Some (seemingly) oddball questions.

Link · Nov 4, 2008

First (and most importantly): I need a radiator. Not like car sized, but rather bigger than say a big CPU heatsink. Problem is, I have no idea what I should be looking for. Perhaps a very small AC unit?

Second: Will coolant be okay in a small fountain pump? If not, anyone know where I can get a small one (~2gpm) that will work, for less than, say, a dialysis pump would cost?

Third: Thermal epoxy. I could use some, and more than can be had in a reasonable number of the tubes sold in computer stores. I think. I don't know for sure. Cheap would be good. Dunno what type of place would sell it, so that's why I'm asking.

If anyone's wondering, I'm going to try liquid cooling a 406 for the LULZ. 8)

PaulM · Nov 4, 2008

Would a motorcycle radiator work?

Mathurin · Nov 4, 2008

I guess computer water cooling is reasonably close to what you're thinking about
http://www.silentpcreview.com/forums/viewforum.php?f=21

Zoot Katz · Nov 4, 2008

Transmission coolers are smallish radiators. Only about 3/4" thick.

These guys can provide high temp epoxy in standard packaging sizes from a half pint to 55 gal. drums
http://www.masterbond.com/produse/produse_ht.html

Small inline pumps. . . hmm. I've seen drill powered impeller pumps for cheap. Any small motor hooked to the shaft would probably drive it.
Run it through a DC - DC converter from your main pack?
I guess you're using anti-freeze as a coolant?

Link · Nov 4, 2008

PaulM said:
Would a motorcycle radiator work?

Might, but they seem to be just a little too big.

Mathurin said:
I guess computer water cooling is reasonably close to what you're thinking about
http://www.silentpcreview.com/forums/viewforum.php?f=21

Hmm...did a search for some watercooling radiators. I didn't know they got that big. Of course, I never had enough money to mod a PC with so I never really looked. :? Should be able to find exactly what I'm looking for along those lines. Looks like the PC industry's got me covered for a pump and coolant, too.

Zoot Katz said:
These guys can provide high temp epoxy in standard packaging sizes from a half pint to 55 gal. drums
http://www.masterbond.com/produse/produse_ht.html

Ty.

Offhand, anyone figure I'll weaken a 406's axle too much if I drill a 5/32-"3/16" hole through center of the axle?

dogman dan · Nov 4, 2008

Look at heater cores for cars. It's a little radiator usually in the dashboard or the firewall that takes hot water from the engine to warm the air blowing through it from the vents. Usually they are about 9"x9" or so. Maybe smaller for a little geo or something.

Not sure what thermal epoxy is, but I really like PC7 to fix things. It can take a bit of heat, like 200F.

I think a fountain pump might not like the hot water. Ordinary pvc gets real soft when heated so it would depend on the type of plastic.

Mathurin · Nov 4, 2008

Wouldn't it make more sense to try 1/2 filling the motor with coolant and superglue cpu heatsinks to both sides the flanges for better transfer/moving the coolant around - or install the pump inside the motor to get coolant on top. Or something

Ben · Nov 4, 2008

1) I'd go with a heater core or a PC radiator.

2) If the coolant isn't too viscous a fountain pump should be fine. You'll want the pump to be an inline one, so you don't need to submerge it.

3) I don't know where to get large amounts, but you'll probably need less than you think.

So are you going to flood the motor or cool the casing?

Link · Nov 4, 2008

I won't need much, but more than I can find without a good deal of searching if I was going to get it locally.

I have two options on how I'm going to do this. I could go with my original idea and stick some copper pipe to the stator, but, giving it a little more thought, it seems it would be much easier to add some covers to the sides of stator and just flood the entire center of the core. There'd probably be dead spot issues, but I might be able to work that out simply by angling the inlet port(s) so that it gives a little rotation to the mass of the coolant.

Anybody with some CAD skills want to model this for me?

Flooding the entire motor would create way too much fluid friction when spinning, and this little tidbit is rather telling about the temperature difference between the two parts of an X5:

HAL9000v2.0 said:
No, I plan to cool coils inside, because coils and inner alu holder (pressed onto shaft) was on 106Â°C and housing was on 52Â°C so I dont think outer cooling will help like Link said. Pictures coming....

Which is where I'm getting the idea the cooling the hottest part of the motor directly will work so well.

