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mid size cars need about 14,000 btu/hr capacity to "pull down" the temperature in a reasonably short time. The unit at this link has about 10,000 btu/hr capacity. It's advantage is that full capacity is working even when the car engine is idling. So it might be enough.

http://www.alibaba.com/product-gs/219708723/Brushless_DC_Electric_Compressor_For_Vehicle.html

Still researching variable speed car ac scroll compressors.

that looks good but at alibabba, they require an order of 40 or more, so though they have some good things, It dont work for do it yourselfers.
 

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Every 12,000 btu's is one ton.
I think an ac scroll compressor is the way to go, but to get the variable speed compressor requires an inverter similar to, but much cheaper than an ac traction motor inverter. It takes normal household 220, turns to dc, then inverts to 3 phase. Also, you need the controls for the inverter to run at the correct speed.
 

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$500 for compressor, $300-$500 for speed controller, Labor and parts to fit into an oem system. Nice for the guys who can afford it. Not for me
 

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Hi. From what I've seen, some of the AC solutions for EVs include a 120V AC compressor that requires an inverter to run off DC. There are others that run off 12/24V like AC units for boats, etc. These solutions start at about $500 and run to $1500. You're left with the task of integrating these to the rest of your car's AC system.

Its always hot here where I live so AC running always is a must. My donor car has an excellent AC system that would just require a pulley off the main electric motor. The issue with this is that I would have to "idle" the motor always. But if AC is a must and there are other things like power steering and maybe a water pump that must run as well, doesn't it make sense to tap the main motor and run these like they do in the ICE? The alternative of two or three smaller electric motors with DC-DC converters and speed controls seems costly for little efficiency gains.

I'm glad we're all talking about this now during the (northern hemisphere) summer. I'm sure that by October you will all forget about this and jump on "heating" topics :- )

JR
 

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The problem with thermoelectric is they are quite poor heat pumps when compared to a compressors.

Thermo electric = 600BTU at 219w = 2.73 btu/w

Compressor R134a = 15,461 BTU at 1900w = 8.14 btu/w



Compressors are around 3x more efficient just from those quick numbers. That is comparing a TECA thermo electric unit to a master flux unit. And the masterflux units don't seem to be that great either since I've seen my window ac unit get around 10 btu/w

If your interested in building your own thermo-electric ac unit, the modules are always up on ebay and they are fairly cheap. I built a mini ac unit a long time ago using a computer heat sink and fan on one side and a water cooling block from a PC on the hot side that ran to a small radiator.

One of the bigger modules: http://cgi.ebay.com/Gigantic-62mm-545-Watt-Thermoelectric-Peltier-Cooler_W0QQitemZ310145901996QQcategoryZ80149QQcmdZViewItemQQ_trksidZp4340.m8QQ_trkparmsZalgo=MW&its=C&itu=UCC&otn=5&ps=63&clkid=7484340904964900186

The other issue is you really need more BTUs to cool a car. Most cars are some where between 10k to 50k BTU. I think I had seen a Acura Integra according to the service manual is 14.2k BTU


Well I know this is an old thread but I couldn't take my own advice about the thermo electric systems and had to try it out. I figured I would reawaken everyone to show you what I put together.

So my fiancee is still driving an old Hyundia around in our 105F heat with no AC and I wanted to create something that runs off the standard alternator that would take the edge off during these summer months.

What I have ended up with so far is a 50mm by 50mm thermoelectric module that has a peak pumping capacity of around 800BTU while consuming around 24 amps at 14.4v. From what I am reading thought the pumping capacity drops when there is a greater temperature difference two sides of the unit so really I'm only getting 500BTUs or so maybe even less :-(



I created a water block on the CNC mill and tied together with a copper computer heat sink that will blow the cool air toward the driver.




Below you can see I was anticipating it pulling moisture out of the air so I created a drip tray for the water to run into a container. The inlet and outlet differential isn’t large enough to create enough condensation that it actually drip down at all.









I also have a 100+gph water pump that keep water moving through my radiator to be mounted in front of the engine radiator. It measures 5 inches x 11in and should have a peak capacity of around 700w with good air flow.


TESTING:

So other day I finally put all these parts together and got the whole system running and the numbers are promising but I really don't know if I will complete the install to the vehicle as I’m not sure if it will really help more than just a fan.

My power supply could only hold around 13.5 volts so the the thermo module is only running at around ~20 amps while my pumps and fans consumed another ~2 amps.

My blower for the cool side pushes about 30CFM and with 90F inlet temp I was reading an outlet temp of 75.2F. This felt noticeably cool on the hand.

My radiator outside was taking in 96.5F air and outputting 115F air. I was using a household box fan taped off to push air through but wasn't really flowing that good. I need to get some good high flow 120mm fans to move air over the radiator for testing but haven't picked them up yet and I think they would give better above numbers if I did.

Of course in a car you would have decent air flowing over the radiator when you are moving. I don't think I can leave computer fans on the radiator on the car as I would image that would over speed on the freeway?


So there you have it. I could go one more size up on the device to around 30 amps at 14.4v but doesn't gain me too much BTUs or if I could some how get 24v I can go up to a 800BTU (1300BTU max) but then the alternator will not be able to keep up.
 

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Nice work but I think you should have taken your own advice ;) Even if you get 800 btus it won't do much at all. I'd think you need at least a couple thousand, probably more.

Agreed, it was for the sake of a new project for my self more than anything, had some fun making it, but numbers rarely lie. I was now thinking about using it as a water chiller (multistage TEC) for a bomb 12v refrigerator / cooler that would use a micro controller for to keep the temps at 34F, maybe use glycol in my water then to allow for sub freezing circulation! The micro controller could even control a reverse on the TEC to do a little bit of heating to defrost the coils.
 

