Electric AC Compressor?

Ted

Ted

The pilot formerly known as Twin Engine Ted
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I'm thinking of building a "removable" AC system for the 310. Basically think like the Arctic Air freon systems, but I want to build it myself. Part of the reason is because I used to be an AC tech and have all the tools, but a lot of it is because Arctic Air wants a lot of money for their unit, and I know I can make it cheaper. Plus, I have a particular area in mind for the 310 that I want to place it, so if I build it myself I can more likely get it to fit.

Does anyone know of cars that come with an electric compressor? I've found a couple of electric compressors online, but I'm thinking an automotive equivalent might be cheaper than some of what I'm finding. It also would probably be more appropriately sized - the ones I'm finding are more sized for RVs and big rigs.
 
I've looked into it too. The best bet I've found are the ones used in pleasure boats. The whole units are rather heavy, but if one wanted to source the comp and then gather up the rest of the bits, that would be the place I would source it.

Having given this some amount of thought, I was going to use a short, but very wide condenser, and put it above the cylinders on the back where the oil cooler would go. I'd put some kind of flap door that could be closed to get max air through the engine, then opened when in flight and could divert some to the condenser. Two very short hoses and mount the evap under the panel like the ones added to old Fords and Dodges. It would also be short, and very wide with two or three fans behind. Have a scupper trough with a drain off to the side through a rubber hose.

Compressor and motor drive could be mounted on the firewall. The idea is to keep everything simple, and compact, and light. Short hoses, short wiring, short comp, and evap. If I get an E-LSA I might investigate with some actual metal rather than just thought experiments. So far, just that.
 
Mitsubishi MU-2's use an electric-driven AC compressor on 28 volts, you might do some research there and see if you can track it down to the manufacturer.
 
Forget cars. You have a 24v airplane, you need tractor parts. Lots of 24v construction equipment has electrical HVAC
 
Skylane81E said:
Where are you going to exhaust the condenser from the cabin?
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Condenser goes on the rear baffle plate, above and to the back of the engine. Usually near the oil cooler on many planes. It would need to be wide and short(height) and it would exhaust right out the back of the baffle plate, and the hot air would exit the lower cowl area just as the hot air through the engine.
 
The new (and well-received) AC system for the Bonanzas has the condenser behind the aft bulkhead, and adds louvers to the right-side skin to allow the hot air to exhaust.
 
Skylane81E said:
Where are you going to exhaust the condenser from the cabin?
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It would require an opening into the tail section, which is just through a flimsy little piece of something. That will keep the warm air back there, and there would be sufficient airflow to meet the demands. A relief tube for the evaporator needs to be added out the bottom, as well. Pretty simple.

Putting the condenser in the engine bay with a flapper valve is definitely NOT a temporary install, and would require a 337 and a lot of work, plus routing a bunch of long AC hoses. A more compressed condenser with a fan attached would be easier and more logical, I think.

Thanks for the other suggestions - I'll start looking into them.

Jeff: True on needing 28V, do you have any specific suggestions for tractor models to look into? I don't have a convenient John Deere dealer next door that I know of.

The 310's cabin is realistically going to have the cooling needs of an SUV. I think most of us looking to put freon air in our planes have similar needs. Spike, I think you and I are looking for very similar setups.

This might also lead to an alternator upgrade, but maybe not. I've been thinking about the PlanePower alternators anyway, and figured we'd put them on when these ones crap out. There would also be the question of how to allow for ground power so that it can be run to cool things off while we're loading up.
 
Ted, we tried every way from Sunday to figure out a way to do useful electric air for my Bo, but it being a 14v plane, no way no how we were going to get enough BTUs from available amperage... just not gonna happen. Were it a 28v plane, whole other world.

Working plan is to have an extra battery to run the system for ground cooling pre-start and to average out the current draw; also, including a crowbar controller to automatically shut down the AC if there were to be excessive current draw relative to available (say, one alternator failed).

A&P even suggested that we could install a second alternator on aft accessory pad, 28v, plus a 28v battery, solely for the AC system; too much, says I; AC in my Bo will involve a belt-driven Sanden compressor on the back of the engine (drive off rear of starter drive).

Smart guy like you ought to be able to get AC in the 310 pretty easily, and that Masterflux unitized compressor / condenser setup is what you need to start with. We though the electric car systems would be a great resource, but they all use much higher voltage (210?), readily available from the battery arrays used in electric cars.

I have some other links / resources for parts / pieces / components here somewhere - maybe I can find them for you tonight.
 
Spike,

I think in a single (with one alternator) the power requirements become difficult to manage, and doubly so on a 14V plane. Didn't realize that your Bo was 14V. Having 28V and two alternators is a big help. We were thinking batteries for ground power as well. If the system ends up being 28V as planned, just another airplane battery back there would do the trick just fine for what we need.

Is the system you're going to be doing an STC or are you going for 337?

I'd appreciate any links/resources you've got.
 
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If this is a "fun" project, maybe you could roll something using Peltier juntions.

