[ausev] A/C in an EV

[Christopher Robison]

On Tue, June 12, 2007 9:06 pm, Claire Sorenson wrote:
> Gary, thanks for the tip.  I think this is the best A/C alternative I have
> seen so far. I was looking for something portable and enviro-friendly.  It
> may seem expensive, but probably no more than retrofitting motors, and
> evaporators, and compressors, fans etc.

The difference is that doing the latter will give you a system you'll be
happy with for a long time. The costs can't really be directly compared,
because what you're getting is so different.

A few people have tried icewater air conditioning, including Mark Kapner
who did it for a while in his Geo, and I briefly experimented with my own
hacked together version a few years ago when I was without A/C in my
Civic. In general, most people who try this find the experience
interesting but dissatisfying.

First, although it seems fun in the beginning, you soon realize: that's a
lot of ice. And when you get where you're going, you now have a lot of
*water* to get rid of. That much water is really heavy, and it sloshes
around in the cooler, making it difficult to handle. You're not going to
want to carry that water very far, so you're probably going to dump it on
the parking lot. Be careful not to slosh it on your upholstery or yourself
-- ice chest lids don't seal well. A related issue is, where do you get
all that ice?  I recall that Kapner got it from the office ice machine; I
wasn't so lucky and had to use what little ice my freezer could produce. 
Dealing with this every day gets to be a hassle after the novelty wears
off.

Second, it's just not really that effective at cooling. I don't know
exactly how cold the evaporator of an automotive A/C gets, but I'll bet
it's a bit colder than ice water. At any rate, the chilled water only
remains at icewater temperatures part way through the radiator warming up
as it goes, whereas in an A/C evaporator, you've got that refrigerant
phase change helping to absorb more heat.

For maybe twenty bucks in parts, I didn't feel like I'd lost much; it was
an interesting experiment and I got what I paid for. Maybe this guy has
built a more effective design, but I don't think there's any way in the
world he could improve it enough to be worth a fourth of what he's asking.

Feel free to try this, but don't expect that you'll be happy with it for
long -- spend accordingly.



-- 
Christopher Robison
chris at ohmbre.org
http://ohmbre.org          <-- 1999 Isuzu Hombre + Z2K + Warp13!