B-Kool

[aviatoreb]

5 minutes ago, exM20K said:

Looks similar but more output than the Artic Air units. No cost obvious on the website.

At least for the Ovation and Acclaim, I would (and may if I spend more time in FL) opt for the  Kelly Aerospace unit.

https://kellyaero.com/mooney-airconditioning-system-now-available/

The company is a Mooney Summit sponsor, too.

It is STC’d, not all that heavy, and I’m trying to work out I’d I can offset much of the weight with lightweight Lithium batteries.

 

https://www.truebluepowerusa.com/products/general-and-business-aviation/#battery-stc-kits

 

Meantime, and in keeping with the subject of this old thread, I’m slumming along with a B-Kool, powered by an added 24V socket in the back wall of the baggage compartment.  It works as advertised, though I’ve found big blocks of ice bang into and dislodge the bilge pump at the bottom.  It is a huge improvement in comfort despite its limited duration.

-dan

The Kelley unit definitely looks like the number one best solution.

I live I the north and don't usually need a cooling solution except for when I travel to the south which I sort of avoid in the hottest months except for occasionally.  I should get a B-Cool - but I worry that lugging around a bunch of heavy ice on a hot tarmac on a 99 degree humid day will only make me even more sweaty on a hot day.  Do people keep the B-cool in the plan and add ice in bags, or do you lift in the whole unit into the baggage bay and set it up while leaning into a hot airplane, or what?

[exM20K]

15 minutes ago, aviatoreb said:

The Kelley unit definitely looks like the number one best solution.

I live I the north and don't usually need a cooling solution except for when I travel to the south which I sort of avoid in the hottest months except for occasionally.  I should get a B-Cool - but I worry that lugging around a bunch of heavy ice on a hot tarmac on a 99 degree humid day will only make me even more sweaty on a hot day.  Do people keep the B-cool in the plan and add ice in bags, or do you lift in the whole unit into the baggage bay and set it up while leaning into a hot airplane, or what?

I pick up bags of ice and carry them in the B kool in my car.  Then I put the empty B-kool in the plane and carefully dump the 2 10-12# bags into the B-Kool.  Add a 20oz bottle of water, and I’m on my way..  Easy peazy.

-dan

[carusoam]

Draining the wasted water back out of the B-Kool…

Uses it’s water pump…

I don’t recall how easy that is…. But, you don’t need to lift a full cooler out of the baggage area… 

Lots of time saved by not having to go to the gym several times each week…

 

Older Mooneys have the nice air vent in the bottom of the baggage area… perfect for a water drain tube…

PP thoughts only…

-a-

[aviatoreb]

5 hours ago, exM20K said:

I pick up bags of ice and carry them in the B kool in my car.  Then I put the empty B-kool in the plane and carefully dump the 2 10-12# bags into the B-Kool.  Add a 20oz bottle of water, and I’m on my way..  Easy peazy.

-dan

Is that the size that you get at like a 7-eleven?

[aviatoreb]

5 hours ago, exM20K said:

I pick up bags of ice and carry them in the B kool in my car.  Then I put the empty B-kool in the plane and carefully dump the 2 10-12# bags into the B-Kool.  Add a 20oz bottle of water, and I’m on my way..  Easy peazy.

-dan

This might the year I finally set such a thing up...

Im too wimpy to just tough it out in the heat.  I'm good in cold - but heat - no way!

[exM20K]

12 minutes ago, aviatoreb said:

Is that the size that you get at like a 7-eleven?

yes, the smaller ones.  big bags are typically 20 or 22#. 

[philip_g]

On 4/14/2022 at 5:35 AM, aviatoreb said:

Someone just posted this on Beechtalk.  Looks interesting.

https://www.peterschiffaero.com/sofie

$5750 as if 2017

 

https://www.cardinalflyers.com/spon/snf/report2018.php

[A64Pilot]

Someone on this forum temporarily installed a compressor type AC, I remember as it exhausted the condenser air through the baggage compt into the empennage.

