WEBVTT Kind: captions Language: en 00:00:00.089 --> 00:00:04.120 You might be seeing a lot of Internet Influencer Hype Advertiser Content 00:00:04.120 --> 00:00:08.280 You Won’t Believe They Don’t Want You To See! lately about these so-called 00:00:08.280 --> 00:00:10.300 personal air conditioners. 00:00:10.300 --> 00:00:13.420 You might have wondered if these might be too good to be true. 00:00:13.420 --> 00:00:16.200 And today I’m here to tell you that you’re right to wonder, 00:00:16.200 --> 00:00:18.960 and the answer to your question is an absolute, 00:00:18.960 --> 00:00:19.760 unequivocal, 00:00:19.760 --> 00:00:20.560 indisputable, 00:00:20.560 --> 00:00:21.780 irrefutable 00:00:21.780 --> 00:00:23.000 probably. 00:00:23.000 --> 00:00:29.820 This thing, as well as most of the devices out there which emulate its design including the Blaux?… 00:00:29.820 --> 00:00:31.260 Blaugh? 00:00:31.260 --> 00:00:35.940 Bloerp?... is a miniature swamp cooler. 00:00:35.940 --> 00:00:38.440 Note; not air conditioner! 00:00:38.440 --> 00:00:40.600 Despite what it may claim on the box. 00:00:40.600 --> 00:00:42.140 Swamp cooler. 00:00:42.150 --> 00:00:46.060 By the way, swamp cooler seems to be a rather US-specific term; 00:00:46.060 --> 00:00:50.680 evaporative cooler is the more technical and also less gross term. 00:00:50.680 --> 00:00:53.800 But swamp is just one syllable so I’m saying that. 00:00:53.800 --> 00:00:55.300 It’s also just more fun! 00:00:55.300 --> 00:00:56.040 Swamp. 00:00:56.040 --> 00:00:56.880 Swomp. 00:00:56.880 --> 00:00:57.660 Swawmp. 00:00:57.660 --> 00:00:58.520 See? 00:00:58.520 --> 00:00:59.340 Deal with it. 00:00:59.340 --> 00:01:04.240 Swamp coolers do work, in fact in parts of the world they’re genuinely wonderful and 00:01:04.240 --> 00:01:07.400 can sometimes negate the need for air conditioning altogether. 00:01:07.400 --> 00:01:10.920 But these are not replacements for air conditioning. 00:01:10.920 --> 00:01:14.820 If you live in a region of the world where the role of air conditioning isn’t just to cool, 00:01:14.820 --> 00:01:18.200 but indeed to provide dehumidification, 00:01:18.200 --> 00:01:20.400 well then these thing are just silly! 00:01:20.400 --> 00:01:24.760 You see, these aren’t air conditioners by any stretch of the imagination. 00:01:24.760 --> 00:01:31.039 However, in a sort of odd twist, swamp coolers do in fact use the same general sort of principle 00:01:31.039 --> 00:01:33.340 as a conventional air conditioner. 00:01:33.340 --> 00:01:39.320 They exploit the fact that as water evaporates, it takes energy from the air in order to do so. 00:01:39.320 --> 00:01:42.520 I talked a bit about latent heat in my video on rice cookers. 00:01:42.520 --> 00:01:46.899 At a very basic level it's simply that in order for a substance to change phases from 00:01:46.900 --> 00:01:49.600 liquid to gas, it requires a lot of energy. 00:01:49.600 --> 00:01:54.640 Water is, believe it or not, a substance and you can see this in action when you boil it. 00:01:54.640 --> 00:01:59.240 It doesn’t just disappear when it reaches boiling point because it takes *more* energy 00:01:59.260 --> 00:02:01.220 to cause it to vaporize. 00:02:01.220 --> 00:02:03.899 The same thing happens when water evaporates. 00:02:03.899 --> 00:02:08.069 You don’t have to get water up to boiling point in order for it to change phases. 00:02:08.069 --> 00:02:12.280 You probably knew that already, the water cycle is a thing and we have rain and stuff 00:02:12.280 --> 00:02:13.920 and the oceans aren’t boiling. 00:02:14.040 --> 00:02:19.280 In any body of water, the water molecules close to the surface can, depending on conditions, 00:02:19.280 --> 00:02:23.360 have enough kinetic energy to free themselves from the liquid phase fairly easily. 00:02:23.360 --> 00:02:28.530 Of course extra energy, for example from the sun, will help but the key thing is no matter 00:02:28.530 --> 00:02:33.049 how water changes phases, it takes a little energy for itself. 00:02:33.049 --> 00:02:38.440 A device like this is simply using that concept to provide *some* cooling. 