Interesting. The 13% gain would have to more than offset the added overhead of the cooling system.

The extra weight isn't that big an issue, as extra mass just adds to the kinetic energy of the moving vehicle which is mostly recouped during regenerative breaking. So the issue is the power use of the cooling system.

I also wonder what would happen if there's a coolant leak. Would the motor be toast?

Let me get this straight - liquid nitrogen and a car accident. Everything that gets that stuff on it turns into a crystalline substance with the strength of glass at best. If it gets on the driver or passenger they are history.

I would rather be sprayed with burning gasoline than hit with liquid nitrogen. At least they can treat the burns in a hospital. So let some one else do the testing of that system I will stay with conventional conductors until they have fool proof system of getting the nitrogen vaporized. Oh wait then there is the problem of the nitrogen vaporizing and exploding.

The energy to keep it cool is not the question, the question is can it made made to work safely? Just how safely? Can you imagine a tech replacing the liquid nitrogen in your car? Have you been trained in handling cryogenic fluids? That stuff is wicked.

Back when I was studying physics we used to have fun dropping items in liquid nitrogen. It bubbles like hell when you drop something into it. Then you can take the item out (like a rubber ball) and drop it on the floor. It will smash into a million pieces.

Maybe the quantity you would need to cool the electric motor would be very small? If your talking about 5-6 ounces that would not be too bad. Not sure how much you would need though.

Trust me, no you don't. When burning gasoline falls on you, it continues to burn. When liquid nitrogen falls on you (as long as you aren't immersed), it's slides off (doesn't wet you), and quickly evaporates.

I work with the stuff on occassion, and it's takes time to freeze things in it. It's not instant like in the movies. My old boss would check liquid nitrogen levels in the dewar containers by putting his bare hands into the stuff for a split second.




On this topic, I'm reminded of my high school chemistry teacher's friend who got fired over a liquid nitrogen stunt. He was also a chemistry teacher, and brought in a dewar of liquid nitrogen. He did all the obligatory stuff, froze a baloon (which shrank proving the gas law), froze a rose and crumped it up. Then he pulled out a latex glove packed with hamburger meat, held it so it looked like it was his real hand, and immersed it until it froze (freaking out his students). Then he pulled it ou and smashed it on the table.

People fainted, and he got fired.

If it's superconducting, the resistance is zero, not close to zero. Perhaps the writer is including resistance in other parts of the circuit.

In my MRI days, we used conventional low temperature superconductors for our field magnets. There were (and still are) cooled with liquid helium. You think liquid nitrogen is cold.

Tom

Mormegil, you wouldn't need a compressor. The liquid N2 is stored, compressed, in a tank. There is no need for a pump. All you would need is a simple radiator hose, and the N2 could exit at the end into the atmsphere (heck, it could be used for air conditioning, and we could eliminate the AC compressor (although Carnot would roll over in his grave)).

Ditto! In the lab we have the "five second rule" for dry ice (CO2(s)), but liquid nitrogen is more like a "one-and-a-half second rule," so I don't know that I would want to risk it. HOWEVER, if you are wearing a lab coat, and it sprays onto your labcoat, it only feels like cold water, and you will be just fine (provided you are not drenched in it).

This talk about spraying and venting makes me think of another MRI story. I may have posted this one before, but I'll tell it again:

The earlier MRI machines had field magnets cooled with both liquid nitrogen and liquid helium. The liquid helium cooled the magnet directly, while the liquid nitrogen was used as a blanket around the liquid helium. It was done this way because liquid nitrogen is a lot cheaper than liquid helium, so we let it take the brunt of ambient heat. The machine in this story was installed in a test suite, and the vent lines from the magnet had not been routed to the outside like they would be in a real installation. A glitch in our testing process caused the magnet to quench, which means all of the energy in the superconducting magnet is suddenly turned into heat. This heat, in turn, started boiling off the liquid gases. The venting gases make a lot of noise and fuss, but mostly it's an expensive inconvenience. Two engineers were in the suite waiting for the quench to end. One of them pulled out a cigarette and his lighter. When he couldn't get a flame from his lighter, he tried it a little closer to the floor and it lit okay. Higher it didn't work, lower it didn't work. There was a narrow band of oxygen between the top layer of helium gas and the bottom layer of cold nitrogen gas. The engineers decided it was a good time to leave.

Tom

Ah, the good ole days

N2 cooling of a motor in an electric car? Not very practical, how often would you need to add N2? It would be a consummable

I see quite a range in LN2 prices on the internet, $0.50 to $20 per liter, so it pays to shop around.

Besides the drama of freezing flowers etc., it can be used to make excellent ice cream, really really fast.

I dunno, way back in the day a "test of manhood" (translation... stupidity), would be to pour liquid nitrogen on your hand (albeit slowly) and the stuff would evaporate as it hits your hand, simply because the continuous heat your body produces is more than enough energy to heat it to a phase change, now if you poured A LOT continuously then yeah stupid, frost bite on your hand. However the scare of "instantly crystallization" with liquid nitrogen would require A LOT of nitrogen, way more than is needed to keep wires superconducting.

edit; whoops didn't see this was already addressed. Oh well I'll leave the graduate lab "war story" for people to enjoy

In college, my physics buddies took me down to the lab and dripped some on the warts on my hands. Went out and played flag football. Shriveled up an fell off in a day. Never came back.