Seemed to me to be a professional installation.

I didn’t dream that did I?

[philip_g]

1 hour ago, A64Pilot said:

Someone on this forum temporarily installed a compressor type AC, I remember as it exhausted the condenser air through the baggage compt into the empennage.

Seemed to me to be a professional installation.

I didn’t dream that did I?

Artic air real ac. I have one in my j.

[aviatoreb]

What's to stop a person from getting a car-model but electric motor AC unit and then build something portable out of that?  I don't know if it can be made to work but I bet it would be way cheaper.

Edited April 17, 2022 by aviatoreb

[EricJ]

10 minutes ago, aviatoreb said:

What's to stop a person from getting a car-model but electric motor AC unit and then build something portable out of that?  I don't know if it can be made to work but I bet it would be way cheaper.

The main practical problems:

Powering it.   It'll likely draw more current than a cigar lighter can provide in order to get much cooling capacity.   The compressors in most cars take several hp to run, which is why your gas mileage goes down noticeably when you turn it on.    It'll take a fairly big electric motor to turn one sufficiently to cool the full cabin.    There are newer ACs that are made to run on variable-speed electric DC motors, like for EVs, but they're still not trivial to power for a portable application.

Getting rid of the heat.   The A/C condenser on a car usualy sits in front of the radiator in order to get first dibs on cooling air.    Something roughly equivalent needs to be provided for something portable, and that's pretty difficult.   A friend put a belt-powered automotive A/C unit in his Brazov (four place retractable, roughly the same size as a Mooney), and put an upside-down hood scoop from a Subaru under the belly with the condenser in it.  It kinda looks like a P-51 radiator scoop under there, which is kinda cool.   Cessna 340s have a similar setup.   I think the long-body Mooneys put the condenser in the tail with a plenum to route outside air through it.   For a portable unit it's just a difficult problem to solve.

Other than that it's not a big deal. 

I think this is why B-Kools and similar are pretty practical and popular for portable applications.

[A64Pilot]

13 hours ago, aviatoreb said:

What's to stop a person from getting a car-model but electric motor AC unit and then build something portable out of that?  I don't know if it can be made to work but I bet it would be way cheaper.

I think electrically driven Auto AC’s are rare, EV’s have them of course as does the Prius, but I believe they are driven by roughly 300V.

‘There exist all in one box solutions similar to portable model you can buy at box stores where you vent a hose out of the window, the ones with two hoses are much more efficient. I have one for when or if we have a hurricane and lose power, I can still cool the bedroom with it running a generator of course.

I’m telling you, someone on this forum installed one, I remember the thread 

[aviatoreb]

2 hours ago, A64Pilot said:

I think electrically driven Auto AC’s are rare, EV’s have them of course as does the Prius, but I believe they are driven by roughly 300V.

‘There exist all in one box solutions similar to portable model you can buy at box stores where you vent a hose out of the window, the ones with two hoses are much more efficient. I have one for when or if we have a hurricane and lose power, I can still cool the bedroom with it running a generator of course.

I’m telling you, someone on this forum installed one, I remember the thread 

That's what I was thinking - an all in one box unit.

Yes I am aware that electrically driven car ac is rather rare, but it exists and it is cheap  relative to anything aviation - but still - its clear the power source is the hard part.

Too bad one couldn't have a honda generator sitting on the belly running the ac.  Hahah...

[aviatoreb]

16 hours ago, EricJ said:

The main practical problems:

Powering it.   It'll likely draw more current than a cigar lighter can provide in order to get much cooling capacity.   The compressors in most cars take several hp to run, which is why your gas mileage goes down noticeably when you turn it on.    It'll take a fairly big electric motor to turn one sufficiently to cool the full cabin.    There are newer ACs that are made to run on variable-speed electric DC motors, like for EVs, but they're still not trivial to power for a portable application.