00:02:38.440 --> 00:02:44.739 All it is is a fan which blows air past some sort of absorbent material which holds water. 00:02:44.739 --> 00:02:49.480 The forced airflow and the large surface area provided by these paper flute things helps 00:02:49.480 --> 00:02:51.720 the water to evaporate quickly. 00:02:51.720 --> 00:02:57.040 As it does so it takes some of the heat energy in the air with it and the effect is that… 00:02:57.040 --> 00:02:58.920 well you get a bit of cooling. 00:02:58.920 --> 00:03:02.480 This is, by the way, exactly how sweating cools you off. 00:03:02.480 --> 00:03:03.260 Fun fact! 00:03:03.260 --> 00:03:08.540 The name swamp cooler is thought to have originated from the musty smell these often develop as 00:03:08.540 --> 00:03:13.280 algae and other fun lifeforms take refuge in their mightily moist matrices. 00:03:13.280 --> 00:03:18.720 If you’ve never encountered a swamp cooler before, well we’ll get into why that might be in a short while, 00:03:18.720 --> 00:03:23.320 but you’ve probably experienced the concept at work in one way or another. 00:03:23.320 --> 00:03:27.980 Those misting fans that blow not just air but also a fine mist of water at you? 00:03:27.980 --> 00:03:30.460 Their goal isn’t just to make you annoyingly damp, 00:03:30.460 --> 00:03:33.420 in fact the hope is that you don’t get wet at all. 00:03:33.420 --> 00:03:38.670 Instead, the spray nozzles atomize the water into a very fine mist, which will quickly 00:03:38.670 --> 00:03:42.620 evaporate and cool the air, sometimes a dramatic amount. 00:03:42.620 --> 00:03:46.960 Even without the fan, if you’ve seen those mister things in a garden or whatever - 00:03:46.960 --> 00:03:49.020 well typically that's the goal. 00:03:49.020 --> 00:03:50.020 Cooling. 00:03:50.040 --> 00:03:53.620 And that’s the same sort of thing that these devices do. 00:03:53.620 --> 00:03:59.260 But there’s a big, big, big big big big huuuuge caveat. 00:03:59.260 --> 00:04:03.960 See, where I live, air conditioning isn’t there just to make a space cooler. 00:04:03.960 --> 00:04:07.299 It’s also there to remove moisture from the air. 00:04:07.299 --> 00:04:12.310 In fact that was the original purpose of air conditioning - to dehumidify the air in factories 00:04:12.310 --> 00:04:17.000 and other industrial buildings where humidity was causing problems on the production line. 00:04:17.000 --> 00:04:19.120 Human comfort was just a bonus. 00:04:19.120 --> 00:04:24.539 Air conditioners can remove moisture because the refrigeration cycle relocates heat energy 00:04:24.539 --> 00:04:29.520 via a liquid refrigerant, which creates a very cold surface which water vapor in the 00:04:29.520 --> 00:04:31.640 air will condense on. 00:04:31.640 --> 00:04:33.900 OK, time to bring this guy out again. 00:04:33.900 --> 00:04:37.300 I’m going to explain what actual air conditioners do, 00:04:37.300 --> 00:04:40.800 and if you’re not interested in this part go ahead and skip to here. 00:04:40.800 --> 00:04:45.600 But, I think it will help to illustrate why these fad devices are… 00:04:45.600 --> 00:04:47.300 fad devices. 00:04:47.300 --> 00:04:51.940 This is a basic window air conditioner operating via the refrigeration cycle. 00:04:51.940 --> 00:04:55.900 This is about as small as they come, but for larger systems everything just gets scaled up 00:04:55.900 --> 00:04:58.380 and sometimes moved around a bit 00:04:58.380 --> 00:05:03.970 The refrigeration cycle really is almost magical, so here’s a brief overview. 00:05:03.970 --> 00:05:07.380 For now, the only things we need to focus on are these pipes. 00:05:07.380 --> 00:05:11.240 Notice that it’s a sealed loop, starting and ending at the heart of the system, 00:05:11.240 --> 00:05:12.620 the compressor. 00:05:12.620 --> 00:05:16.880 All these various pipes are filled with a special chemical called a refrigerant. 00:05:16.880 --> 00:05:19.020 What’s so special about refrigerants? 00:05:19.020 --> 00:05:20.940 Well, I’ll show you! 00:05:20.940 --> 00:05:23.940 This is a can of R134a 00:05:23.940 --> 00:05:28.600 (also known as 1,1,1,2-tetrafluoroethane). 