In regards to the radiator, I haven't tossed out the idea of winding a load of pipe around the frame just yet. I'm still thinking the far greater surface area a proper radiator offers will be a better choice, even if I have to figure out where to actually put it.

Ben · Nov 4, 2008

I'd go with enclosing the sides of the stator.

So how are you going to get the coolant in there? Through the axle?

recumpence · Nov 4, 2008

I built a liquid cooled car stereo amplifier 12 years ago. I used a racing oil cooler and a small 12 volt pop-up camper water pump. Both worked well with antifreeze.

The amp ran very cool and the system proved to be reliable.

Hmm, I may still have one of the pumps lying around my garage.

Matt

Link · Nov 4, 2008

Ben said:
I'd go with enclosing the sides of the stator.

So how are you going to get the coolant in there? Through the axle?

Yeah, I'm thinking that's better in just about every way. I'll probably go with that.

Undecided on how to attach the lines. Either a hole through the axle, or a pipe under the bearing, same way the wires exit. The problem with the hole in the axle is that it makes it a little weaker. Still, it's a pretty hefty piece of metal, so I think it'd be okay. I'd need to attach pegs to the motor to protect the tubes attached, but I'd probably be doing that anyway.

If I were to go with a tube under the bearing, I'd have to remove a fair bit of metal. And I'd have to deal with actually getting the tube under the bearing, which may turn out to be impossible without a very large channel in the axle, defeating the strength advantage I'd be going for.

I'm leaning toward a hole in each side of the axle.

recumpence said:
I built a liquid cooled car stereo amplifier 12 years ago. I used a racing oil cooler and a small 12 volt pop-up camper water pump. Both worked well with antifreeze.

The amp ran very cool and the system proved to be reliable.

Hmm, I may still have one of the pumps lying around my garage.

Matt

Yeah, I was observing a pair of glasses out of the dishwasher earlier because I was thirsty. The one I filled with water cooled off in about 8 seconds, while the other stayed warm for like 5 minutes. My conclusion: Water thermal conductivity > air thermal conductivity.

So what kind of power you figure I could get out of this hub? I was gonna try for 5kW peak.

recumpence · Nov 4, 2008

Reliable power is directly related to neat dissipation. If you can get liquid cooling to work properly, I would say 5kw is not out of the question.

Matt

Link · Nov 5, 2008

Okay, got a Thermaltake p500. Would have gone with the fish/fountain pump thing, but they really aren't capable of decent flow rates and pressures unless you get big ones. Figure if the Thermaltake doesn't work out, I can see how it takes to a bit of overvolting. 8)

Have my eye on some very small radiators. Not sure what kind of dissipation a piddly 80mm is capable of (even if it is all-copper), but radiators are cheap. I can either add more or get a bigger one.

Don't have anything lying around that's particularly suitable for covering the sides of the core. Not sure I can bond ABS to metal, so maybe some light sheet aluminum?

Miles · Nov 5, 2008

Did you see this?
http://www.xtremesystems.org/forums/showthread.php?t=160727

Ben · Nov 5, 2008

I know one thing that's common with PC setups is galvanic corrosion from the mixing of different metals within the loop. Just something to think about.

I'd say the 80mm rad is capable of around 100W of heat dissipation, but it's just a rough estimate. 120mm would probably about double that.

Will you be running fans with the radiator or just using it passively?

What's the head like on the pump? You'll want it to be fairly high, otherwise you won't get much flow through the constriction at the bearing/axle. Don't worry, it's 1.8m. Could be higher, but meh.

Link · Nov 5, 2008

Yeah. I was thinking alu wouldn't be prone to rusting, then remembered, Duh, the entire core is steel. Prolly coat it in the same clear spray enamel (or it might just be clear paint, I don't remember) I put on the other bike's BMS and controller.

Figure I'll just use the 80mm for testing. It's at like $0.99 right now, so no biggie. Maybe dual 120mm. Where'd you come up with 100W, anyway?

Probably with fans. The radiators are already made to have them attached, so why not?

Yeah, I heard the pressure could be better, but I'm not looking to move little bits of heat away as fast as I can to keep things cold, just a lot of it to keep things from overheating. So I don't need as much liquid moving since I can allow it to get a lot hotter than what a PC modder would.

Ben · Nov 5, 2008

Link said:
Where'd you come up with 100W, anyway?

I just searched around for some dissipation figures for PC radiators and then made a rough estimate based on 80mm area vs 120mm area.