Getting rid of the heat.   The A/C condenser on a car usualy sits in front of the radiator in order to get first dibs on cooling air.    Something roughly equivalent needs to be provided for something portable, and that's pretty difficult.   A friend put a belt-powered automotive A/C unit in his Brazov (four place retractable, roughly the same size as a Mooney), and put an upside-down hood scoop from a Subaru under the belly with the condenser in it.  It kinda looks like a P-51 radiator scoop under there, which is kinda cool.   Cessna 340s have a similar setup.   I think the long-body Mooneys put the condenser in the tail with a plenum to route outside air through it.   For a portable unit it's just a difficult problem to solve.

Other than that it's not a big deal. 

I think this is why B-Kools and similar are pretty practical and popular for portable applications.

Yeah - as I think about it - ice is in a way already a battery in a sense.  It is storing the energy it took to cool it - in modern times its the electric energy of your freezer.  So then if you transport it then you have a cheap storage of that energy in form of water ice.

Actually now that I think of it - ice used to be an industry before electric freezing (or steam powered freezing),  They used to cut up lake ice from cold climates like right here, with saws in olden times and store it in insulated houses throughout the summer.  But it was also an export industry - they used to cut up lake ice and put the big blocks on sailing ships and send it as far as to India!  Lake ice cutting was still existing in a form up until generally the 1950s since in some sense it was still competitive for convenience to freezing your own up until about then.

Back to the topic - ok - ice IS a battery.  And it is rechargable - just refreeze the water.  (although with economics and convenience it is sometimes easier to go back to the 7-eleven and buy another bag).  But here is my question - is there another substance - some other cold or frozen chemical that has more specific heat that would be more efficient for weight and or time utility than water?  Just a thought experiment since it is hard to imaging something more efficient than water? Maybe a fraction of carbon of dioxide - dry ice - in the B-cool would make for a longer lasting cool than simply water ice alone?  Dry ice at least is still a relatively common easily obtainable stuff.  Around here its available at any hunting store since it does last longer than water ice.  And if a person is sufficiently motivated they could buy a dry ice freezer/maker for their hangar.

https://www.amazon.com/Bel-Art-Frigimat-Cub-Maker-F38874-0000/dp/B0013J1UTM/ref=sr_1_10?crid=28ZSCL6PYMR2P&keywords=dry+ice+machine&qid=1650296323&sprefix=dry+ice+machin%2Caps%2C82&sr=8-10

[A64Pilot]

19 hours ago, philip_g said:

Artic air real ac. I have one in my j.

I just saw you responded, do you have a link to that thread, and how well has it worked?

[A64Pilot]

2 hours ago, aviatoreb said:

Yeah - as I think about it - ice is in a way already a battery in a sense.  It is storing the energy it took to cool it - in modern times its the electric energy of your freezer.  So then if you transport it then you have a cheap storage of that energy in form of water ice.

Actually now that I think of it - ice used to be an industry before electric freezing (or steam powered freezing),  They used to cut up lake ice from cold climates like right here, with saws in olden times and store it in insulated houses throughout the summer.  But it was also an export industry - they used to cut up lake ice and put the big blocks on sailing ships and send it as far as to India!  Lake ice cutting was still existing in a form up until generally the 1950s since in some sense it was still competitive for convenience to freezing your own up until about then.

Back to the topic - ok - ice IS a battery.  And it is rechargable - just refreeze the water.  (although with economics and convenience it is sometimes easier to go back to the 7-eleven and buy another bag).  But here is my question - is there another substance - some other cold or frozen chemical that has more specific heat that would be more efficient for weight and or time utility than water?  Just a thought experiment since it is hard to imaging something more efficient than water? Maybe a fraction of carbon of dioxide - dry ice - in the B-cool would make for a longer lasting cool than simply water ice alone?  Dry ice at least is still a relatively common easily obtainable stuff.  Around here its available at any hunting store since it does last longer than water ice.  And if a person is sufficiently motivated they could buy a dry ice freezer/maker for their hangar.

https://www.amazon.com/Bel-Art-Frigimat-Cub-Maker-F38874-0000/dp/B0013J1UTM/ref=sr_1_10?crid=28ZSCL6PYMR2P&keywords=dry+ice+machine&qid=1650296323&sprefix=dry+ice+machin%2Caps%2C82&sr=8-10

These things work by pumping cold water through a radiator and blowing air over that radiator, dry ice is way too cold to have water, you could do it I guess but carbon dioxide is not what your wanting to breathe, I doubt it could build up to a dangerous level but it’s something to consider.

