You might be seeing a lot of
Internet Influencer Hype Advertiser Content You Won’t Believe They Don’t Want You To See!
lately about these so-called personal air conditioners. You might have wondered if these might be
too good to be true. And today I’m here to tell you that you’re
right to wonder, and the answer to your question is an absolute, unequivocal, indisputable, irrefutable probably. This thing, as well as most of the devices out there which emulate its design including the Blaux?… Blaugh? Bloerp?... is a miniature swamp cooler. Note; not air conditioner! Despite what it
may claim on the box. Swamp cooler. By the way, swamp cooler seems to be a rather US-specific term; evaporative cooler is the more technical and also less gross term. But swamp is just one syllable so I’m saying
that. It’s also just more fun! Swamp. Swomp. Swawmp. See? Deal with it. Swamp coolers do work, in fact in parts of
the world they’re genuinely wonderful and can sometimes negate the need for air conditioning
altogether. But these are not replacements for air conditioning. If you live in a region of the world where
the role of air conditioning isn’t just to cool, but indeed to provide dehumidification, well then these thing are just silly! You see, these aren’t air conditioners by
any stretch of the imagination. However, in a sort of odd twist, swamp coolers
do in fact use the same general sort of principle as a conventional air conditioner. They exploit the fact that as water evaporates,
it takes energy from the air in order to do so. I talked a bit about latent heat in my video
on rice cookers. At a very basic level it's simply that in
order for a substance to change phases from liquid to gas, it requires a lot of energy. Water is, believe it or not, a substance and
you can see this in action when you boil it. It doesn’t just disappear when it reaches
boiling point because it takes *more* energy to cause it to vaporize. The same thing happens when water evaporates. You don’t have to get water up to boiling
point in order for it to change phases. You probably knew that already, the water
cycle is a thing and we have rain and stuff and the oceans aren’t boiling. In any body of water, the water molecules
close to the surface can, depending on conditions, have enough kinetic energy to free themselves
from the liquid phase fairly easily. Of course extra energy, for example from the
sun, will help but the key thing is no matter how water changes phases, it takes a little
energy for itself. A device like this is simply using that concept
to provide *some* cooling. All it is is a fan which blows air past some
sort of absorbent material which holds water. The forced airflow and the large surface area
provided by these paper flute things helps the water to evaporate quickly. As it does so it takes some of the heat energy
in the air with it and the effect is that… well you get a bit of cooling. This is, by the way, exactly how sweating
cools you off. Fun fact! The name swamp cooler is thought to have originated
from the musty smell these often develop as algae and other fun lifeforms take refuge
in their mightily moist matrices. If you’ve never encountered a swamp cooler before, well we’ll get into why that might be in a short while, but you’ve probably
experienced the concept at work in one way or another. Those misting fans that blow not just air but
also a fine mist of water at you? Their goal isn’t just to make you annoyingly
damp, in fact the hope is that you don’t get wet at all. Instead, the spray nozzles atomize the water
into a very fine mist, which will quickly evaporate and cool the air, sometimes a dramatic
amount. Even without the fan, if you’ve seen those
mister things in a garden or whatever - well typically that's the goal. Cooling. And that’s the same sort of thing that these
devices do. But there’s a big, big, big big big big huuuuge
caveat. See, where I live, air conditioning isn’t
there just to make a space cooler. It’s also there to remove moisture from
the air. In fact that was the original purpose of air
conditioning - to dehumidify the air in factories and other industrial buildings where humidity
was causing problems on the production line. Human comfort was just a bonus. Air conditioners can remove moisture because
the refrigeration cycle relocates heat energy via a liquid refrigerant, which creates a
very cold surface which water vapor in the air will condense on. OK, time to bring this guy out again. I’m going to explain what actual air conditioners
do, and if you’re not interested in this part go ahead and skip to here. But, I think it will help to illustrate why
these fad devices are… fad devices. This is a basic window air conditioner operating
via the refrigeration cycle. This is about as small as they come, but for
larger systems everything just gets scaled up and sometimes moved around a bit The refrigeration cycle really is almost magical,
