Fancy a new blower?

[Áedán]

I was looking for sources of blowers on the web earlier, and I found an interesting site that might be of use to those in the US. Typical, as I'm in the UK! Pictures are below. Obviously as I'm in the UK, I've no idea what these guys are like!

First up, anyone fancy a blower? They have a number from small (10CFM) to LARGE (436CFM). Link

Secondly, anyone fancy a mini refrigeration unit? I've no idea how good it would be for watercooling however! Link

[Gizmo]

Originally Posted by Áedán

Secondly, anyone fancy a mini refrigeration unit? I've no idea how good it would be for watercooling however! Link

Not very good, I'm afraid. The compressor is 1/12 hp, and the unit is only rated for 200 BTU, or about 65 watts.

[Áedán]

Make a good water cooler though

[cloasters]

A couple of the 436 cfm models might make a good snow blower.

[Gizmo]

Originally Posted by cloasters

A couple of the 436 cfm models might make a good snow blower.

SNOW BLOWER?!

That's more like your own portable hurricane, man!

[danrok]

I got this one http://www.aoaforums.com/frontpage/i...=227&Itemid=34

from http://www.chillblast.com/customer/home.php

[Áedán]

The blowers are good for people who use radiators on their watercooling setup. The fins on most radiators are close enough together that they present a fair bit of resistance to a normal fan. Blowers, although they don't blow as much air, tolerate higher pressures far better. This is just what a radiator needs!

[danrok]

So, how would you go about mounting a blower on a rad so that it blows over the whole area?

[Áedán]

To a certain extent (I'm sure Kaitain will correct me here!), you don't need to funnel the airflow as long as the blower can build up some pressure. The air will make it's way out where ever it can!

[Gizmo]

Actually, if I were mounting a blower on my rad, I think I'd probably mount it so that it was PULLING air, rather than pushing it. Either way, you'll need to build some kind of plenum to get maximum effect, but I would think that the plenum would need to be rather deeper if you were blowing air through the unit.

[Áedán]

You don't want them pulling air. They're less efficient at pulling air than pushing air. That said, if you put a 436cfm fan on a typical radiator, I don't think it'd make that much difference between intake and exhaust...

It's just a shame I can't get any decent blowers in the UK. It seems almost easy in the US!!

[Kaitain]

Originally Posted by Áedán

To a certain extent (I'm sure Kaitain will correct me here!), you don't need to funnel the airflow as long as the blower can build up some pressure. The air will make it's way out where ever it can!

Correct - a typical centrifugal blower (pictured top) will raise up to about 3psi head. By the nature of their design, there is no "dead" spot.

Axial fans, which are more typically used in computers, can only raise about 0.5 psi head. They also have a "dead" spot 1 blade radius running parallel to the axis due to the need for a hub and the shaping of the blades.

What this means in simple terms is that a centrifugal blower at the same rating is about 6 times more effective at pushing air through an obstruction than an axial one. Imagine a 2400cfm axial fan in place of that 400cfm one

Originally Posted by gizmo

Actually, if I were mounting a blower on my rad, I think I'd probably mount it so that it was PULLING air, rather than pushing it. Either way, you'll need to build some kind of plenum to get maximum effect, but I would think that the plenum would need to be rather deeper if you were blowing air through the unit.

Nope, the idea that fans "suck" better than they "blow" is a myth. Fans work by taking air in at point A and accelerating it such that the back-pressure equals its maximum pressure head. If you suck air through an obstruction, the pressure of the air drops as it passes through the obstruction. The best you can then do is accelerate it from a slight negative pressure to a slight positive pressure. This results in a much slower air flow than if you push static air through the same obstruction, when you can bring a higher pressure to bear on the obstruction. Inlet pressure is proportional to flow rate. Not well explained I know, but I'm not planning to draw pictures here

With centrifugal blowers, this is even more of a problem. If you prevent air getting to them, you're a few minutes away from having a lump of molten plastic where once a fan used to be.

By design, centrifugal blowers don't necessarily need a plenum. But then, having one doesn't hurt either, if it allows you to mount the blower in a more convenient location.

Thus ends today's process engineering lecture

[Daniel ~]

Check the adsence ad,A Supercharger no less! ":O}

[cadaveca]

i have a couple of those types of fan from thermaltake. They get quite noisy just from the pure volume of air they pull, and when that air hits the blades.

At my acreage, we use a large blower fan in front of the door to keep mosquitoes out. Once you adjust to the sound (it blends into background, like an a/c would, at least to me), it is definately a marvel at how efficient they are. The noise...and not of the motor, can be quite montrous!

Using one on a standard heatsink allowed me to lower fanspeed, and therefor noise, becasue of the lack of a deadspot, most often right where the actual core is.


I'd say they are a bit more akin to a turbo!

[Gizmo]

Originally Posted by Kaitain

Nope, the idea that fans "suck" better than they "blow" is a myth. Fans work by taking air in at point A and accelerating it such that the back-pressure equals its maximum pressure head. If you suck air through an obstruction, the pressure of the air drops as it passes through the obstruction. The best you can then do is accelerate it from a slight negative pressure to a slight positive pressure. This results in a much slower air flow than if you push static air through the same obstruction, when you can bring a higher pressure to bear on the obstruction. Inlet pressure is proportional to flow rate. Not well explained I know, but I'm not planning to draw pictures here

With centrifugal blowers, this is even more of a problem. If you prevent air getting to them, you're a few minutes away from having a lump of molten plastic where once a fan used to be.

By design, centrifugal blowers don't necessarily need a plenum. But then, having one doesn't hurt either, if it allows you to mount the blower in a more convenient location.

Thus ends today's process engineering lecture

I'm quite aware that fans blow better than they suck, but thanks for that anyway. The only reason I mentioned mounting the fan to suck air through the rad was because if you don't, then you are stuck with a much deeper solution than with an axial fan, and I figured that the tradeoff in CFM would be made up for by the efficiency. Could be wrong though. Wouldn't be the first time.

[Kaitain]

As I say, centrifugal fans are slightly less forgiving about having a restricted inlet pressure. You tend to have to overrate them significantly if you're expecting to pull air rather than push it (look at the power consumption on the average hoover).

For axial fans it doesn't matter, since their greatest output is noise anyway