I think dry ice is too difficult and expensive to make work well, if your going to pay those kinds of bucks go to a compressor based cooler.

My experience with them is you get 20, maybe 30 min of cooling and it’s done. My expectation of a compressor that my airplane may can power is one that could pre-cool the airplane over a couple of hours on shore power in the hangar and then keep you cool long enough to get through run-up and up to altitude where in cooler temps at altitude it could cope.

But it’s never going to cool off an already heat soaked airplane.

‘The problem is power, 1HP is 745 watts from memory and an automotive ac pulls 5 HP. it’s tough to find a definitive answer but a car AC pulls about 5 HP, now if we accept that we need that big of an AC 5 x 745 = 3,735 watts, div by 14 give us 266 amps, quite a bit more than we can supply, so we have to go smaller.

‘We put AC’s sourced from these people for the Thrush, it worked pretty good but pulled 100 amps at 28V so 2,800 watts which is still way more than we can power

https://zeesystemsinc.com/air-conditioning/

Edited April 18, 2022 by A64Pilot

[aviatoreb]

22 minutes ago, A64Pilot said:

These things work by pumping cold water through a radiator and blowing air over that radiator, dry ice is way too cold to have water, you could do it I guess but carbon dioxide is not what your wanting to breathe, I doubt it could build up to a dangerous level but it’s something to consider.

I think dry ice is too difficult and expensive to make work well, if your going to pay those kinds of bucks go to a compressor based cooler.

My experience with them is you get 20, maybe 30 min of cooling and it’s done. My expectation of a compressor that my airplane may can power is one that could pre-cool the airplane over a couple of hours on shore power in the hangar and then keep you cool long enough to get through run-up and up to altitude where in cooler temps at altitude it could cope.

But it’s never going to cool off an already heat soaked airplane.

‘The problem is power, 1HP is 745 watts from memory and an automotive ac pulls 5 HP. it’s tough to find a definitive answer but a car AC pulls about 5 HP, now if we accept that we need that big of an AC 5 x 745 = 3,735 watts, div by 14 give us 266 amps, quite a bit more than we can supply, so we have to go smaller.

‘We put AC’s sourced from these people for the Thrush, it worked pretty good but pulled 100 amps at 28V so 2,800 watts which is still way more than we can power

https://zeesystemsinc.com/air-conditioning/

I'm just brain storming.  Meaning spit balling ideas.

I imagine dry ice would be no good on its own in a B-Cool, but I still think maybe - dry ice may do something useful if say added in ratios to standard ice which would produce cold water for the radiator.  Perhaps 1/3 dry ice and 2/3 water ice?  1/2 1/2?  The dry ice would keep the cold stuff cold for longer.  I bet - but would want confirmed before I would even think of doing it - that the carbon monoxide gas wouldn't be a problem, since its probably not much and otherwise its a not noxious gas and as far as I know the only danger would be crowding out oxygen if it were a tightly sealed cabin.  But with good standard airflow, I would guess its not much of a problem.

So what if FBO's carried dry ice?  Yeah!  That would do it.  Otherwise, there is a hunting store like 2 mi from the airport here - only it doesn't get that hot here.  SO Im not going to bother.  Anyway just an idea. For the fun of it.  I suppose make your own is quite possible - when at home.  I bet some dry ice would improve the operation of a B-cool but be a little below the convenience to get factor.

Otherwise you and others have me convinced that a real AC is too much nuisance to home make and if I lived in Texas I probably would pay the big bucks for perhaps the Kelley unit.