so here’s a brief overview. For now, the only things we need to focus
on are these pipes. Notice that it’s a sealed loop, starting
and ending at the heart of the system, the compressor. All these various pipes are filled with a special chemical called a refrigerant. What’s so special about refrigerants? Well, I’ll show you! This is a can of R134a (also known as 1,1,1,2-tetrafluoroethane). It’s typically used in cars but is currently being
phased out. Now you obviously can’t feel this through
your screen but this can is clearly filled with a liquid. You can shake it and tell that there’s definitely
something sloshing around in there. Maybe you can hear it. [sloshy liquidy sounds] Put it on a scale and you can see that it
weighs what it says it does plus the can. But here’s the key thing - this would really
prefer to not be a liquid right now. The boiling point of this chemical is -15° Fahrenheit,
or -26°C That’s really cold! So why is it still a liquid? It’s at room temperature but also not a gas. How? Well, because it’s trapped in this can. It’s under pressure, and when you confine
a gas into a small space (and thus increase the pressure it’s under)
you raise its boiling point. Right now, at room temperature, the pressure
in this can is about 70 psi. Not tremendously high. And so long as it’s in this can, it will
stay a liquid. It doesn’t have room to expand into a gas. But, if I were to puncture a hole in this
can, which I’m not going to do because this chemical is environmentally problematic, it would instantly begin boiling once the pressure is relieved. And the key is, in order for it to do that,
it has to remove energy from the space it's in. The latent heat of vaporization doesn’t
just go away when the refrigerant is at a higher temperature than boiling - it still
needs to get energy from some place to change phases - or boil. It will initially do that from itself, causing
the liquid to get very cold very quickly, but then it will actually pull energy from
its surroundings to keep boiling. It becomes an area devoid of heat energy,
so ambient energy will naturally spill into it. That makes the air around it get colder. But, once it’s all expanded to a gas, we’ve achieved
equilibrium and the energy transfer stops. The single most important property of refrigerants is
that they don’t need to be under very high pressures in order for us to raise their boiling
point above ambient temperature. This can really isn't that strong at all
and yet it’s able to keep the refrigerant a liquid. In fact, fun fact! Those cans of computer duster you can buy? Those are filled with a refrigerant. If you thought that was just compressed air Nope! It’s a refrigerant. You need very strong tanks to hold back compressed
air. Just look at this little three gallon air
compressor. This tank is made of thick steel and when
charged to its max of 110 PSI, it barely holds enough air to fill a tire. Because selling a can of compressed air would
require expensive steel cans that can accomplish hardly any dusting work, these cans are filled with a liquid refrigerant which expands into a gas as it is vented by the spray nozzle. [ffffssssssstttt] This allows for much more dusting to occur. And is precisely why these cans get
cold as you use them! It’s a refrigerant briefly refrigerating. If you spray them upside down you’ll release
liquid refrigerant and you can witness it boil away with your very eyes. [phwwwwwoooooosssshhh] A slightly terrifying thing about these is
that many refrigerants are terribly potent greenhouse gases, and the idea that we just
sell cans of the stuff with the express intent of venting directly to the atmosphere is more than
slightly unsettling. This particular can is full of R152a,
or 1,1-Difluoroethane. Now, as far as refrigerants go, it’s not
*that* bad. It has a global warming potential of 140, which sounds pretty bad but it's about
about an order of magnitude less than R134a, and also its atmospheric lifetime is only
slightly more than a year (again, about an order of magnitude better than this). So, in all likelihood it’s probably not that bad. Still, I would highly encourage you to look
up what refrigerant is used in your preferred duster (if you have one) or better yet find alternative means of dusting your computer junk. And by the way, this very same chemical is
often used as a propellant in products like spray paint and hair spray, and we used to
use good ‘ol R-12, everyone’s least favorite ozone-depleting chlorofluorocarbon (CFC) trade named Freon for that task. Yeah, the ozone layer still hasn’t forgiven
us for that one. But anyway, because you don’t need terribly
high pressures to hold refrigerants in liquid form, we can easily build a machine which
will force it to condense and evaporate when and where we want it to. And that’s what an air conditioner or refrigerator