00:05:28.600 --> 00:05:32.180 It’s typically used in cars but is currently being phased out. 00:05:32.199 --> 00:05:37.699 Now you obviously can’t feel this through your screen but this can is clearly filled with a liquid. 00:05:37.700 --> 00:05:41.680 You can shake it and tell that there’s definitely something sloshing around in there. 00:05:41.680 --> 00:05:42.740 Maybe you can hear it. 00:05:42.740 --> 00:05:44.300 [sloshy liquidy sounds] 00:05:44.300 --> 00:05:48.560 Put it on a scale and you can see that it weighs what it says it does plus the can. 00:05:48.560 --> 00:05:54.540 But here’s the key thing - this would really prefer to not be a liquid right now. 00:05:54.540 --> 00:06:00.460 The boiling point of this chemical is -15° Fahrenheit, or -26°C 00:06:00.460 --> 00:06:02.580 That’s really cold! 00:06:02.580 --> 00:06:04.360 So why is it still a liquid? 00:06:04.360 --> 00:06:07.290 It’s at room temperature but also not a gas. 00:06:07.290 --> 00:06:08.290 How? 00:06:08.290 --> 00:06:10.389 Well, because it’s trapped in this can. 00:06:10.389 --> 00:06:13.880 It’s under pressure, and when you confine a gas into a small space 00:06:13.880 --> 00:06:17.980 (and thus increase the pressure it’s under) you raise its boiling point. 00:06:17.980 --> 00:06:22.360 Right now, at room temperature, the pressure in this can is about 70 psi. 00:06:22.360 --> 00:06:24.200 Not tremendously high. 00:06:24.200 --> 00:06:27.360 And so long as it’s in this can, it will stay a liquid. 00:06:27.360 --> 00:06:30.090 It doesn’t have room to expand into a gas. 00:06:30.090 --> 00:06:33.260 But, if I were to puncture a hole in this can, 00:06:33.260 --> 00:06:36.800 which I’m not going to do because this chemical is environmentally problematic, 00:06:36.800 --> 00:06:41.060 it would instantly begin boiling once the pressure is relieved. 00:06:41.060 --> 00:06:47.040 And the key is, in order for it to do that, it has to remove energy from the space it's in. 00:06:47.040 --> 00:06:51.020 The latent heat of vaporization doesn’t just go away when the refrigerant is at a 00:06:51.020 --> 00:06:56.660 higher temperature than boiling - it still needs to get energy from some place to change phases 00:06:56.660 --> 00:06:57.949 - or boil. 00:06:57.949 --> 00:07:02.980 It will initially do that from itself, causing the liquid to get very cold very quickly, 00:07:02.980 --> 00:07:07.560 but then it will actually pull energy from its surroundings to keep boiling. 00:07:07.560 --> 00:07:13.580 It becomes an area devoid of heat energy, so ambient energy will naturally spill into it. 00:07:13.580 --> 00:07:16.320 That makes the air around it get colder. 00:07:16.320 --> 00:07:22.920 But, once it’s all expanded to a gas, we’ve achieved equilibrium and the energy transfer stops. 00:07:22.920 --> 00:07:28.640 The single most important property of refrigerants is that they don’t need to be under very high pressures 00:07:28.640 --> 00:07:32.820 in order for us to raise their boiling point above ambient temperature. 00:07:32.820 --> 00:07:38.020 This can really isn't that strong at all and yet it’s able to keep the refrigerant a liquid. 00:07:38.020 --> 00:07:40.360 In fact, fun fact! 00:07:40.360 --> 00:07:42.820 Those cans of computer duster you can buy? 00:07:42.820 --> 00:07:45.200 Those are filled with a refrigerant. 00:07:45.210 --> 00:07:47.200 If you thought that was just compressed air 00:07:47.200 --> 00:07:49.100 Nope! It’s a refrigerant. 00:07:49.100 --> 00:07:52.920 You need very strong tanks to hold back compressed air. 00:07:52.920 --> 00:07:55.220 Just look at this little three gallon air compressor. 00:07:55.220 --> 00:08:00.720 This tank is made of thick steel and when charged to its max of 110 PSI, 00:08:00.720 --> 00:08:03.400 it barely holds enough air to fill a tire. 00:08:03.400 --> 00:08:07.660 Because selling a can of compressed air would require expensive steel cans 00:08:07.660 --> 00:08:10.020 that can accomplish hardly any dusting work, 00:08:10.020 --> 00:08:16.240 these cans are filled with a liquid refrigerant which expands into a gas as it is vented by the spray nozzle. 