E

 

[N201MKTurbo]

 

7 minutes ago, aviatoreb said:

I'm just brain storming.  Meaning spit balling ideas.

I imagine dry ice would be no good on its own in a B-Cool, but I still think maybe - dry ice may do something useful if say added in ratios to standard ice which would produce cold water for the radiator.  Perhaps 1/3 dry ice and 2/3 water ice?  1/2 1/2?  The dry ice would keep the cold stuff cold for longer.  I bet - but would want confirmed before I would even think of doing it - that the carbon monoxide gas wouldn't be a problem, since its probably not much and otherwise its a not noxious gas and as far as I know the only danger would be crowding out oxygen if it were a tightly sealed cabin.  But with good standard airflow, I would guess its not much of a problem.

So what if FBO's carried dry ice?  Yeah!  That would do it.  Otherwise, there is a hunting store like 2 mi from the airport here - only it doesn't get that hot here.  SO Im not going to bother.  Anyway just an idea. For the fun of it.  I suppose make your own is quite possible - when at home.  I bet some dry ice would improve the operation of a B-cool but be a little below the convenience to get factor.

Otherwise you and others have me convinced that a real AC is too much nuisance to home make and if I lived in Texas I probably would pay the big bucks for perhaps the Kelley unit.

E

 

The latent heat of sublimation for dry ice is almost twice as much as the latent heat of fusion of water ice. The problem is keeping the heat transfer to a manageable level. If you put the dry ice in an insulated container so heat would transfer into it at a slow enough rate, I think it would work. If you put it directly on the water ice, it would super cool the water ice and quickly sublimate. The super cooled temperature would increase the heat loss through the cooler's insulation. If you put the dry ice in a poor insulator, like thin Styrofoam or newspaper, so it wouldn't sublimate quite so fast, it may work. You need to keep in mind that the dry ice will generate a lot of CO2. You need to make sure you don't asphyxiate the crew and passengers. 

[Fly Boomer]

Not sure about heat of sublimation, latent heat of fusion, or super cooling (sounds like Thermodynamics -- bad memories) but I can tell you that throwing a chunk of dry ice in water causes the dry ice to violently change from solid to gas.  If you put dry ice and water together, better have a good ventilation plan.

[WaynePierce]

I've been seeing Jeff Foxworthy being a spokesperson for a unit just like the B-Kool (which I have) but can't find a link to it right now. It actually looks like it may be engineered a little better and has a battery option. I've seen this on Facebook, but just like Facebook, when you want to find something particular it isn't there...

Googlefoo proved useful: https://www.icybreeze.com/compare-versions/

 

 

 

Edited April 18, 2022 by WaynePierce

[Will.iam]

we get 10 lbs of dry ice every holloween to put into the punch bowl.  most kroger stores carry it just look for the penguin cooler by the checkout.  in 30 mins it has the punch as a slurry and in 45 mins like ice cream.  So you would have to make sure the unit was on to constantly be pumping heat into the water or it would turn into ice and stop your pump from running the water through the radiator.  as far as dry ice, airlines limit you to 5lbs per person for carryon.  I honestly think with the amount of holes and ventilation our cabins have it would be low risk if any at all.  and unlike carbon monoxide, your lungs would gladly trade carbon dioxide for oxygen as soon as it could get it.  I.E. you start feeling faint or light headed or elevated heart rate just open the airvents more or point one to your face and that should fix it.

[EricJ]

2 hours ago, aviatoreb said:

I'm just brain storming.  Meaning spit balling ideas.

I imagine dry ice would be no good on its own in a B-Cool, but I still think maybe - dry ice may do something useful if say added in ratios to standard ice which would produce cold water for the radiator.  Perhaps 1/3 dry ice and 2/3 water ice?  1/2 1/2?  The dry ice would keep the cold stuff cold for longer.  I bet - but would want confirmed before I would even think of doing it - that the carbon monoxide gas wouldn't be a problem, since its probably not much and otherwise its a not noxious gas and as far as I know the only danger would be crowding out oxygen if it were a tightly sealed cabin.  But with good standard airflow, I would guess its not much of a problem.