does. The compressor, which by the way is the same
sort of thing as any old air compressor but it’s sealed in this black cylinder so that
it’s surrounded by refrigerant and also doesn’t leak, squeezes it into the confined space
of this first heat exchanger known as the condenser. That causes it to get quite hot but more importantly
increases its boiling point dramatically as pressure in the condenser builds. With the aid of these fins and a fan forcing
air through them, it will get cooled back down as it travels through the pipes. By the time it’s at the end, it has condensed
into a liquid. Let’s take a look at that with a thermal
camera. This has been off overnight so everything
is close to room temperature. It’s amazing how quickly the condenser heats
up, and also how uniformly. Almost instantly the pressure is high enough
for some of the refrigerant to start condensing on the inner walls of the pipes. And just as an evaporating refrigerant steals
energy from its surroundings to boil, a condensing refrigerant releases energy as it becomes
liquid again. That’s why the condenser gets hot - the
refrigerant is releasing a ton of heat energy as it changes phases. Liquid refrigerant will eventually start to
build up at the end of the condenser, and it will usually be cooled down a little further (which, incidentally, is called subcooling in HVAC parlance) before it reaches the metering device. This ensures a decent volume of liquid refrigerant is at the metering device in preparation for the next step, and is precisely why the amount
of refrigerant inside any given refrigeration system, known as the charge, is so critical
for proper function. The restriction created by the metering device
facilitates a dramatic pressure imbalance between the two sides of the system, because
just as the compressor is creating high pressure on its output side, its input side creates
suction and thus low pressure. The metering device can be as simple as a
capillary tube which restricts the volume of refrigerant that can pass through it, or
it can be as complex as a thermal expansion valve which reacts to changes in thermal load
to ensure optimal refrigeration performance. That’s deeper than we need to be going, but once
liquid refrigerant passes into the next chamber, another heat exchanger called the
evaporator, its boiling point plummets. Now that it’s in a low pressure environment,
it starts to boil just like the refrigerant you release from a can of computer duster. And it needs energy in order to do that, so
it takes it from the air around the evaporator, making it get very cold. Again, let’s take a look with a thermal
camera. As soon as it’s switched on, the evaporator
becomes a sink of coldness, a place where energy in the room will naturally go. The refrigerant in here NEEDS energy to evaporate,
and it MUST evaporate because the pressure is too low for it to remain a liquid. The fins of the evaporator help it to scavenge
energy from the air, which ends up cooling the room. Once the refrigerant has reached the end, assuming the charge is correct, it will have absorbed all the energy it can. It will then re-enter the compressor and the cycle
repeats. Now the energy it just picked up from inside the room can be expelled in the condenser. The conditioning part of air conditioning
happens thanks to the fact that the evaporator gets very cold. Moisture in the air will condense on cold
surfaces. You’ve seen that before when holding a glass of ice water on a humid day. That happens because air’s ability to hold
moisture is dependent on its temperature. Drop the temperature and it can’t hold as
much water, so the water that it’s in it condenses out of it and onto the cold surface
of the glass. Fun fact! That’s how clouds and storms and dew happen. Because the evaporator gets so cold and air rushes through its fins, that air will lose its ability to hold moisture so it loses its
water and the evaporator will get very wet as time goes on. Thanks to surface tension and gravity, that
collected water (called condensate) will travel down the fins into either some sort of drip
pan or in the case of many window units simply the bottom of the machine where it can seep to the
outside. Newer models like this will intentionally collect it around the condenser, and the condenser fan’s blade (or even, as is the case here,
a specialized component of it) splashes water onto the condenser, increasing the efficiency and effectiveness of the air conditioner through, somewhat ironically, evaporative cooling. In fact, in this one, the condenser is actually
shaped so that part of it sits in collected condensate. And it’s done quite cleverly at the very
end of the condenser's loop. The refrigerant should at this point already
be liquid and piling up at the metering device, but the water will cool it further making
