An Arduino Liquid Cooling System

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An Arduino Liquid Cooling System

Postby Bartimaeus » Tue Jun 25, 2013 3:32 pm

I've been putting off this thread for months and now I'm almost finished with the project. For Farfle's electromotard (link to thread): http://endless-sphere.com/forums/viewtopic.php?f=12&t=49359 he wanted a liquid cooling system so he could use his homemade outrunner with the next size larger Sevcon controller. It's a simple enough design, where the water is sprayed into the motor when the motor is hot enough to turn it into steam. The steam then gets sucked out from the side vent holes.

The main concern was keeping the magnets cool, since Farfle's last motor failed when the magnets were demagnetized from the heat. You can only monitor the temperature of something spinning at ~3,000rpm a few ways, so he asked me if I could make something that used an infared temperature sensor.

The final result (so far) consists of an Arduino Pro Mini from Sparkfun, an 8x2 character LCD, a Melexis MLX90614 IR temp sensor, a thermistor (located in the stator of the motor), a piezoelectric buzzer, xBee modules, and some other parts like the pump and water tank (camelbak bladder ftw!). The Arduino does several things: it monitors the temperature readings from the thermistor and the IR temp sensor and turns the pump on and off based on the programmed trigger temp level, checks the current that is being drawn by the pump to see if it is moving water or not (there is a significant difference in the current drawn when the pump is moving water versus air or sucking on an empty tank), updates the LCD screen and some indicator LEDs with the temperatures and pump/tank status, and takes the Cycle Analyst's serial output and appends the two temperature readings and the pump status (on/off) to the end and sends the new data out to the xBee module and a Sparkfun openLog serial logger, where it is logged to a microSD card and sent to another xBee offboard the bike, where it can be displayed on a laptop or to an Android phone using a bluetooth serial module and the Cycle Dash app I've made (thread: http://endless-sphere.com/forums/viewtopic.php?f=2&t=45661 ). This will let Farfle monitor the data in real time while I race the bike and try not to crach ;)

I will try to dig up some more photos and documentation, but for now here's an old video of the very first prototype:

and some pictures of the system in various stages:

Image


Image

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I will post the Arduino sketch soon, need to get the most recent version from my other computer. More details to come, you'll find updates being posted on the Team Farfle blog and FB pages (plug):

http://farfleselectrics.blogspot.com/

https://www.facebook.com/TeamFarfleRacing
Team Farfle Website: http://www.farfleracing.com/
Team Farfle Facebook Page: https://www.facebook.com/TeamFarfleRacing
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Re: An Arduino Liquid Cooling System

Postby Bartimaeus » Tue Jun 25, 2013 3:35 pm

Also here is a picture of the motor. The brass tubing is closed at the end and has holes on the outside to spray the water in several directions within the motor:
Image
Team Farfle Website: http://www.farfleracing.com/
Team Farfle Facebook Page: https://www.facebook.com/TeamFarfleRacing
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Re: An Arduino Liquid Cooling System

Postby Bartimaeus » Thu Jun 27, 2013 9:11 am

Here is the most recent version of the code:
Attachments
Bike_Temp.zip
(7.27 KiB) Downloaded 34 times
Team Farfle Website: http://www.farfleracing.com/
Team Farfle Facebook Page: https://www.facebook.com/TeamFarfleRacing
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Re: An Arduino Liquid Cooling System

Postby etriker » Sat Jun 29, 2013 4:11 pm

Cool ! thanks for sharing ! :)
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Re: An Arduino Liquid Cooling System

Postby Bartimaeus » Wed Jul 24, 2013 11:06 am

Learned some disturbing stuff about the liquid cooling system during our trip down to Leguna Seca. Apparently the water is being pumped into the motor too quickly, causing it to fill with water instead of turning into steam. Since it's an outrunner that meant that the rear tire was getting sprayed with water, effectively meaning that we were the only ones on the racetrack who were riding in the rain. I got into a pretty spectacular crash because of it (no major injuries to me or the bike thankfully besides bending the handlebars a bit and ripping out some of the stiches in my leathers). We've got some pretty good on board footage that shows just how bad the problem was (we had a camera mounted under the bike right behind the motor which got sprayed with water pretty badly at times.

Here's the video (you can see how bad the spraying was around the 1:49 mark. The crash is around the 2:30 mark, at 3:08 you can see me picking the bike back up and a ton of water pouring out of the side):


There was also trouble with the I2C for the IR temp sensor. It was just too noisy on the bike (phase wires had up to 400A running through them!) , and it was causing the Arduino to freeze while it waited for a response. Right now have the IR sensor disabled, but I'm planning on re-configuring it to run with its PWM output with a capacitor so it can just be an analog read.

And even with all of the flaws, when the pump did trigger the temperature in the motor dropped like a rock. Manually running water into the motor gives the same rapid drop, and only about 8oz. of water was needed to make the motor go from ~250C to ~130C when we were up at the Horn Rapids track last weekend in the 106F+ weather (check out the team blog/ES thread for details on that)
Team Farfle Website: http://www.farfleracing.com/
Team Farfle Facebook Page: https://www.facebook.com/TeamFarfleRacing
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