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Discussion Starter #1
After coming out to my car on a recent 85 degree day, where the inside felt as if it were 110 in the car, I began to think of possible ways to make cooled seats (they have heated seats, why not cooled seats?) So I came up with 3 options:
1. Gut a very small mini refrigerator and attach the system to the back of the seat with the coils running behind the seat foam. (Simply not practical and way too heavy)
2. Modifying the seats to allow ventilation and possibly a small fan to push air. (If the car is already like an oven, this won't help much, and may weaken the seat)
3. Thermoelectric (Peltier) cooling devices...

Now I know there has been a few threads several years back about cooling intake temperatures, but cooling a car seat seems like a little more simple of an application...

Upon further research I came across a handful of products that actually use thermo-electric cooling chips, only it is more of a seat cover, with liquid flowing through the pad that circulates over the cooling chip:
12 Volt DC Car Thermo-Electric Cool or Heat Seat Cushion

Now the stock seats are pretty small and wouldn't have much room for a thick cover on top, so why not reupholster the seat and build in a similar system into the fabric? There seems to be several of these peltier cooling chips online, and with a 60 degree temp difference, it seems like it would be a practical application.
TEC Thermoelectric Cooler Cooling Peltier Plate MAX 90W 12V 40mmx40mm | eBay

Anyone with experience in the field know if this would be very practical for a small application such as a car seat?
 

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At 40 mm that is less than 2 inches square. Just doesn't seem practical, at least that particular one. What about a remote start? Start it up and let it cool before you get in? (be careful about local laws for letting a car run unattended)
 

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many fancy cars have these which I beleive are based on thermo electric junctions. The challenge is how the heat is rejected from the hot side.

I would investigate how the oems do it at and more or less copy it.
 

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Discussion Starter #5 (Edited)
At 40 mm that is less than 2 inches square. Just doesn't seem practical, at least that particular one. What about a remote start? Start it up and let it cool before you get in? (be careful about local laws for letting a car run unattended)
rotfl Ironically enough I installed one (mainly for the better alarm), but I hadn't mentioned it because the "purist" members who don't actually DAILY DRIVE their cars love to ridicule mercilessly. It sure made the cold VA winter SO much better, but in the high heat the car is like an oven, and even running the car for 10-15min still isn't even enough to cool it down to keep from sweating bullets.

Yet as bad as the AC is in these cars, I'm surprised this idea hasn't been proposed yet...

As for the chip itself, the one in the 2nd link is only one chip; I'd imagine running coolant over a few chips would be sufficient?? Obviously the seat cover in the 1st link managed to accomplish this, so why not integrate it into the seats themselves? I guess the main questions are how many chips and how to mount them so fluid can flow over them and the back can ventilate out the heat removed.
 

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I have worked with peltiers to perform exotic cooling projects. Challenges:
1. High current consumption for the amount of heat moved, 96 watts electricity (8 amps at 12 volts) to move 35 watts of heat (amazingly inefficient).
2. Extreme high side hot temperatures, I am guestimating about 150 to 170 degrees on the hot side.
3. A human body represents roughly 100 watts of heat, so about 300 watts of electricity (25 amps at 12 volts) to provide break-even cooling.
4. Where are you going to blow off the heat from the high side of the peltier?
5. Potential fluid leaks (from the piping) on the inside of your car.

You might be better served using "cool shirt" technology in your approach.
 

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Discussion Starter #7
Hmmm if they are so inefficient then how come there are devices like portable mini-fridges and that cooling seat pad already? addertooth, do you know if they use the same peltier type technology? And any estimate of how many watts the AC system puts out to get a reference?

For the heat dissapation I would think an aluminum heat sink with a small computer fan type device would work?

If the peltier chip method would not be practical, any other suggestions aside from the first 3?
 

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...
1. Gut a very small mini refrigerator and attach the system to the back of the seat with the coils running behind the seat foam. (Simply not practical and way too heavy)
...
I think your part in red is wrong.
The peltier coolers are not what you want.