doubly sure this actually happens and also increasing subcooling, again that’s the
amount the refrigerant is able cool further after it has condensed. That increases efficiency and effectiveness
by allowing the evaporator to absorb a little more energy after the refrigerant boils. Remember that when it boils it first takes
energy from itself, so in general the cooler you can make it before it re-enters
the evaporator the better (though there is some nuance there). Some people claim that this practice reduces
the life of the condenser through promotion of corrosion but those are just some people
who didn’t engineer the thing. Also, the evaporator which is exactly the
same sort of thing, made of the same materials and everything, gets wet constantly as it
operates but I digress. So here’s the key thing - the refrigerant
in here is trapped and is making a continuous circuit. We’re forcing it to boil, then condense, boil,
condense, boil, condense, boil and condense over and over and over and over and over again. And over again. And most importantly, we control where those
two things happen. We’re using the properties of latent heat
to our advantage, in a deliberate and controlled way. We call this a heat pump. With it we can collect and concentrate heat
energy in one location, and move it to another to be released. In one direction this will cool a room by
moving heat to outside, but the cycle can be reversed, which is becoming increasingly common. Since the refrigerant is actually performing
the work when it changes phases, it can move four or five times as much energy as the heat pump consumes in the compressor (depending on conditions). It’s the closest thing we have to free energy,
and is very neat. Every real air conditioner, even the terrible
single-hose portable air conditioners which you should avoid at all costs as I explained here (feel free to skip around that video as we’re covering some of the same things again) has a hot side and a cold side. The cold side collects energy, and the hot
side releases it. Move energy out of a space and you cool it,
move it into the space and you heat it. This thing, though… you’ll find no sides
at all. It’s basically just a wet sponge and a fan
which presents two giant flaws. The first is that there’s no self-contained
loop. While you most certainly can use water to
cool air, once it evaporates you need to add more. Water generally isn’t scarce (except for where it is) so for the most part this is more of an annoyance than anything else but it is noteworthy. And the second flaw? Well, now it’s time to answer the question
at hand. Do these even work? Well, as a concept these can technically work. In fact, you can even see a slight cooling
effect going on here in the thermal camera. I’ll emphasize slight, but honestly it is
pretty interesting how it manages to achieve cooling with nothing but room-temperature
tap water. And it was more powerful than I expected,
with the air leaving it being about 2 or 3° F below ambient temperature. Yes, my expectations were indeed that low. But now here comes the gigantic caveat. The real dealbreaker is that, if you haven’t
figured this out already, a swamp cooler doesn’t dehumidify - it adds humidity! In order for a swamp cooler to do anything at all, it has to help water inside it evaporate. And that makes the ambient humidity go up. In case you thought, oh, well no big deal,
at least it’s cooler well here’s the other thing - if the ambient humidity is already high, then swamp coolers just don’t work. They can’t work. It literally becomes impossible. The air has to be able to take on more moisture
in order for the cooling effect to even happen, and if you’re at or near the saturation
point well then you’re just SOL. The air that comes from this feels a bit cooler
than air coming from an ordinary fan but… not by much. In this test I pointed the louvers so it was blowing right
on this thermostat (because apparently I don’t have a thermometer) so I could get a fairly
accurate temperature reading. And, well, 64 degrees was the best it could
muster. That’s down from an ambient temperature
of about 67 maaaaaybe 68. So at best it produced a 4 degree temperature
drop. This becomes even more damning when you consider
that this was in an air conditioned space already! Relative humidity was about 50% when I tested
this. Outside, though, it was around 80%. It flat out would not work if it were my only
source of cooling. To really drive home how much like air conditioners
these aren't, I used the thermostat again to see what the air exiting the air conditioner
was and… yeah. That’s actually cold. In short, swamp coolers only work up to a
point. And, because we’re dealing with relative
humidity (which itself affects how hot a given temperature feels to us) it’s anything but
simple. As a general rule, a swamp cooler could, assuming