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Don't TEC's have horrible efficiency? I would think sizing it up to something that would move as much heat as a typical car heat pump would take several thousand watts.
 

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Don't TEC's have horrible efficiency? I would think sizing it up to something that would move as much heat as a typical car heat pump would take several thousand watts.
Yep very very true! For the same BTUs you would at least 3x more watts if not more. I'm not sure if your reply was directed at me but I wasn't planing on sizing it up at all. I did say multistage TEC for my cooler idea but that only would decrease my BTU and increase my temperature difference on the plates. That was just for cooling something like an ice chest or so. They look like this:

 

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Here is a link to my Air Conditioning install write up. I used the MasterFlux Sierra compressor. At 2kw it is rated 19,000 BTU/hr.

http://etischer.com/awdev/aircon.html


In the pic above, it would be kinda cool to mount the thermo-electric cooler directly to the keg rather than cooling the air around it. You could cool your keg much quicker, and probably get it colder.
 

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Here is a link to my Air Conditioning install write up. I used the MasterFlux Sierra compressor. At 2kw it is rated 19,000 BTU/hr.

http://etischer.com/awdev/aircon.html


In the pic above, it would be kinda cool to mount the thermo-electric cooler directly to the keg rather than cooling the air around it. You could cool your keg much quicker, and probably get it colder.

Read through your post a while back but realized I never responded here. Very nice setup, thanks for taking the time to put all the photos and information up. I was always interested in the masterflux setups and their site leaves a lot to be desired. Look like your in the area too! You blog on your car is a huge wealth of info!


Just FYI I am selling off my thermoelectric setup if anyone was interested in experimenting with it. I'm selling it complete with the radiator (w/ 2x 200cfm fans, pump, water block, copper cooler, tubing, all mounting and my reservoir. I'm running out of cash to keep other projects alive. I try and make a post in the classified section soon too.
 

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Here is a link to my Air Conditioning install write up. I used the MasterFlux Sierra compressor. At 2kw it is rated 19,000 BTU/hr.

http://etischer.com/awdev/aircon.html.
Hello, how well did this system wind up working? And, is it possible that a smaller compressor like a 6000BTU compressor might work? I'm looking at doing a full size regular cab pickup electric AC conversion. Thanks.
 

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I haven't used it much in the last few months since it is winter here, but in the summer it worked well. It is slightly under powered compared to an I.C.E powered A/C. On the 100 degree days, I usually run it at full speed and it takes about 15-30 mins to get the car cool. I would not recommend going smaller unless you really need the inch or two space savings.

The compressor I'm using is already very small. By the time you add fittings and hoses, the difference in size for the smaller compressor will be negligible.



I'd recommend flushing the system and replacing the drier with a new one.


Hello, how well did this system wind up working? And, is it possible that a smaller compressor like a 6000BTU compressor might work? I'm looking at doing a full size regular cab pickup electric AC conversion. Thanks.
 

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I see. I was more concerned with electrical usage than physical size. This will have to be powered by my ICE alternator. While I may do a conversion one day, right now I'm more interested in increasing the efficiency of what I have as well as moving some weight from the front of my truck to the rear.

Question, assuming that this is on an EV converted car, did you install an electric fan to pull across the condenser? If not this may be part of why you aren't getting cool enough. Even on an ICE car with the factory system, the car must be going 45MPH or so to generate enough airflow to not need a fan on the condenser. Also, a variable orifice may help your performance. They cost a bit more than a regular orifice valve, but will automatically adjust to give you the best cooling performance. I used one on my 87 S15 pickup when I converted it to R134a, and it seemed to give me performance at least as good as the R12 did. Third, a parallel flow condenser may help. A parallel flow condenser is supposed to be able to reject heat as well as a condenser about 30 percent larger than the regular one it replaces. Thanks for the info though, I see a lot of folks talking about this, but few who actually do and of the ones that do few report their results.
 

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The condenser has an electric fan, but no longer has a belt driven fan. The electric fan is two speeds. It runs at low speed whenever the compressor is running and at high pressure it kicks into high speed, this only happens when parked for more than a few minutes with the compressor at 100%. The compressor can be throttled back to run at reduced power.

You will be much better off with a belt driven compressor, the ICE has horsepower to spare and it would be a direct mechanical flow of power to the AC compressor. An alternator won't supply enough power to run the AC compressor, especially with the engine at idle. My compressor is 2kw and is barely adequate. It's not a matter of air flow though the condenser, it's a horsepower limitation of the compressor.



I see. I was more concerned with electrical usage than physical size. This will have to be powered by my ICE alternator. While I may do a conversion one day, right now I'm more interested in increasing the efficiency of what I have as well as moving some weight from the front of my truck to the rear.

Question, assuming that this is on an EV converted car, did you install an electric fan to pull across the condenser? If not this may be part of why you aren't getting cool enough. Also, a variable orifice may help your performance. They cost a bit more than a regular orifice valve, but will automatically adjust to give you the best cooling performance. I used one on my 87 S15 pickup when I converted it to R134a, and it seemed to give me performance at least as good as the R12 did. Third, a parallel flow condenser may help. A parallel flow condenser is supposed to be able to reject heat as well as a condenser about 30 percent larger than the regular one it replaces. Thanks for the info though, I see a lot of folks talking about this, but few who actually do and of the ones that do few report their results.
 

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Yeah, I realize the engine's got power to spare, but I'm hoping to get away from it eventually. If I make a conversion to full EV I want to make sure that everything currently driven by the engine has been removed beforehand. Thanks for the information on your setup though, it was most helpful.
 
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