00:08:16.240 --> 00:08:16.940 [ffffssssssstttt] 00:08:17.580 --> 00:08:20.520 This allows for much more dusting to occur. 00:08:20.520 --> 00:08:25.500 And is precisely why these cans get cold as you use them! 00:08:25.500 --> 00:08:28.260 It’s a refrigerant briefly refrigerating. 00:08:28.260 --> 00:08:31.380 If you spray them upside down you’ll release liquid refrigerant 00:08:31.380 --> 00:08:34.220 and you can witness it boil away with your very eyes. 00:08:34.220 --> 00:08:35.780 [phwwwwwoooooosssshhh] 00:08:37.450 --> 00:08:42.160 A slightly terrifying thing about these is that many refrigerants are terribly potent 00:08:42.160 --> 00:08:46.700 greenhouse gases, and the idea that we just sell cans of the stuff with the express intent 00:08:46.700 --> 00:08:50.420 of venting directly to the atmosphere is more than slightly unsettling. 00:08:51.200 --> 00:08:57.080 This particular can is full of R152a, or 1,1-Difluoroethane. 00:08:57.080 --> 00:09:01.580 Now, as far as refrigerants go, it’s not *that* bad. 00:09:01.590 --> 00:09:04.120 It has a global warming potential of 140, 00:09:04.120 --> 00:09:09.340 which sounds pretty bad but it's about about an order of magnitude less than R134a, 00:09:09.340 --> 00:09:12.860 and also its atmospheric lifetime is only slightly more than a year 00:09:12.860 --> 00:09:15.770 (again, about an order of magnitude better than this). 00:09:15.770 --> 00:09:19.840 So, in all likelihood it’s probably not that bad. 00:09:19.840 --> 00:09:24.880 Still, I would highly encourage you to look up what refrigerant is used in your preferred duster 00:09:24.880 --> 00:09:26.100 (if you have one) 00:09:26.100 --> 00:09:29.840 or better yet find alternative means of dusting your computer junk. 00:09:29.840 --> 00:09:34.120 And by the way, this very same chemical is often used as a propellant in products like 00:09:34.130 --> 00:09:37.900 spray paint and hair spray, and we used to use good ‘ol R-12, 00:09:37.900 --> 00:09:41.040 everyone’s least favorite ozone-depleting chlorofluorocarbon (CFC) 00:09:41.040 --> 00:09:43.620 trade named Freon for that task. 00:09:44.360 --> 00:09:47.060 Yeah, the ozone layer still hasn’t forgiven us for that one. 00:09:47.070 --> 00:09:52.320 But anyway, because you don’t need terribly high pressures to hold refrigerants in liquid form, 00:09:52.320 --> 00:09:56.640 we can easily build a machine which will force it to condense and evaporate 00:09:56.640 --> 00:09:59.120 when and where we want it to. 00:09:59.120 --> 00:10:03.600 And that’s what an air conditioner or refrigerator does. 00:10:03.610 --> 00:10:07.040 The compressor, which by the way is the same sort of thing as any old air compressor 00:10:07.040 --> 00:10:12.320 but it’s sealed in this black cylinder so that it’s surrounded by refrigerant and also doesn’t leak, 00:10:12.320 --> 00:10:17.860 squeezes it into the confined space of this first heat exchanger known as the condenser. 00:10:17.860 --> 00:10:23.200 That causes it to get quite hot but more importantly increases its boiling point dramatically 00:10:23.200 --> 00:10:25.820 as pressure in the condenser builds. 00:10:25.820 --> 00:10:29.300 With the aid of these fins and a fan forcing air through them, 00:10:29.300 --> 00:10:32.400 it will get cooled back down as it travels through the pipes. 00:10:32.400 --> 00:10:35.580 By the time it’s at the end, it has condensed into a liquid. 00:10:35.580 --> 00:10:37.840 Let’s take a look at that with a thermal camera. 00:10:37.840 --> 00:10:41.660 This has been off overnight so everything is close to room temperature. 00:10:41.660 --> 00:10:45.840 It’s amazing how quickly the condenser heats up, and also how uniformly. 00:10:45.840 --> 00:10:50.400 Almost instantly the pressure is high enough for some of the refrigerant to start condensing 00:10:50.400 --> 00:10:52.400 on the inner walls of the pipes. 00:10:52.400 --> 00:10:57.220 And just as an evaporating refrigerant steals energy from its surroundings to boil, 00:10:57.220 --> 00:11:01.660 a condensing refrigerant releases energy as it becomes liquid again. 