Air conditioning

[bcg]

Not long ago, this back wall unit was advertised in my FB feed. I thought it was a self contained 24v AC at first and sent it to @LANCECASPER thinking maybe it could be an alternative since PlaneAC is no more. Turned out it was just the head unit part but, it sent me down a rabbit hole trying to reverse engineer the PlaneAC. I've been using the Ecowave Flow 2 and it's ok but, not great. Really, it's only good for the person it's blowing directly on, with 2 people in the plane someone is going to sweat. When my wife is with me, I'm the one sweating.
 
I came across some 12v AC kits with electric compressors, they need 60ish amps at 12v to run, which would be borderline for my alternator however, with a buffer battery I think I can make it work. So I ordered one to work out a prototype and see if it's possible. The condenser is going to be my biggest challenge, the one that comes with it is probably too large...unless I can talk my IA into letting me mount it in the tail and sign it off for me with a 337. I'd just need a couple of small holes in the baggage compartment bulkhead to pass the refrigerant lines through and a new W&B. It doesn't change anything structurally, I'll have a chat with him and see what he thinks. I'd say my odds of convincing him are 50/50, at best but, he can't say yes if I don't ask. If he says no way, then I'll figure out a way to fully self contained like PlaneAC did
 
Anyway, like the Mooney Mover, this will be a share as I go project. It's going to take a little while to work it all out. If anyone has suggestions for a more compact condenser, I'd be interested.  Something with double rows could work. This is supposed to be a 10,000 BTU system and this one is actually a heat pump because the cool only was unavailable.
 
Any comments and/or suggestions are welcome.

[MikeOH]

How much does all that weigh?

Check your 'buffer' battery capability/capacity carefully because, on the ground when you really need the AC, the engine is NOT going to be running at a high enough rpm for the alternator to help much. I.e. most of that 60 Amps is going to have to come from the battery for as long as you need to startup, taxi, run-up, and wait for release.

Also, I'd be very careful with tying in a non-aviation electrical item into the aircraft's electrical system (alternator and ship's battery).

[bcg]

How much does all that weigh?
Check your 'buffer' battery capability/capacity carefully because, on the ground when you really need the AC, the engine is NOT going to be running at a high enough rpm for the alternator to help much. I.e. most of that 60 Amps is going to have to come from the battery for as long as you need to startup, taxi, run-up, and wait for release.
Also, I'd be very careful with tying in a non-aviation electrical item into the aircraft's electrical system (alternator and ship's battery).

31 pounds for the AC stuff, 21 for the battery. The Ecoflow is 50 pounds with battery so, it's a wash there.

I'm using a 100Ah LifePO4 for.the buffer battery. That should handle ground ops and then recharge some in flight. I see this as really running off the battery with the alternator just charging that more than running off the airplane electrical. That's how the Ecoflow runs, it uses its own battery and I have a 10A charging cable going to it. For this, I'd run heavier wire on its own 50A breaker, like the PlaneAC called for. I haven't figured out what yet but, I'm going to put some sort of electrical isolation on so this won't cause any feedback to the electrical system. Might be as simple as a couple of diodes, I need to dig into that more.

Sent from my Pixel 9 Pro XL using Tapatalk

[IvanP]

Would love to have A/C in Bravo for summer ground ops. Unfortunately my current W&B would make such endeavor an exercise in futility. 

Good luck with it. Hope it will work for you and others. 

[MikeOH]

I've toyed with the idea of using dry ice, rather than water ice, to build an "Arctic Cool" type of system.  Dry ice at minus whatever it is, has almost twice the heat capacity of water ice and it doesn't leave behind all that water to get rid of! Dry ice sublimes at less than 0.5 lb/hour.  At the higher heat capacity you'd only need about half as many pounds of dry ice and very likely to last 6 hours, or more!

Thing is, it is IMPERATIVE to have a fool-proof system to vent the sublimated CO2 gas overboard; 1 pound of dry ice generates about 8.5 cubic feet of CO2!  Mooney cabin is around 75 cubic feet, so directly adding over 4 cubic feet per hour of CO2 to the cabin would be seriously bad!