Look up <google> Coolsuit.
 

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Wek120,
Last peltier project I built required a massive 6 inch by 8 inch heatsink with triple high speed fans to carry the heat away from a single peltier. High-side temperatures was 105 degrees even with the large heatsink and triple fans. The high side heatsink was in an air-conditioned space. Had the heatsink been exposed to outside temperatures of 100 degrees the highside temperature would have been about 150 degrees. Yes, Peltiers have been used for camping cooler chests for several years. What Coleman (and other vendors) do not tell you is: When the outside temperature exceeds 100F, the inside of the cooler chest is only cooled to about 60F (far warmer than normal refridgerator temperatures). A dorm refridgerator cycles on and off to maintain it's temperatures, a peltier normally runs continuously. So AVERAGE power required for a dorm fridge (for a specific temperature) is about 1/4 to 1/3 of a peltier solution. But, a peltier is much much lighter and has no moving parts (other than the fan(s) cooling the high side, and does not required 110VAC to operate.
 

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Coolers are an enclosed small insulated system. Your seats are not, and would require significantly higher power for any noticible effect.
 

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I've owned cars with cooled seats. They worked by routing cooled air from the AC system through small tubes, and then into perforated seats that have holes in the seat and back cushions. Lotus seats are solid leather, so you'd need to change the center section. The advantage is little additional weight, the disadvantage is of course it relies on the weak AC systems already in place.

I've been thinking about this for two reasons: I find that the aerodynamics of the car are especially efficient at routing hot air from the radiators up and over the windshield. Wouldn't it be great to have small tubes that run from the vents under the dash along/under the console, and then up along/behind the seats exiting near the "headrest" like the Mercedes airscarf system. This system works both ways, providing cool air in the summer, and warm air in the fall/spring. Plus, it's nearly weightless. There's plenty of heat from the vents, but it never gets near your face/head.

The cooled seats are a different challenge. One option is to purchase the parts used in Middle East countries for the auxiliary air conditioner, and route that output to tubes in the seats. There is of course a weight penalty, but it's already designed to fit behind the seats.
 

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Discussion Starter #13 (Edited)
Just to clear things up, this is something just used during startup to keep from sweatting bullets while the rest of the car cools down.

That coolsuit runs off ice water, and bringing out a cooler full of ice every time you start your car would be a little ridiculous. Pushing air through the seat probably wouldn't be all that cool considering the surrounding air in or outside the car will still be really hot.
As for the peltier chip, I would think if you need a huge heatsink, it must mean it's removing a Significant amount of heat, and even at 60 degrees, that seems like it would it would be more than enough to keep it cool, no?
Most refridgerators seem pretty heavy, and I would think most of the weight would come from the critical components?

How about this:
4th option - Tapping into the AC refridgerant line before the AC housing?
The coils get so cold they freeze over anyway, so adding a parallel loop before the coils would be a win win option? Think of it like an electrical circuit; you add a parallel loop with a valve to control flow similar to a resistor. You can adjust the valve so its normally not flowing though the loop unless you open it slightly.
Sort of like this:
 

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Discussion Starter #15 (Edited)
Yea engineer here :rolleyes:
The problem with that is when your car is already 110 inside, that won't help much, it just blows already hot air, hence the proposed methods of forced cooling

One more idea; running separate tubing around part of the AC coils then to the seats. It would be easier to setup, but not nearly as efficient because you would have to transfer the heat first to the tubing from the AC coils, then to the seat, versus directly from AC coil to seat.

I would think just adding a small extra loop with a constant diameter tubing would essentially be the equivalent of a slightly longer evap line and a slight bit more refrigerant in the system, posing no real change in the thermodynamic cycle.
 

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Discussion Starter #17
Why not just exchange heat to liquid with the A/C?
You mean like a separate loop not connected with the AC? Thats what I meant by "running separate tubing around part of the AC coils then to the seats" the only thing is it probably wouldn't be very cool
 

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was there ever any progress to the improvement to the blower in the aircon system?
 
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