00:11:01.660 --> 00:11:06.060 That’s why the condenser gets hot - the refrigerant is releasing a ton of heat energy 00:11:06.060 --> 00:11:07.980 as it changes phases. 00:11:07.980 --> 00:11:11.720 Liquid refrigerant will eventually start to build up at the end of the condenser, 00:11:11.720 --> 00:11:14.300 and it will usually be cooled down a little further 00:11:14.300 --> 00:11:17.880 (which, incidentally, is called subcooling in HVAC parlance) 00:11:17.880 --> 00:11:20.300 before it reaches the metering device. 00:11:20.300 --> 00:11:26.100 This ensures a decent volume of liquid refrigerant is at the metering device in preparation for the next step, 00:11:26.100 --> 00:11:31.060 and is precisely why the amount of refrigerant inside any given refrigeration system, 00:11:31.060 --> 00:11:35.100 known as the charge, is so critical for proper function. 00:11:35.100 --> 00:11:39.980 The restriction created by the metering device facilitates a dramatic pressure imbalance 00:11:39.980 --> 00:11:44.670 between the two sides of the system, because just as the compressor is creating high pressure 00:11:44.670 --> 00:11:49.990 on its output side, its input side creates suction and thus low pressure. 00:11:49.990 --> 00:11:53.980 The metering device can be as simple as a capillary tube which restricts the volume 00:11:53.980 --> 00:11:59.010 of refrigerant that can pass through it, or it can be as complex as a thermal expansion valve 00:11:59.010 --> 00:12:03.440 which reacts to changes in thermal load to ensure optimal refrigeration performance. 00:12:03.980 --> 00:12:09.560 That’s deeper than we need to be going, but once liquid refrigerant passes into the next chamber, 00:12:09.560 --> 00:12:14.580 another heat exchanger called the evaporator, its boiling point plummets. 00:12:14.580 --> 00:12:19.140 Now that it’s in a low pressure environment, it starts to boil just like the refrigerant 00:12:19.140 --> 00:12:21.440 you release from a can of computer duster. 00:12:21.440 --> 00:12:26.900 And it needs energy in order to do that, so it takes it from the air around the evaporator, 00:12:26.900 --> 00:12:28.880 making it get very cold. 00:12:29.440 --> 00:12:31.820 Again, let’s take a look with a thermal camera. 00:12:31.820 --> 00:12:36.320 As soon as it’s switched on, the evaporator becomes a sink of coldness, 00:12:36.320 --> 00:12:39.900 a place where energy in the room will naturally go. 00:12:39.900 --> 00:12:45.750 The refrigerant in here NEEDS energy to evaporate, and it MUST evaporate because the pressure 00:12:45.750 --> 00:12:48.460 is too low for it to remain a liquid. 00:12:48.460 --> 00:12:54.100 The fins of the evaporator help it to scavenge energy from the air, which ends up cooling the room. 00:12:54.100 --> 00:12:56.020 Once the refrigerant has reached the end, 00:12:56.020 --> 00:13:00.300 assuming the charge is correct, it will have absorbed all the energy it can. 00:13:00.300 --> 00:13:03.460 It will then re-enter the compressor and the cycle repeats. 00:13:03.460 --> 00:13:08.780 Now the energy it just picked up from inside the room can be expelled in the condenser. 00:13:08.780 --> 00:13:13.000 The conditioning part of air conditioning happens thanks to the fact that the evaporator 00:13:13.000 --> 00:13:14.920 gets very cold. 00:13:14.920 --> 00:13:17.880 Moisture in the air will condense on cold surfaces. 00:13:17.880 --> 00:13:22.000 You’ve seen that before when holding a glass of ice water on a humid day. 00:13:22.000 --> 00:13:26.840 That happens because air’s ability to hold moisture is dependent on its temperature. 00:13:26.840 --> 00:13:30.480 Drop the temperature and it can’t hold as much water, so the water that it’s in it 00:13:30.480 --> 00:13:34.080 condenses out of it and onto the cold surface of the glass. 00:13:34.080 --> 00:13:34.940 Fun fact! 00:13:34.940 --> 00:13:38.280 That’s how clouds and storms and dew happen. 