[N201MKTurbo]

18 minutes ago, MikeOH said:

I've toyed with the idea of using dry ice, rather than water ice, to build an "Arctic Cool" type of system.  Dry ice at minus whatever it is, has almost twice the heat capacity of water ice and it doesn't leave behind all that water to get rid of! Dry ice sublimes at less than 0.5 lb/hour.  At the higher heat capacity you'd only need about half as many pounds of dry ice and very likely to last 6 hours, or more!

Thing is, it is IMPERATIVE to have a fool-proof system to vent the sublimated CO2 gas overboard; 1 pound of dry ice generates about 8.5 cubic feet of CO2!  Mooney cabin is around 75 cubic feet, so directly adding over 4 cubic feet per hour of CO2 to the cabin would be seriously bad!

I thought we went through this dry ice thing a while back. While dry ice has more sensible heat capacity, water ice has much more latent heat capacity. I think super cooled water ice is your best bet. You could cool your water ice with dry ice before you used it. That would really be the best you could do.

[bcg]

I've toyed with the idea of using dry ice, rather than water ice, to build an "Arctic Cool" type of system.  Dry ice at minus whatever it is, has almost twice the heat capacity of water ice and it doesn't leave behind all that water to get rid of! Dry ice sublimes at less than 0.5 lb/hour.  At the higher heat capacity you'd only need about half as many pounds of dry ice and very likely to last 6 hours, or more!
Thing is, it is IMPERATIVE to have a fool-proof system to vent the sublimated CO2 gas overboard; 1 pound of dry ice generates about 8.5 cubic feet of CO2!  Mooney cabin is around 75 cubic feet, so directly adding over 4 cubic feet per hour of CO2 to the cabin would be seriously bad!

I started reading this and immediately thought "but CO2" and then you addressed it at the end...lol

Sent from my Pixel 9 Pro XL using Tapatalk

[MikeOH]

5 minutes ago, N201MKTurbo said:

I thought we went through this dry ice thing a while back. While dry ice has more sensible heat capacity, water ice has much more latent heat capacity. I think super cooled water ice is your best bet. You could cool your water ice with dry ice before you used it. That would really be the best you could do.

Maybe I'm wrong, but my research shows the latent heat of vaporization for water ice is 144 btu/pound, but COOLING the ice below 32 F only gets you 0.5 btu/F.  Most ice is purchased is around 20 F to 25 F, so only another 6 btu/pound, so around 150 btu/pound is the best you're going to do.

Dry ice's latent heat of sublimation is nearly 250 btu/pound.  Dry ice is at about -110 F, so you could pick up another 80 btu if you used the dry ice to cool the water ice as you suggested; that would get you around 225 btu/pound.  But, that seem quite the hassle as you still need to get rid of the water!

Again, this is just 'back of envelope' spit-balling, so my numbers may be way off

[N201MKTurbo]

2 minutes ago, MikeOH said:

Maybe I'm wrong, but my research shows the latent heat of vaporization for water ice is 144 btu/pound, but COOLING the ice below 32 F only gets you 0.5 btu/F.  Most ice is purchased is around 20 F to 25 F, so only another 6 btu/pound, so around 150 btu/pound is the best you're going to do.

Dry ice's latent heat of sublimation is nearly 250 btu/pound.  Dry ice is at about -110 F, so you could pick up another 80 btu if you used the dry ice to cool the water ice as you suggested; that would get you around 225 btu/pound.  But, that seem quite the hassle as you still need to get rid of the water!

Again, this is just 'back of envelope' spit-balling, so my numbers may be way off

Don’t forget the density of the two.

[Yetti]

38 minutes ago, MikeOH said:

I've toyed with the idea of using dry ice, rather than water ice, to build an "Arctic Cool" type of system.  Dry ice at minus whatever it is, has almost twice the heat capacity of water ice and it doesn't leave behind all that water to get rid of! Dry ice sublimes at less than 0.5 lb/hour.  At the higher heat capacity you'd only need about half as many pounds of dry ice and very likely to last 6 hours, or more!