This won't scratch your itch to break out your old refrigerant manifold, but you might be able to gang them appropriately for your ship's voltage.
 
http://www.imarketcity.com/frfr5btupoac.html

Kinda heavy but you can take it apart and maybe lose some weight... Run an inverter to power it or have a switch over to cool the plane before flight using 120 v shore power..... And at 360 bucks, the experiment can't break the bank if the idea fails.:dunno:
 
The AirTractor crop-dusters that I used to support were all electric AC. They were turbine, though, so they had some high V power systems.

As far as tractor systems, every piece of heavy equipment I have ever operated had engine driven AC.
 
Well, it is a fun project but it's also a functional project. Realistically it needs to have 5-10k BTU capacity.

Even crazier of an idea... Design it so in the winter it could be used as a heat pump for auxiliary heating and pre-heat. :)
 
Ted DuPuis said:
Well, it is a fun project but it's also a functional project. Realistically it needs to have 5-10k BTU capacity.

Even crazier of an idea... Design it so in the winter it could be used as a heat pump for auxiliary heating and pre-heat. :)
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In some of the manufacturing facilities I have worked in, we found that we could put a smaller a/c unit with a very focused air flow area and get the same effect as cooling a large area. Added bonus was that the workers remained in the focused 'cool' work area more ;). You might get away with a smaller cooling unit by doing something fancy with the duct work to deliver the cool air where it's needed (back of the neck seems to work very well).
 
Ted DuPuis said:
Putting the condenser in the engine bay with a flapper valve is definitely NOT a temporary install, and would require a 337 and a lot of work, plus routing a bunch of long AC hoses. A more compressed condenser with a fan attached would be easier and more logical, I think.
.
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Iv'e also looked into the fully self-contained unit design you're thinking of, and it can be done, but you need to exhaust that air, and once you cut skin, you have to have a 337. My only ideas on exhaust from the cabin were to cut a 'window' port in one of the rear windows and duct it out that like a free standing AC unit you find on ebay.

The hassle with that is the loss of efficiency. Since the whole unit is in the cabin, you have to get rid of the BTUs from the condenser, but also the fan motor to run the air through the condenser and the condenser drive motor.

I couldn't see any way around the 337 route cause like Spike said, you've gotta have a bunch of amps on tap to run all that stuff. My Prius C has an all electric HVAC and it puts out some serious cold air, It might pay to look at the newer Prius stuff cause there is no engine driven pump.
 
Chris, that was what I planned on doing. Idea would have hoses ducted up to the front, adjustable to point towards each seat. Added benefit of easy reconfiguration if I also did the heat pump idea.

Although you don't have to worry about people leaving their seats in the 310. ;)
 
Ted DuPuis said:
Well, it is a fun project but it's also a functional project. Realistically it needs to have 5-10k BTU capacity.

Even crazier of an idea... Design it so in the winter it could be used as a heat pump for auxiliary heating and pre-heat. :)
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I would definitely wire it to that you could pre-cool the cabin using shore power in summer. I don't have a specific tractor model in mind, but I'd point out that typically ag equipment is 12v and construction equip is 24V, so I'd say hit your local cat, case, volvo, etc dealer and see what they might have. Also your local version of TSC, Farm&Fleet, etc type stores. There are all sorts of retrofit AC units where you cut a hole in the cab roof and bolt them on. Inside one of these boxes would be all the bits you need. And considering the amount of glass in a typical machine cab these boxes probably have plenty of BTU's for a 310 cabin.
 
I'm not a professional in this area, but won't power requirements sink this project? Where will you get enough power to run it?
 
bullwinkle said:
I'm not a professional in this area, but won't power requirements sink this project? Where will you get enough power to run it?
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stepping back and looking at it big picture, many bulldozers or wheel loaders (24V) with such a setup have a single 120ish amp alternator and far more high-amperage lights to operate than the landing lights on the 310. The 310 probably has a pair of 90+ amp alternators.

It's not a project I'd have any interest in for my plane, but I don't why it wouldn't be feasible given enough desire and tinkering ability.
 
Older King Airs have electric air conditioning, like our 65-A90.

But, we would always run it with a GPU. I can't imagine battery that would run it for the 20 minutes required to cool the cabin when it has been sitting in the sun.
 
bullwinkle said:
I'm not a professional in this area, but won't power requirements sink this project? Where will you get enough power to run it?
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From the two alternators, which are plenty sufficient stock and will be even better if upgraded, which we've been thinking about doing anyway.

The Arctic Air freon units demand 19-37 amps, depending on which one you buy. That's easily doable in the summer for us, and I think their amperage is probably similar to what we'll use given it will be a similar design.

Keep in mind in the winter this plane has to run prop heat, dual heated pitot tubes, and the Janitrol heater (two fans plus ignition). We have LED landing and taxi lights, with expectations to make other lights LED in the future.

Keith AC, which is STC'd in a lot of bigger Twin Cessnas, is also all electric.
 