So what if FBO's carried dry ice?  Yeah!  That would do it.  Otherwise, there is a hunting store like 2 mi from the airport here - only it doesn't get that hot here.  SO Im not going to bother.  Anyway just an idea. For the fun of it.  I suppose make your own is quite possible - when at home.  I bet some dry ice would improve the operation of a B-cool but be a little below the convenience to get factor.

Otherwise you and others have me convinced that a real AC is too much nuisance to home make and if I lived in Texas I probably would pay the big bucks for perhaps the Kelley unit.

E

 

There are camping/tailgating/boating/fishing/outdoor fora filled with threads about the nuances of argument about what is best to put in a cooler for longest/best/whatever cooling of food/drink/beer/whatever.   Opinions vary, but usually boil down to ice vs freezer packs vs optimal ratio combinations of the two.   Suggestions of exotic materials, like CO2, usually get dismissed for the same practicality reasons brought up previously here.

I throw a number of freezer packs in the B-kool, fill in between them and the rest of the way up with ice, and then just enough water in the bottom for the pump to circulate it through the heat exchanger.   That seems to work really well, enough that it supported multiple-hour missions at relatively low altitude doing instrument approaches in Phoenix in the summer while I was getting my instrument rating.   i.e., it ran the whole time and was still blowing cold air at the end of the missions.   That's all I'll ever need, so the basic specs are met by this configuration.    Usually it's much easier as I only have it on long enough to get off the ground and up to about 5k feet or so, and then it only comes back on descending through a similar altitude when it starts to get uncomfortable.   It can sit in the airplane, off, for quite a few hours and still be able to do that.    For just about all of the flying I do it does what I need, but the cost is that I have to prep it before the flight, shlep it into the airplane, drain it afterward, etc., etc.   I get the useful load back when I'm not using it.

All that said, it is nice to just push a button.    The brand-newSeminole I did my ME training in had factory A/C, and even in May in Scottsdale it couldn't keep up and didn't keep the cabin very cool.    I'd have rather had the B-Kool.   

In Hitchiker's Guide to the Galaxy they used captive black holes in small craft as heat sinks so that thrill seekers could surf solar flares off of stars.   Maybe somebody can leverage that technology to cool air in an airplane cabin. 

Edited April 18, 2022 by EricJ

[aviatoreb]

2 hours ago, N201MKTurbo said:

 

The latent heat of sublimation for dry ice is almost twice as much as the latent heat of fusion of water ice. The problem is keeping the heat transfer to a manageable level. If you put the dry ice in an insulated container so heat would transfer into it at a slow enough rate, I think it would work. If you put it directly on the water ice, it would super cool the water ice and quickly sublimate. The super cooled temperature would increase the heat loss through the cooler's insulation. If you put the dry ice in a poor insulator, like thin Styrofoam or newspaper, so it wouldn't sublimate quite so fast, it may work. You need to keep in mind that the dry ice will generate a lot of CO2. You need to make sure you don't asphyxiate the crew and passengers. 

I agree with everything you said.

So maybe I think its not such a good idea to just throw in some dry ice.

But a specially designed system with some ice and some isolated separated dry ice with gas capture.... could be longer lasting.

Or is there some more exotic substance which would be even better and best run in an isolation unit that you freeze and refreeze - which really is a way of storing electric energy in the form of cold which as it melts is exactly what we want.  Some exotic substance that has even better latent heat, and could be kept entirely in a closed system so you recapture and just refreeze the stuff when you get home with some kind of built in slow-refreeze process.

[aviatoreb]

35 minutes ago, EricJ said:

There are camping/tailgating/boating/fishing/outdoor fora filled with threads about the nuances of argument about what is best to put in a cooler for longest/best/whatever cooling of food/drink/beer/whatever.   Opinions vary, but usually boil down to ice vs freezer packs vs optimal ratio combinations of the two.   Suggestions of exotic materials, like CO2, usually get dismissed for the same practicality reasons brought up previously here.