It could even be more, because some 80mm HSFs can dissipate the 100W+ that a CPU will put out. The general consensus in the PC cooling area is that high quality air cooling is about as good as, or slightly better than low quality water cooling.

Gregory · Nov 5, 2008

aussiejester has plenty of pc water cooling experience

Link · Nov 5, 2008

Ben said:
I just searched around for some dissipation figures for PC radiators and then made a rough estimate based on 80mm area vs 120mm area.

It could even be more, because some 80mm HSFs can dissipate the 100W+ that a CPU will put out. The general consensus in the PC cooling area is that high quality air cooling is about as good as, or slightly better than low quality water cooling.

Hmm...any idea what sort of temperature gradient that's at? I'm guessing a 406 could be allowed to get quite a bit hotter than an overclocked CPU, so the greater temperature difference will probably allow the radiator to dissipate more than what's used to keep a CPU cool...

Gregory said:
aussiejester has plenty of pc water cooling experience

He left.

Ben · Nov 6, 2008

Link said:
Hmm...any idea what sort of temperature gradient that's at?

No idea.

I just had a thought. You could get the side cover of the motor machined to fit a larger diameter bearing, allowing you to run some larger lines to the stator.

Link · Nov 8, 2008

Ben said:
I just had a thought. You could get the side cover of the motor machined to fit a larger diameter bearing, allowing you to run some larger lines to the stator.

Then I'd need a bigger axle, too...:|

Plus the part of the sideplate that holds the bearing is only like 1/8" thick.

Anyway, the pump showed up the other day. It made a funny rattling sound when I was testing it dry, but not really when it was pumping water. It didn't seem like a problem, so I left it. I took the pump apart to see how it was put together.

And inadvertently discovered the source of the rattling. Apparently sometime during shipping, the axle that holds the rotor on had broken. Why it's made of plastic instead of stainless steel is beyond me. :roll:

But it's an easy fix.

If the axle breaks again, I'm just going to drill out the old one and replace it with something more durable. These pumps are pretty expensive (this one's low-end and cost $50), so I'd rather not have to get another one.

I noted that it's pretty much just an outrunner, so even if it doesn't put out enough flow and its controller can't handle, say, 24V, there are plenty in the RC world that can. :wink: The holes in the rotor were an interesting touch; water is pulled through them by the vanes, drawing more water around the back of the rotor to cool the coils. Clever. Especially since that probably allows me to run a fair bit of power through this thing if I so choose.

Anyone know what that yellow wire is for? I think it's an on/off signal or something, but eh.

Pete · Nov 8, 2008

3 wire is the same as a CPU fan. Yellow is the RPM feedback that some systems use to trigger an alarm if the CPU fan RPM drops below a threshold you can usually setup in the BIOS

HAL9000v2.0 · Nov 8, 2008

Older watercooled Piaggio and similar italian 50cc scooters has radiators 150x100x20mm with 10mm inlet/outlet pipes.If this is too big (I think it is.) you can use oil cooler from some 600cc or higher motor bike. Kawasaki GPZ500RR has one 125x40x25mm. I have it at home and it is light.
Also you can use pump for windscreen washers from smaller car. If it is too small, pumps for headlight washers are bigger. If you do not want 12V, Trucks work on 24V.

Go,go Link, can't wait to see the numbers...

TylerDurden · Nov 8, 2008

Link said:
Yeah, I was observing a pair of glasses out of the dishwasher earlier because I was thirsty. The one I filled with water cooled off in about 8 seconds, while the other stayed warm for like 5 minutes. My conclusion: Water thermal conductivity > air thermal conductivity.

Continuing in the realm of science, one might consider...

How hot does the stator get at rated-load?
How hot will the stator get at expected load?
How much water @ ambient will be req'd to cool the stator to rated-load temp?
How much water can you get past the stator through the axle?
How big should the radiator be to cool water @ stator temp to ambient without a fan, or with one?

(10sec pause)

Now that you have considered those questions, simply proceed and see what the motor will take.

Regarding cad.. Blender, Sketchup, Daz, Alibre... take a break from the Brawl.

Some (seemingly) oddball questions.

1 MW

100 W

100 kW

100 kW

1 MW

1 PW

100 kW

100 W

1 MW

100 W

1 GW

1 MW

1 GW

1 MW

100 TW

100 W

1 MW

100 W

100 kW

1 MW

100 W

1 MW

100 W

10 kW

100 GW

Similar threads