> Re: Cooling Fan air Flow direction
thank you for looking at my diagrams and the helpful dimensions of the fan, i will be making some changes soon.
About the power i have read that if you use a usb for power, it will become a somewhat heating problem because it is a load on the battery. so i decided to use a different power source a battery pack with a dc power source. and using toggle switches 8) to turn them on/off.
once again thank you for all your help. and i did not mean to question you or sound offensive


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