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  #11  
Old 07-27-2012, 05:05 AM
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Default Re: Water cooling methods and effectiveness.

Quote:
Conclusion: Unless your motor is operating within the last 30% region, this cooling method is not effective. The only way it would be effective is if you were really marginal and it kept the motor from over temping.
Quote:
I wouldn't throw it out yet. It might show only 5 but that is with a fairly cool motor. 60C on the stator winding is hardly taxing the motor. Get it up to 150C and try your experiment.
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I was thinking the same thing as major, heat flow is proportional to temperature difference. It should move much more heat at higher temperatures
Yah, I think we all are in agreement on this point. So Maybe we could adopt a rule. Like your motor temp needs to be above 50% of it's maximum rating before water cooling even becomes viable.


Miz
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  #12  
Old 07-27-2012, 05:17 AM
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Default Re: Water cooling methods and effectiveness.

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Originally Posted by mizlplix View Post
Yah, I think we all are in agreement on this point. So Maybe we could adopt a rule. Like your motor temp needs to be above 50% of it's maximum rating before water cooling even becomes viable.


Miz
Sound good to me.
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  #13  
Old 07-27-2012, 08:46 AM
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Default Re: Water cooling methods and effectiveness.

I'm planning on experimenting with Open Revolt controllers and want to build chill plates for them, instead of finned heat sinks. Also, the motor going in my e-bike, for the first stage is a little ProTech permanent magnet, totally enclosed, deal. Even though it's not slated to be in the bike long, and will really only be used around the aisles of the shop, or at events (if we still don't have the actual Mars motor), I am planning to build a little cooler for it. It is actually the motor I bought for the big cooling blower unit on the Model E, so this motor cooler might have a purpose beyond the fist stage of the bike.

I thought about wrapping it with copper tubing, ala Miz, but had two concerns with that. One, the contact surface of the round section tubing is so small, against the motor frame - kind of like a motorcycle tire. Two, the coolant has to travel through the entire length of the tubing to get the heat away from the motor. I believe you said you used 75ft of copper tubing Miz? That seems like an awfully long time to carry heat, and if it works well the coolant is at motor temp for a lot of that journey, and unable to collect more heat from the motor. It would be interesting to shoot the tubing at different points with an infrared to see if it's cooler at the inlet side than the outlet...

One of my Team members and I came up with the idea to make two aluminum pieces that cup around the frame tightly and are clamped together. Holes will be drilled through the cooling plates, threaded, tapped, and fitted with compression nipples, on the ends; then fitted to a little hand fabricated tank on each end - like a radiator. I haven't modeled the tanks yet, and this model is just a rough sketch, but try to imagine a little half-round, miniature, tank with eleven little short flanged sections of tubing soldered or welded to it, with compression nuts on them.


I admit, it's a helluva lot of fabrication, but we're prone to this type of excess. Someone may be able to simplify this basic concept and implement it. The main point is all the water comes in cool, makes an equal path across the motor frame, and exits (hopefully) full of waste heat.


As I said, this is just a rough sketch to communicate the idea, and help me think it through. To fit in the mock-up case I made to go over this little motor, I can't have those big clamping bolts. I did those for here to illustrate the concept.
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  #14  
Old 07-27-2012, 09:29 AM
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Default Re: Water cooling methods and effectiveness.

My impression was that miz understands heat flow is proportional to heat transfer coefficient and temperature differential. Seems his point was that the former is low due to small contact area, so the coil only provides a small amount of additional cooling, and for his normal driving conditions it isn't required.

Quote:
Originally Posted by mizlplix View Post
Conclusion: Unless your motor is operating within the last 30% region, this cooling method is not effective. The only way it would be effective is if you were really marginal and it kept the motor from over temping.

I am in the first 30% region. I really do not need any type of extra cooling.
It just adds extra cost, weight, complexity and ultimately draws from the pack (mileage).Miz
Heat is more of an issue with my controller than my motor, but it typically doesn't get over about 55-57 C with ambient in upper 90's. What temperature was your controller miz,and how are you cooling it?
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Old 07-27-2012, 10:06 AM
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Default Re: Water cooling methods and effectiveness.

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Originally Posted by toddshotrods View Post
I'm planning on experimenting with Open Revolt controllers and want to build chill plates for them, instead of finned heat sinks. Also, the motor going in my e-bike, for the first stage is a little ProTech permanent magnet, totally enclosed, deal. Even though it's not slated to be in the bike long, and will really only be used around the aisles of the shop, or at events (if we still don't have the actual Mars motor), I am planning to build a little cooler for it. It is actually the motor I bought for the big cooling blower unit on the Model E, so this motor cooler might have a purpose beyond the fist stage of the bike.

I thought about wrapping it with copper tubing, ala Miz, but had two concerns with that. One, the contact surface of the round section tubing is so small, against the motor frame - kind of like a motorcycle tire. Two, the coolant has to travel through the entire length of the tubing to get the heat away from the motor. I believe you said you used 75ft of copper tubing Miz? That seems like an awfully long time to carry heat, and if it works well the coolant is at motor temp for a lot of that journey, and unable to collect more heat from the motor. It would be interesting to shoot the tubing at different points with an infrared to see if it's cooler at the inlet side than the outlet...

One of my Team members and I came up with the idea to make two aluminum pieces that cup around the frame tightly and are clamped together. Holes will be drilled through the cooling plates, threaded, tapped, and fitted with compression nipples, on the ends; then fitted to a little hand fabricated tank on each end - like a radiator. I haven't modeled the tanks yet, and this model is just a rough sketch, but try to imagine a little half-round, miniature, tank with eleven little short flanged sections of tubing soldered or welded to it, with compression nuts on them.