00:13:38.560 --> 00:13:42.140 Because the evaporator gets so cold and air rushes through its fins, 00:13:42.140 --> 00:13:48.140 that air will lose its ability to hold moisture so it loses its water and the evaporator will get very wet 00:13:48.140 --> 00:13:49.660 as time goes on. 00:13:49.660 --> 00:13:54.760 Thanks to surface tension and gravity, that collected water (called condensate) will travel 00:13:54.770 --> 00:13:59.470 down the fins into either some sort of drip pan or in the case of many window units simply 00:13:59.470 --> 00:14:03.160 the bottom of the machine where it can seep to the outside. 00:14:03.160 --> 00:14:08.540 Newer models like this will intentionally collect it around the condenser, and the condenser fan’s blade 00:14:08.540 --> 00:14:11.720 (or even, as is the case here, a specialized component of it) 00:14:11.720 --> 00:14:17.040 splashes water onto the condenser, increasing the efficiency and effectiveness of the air conditioner 00:14:17.040 --> 00:14:20.360 through, somewhat ironically, evaporative cooling. 00:14:20.360 --> 00:14:26.420 In fact, in this one, the condenser is actually shaped so that part of it sits in collected condensate. 00:14:26.420 --> 00:14:30.900 And it’s done quite cleverly at the very end of the condenser's loop. 00:14:30.900 --> 00:14:35.300 The refrigerant should at this point already be liquid and piling up at the metering device, 00:14:35.300 --> 00:14:39.440 but the water will cool it further making doubly sure this actually happens and also 00:14:39.440 --> 00:14:43.690 increasing subcooling, again that’s the amount the refrigerant is able cool further 00:14:43.690 --> 00:14:45.540 after it has condensed. 00:14:45.540 --> 00:14:50.440 That increases efficiency and effectiveness by allowing the evaporator to absorb a little 00:14:50.440 --> 00:14:53.460 more energy after the refrigerant boils. 00:14:53.460 --> 00:14:58.320 Remember that when it boils it first takes energy from itself, so in general the 00:14:58.320 --> 00:15:02.100 cooler you can make it before it re-enters the evaporator the better 00:15:02.100 --> 00:15:04.000 (though there is some nuance there). 00:15:04.000 --> 00:15:08.140 Some people claim that this practice reduces the life of the condenser through promotion 00:15:08.140 --> 00:15:12.180 of corrosion but those are just some people who didn’t engineer the thing. 00:15:12.180 --> 00:15:17.100 Also, the evaporator which is exactly the same sort of thing, made of the same materials 00:15:17.100 --> 00:15:21.320 and everything, gets wet constantly as it operates but I digress. 00:15:21.320 --> 00:15:25.160 So here’s the key thing - the refrigerant in here is trapped 00:15:25.160 --> 00:15:27.520 and is making a continuous circuit. 00:15:27.520 --> 00:15:32.540 We’re forcing it to boil, then condense, boil, condense, boil, condense, boil and condense 00:15:32.540 --> 00:15:34.860 over and over and over and over and over again. 00:15:34.860 --> 00:15:35.940 And over again. 00:15:35.980 --> 00:15:40.280 And most importantly, we control where those two things happen. 00:15:40.280 --> 00:15:43.400 We’re using the properties of latent heat to our advantage, 00:15:43.400 --> 00:15:46.040 in a deliberate and controlled way. 00:15:46.040 --> 00:15:48.060 We call this a heat pump. 00:15:48.060 --> 00:15:51.860 With it we can collect and concentrate heat energy in one location, 00:15:51.860 --> 00:15:54.620 and move it to another to be released. 00:15:54.620 --> 00:15:58.280 In one direction this will cool a room by moving heat to outside, 00:15:58.280 --> 00:16:02.020 but the cycle can be reversed, which is becoming increasingly common. 00:16:02.020 --> 00:16:05.900 Since the refrigerant is actually performing the work when it changes phases, 00:16:05.900 --> 00:16:11.340 it can move four or five times as much energy as the heat pump consumes in the compressor 00:16:11.340 --> 00:16:12.750 (depending on conditions). 