Thread: New DC advice sought

Originally Posted by John Samuel

Bob,
Ouch! 100 CFM (and a 2" to 3" line) is more than I had imagined. That's about one ninth of my total air flow. so I don't think I would be willing to sacrifice that.
Cheerio!
John

Yep there's a lot of wasted energy in motors.
Even in higher efficiency 3 phase motors that are around 85% efficient , 15% of 3 kW is 450W! and that is mostly in the form of heat that has to be got rid of somehow.
On a machine where the motor is unloaded most of the time this is not as big a worry as a DC where the motor is constantly fully loaded.

Actually the whole 3kW has to eventually dissipate as heat, another good reason to get the DC outside the shed, well in Oz mostly anyway.

Originally Posted by BobL

The top half of a cyclone represents a fair size volume and more importantly, your cyclone and impeller made of metal and will act as a sort of heat exchanger transferring heat from the motor to the air inside the enclosure through the metal walls of the cyclone and be carried away with the exhausted air. I'd say this is a significantly different setup from enclosing just the motor.

I hadn't actually thought about it that way, given that my motor is a flange mount which is directly coupled to the top of the cyclone heat would transfer to the top of the cyclone, also the airflow from the motor cooling fan would impinge on the top of the cyclone, also heat would be drawn along the motor shaft to the fan, both would dissapate heat, at a slow rate I'd guess but it might just be enough.

If I could measure accurately enough I should see a rise in temp in the exhaust air above the inlet air, using some round figures if I had a 1°C change and a mass flow rate of 5kg/sec of air that would be 5kw, nope, this is way too high, I only have a 3kw motor, at a wild guess it might be closer to 0.1° temp change which would be 0.5kw cooling which is not to be sneezed at.

It just goes to show the differences in our DC systems, what I get away with someone may not simply because of the way a motor is mounted.



Pete

Originally Posted by pjt

If I could measure accurately enough I should see a rise in temp in the exhaust air above the inlet air, using some round figures if I had a 1°C change and a mass flow rate of 5kg/sec of air that would be 5kw, nope, this is way too high, I only have a 3kw motor, at a wild guess it might be closer to 0.1° temp change which would be 0.5kw cooling which is not to be sneezed at.

That's about all you need.

Out of interest ... How much are you guys paying for a clearvue system ? And from where ?

Sent from my HTC Sensation Z710a using Tapatalk

http://www.clearvueoz.com.au/

And so my ventures into dust extraction begin.

Picked this up today .. will be a little while before I set up full cabinet and ducting, but at least I can catch chips from the thicknesser for my current job.



Assembly went without issue .. all parts included .. all holes line up .. no crossed threads or anything.

The only thing I don't like is the position of the on/off switch, which is mounted on the motor behind the inlet. Would have thought a mounting point on the "front" would be better .. but I can cope I think.

Haven't looked at what it would take to relocate yet ... More important tasks on the list.