[ausev] electric a/c system

[Chris Cooper]

Been there. Done that.

Peltiers are about 40% efficient so you would produce more heat than
cool. You would have to sink the hot side outside of the area to be
cooled. Car A/C units produce about 10,000-20,000 BTU's and are about
70-90% efficient depending on compressor speed and outside air cooling
the condenser. You would need about 20 Peltiers to even crack the heat
in a vehicle. That's 960watts best case. If you wanted to experiment
with Peltiers, I would go the route of localized cooling; that's my next
project. Are we back to a space suit now? Or at least a space helmet?
What is the end result? Cooling the air in the cabin, or cooling YOU?
Something to think about. One advantage of Peltiers is you can connect
them in series and drive them directly with high voltage. A 96V system
could directly drive 8 Peltiers. 

 

Maybe the comical pictures of vehicles I've seen with a window unit
hanging out of the rear window  of a car actually have some merit to
them... they are about 90% efficient nowadays. You would need a pretty
hefty inverter, but inverters are about 90% efficient too and there are
some 48V inverters out there. You can get about 5000BTU's on less than
550 watts. 

 

I had the opportunity once to drive one of the GM EV1 prototypes a few
years back and I asked the engineer how the A/C worked. It was
basically, very basically, a 330V(?) self contained A/C compressor unit
similar to  but smaller than a home central unit. It ran full speed
continuously eliminating the loss of cooling you get from idling at stop
lights, etc...

 

 

 

Chris Cooper

Manager, Computer Services

Department of Biomedical Engineering

University of Texas @Austin

<http://www.bme.utexas.edu> 

________________________________

From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
Behalf Of Joey Carroll
Sent: Wednesday, August 23, 2006 4:26 PM
To: ausev at austinev.org
Subject: [ausev] electric a/c system

 

Hi everyone,
New guy here. No EV yet, but im looking at converting an 84 CRX, and I
had some input on the 12v Aircon systems. I'm not sure if anyone has
seen this story before, its about how 2 teenagers made a compressor free
air conditioner using peltier thermoelectric chips. I know they aer
terribly inefficient compared to phase change cooling, but I think there
is some potential there. I recently got 2 of these chips off ebay for
around $16, just to play around with, I'll bring them to the next open
garage or meet if anyone wants to check them out. 
link: http://www.treehugger.com/files/2005/07/teens_invent_fr.php

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