it’s a good one, cool to within a few degrees of the wet-bulb temperature. Now, what is the wet-bulb temperature, you ask? Heh, well annoyingly it is the lowest temperature
that can be achieved through evaporative cooling. I know. It describes itself. Hang on, I’ll try… Basically, the wet-bulb temperature is what
a thermometer which has its bulb wrapped in wet cotton or the like will read. It’s affected by how quickly the water evaporates
from that little cotton ball. It presents the theoretical minimum temperature an evaporative cooler can hope to obtain, and as humidity goes up, so does the wet-bulb temperature. When humidity is 100%, the wet-bulb temperature
is the same as the dry-bulb (also known as… normal) temperature
because the air cannot take on more moisture. Given my sense of humor I’m sure I’ve
been called a dry bulb a few times. Honestly, all you need to know is that as humidity goes up the ability for these to work goes down. I mean, that makes sense, given that they’re basically
little humidifiers, and explains why calling these air conditioners is super dumb. Now, are they without value? Well… it depends. It might be nice to use this on my desk as
a supplement to central air conditioning. Maybe I could run that a little less. After all a three degree
temperature drop is definitely noticeable. But certainly it won’t make a dramatic difference
and it definitely isn’t going to cool the room. In arid places, swamp coolers work amazingly! Many people have them to supplement traditional
air conditioning and it dramatically lowers energy needs (at the expense of increased
water usage). And, since you typically want a little more
humidity in aird places anyway, they’re a win-win. Swamp coolers can also help the efficiency
of split air conditioning systems by cooling the space around the condenser coils and thus
increasing their effectiveness. Kinda like how this one pools the condensate around the condenser. You can see this in practice in this video
made by HVACR videos. You should check out that channel if you want
to see some of the various commercial refrigeration and air conditioning systems out there up
close, as well as the various ways they fail and how issues are diagnosed and repaired. It’s really a great channel for that sort of thing. But here in the Midwest where humidity can
often be oppressive, swamp coolers don’t do much and actually just make things worse. Now, this little thing, to its credit, suggests
that you put ice cubes in it. Which is, well, somewhat hilarious
because then you’re actually using your refrigerator to cool you down and you know what? I approve! Not in any practical way, of course. It’s absolutely silly. Your refrigerator made that ice by pulling energy out
of water and dumping into your kitchen. But technically it would work at least a ‘lil
bit. But in general these desktop personal coolers are only sometimes able to do anything at all. It depends entirely on where you live and
also varies day to day. Now just because I’m not a total jerk about
these things, I have in fact tested this in a few scenarios. And while I think that sure, it provides a
cooling effect, it’s not the miracle product that you HAVE TO BUY that all of the ads out
there are proclaiming them to be. And how on Earth this little thing managed
to get all these five star reviews is … Suspicious! And also, right now, these are horribly overpriced! It is literally a computer case fan, a hunk
of cheap plastic, and a bit of paper with a tiny control board for everything. It’s powered over USB and they don’t even
give you the courtesy of providing a power supply. These should cost no more than $25 and even
then, that’s a lot for what it is. Plus, the water absorbing material should be
replaced periodically. It gets gross over time, and do any of these
companies provide replacements? Who knows! Keep in mind also that by adding humidity
you’re making your air conditioner work harder. Getting water to condense removes heat energy
that we can’t feel - that’s the whole latent heat bit. So if you have a lot of moisture in the air,
your air conditioner needs to run longer to provide the same amount of cooling thanks
to all that water that’s condensing on the evaporator. Using a mini-swamp cooler in an already-humid
place makes your struggling air conditioner struggle even more (though admittedly, not
much given the small amount of water this thing is capable of putting out over a day). So - these things. Are they a scam? Well, they just barely pull off a no on a technicality. I mean, calling it an air conditioner is an
outright lie. But if they’re sold as “personal cooling devices” then… well yeah I suppose that’s technically true. But they’re only useful in certain places
and certain situations. This is not a personal air conditioner, and while
I wish it was as easy as Just Add Water!
