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PEM Cooler Design

Discussion in 'Roadster: Technical' started by asgard, Aug 20, 2013.

  1. asgard

    asgard Member

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    CA
    Thinking out loud....
    A flat plate heat exchanger that's bonded to the top of the PEM using a thermal adhesive might do the trick.
    A few plates of something like this:
    http://www.aavid.com/sites/default/files/products/liquid/pdf/liquid-cold-plate-datasheet-hicontact.pdf

    Aavid can custom design a plate as wide as 250 inches.
    This plate is only 0.6 inches thick. Does anyone know if there is enough clearance above the PEM for this?
    The plate can be bonded to the top of the PEM surface using a 3M thermal adhesive.

    The plates would have to be routed to a small electrical pump and then another heat exchanger mounted on the bottom of the vehicle.

    Tesla should have done this inside the PEM (there are some pretty good liquid cooled IGBT solutions out there) but<br>outside the PEM should help considerably too.
     
  2. dhrivnak

    dhrivnak Active Member

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    Interesting idea. One could put in a piece of 5/8" plywood to see if there is clearance. It would likely be close.
     
  3. djp

    djp Roadster 2.0 VIN939

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    I think you'd need to be careful you don't end up cooling the temperature sensor more than the PEM, and then exceed its limits without realizing it.
     
  4. asgard

    asgard Member

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    Good point. Where exactly is the temperature sensor? It should not be close to the surface - it should be measuring the internal temps anyway.
     
  5. djp

    djp Roadster 2.0 VIN939

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    It would be worth asking a ranger, I haven't seen a schematic for the PEM and opening it up breaks warranty.

    The battery pack has a temperature sensor on each brick which is a great design. Hopefully they've been smart with the PEM too.
     
  6. richkae

    richkae VIN587

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    I've always been power limited by the motor overheating, not the PEM.
     
  7. Doug_G

    Doug_G Lead Moderator

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    Ditto. I was at the track yesterday, and the PEM didn't even get warm. The motor sure did.
     
  8. hcsharp

    hcsharp Active Member

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    Part of the standard annual maintenance is to clean the PEM to restore its full cooling efficiency but they rarely clean out the motor cooling ducts. The last time I had a ranger here we pulled the circular covers off the motor cooling intake and blew it out. There was a lot of dirt and a few leaves in there. The motor cooled down noticably quicker after we were done.
     
  9. strider

    strider Active Member

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    I propose to just use the battery coolant by extending the loop from the reservoir through the PEM and then back to the reservoir.

    I almost never get to power limited but my PEM is almost always at the last blue bar when doing my daily driving during the summer. I charge at work and charge/park in the sun so the PEM never cools down. I'm worrying about shortening its life due to heat as electronics and heat are not friends.

    I will do some experimenting with this next Spring. My warranty is valid until November and PEM heat isn't a problem during the winter.
     

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