00:16:12.750 --> 00:16:17.660 It’s the closest thing we have to free energy, and is very neat. 00:16:17.660 --> 00:16:22.860 Every real air conditioner, even the terrible single-hose portable air conditioners 00:16:22.860 --> 00:16:26.460 which you should avoid at all costs as I explained here 00:16:26.460 --> 00:16:29.840 (feel free to skip around that video as we’re covering some of the same things again) 00:16:29.840 --> 00:16:33.330 has a hot side and a cold side. 00:16:33.330 --> 00:16:37.380 The cold side collects energy, and the hot side releases it. 00:16:37.380 --> 00:16:42.820 Move energy out of a space and you cool it, move it into the space and you heat it. 00:16:43.200 --> 00:16:46.960 This thing, though… you’ll find no sides at all. 00:16:46.960 --> 00:16:51.920 It’s basically just a wet sponge and a fan which presents two giant flaws. 00:16:51.920 --> 00:16:54.760 The first is that there’s no self-contained loop. 00:16:54.760 --> 00:17:00.660 While you most certainly can use water to cool air, once it evaporates you need to add more. 00:17:00.660 --> 00:17:02.680 Water generally isn’t scarce 00:17:02.680 --> 00:17:04.260 (except for where it is) 00:17:04.260 --> 00:17:08.760 so for the most part this is more of an annoyance than anything else but it is noteworthy. 00:17:08.760 --> 00:17:10.100 And the second flaw? 00:17:10.100 --> 00:17:12.920 Well, now it’s time to answer the question at hand. 00:17:12.920 --> 00:17:14.840 Do these even work? 00:17:14.840 --> 00:17:19.120 Well, as a concept these can technically work. 00:17:19.120 --> 00:17:23.279 In fact, you can even see a slight cooling effect going on here in the thermal camera. 00:17:23.279 --> 00:17:27.920 I’ll emphasize slight, but honestly it is pretty interesting how it manages to achieve 00:17:27.920 --> 00:17:31.200 cooling with nothing but room-temperature tap water. 00:17:31.200 --> 00:17:36.060 And it was more powerful than I expected, with the air leaving it being about 2 or 3° F 00:17:36.060 --> 00:17:38.120 below ambient temperature. 00:17:38.120 --> 00:17:41.320 Yes, my expectations were indeed that low. 00:17:41.320 --> 00:17:44.600 But now here comes the gigantic caveat. 00:17:44.600 --> 00:17:48.420 The real dealbreaker is that, if you haven’t figured this out already, 00:17:48.420 --> 00:17:53.480 a swamp cooler doesn’t dehumidify - it adds humidity! 00:17:53.480 --> 00:17:59.720 In order for a swamp cooler to do anything at all, it has to help water inside it evaporate. 00:17:59.720 --> 00:18:02.780 And that makes the ambient humidity go up. 00:18:02.780 --> 00:18:06.340 In case you thought, oh, well no big deal, at least it’s cooler 00:18:06.340 --> 00:18:11.040 well here’s the other thing - if the ambient humidity is already high, 00:18:11.040 --> 00:18:13.640 then swamp coolers just don’t work. 00:18:13.640 --> 00:18:15.040 They can’t work. 00:18:15.040 --> 00:18:17.279 It literally becomes impossible. 00:18:17.280 --> 00:18:22.440 The air has to be able to take on more moisture in order for the cooling effect to even happen, 00:18:22.440 --> 00:18:26.920 and if you’re at or near the saturation point well then you’re just SOL. 00:18:26.929 --> 00:18:32.660 The air that comes from this feels a bit cooler than air coming from an ordinary fan but… 00:18:32.660 --> 00:18:34.260 not by much. 00:18:34.260 --> 00:18:38.380 In this test I pointed the louvers so it was blowing right on this thermostat 00:18:38.380 --> 00:18:40.320 (because apparently I don’t have a thermometer) 00:18:40.320 --> 00:18:43.350 so I could get a fairly accurate temperature reading. 00:18:43.350 --> 00:18:46.990 And, well, 64 degrees was the best it could muster. 00:18:46.990 --> 00:18:51.740 That’s down from an ambient temperature of about 67 maaaaaybe 68. 00:18:51.740 --> 00:18:55.080 So at best it produced a 4 degree temperature drop. 00:18:55.080 --> 00:18:57.460 This becomes even more damning when you consider that 00:18:57.460 --> 00:19:00.620 this was in an air conditioned space already! 00:19:00.620 --> 00:19:04.260 Relative humidity was about 50% when I tested this. 00:19:04.260 --> 00:19:07.300 Outside, though, it was around 80%. 00:19:07.300 --> 00:19:11.460 It flat out would not work if it were my only source of cooling. 00:19:11.460 --> 00:19:16.860 To really drive home how much like air conditioners these aren't, I used the thermostat again 00:19:16.870 --> 00:19:20.769 to see what the air exiting the air conditioner was and… yeah. 00:19:20.769 --> 00:19:22.900 That’s actually cold. 00:19:22.900 --> 00:19:26.760 In short, swamp coolers only work up to a point. 