I throw a number of freezer packs in the B-kool, fill in between them and the rest of the way up with ice, and then just enough water in the bottom for the pump to circulate it through the heat exchanger.   That seems to work really well, enough that it supported multiple-hour missions at relatively low altitude doing instrument approaches in Phoenix in the summer while I was getting my instrument rating.   i.e., it ran the whole time and was still blowing cold air at the end of the missions.   That's all I'll ever need, so the basic specs are met by this configuration.    Usually it's much easier as I only have it on long enough to get off the ground and up to about 5k feet or so, and then it only comes back on descending through a similar altitude when it starts to get uncomfortable.   It can sit in the airplane, off, for quite a few hours and still be able to do that.    For just about all of the flying I do it does what I need, but the cost is that I have to prep it before the flight, shlep it into the airplane, drain it afterward, etc., etc.   I get the useful load back when I'm not using it.

All that said, it is nice to just push a button.    The brand-newSeminole I did my ME training in had factory A/C, and even in May in Scottsdale it couldn't keep up and didn't keep the cabin very cool.    I'd have rather had the B-Kool.   

In Hitchiker's Guide to the Galaxy they used captive black holes in small craft as heat sinks so that thrill seekers could surf solar flares off of stars.   Maybe somebody can leverage that technology to cool air in an airplane cabin. 

Maybe I am over doing a solution to a problem that's not a problem.  B-cool sounds cool.  Maybe this is the year I get it - as I said I don't need it for flying at my home area - up at the Canadian border - too often - but when say I visit my mom in the South -' its hot in the summer!  But then .... ice on the road.  Thanks for the suggestions all.

OK - back to your over the top brain storming - hitchhiker's guide to the galaxy - love it.  BUT - I have to be critical on this one.  A mini black hole, fine.  They can theoretically be quite tiny.  But often - even a quite small one can be very massive.  So suppose you put a mini one in your luggage compartment, well there's problems.  Lots of them.

Stephen Hawkins argued that black holes smaller than 10^-8kg just won't exist for quantum mechanical reasons.  And really small ones would evaporate almost instantly because of Hawking radiation.  Ok, all that aside, the Schwarzschild radius of a 10^12kg black hole is 1.48 x 10^-13 which is really small because remember the diameter of your typical Joe Average atom is 10^-10.  So way smaller.  So that's a really small black hole that you will have no problem fitting into your baggage compartment.  But then what?  How are you going to get it to stay in your baggage compartment when you go flying?  Its so massive it will just want to stay there as soon as you start your take off roll - so there you go without your mini black hole that now made a (very small) in the back of your airplane as you essentially fly away from it leaving it in place.  But wait, that's not really what would happen - it would - since it has mass, and gravity - start falling toward the center of the earth, straight through the ground...reach the middle of the earth ..shoot on past, and then rise asymptotically to the other side where it would briefly appear above ground (assuming same AGL) and then turn around and start falling back - however not back to where it started since earth is rotating through its day.  Besides that - how are you going to put it into your baggage compartment in the first place?  I mean what - special gloves???!!

Folks I really think this is impractical.  Forget the mini black hole.  Let's talk about the kelley stc air conditioner again.  Its probably cheaper too.

[N201MKTurbo]

6 hours ago, aviatoreb said:

I agree with everything you said.

So maybe I think its not such a good idea to just throw in some dry ice.

But a specially designed system with some ice and some isolated separated dry ice with gas capture.... could be longer lasting.

Or is there some more exotic substance which would be even better and best run in an isolation unit that you freeze and refreeze - which really is a way of storing electric energy in the form of cold which as it melts is exactly what we want.  Some exotic substance that has even better latent heat, and could be kept entirely in a closed system so you recapture and just refreeze the stuff when you get home with some kind of built in slow-refreeze process.

Water already has the highest specific heat. So you won’t find anything better. Supercooled water ice is probably your best bet.