h a l f b a k e r yI CAN HAZ CROISSANTZ?
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I was just reading an idea here, regarding electrically driven AC for cars. As far as I know this has been done already on several advanced electric vehicles. Those vehicles used small, electric motor driven, heat pumps.
My idea is to attack the problem from a different front, the cause.
Why
not thermally insulate our vehicles? Insulation technology has come a long way in recent years; perhaps even far enough to give us windows in our cars with similar properties to the best windows on our homes. After the windows, we could insulate the doors, roof and floor.
Imagine that. Your car would no longer be too hot to enter after 20 minutes in a parking lot in summer, and in winter it’d be toasty warm just from the heat of the occupants.
This would not only decrease the amount of energy needed to pump heat out of the vehicle (air conditioning), but also allow one to run the HVAC fans at a much lower speed, thus reducing noise.
I suppose with all that insulation, the road noise would also be greatly reduced.
There’s no denying that electric cars are the next major step in automotive technology. As the need to conserve battery life arises, I’m sure ideas like this will take off.
Some related ideas
http://eetd.lbl.gov...4/ThermalSkins.html
[Fussass, Oct 04 2004, last modified Oct 21 2004]
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I wonder what the R value is of the acoustic insulation used in very quiet cars like the LS430s, etc. I bet they are slower to transfer thermal energy than their less insulated brethren, though. |
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Some luxury cars (Mercedes, for example) use double-paned windows for sound deadening purposes. I suppose they have insulating properties as well. |
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You are right, present ACs are burning too much fuel. The trouble with cars is that they have a lot of glass, and that the glass must pass most of the visible light. Even special glasses that block all infrared still pass about half of the solar heat. The link describes an ideal glass. There is mention in the link about a photocell powered vent fan for parked cars, something that could be fitted to existing autos. What else could be done for present cars, maybe along the lines of shading while parked? |
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Shading makes a gigantic difference. There are a couple ideas on this site for portable shades. |
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So it's not really better AC for cars? Sounds like a "me too" or "let's all". |
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I've heard of house windows that will "tint" themselves to the point of opaquness with the flip of a switch. Perhaps something like this for cars?
Turn on the ignition, windows go clear. Turn off the ignition, windows become opaque.
It'd have to be a system where the natural state of the window would be transparant. It'd be a drag to have the glass go opaque while you're driving. |
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Oh dear. I thought AC stood for 'Armour Class'. That brought my youth rushing back. Mind you, better armour class for cars can only be a good thing. |
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If you simply had fewer contact points between the body of the car and the interior, it would help matters. |
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This has got me reading, and I have learned about “low E” coatings for glass and plastic. Maybe this is common knowledge but I missed it. This low E is the stuff that [a_passmore] is talking about as used on buildings. It really does reflect most of the IR and pass the visible. The reflecting part matters, not absorbing like regular tinting. Absorbing light make the glass hot and warms up the interior anyway. Reflecting it keeps the glass cool.
The darkness of car windows is the subject of statutes and regulations. It seems that it is allowed to darken them to pass only 35% of visible light. A lowE coating that passes 40% visible and 8% IR would cut heat-gain to 23% of plain glass.
So, until a new generation of cars comes out, can a lowE plastic film be used on car windows? Does anyone here have experience with it on buildings? |
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I like the idea of building a car specifically to attack the problem of efficient vehicle air-conditioning. I envision something like a puffy VW bug or a styrofoam cooler with wheels. Most of the US cars are built with the national market in mind, which includes both southern California and sunny Buffalo, N.Y. You buy (usually) the same car for both. But automakers do offer engine block heaters, so the idea of taking it to the next level, and specifically designing a cold, clean, air conditioned vehicle for the Latin/Carib and subtropical US market (which is only going to get bigger until the ice caps melt) is kind of cool. Probably sell a lot of them in Buffalo. |
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//double-glazing //
Mmmm... double-glazing... *drools* |
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My new Toyota (2004 Sienna) has low-E glass coating specifically to reduce air-conditioning needs. As for insulation, cars are already insulated, it accounts for a significant weight of the vehicle. |
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With respect to the glass, I am sure there are safety considerations at work here. In fact, one reason why cars get hot is the dash is usually a dark color so as not to reflect light, which would obscure the driver's vision. |
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If we really want to reduce A/C drain on engine power output here are my ideas: |
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(1) More efficient diffusion of a/c through porous roof and walls. |
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(2) Cooled or air-ventilated seats and steering wheel |
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(3) A/C controls that are less tolerane of user override. Incorrect control settings such as "60 deg F, max fan, front vents only" are an energy waster. |
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(4) Intelligent cooling, which detects 'kick-down' (the accelerator has been floored), and releases a clutch on the compressor belt. This could be used for small cars with sub-60 cu in (under a liter) engines. Don't laugh, it could be the future. (See separate idea) |
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Hi everyone.
I have an expensive,but practical idea....I think:
Why not keep your compressor, if it is in good shape and use an AC electric motor to push the compressor?
You would need an AC inverter, but it would have to be pure sine wave and be of a mega wattage. This is the same kind of deal as with an RV and in some cases, a deluxe big rig. AC motors are far more powerful than DC, and little would change with your automotive air conditioning system. The exceptions would just be where to place the compressor already in use and the electric motor driving it.
I have 2 S-10 extended cab pickups. Seems like I could just dedicate part of my truck tool box to the compressor and motor and run lines from underneath truck into bottom of truck box.
Cost? Let's say $1,000 - $2,000. Maybe we get away with $1,500. About the price of putting in a regular air conditioning system on a vehicle without one to start with. Seems VERY worthwhile in the long run. |
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I don't see an original idea here. Unless you're driving a very old and poor quality car, there is going to be some kind of insulation to help with temperature and noise. I do like [cloudface]'s idea of making the exterior of a car out of styrofoam. It would protect against crashes very well, unless the car caught on fire. |
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You might want to shild it from the fuel filler neck as well, since gasoline + styrofoam = napalm. |
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Having driven a double-glazed car for a few days in sub zero
temperatures, I can say that there is a downside. You need
the leaking heat (heat is largely free in cars) to melt the ice
on the windows. Double glazing stops this, to the extent
where once ice has been cleared, it can re-form. |
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" Don't laugh, it could be the future. (See separate idea) " |
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What if the car's front dashboard were surfaced in
something like Scotchlite? This is a highly retro-reflective
material, which sends (visible) light back in the direction
from whence it came. It shouldn't be too hard to engineer
it to work on a broader spectrum of light, including
infrared. |
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What if the car's front dashboard were surfaced in
something like Scotchlite? This is a highly retro-reflective
material, which sends (visible) light back in the direction
from whence it came. It shouldn't be too hard to engineer
it to work on a broader spectrum of light, including
infrared. |
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