h a l f b a k e r y
non-lame halfbakery tagline

meta:

account: browse anonymously, or get an account and write.

 user: pass:
register,

# AC in the trunk.

Because why not?
 (+4, -2) [vote for, against]

So on my car (and every other car) the AC system is under the hood. Where it is exposed to the heat of the engine compartment, hard to get to for repairs, and adds clutter to the engine bay.

So why not put the whole thing in the trunk? Obviously the compressor would have to be powered by an electric motor instead of the car's engine, but you could make up for the weight by reducing the amount of piping that runs all around the engine. Now the AC won't have to fight the heat in the engine compartment, and if stuck the air intakes into the (normally fake) sidescoops on the backs of some cars you could pull in fresh air from somewhere other than the hot surface of the hood.

It could be well hidden behind the trunk carpeting so it wasn't in the way, and the cabin could be cooled from behind mainly, and the aux. air could be supplied through an insulated pipe to the driver.

One final advantage is that in a sporty car the ~50 pounds of AC equipment in the trunk would help to balance out the car to get that perfect 50/50 ratio for handling.

 — DIYMatt, Jun 30 2010

I think you'll find that in REALLY sporty cars the engine is in the back!
 — gnomethang, Jun 30 2010

REALLY sporty cars have the engine in the middle, not the back.
 — Alx_xlA, Jun 30 2010

[+] except now you need separate ductwork for the A/C
 — FlyingToaster, Jun 30 2010

 // electric motor //

 There's a flaw in the idea, straight off.

 You still have the mass of the A/C compressor, but now you're adding the mass of the motor, and the alternator has to be uprated in proportion.

Based on a 3kW refrigeration plant and allowing an optimistic 3:1 efficiency, that's a 1kW motor. On a 12V system, that's about 80 A, which is going to require some fairly heavy cables.
 — 8th of 7, Jun 30 2010

What do you need cables for? Use a copper chassis to provide electical power throughout the vehicle.
 — Jinbish, Jun 30 2010

 The part of the AirCon that needs to be kept cool is the condensor. This is normally located in front of the radiator, exposed to plenty of fresh air.

 [Jibnish] back in the old days, steel bodywork and chassis were used as part of the electrical circuit. Most common electrical faults were traceable to poor connection to the chassis.

Copper is expensive, soft and much less stiff than steel, so a shit material for a chassis.
 — Twizz, Jun 30 2010

[Twizz]: I did not know that chassis (pl?) were used as part of a circuit - that seems like a *terrible* idea. I suggested copper because a copper car would be daft, on second thoughts I should've suggested gold. Gold is an ideal car chassis material because of the high conductivity and maleability - which lends itself *perfectly* to crumple zones...
 — Jinbish, Jun 30 2010

Gold would be much too soft. Now a gold-plated car, on another hand...
 — RayfordSteele, Jun 30 2010

Gold can be alloyed and work hardened more than most people think. I believe we may be onto something here.
 — pocmloc, Jun 30 2010

 // a gold-plated car, //

[MaxwellBuchanan] has some, we believe.
 — 8th of 7, Jun 30 2010

Not that I think this is a good idea, but you could run the A/C compressor off an exhaust turbo or instead have A/C made of 2 mated Stirlings.
 — marklar, Jun 30 2010

 //back in the old days, //

Hey! My vehicle uses the chassis as the earth. Doesn't yours? I'm no autoelectrician and I drive a 12-year old 4wd, but I was pretty sure that was universal. Tell me your engine has a big fat earth strap going to the chassis. Tell me your battery negative terminal goes straight to the chassis. Tell me your starter motor has only a positive lead on the load side and is earthed through the bell housing... I mean without thec chassis as the earth bus, you need 2X the wiring...
 — Custardguts, Jul 01 2010

they make cars these days without chassis grounds ? O_o
 — FlyingToaster, Jul 01 2010

 [annotate]

back: main index