JHW said:
It's not a project I'd have any interest in for my plane, but I don't why it wouldn't be feasible given enough desire and tinkering ability.
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Obviously the plane and its occupants have survived 45 years without AC. Our missions with it have proven to make it a desirable feature - unlike any other aircraft I've flown, the 310 has a particularly sauna-like interior that is brutally warm for a large number of flight ops. On my Belize trip, I was feeling fatigued at the end of it, mainly due to the heat for hours on end. However the heat becomes a fatiguing and detrimental issue mostly on takeoff and landing, when it gets hottest in the plane, which one could argue as a human factors safety concern.

At least, that helps my justification for the project. :D
 
kgruber said:
But, we would always run it with a GPU. I can't imagine battery that would run it for the 20 minutes required to cool the cabin when it has been sitting in the sun.
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I think it'd be doable for this for 10-20 minutes, but I absolutely would not use the main aircraft battery for it. So separate battery setup would be required.

The main question to me power wise is whether at idle the engines will power it on stock alternators. I think it will at 1000 RPM idle. And if not, more reasoning to upgrade the alternators.
 
Ted DuPuis said:
The Arctic Air freon units demand 19-37 amps, depending on which one you buy. That's easily doable in the summer for us, and I think their amperage is probably similar to what we'll use given it will be a similar design.
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So you're looking at needing to wire for 45 amps. That's going to be what, 8 gauge wire?

Can one hard-wire something and have it be "temporary" if not you're going to need to come up with some "temporary" connector that is pretty damn heavy duty. Not like you're going to do 45 amps off a cigarette plug.
 
I think Emerson makes a scroll compressor where the stationary half can be "retracted" away from the rotating half. The purpose is to reduce starting current. A feature like that would be nice to have.
 
Ted DuPuis said:
I think it'd be doable for this for 10-20 minutes, but I absolutely would not use the main aircraft battery for it. So separate battery setup would be required.

The main question to me power wise is whether at idle the engines will power it on stock alternators. I think it will at 1000 RPM idle. And if not, more reasoning to upgrade the alternators.
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If you're doing 37 amps at 24 volts you're going to need a pretty serious battery setup to run it for 20 minutes.

You don't want to pull even deep cycle batteries below 50% capacity. So you're going to need a battery configuration that could do 37 amps at 24 volts for a hour.

Two 24M marine batteries could give you 37 amps at 24 volts for 30 minutes I would think. That'd be the MINIMUM battery size you'd want for that. You're looking at 41 lbs per battery so 82 lbs right there. You might even need to go bigger...
 
jesse said:
So you're looking at needing to wire for 45 amps. That's going to be what, 8 gauge wire?

Can one hard-wire something and have it be "temporary" if not you're going to need to come up with some "temporary" connector that is pretty damn heavy duty. Not like you're going to do 45 amps off a cigarette plug.
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Talking with flyingmoose about it, probably 6 GA.

Keep in mind, the Arctic Air units are also "temporary" install.
 
jesse said:
If you're doing 37 amps at 24 volts you're going to need a pretty serious battery setup to run it for 20 minutes.

You don't want to pull even deep cycle batteries below 50% capacity. So you're going to need a battery configuration that could do 37 amps at 24 volts for a hour.

Two 24M marine batteries could give you 37 amps at 24 volts for 30 minutes I would think. That'd be the MINIMUM battery size you'd want for that. You're looking at 41 lbs per battery so 82 lbs right there. You might even need to go bigger...
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Good points. I could afford the useful load hit, but this might make a 110V plug-in more desirable for that.

Either way, ground power is a nice to have rather than a need to.
 
So I took a look at some of the links. Few thoughts:

Spike, your link looks promising to the MasterFlux setup. Ideally I'm trying to fit something on the hat rack, and I think that will be a bit too large, though. But I also just might not be able to fit something on the hat rack. That would make the compressor, and condenser part easy. The other neat part would be being able to use hard lines and solder it all, rather than have hoses and deal with the associated cost and hassle there. So that could be a nifty idea.

I'm guessing that Arctic Air uses a blower motor that's something like this:

http://www.attwoodmarine.com/store/product/store/turbo-4000-ii

Now the question is that Arctic Air talks about their units as 200 cfm or 400 cfm. This is a 200 cfm motor, but the tech sheet:

http://www.attwoodmarine.com/userfiles/store/product/files/1238/1731.pdf

Says 200 in open flow, 100 in system. So, not quite sure how that ends up working out. Thoughts?
 
Spike, did you find out what one of those MasterFlux compressors is supposed to cost?
 
If I were doing this I'd look into a variable speed compressor like what's often used in "ductless" (aka split) AC units. That way you could run with less power when the engines are idling without draining the batteries. You'd need an "inverter" to power the motor but that could be located close to the main bus with lighter gauge wire carrying higher voltage to the motor.
 
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As I figured, that Masterflux is pretty spendy. So not out of the question, but something to consider.

Any thoughts on the blowers I linked to a few posts up? If that's similar to what Arctic Air uses, two should be sufficient, or go to 4 for extra cooling.
 
Yep, that's similar to the idea I've got.

Been wanting to make the 310 experimental for a while. ;)
 
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