I admit, it's a helluva lot of fabrication, but we're prone to this type of excess. Someone may be able to simplify this basic concept and implement it. The main point is all the water comes in cool, makes an equal path across the motor frame, and exits (hopefully) full of waste heat.

As I said, this is just a rough sketch to communicate the idea, and help me think it through. To fit in the mock-up case I made to go over this little motor, I can't have those big clamping bolts. I did those for here to illustrate the concept.
You will have the same issue as miz, small surface contact area. A gap of only tens of microinches will reduce cooling greatly, as then heat transfer is by convection rather than conduction. There is no way you will get the surfaces of two rigid parts so perfectly matched that they have more than a couple percent contact area. Even if you could, the contact area would then be limited to a few percent anyway due to surface roughness for say a 40 micro-inch surface finish. Heat sink compound will help considerably, but it won't compensate poor machining. Need to minimize that gap, maximize contact area. Turbulent fluid flow also helps, as it breaks up the boundary layer in the fluid, increasing heat transfer from the metal to the fluid. But that is a much smaller effect than reducing the heat transfer coefficient between the jacket and motor. I agree with the need to shorten the tubing length to maximize the delta T between fluid and motor over the entire length.
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  #16  
Old 07-27-2012, 10:54 AM
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Default Re: Water cooling methods and effectiveness.

Quote:
Originally Posted by toddshotrods View Post
I'm planning on experimenting with Open Revolt controllers and want to build chill plates for them, instead of finned heat sinks. Also, the motor going in my e-bike, for the first stage is a little ProTech permanent magnet, totally enclosed, deal. Even though it's not slated to be in the bike long, and will really only be used around the aisles of the shop, or at events (if we still don't have the actual Mars motor), I am planning to build a little cooler for it. It is actually the motor I bought for the big cooling blower unit on the Model E, so this motor cooler might have a purpose beyond the fist stage of the bike.

I thought about wrapping it with copper tubing, ala Miz, but had two concerns with that. One, the contact surface of the round section tubing is so small, against the motor frame - kind of like a motorcycle tire. Two, the coolant has to travel through the entire length of the tubing to get the heat away from the motor. I believe you said you used 75ft of copper tubing Miz? That seems like an awfully long time to carry heat, and if it works well the coolant is at motor temp for a lot of that journey, and unable to collect more heat from the motor. It would be interesting to shoot the tubing at different points with an infrared to see if it's cooler at the inlet side than the outlet...

One of my Team members and I came up with the idea to make two aluminum pieces that cup around the frame tightly and are clamped together. Holes will be drilled through the cooling plates, threaded, tapped, and fitted with compression nipples, on the ends; then fitted to a little hand fabricated tank on each end - like a radiator. I haven't modeled the tanks yet, and this model is just a rough sketch, but try to imagine a little half-round, miniature, tank with eleven little short flanged sections of tubing soldered or welded to it, with compression nuts on them.


I admit, it's a helluva lot of fabrication, but we're prone to this type of excess. Someone may be able to simplify this basic concept and implement it. The main point is all the water comes in cool, makes an equal path across the motor frame, and exits (hopefully) full of waste heat.


As I said, this is just a rough sketch to communicate the idea, and help me think it through. To fit in the mock-up case I made to go over this little motor, I can't have those big clamping bolts. I did those for here to illustrate the concept.
To get around all of the tapping and compression nipples, cut channels instead of bores, and press copper tubing into the channels. A manifold can be made so there are several parallel flow paths. You still need to figure out how to thermally couple the plate to the curved surface of the motor.
cold_plate_custom%201.gif
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  #17  
Old 07-27-2012, 11:22 AM
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Default Re: Water cooling methods and effectiveness.

Quote:
Originally Posted by tomofreno View Post
You will have the same issue as miz, small surface contact area. A gap of only tens of microinches will reduce cooling greatly, as then heat transfer is by convection rather than conduction. There is no way you will get the surfaces of two rigid parts so perfectly matched that they have more than a couple percent contact area. Even if you could, the contact area would then be limited to a few percent anyway due to surface roughness for say a 40 micro-inch surface finish. Heat sink compound will help considerably, but it won't compensate poor machining. Need to minimize that gap, maximize contact area...
Good points. We can machine the jacket and even turn the motor frame, but your point is well taken about the tolerances. One thing about that though - the chill plates people use on controllers can't have any better contact area, even if they're machined flat and they seem to work well enough?





Quote:
Originally Posted by Joey View Post
To get around all of the tapping and compression nipples, cut channels instead of bores, and press copper tubing into the channels. A manifold can be made so there are several parallel flow paths...
That's a thought.




Quote:
Originally Posted by Joey View Post
...You still need to figure out how to thermally couple the plate to the curved surface of the motor...
I can make the jacket thin enough to flex, and slightly undersized, so that it has to be forced around the frame; or make the jacket in smaller sections, like four, or six, instead of two...
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  #18  
Old 07-27-2012, 12:30 PM
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Default Re: Water cooling methods and effectiveness.

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Originally Posted by toddshotrods View Post
I once worked on (tore apart and reassembled) an induction motor having coolant passages like you show. They appeared to be bored in a solid steel thick wall tube. It was slightly longer than the stator. Stator appeared to be heat shrunk pressed inside. No gettin' that sucker apart. Then the longintudinal passages were gasket sealed and headered (is that a word?---like a manifold:-)) off by the end bells themselves which had a single in and single out port.

Hope that made sense

major
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  #19  
Old 07-27-2012, 12:31 PM
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Default Re: Water cooling methods and effectiveness.

Check http://www.diyelectriccar.com/forums...ighlight=luigi

Catavolt talks of water cooling in the bike thread also.
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  #20  
Old 07-27-2012, 05:27 PM
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Default Re: Water cooling methods and effectiveness.


Like This? Except this is the housing it's self. (Copyright Ivansgarage)
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