Thing is, it is IMPERATIVE to have a fool-proof system to vent the sublimated CO2 gas overboard; 1 pound of dry ice generates about 8.5 cubic feet of CO2!  Mooney cabin is around 75 cubic feet, so directly adding over 4 cubic feet per hour of CO2 to the cabin would be seriously bad!

I read an accident report of the Labcore plane transporting samples stored on dry ice. 

[MikeOH]

Just now, Yetti said:

I read an accident report of the Labcore plane transporting samples stored on dry ice. 

YUUP! That's why I don't think this idea is worth pursuing.  The venting needs to be 100% effective and 100% reliable. Not realistic.  I've considered a CO2 monitor, but when it goes off just what are you going to do? Crawl in the back seat and start throwing the dry ice out the storm window??? (Better have gloves on)

[N201MKTurbo]

https://www.amazon.com/KooingTech-Submersible-Transfer-Portable-Stainless/dp/B0DMFG2STN/ref=sr_1_13_sspa?

 

[MikeOH]

3 minutes ago, N201MKTurbo said:

Don’t forget the density of the two.

My numbers were BTU/pound for both dry ice and water ice.

Dry ice is denser than water (at least it's always sunk when I've dropped in water for Halloween 'effects')

[N201MKTurbo]

4 minutes ago, MikeOH said:

My numbers were BTU/pound for both dry ice and water ice.

Dry ice is denser than water (at least it's always sunk when I've dropped in water for Halloween 'effects')

You are correct, 1.55 gm/cc

[IvanP]

While my plane gets pretty hot in the summer, lugging large amounts of ice to the plane does not really seem a good solution to me. Bringing in substance that releases large quantity of suffocating gas even less so. I settled on the KoolScoop that I modified so it is removable and does not stay attached to the window and it seems to provide some relief on the hot days, albeit not as good as A/C.  

Total investment $50 plus some time to modify the scoop. Stays in the side pocket all year round and deployed when needed. Negligible effect on useful load and my back. Reasonably satisfactory result. 

[Schllc]

1 hour ago, IvanP said:

While my plane gets pretty hot in the summer, lugging large amounts of ice to the plane does not really seem a good solution to me. Bringing in substance that releases large quantity of suffocating gas even less so. I settled on the KoolScoop that I modified so it is removable and does not stay attached to the window and it seems to provide some relief on the hot days, albeit not as good as A/C.  

Total investment $50 plus some time to modify the scoop. Stays in the side pocket all year round and deployed when needed. Negligible effect on useful load and my back. Reasonably satisfactory result. 

I have to agree, I live in south Florida and have had several mooney’s with ac, and the kool scoop makes ground ops totally tolerable and once you’re over 8k all is well. 
I have an endless battle with the ac in my A and if I could use something like the scoop in that plane I would in a heartbeat. 
unfortunately a pressurized plane has bleed air and you just get cooked without ac and it sucks!

[IvanP]

19 minutes ago, Schllc said:

I have to agree, I live in south Florida and have had several mooney’s with ac, and the kool scoop makes ground ops totally tolerable and once you’re over 8k all is well. 
I have an endless battle with the ac in my A and if I could use something like the scoop in that plane I would in a heartbeat. 
unfortunately a pressurized plane has bleed air and you just get cooked without ac and it sucks!

That is where the Bravo shines. We usually cruise 15k and above and it is not uncommon to turn the heater on even in the summer. 

[Scott Ashton]

12 hours ago, MikeOH said:

YUUP! That's why I don't think this idea is worth pursuing.  The venting needs to be 100% effective and 100% reliable. Not realistic.  I've considered a CO2 monitor, but when it goes off just what are you going to do? Crawl in the back seat and start throwing the dry ice out the storm window??? (Better have gloves on)

Dry ice is haz mat and dangerous goods, and is higHly regulated for transport.   I wouldn’t mess with it….

https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173/subpart-E/section-173.217?OR=OfficeMobile