I regret to inform you that it is not. If you’d like to take a little test drive
of this concept, I’d suggest you make your own evaporative cooler to see if it would even do anything for you. You could probably just glue a few kitchen
sponges to a dinner plate in an upright position, with a bit of space between them, add some water so the sponges absorb it, and
put that contraption in front of a small desk fan and get way more cooling than this thing
could ever hope to produce. Any time you see a cooling device for sale
which doesn’t require either a hose for exhaust or actual installation, it’s not
an air conditioner. There has yet to be a device you can just
plop on your desk and actually get air conditioning from. In fact, that’s impossible. So while I can’t quite call this a useless
device, it’s alarmingly disingenuous, terribly overpriced, and almost always not worth your time. Thanks for watching! This is now, I believe, the third time I’ve
explained the refrigeration cycle without actually making a video specifically about
it. It really is a remarkable achievement of humanity, and
heat pumps are going to become increasingly common and important as we move into the age
of electrification. For sure you’ll be seeing a video about
that before too long, and I think then we’ll get into the real nitty-gritty like all those
terrible refrigerants we used to use and how we can move forward with grace. But for now, le bloops. ♫ disingenuously smooth jazz ♫ But swamp is just one syllabo… syllabo… But swamp is just one syllabo… syllable! I said “syllabo”... twice now Now the energy it picked up from cooling the process…. From the cooling process… uugghghhg But! I think it will help to illustrate why these .... oh I need it here, ha! In fact, fun fact! [clink as the nozzle hits the table]
The… shoot. And if you’re not interested in this part,
go ahead and skip to here. But, I think it will help to… that’s right
in front of my face, that’s a bad idea. The air that comes from this feels a little
bit cooler than the air coming from an ordinary fan, but not my much. Not My much. It’s not MY much it’s YOUR much! The way these things are marketed? Not cool. Oh I regret not working that into the script somehow. But now it's the secret end joke, so yay!
Or, as a HyVee employee once told me: "This isn't people weather, this is corn weather."
Fortunately, I live in inland Norhern California, where 100° highs aren't as oppressive as you'd think, because they're accompanied by 20% relative humidity. Some houses rely solely on swamp coolers, although they don't provide much releif during the few weeks a year that the low temperatures are still in the 70's, and it's hot and humid at night.
I just need to convince my roommates that running a box fan or ceiling fan, in an empty room, won't cool it down and even heats it slightly.
IIRC the principle is used in deserts for over a thousand years:
https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Qanat_wind_tower.svg/567px-Qanat_wind_tower.svg.png
Since the air is very dry the added humidity doesn't matter
Question unrelated to the specific content of the video, but does anyone know where to find the amazing vintage technology tshirts u/TechConnectify so often wears?
This reminded me of the ECOAC kickstarter (that seems to have ended up being vaporware) where the idea was to cool the air with a peltier element while having the hot-side heatsink be a container of water, which means once that heats up you would swap it and quite literally removing the heat from the room.
Most likely ended up being unfeasible because of the absolutely terrible efficiency of Peltier elements.
But it could be a neat secondary use for that cooler box nobody ever uses, fill it with cold water and set it to "hot", then dump it out once the water heats up enough and repeat...
It's very common for homes in arid regions, like Arizona, to use a swamp cooler instead of an air conditioner.
But in humid regions, they're practically useless.
The only good thing about these is it looks like you could put a few ice cubes in it. That’d provide a little more efficient cooling for a small area, kinda like small desk fans. It’d only last for a short while before the ice melts though.
I was kinda hoping to see you actually build that DIY sponge-plate-cooler to really prove that point. Maybe it'd have been more trouble than worth it, though.
And I'm gonna be the snarky guy from a cold country who goes "-26C is 'really' cold? You mean the temperature during that time between autumn and spring?"
I feel like these personal coolers are so overpriced.
They're mostly just a small fan, a water container, a wetting element, and some small electronics inside a plastic box. Why are these sold at $20 or even $40?
If it's a crowdfunded product then of course it can go upwards to a ridiculous $230 (and $30+ for a single replacement filter), even if it could actually be just a cheap white label Chinese cooler with a logo stamped on it.
(I'm not saying that the products I mentioned are Chinese white label for a fact, though it could be. I currently don't feel like wading through AliExpress or Alibaba.)
Next up, you should do an episode on the Sony Reon, which is a similar "personal air conditioner" idea, but by an actual reputable company. It looks like it uses Peltier cooling.