00:19:26.770 --> 00:19:31.270 And, because we’re dealing with relative humidity (which itself affects how hot a given 00:19:31.270 --> 00:19:35.100 temperature feels to us) it’s anything but simple. 00:19:35.100 --> 00:19:40.960 As a general rule, a swamp cooler could, assuming it’s a good one, cool to within a few degrees 00:19:40.960 --> 00:19:42.940 of the wet-bulb temperature. 00:19:42.940 --> 00:19:45.720 Now, what is the wet-bulb temperature, you ask? 00:19:45.720 --> 00:19:50.640 Heh, well annoyingly it is the lowest temperature that can be achieved through evaporative cooling. 00:19:51.260 --> 00:19:52.000 I know. 00:19:52.000 --> 00:19:53.269 It describes itself. 00:19:53.269 --> 00:19:55.289 Hang on, I’ll try… 00:19:55.289 --> 00:19:59.830 Basically, the wet-bulb temperature is what a thermometer which has its bulb wrapped in 00:19:59.830 --> 00:20:02.049 wet cotton or the like will read. 00:20:02.049 --> 00:20:06.720 It’s affected by how quickly the water evaporates from that little cotton ball. 00:20:06.720 --> 00:20:11.480 It presents the theoretical minimum temperature an evaporative cooler can hope to obtain, 00:20:11.480 --> 00:20:16.169 and as humidity goes up, so does the wet-bulb temperature. 00:20:16.169 --> 00:20:20.860 When humidity is 100%, the wet-bulb temperature is the same as the dry-bulb 00:20:20.860 --> 00:20:26.300 (also known as… normal) temperature because the air cannot take on more moisture. 00:20:26.300 --> 00:20:30.059 Given my sense of humor I’m sure I’ve been called a dry bulb a few times. 00:20:30.060 --> 00:20:36.360 Honestly, all you need to know is that as humidity goes up the ability for these to work goes down. 00:20:36.360 --> 00:20:39.500 I mean, that makes sense, given that they’re basically little humidifiers, 00:20:39.500 --> 00:20:43.389 and explains why calling these air conditioners is super dumb. 00:20:43.389 --> 00:20:46.240 Now, are they without value? 00:20:46.240 --> 00:20:47.620 Well… it depends. 00:20:47.620 --> 00:20:52.080 It might be nice to use this on my desk as a supplement to central air conditioning. 00:20:52.080 --> 00:20:53.940 Maybe I could run that a little less. 00:20:53.940 --> 00:20:57.880 After all a three degree temperature drop is definitely noticeable. 00:20:57.920 --> 00:21:03.600 But certainly it won’t make a dramatic difference and it definitely isn’t going to cool the room. 00:21:04.060 --> 00:21:08.180 In arid places, swamp coolers work amazingly! 00:21:08.180 --> 00:21:12.580 Many people have them to supplement traditional air conditioning and it dramatically lowers 00:21:12.590 --> 00:21:16.070 energy needs (at the expense of increased water usage). 00:21:16.070 --> 00:21:22.240 And, since you typically want a little more humidity in aird places anyway, they’re a win-win. 00:21:22.240 --> 00:21:26.580 Swamp coolers can also help the efficiency of split air conditioning systems by cooling 00:21:26.590 --> 00:21:30.500 the space around the condenser coils and thus increasing their effectiveness. 00:21:30.500 --> 00:21:34.169 Kinda like how this one pools the condensate around the condenser. 00:21:34.169 --> 00:21:38.340 You can see this in practice in this video made by HVACR videos. 00:21:38.340 --> 00:21:41.929 You should check out that channel if you want to see some of the various commercial refrigeration 00:21:41.929 --> 00:21:46.509 and air conditioning systems out there up close, as well as the various ways they fail 00:21:46.509 --> 00:21:48.999 and how issues are diagnosed and repaired. 00:21:49.000 --> 00:21:51.740 It’s really a great channel for that sort of thing. 00:21:51.740 --> 00:21:55.300 But here in the Midwest where humidity can often be oppressive, 00:21:55.300 --> 00:21:59.759 swamp coolers don’t do much and actually just make things worse. 00:21:59.759 --> 00:22:04.350 Now, this little thing, to its credit, suggests that you put ice cubes in it. 00:22:04.350 --> 00:22:08.649 Which is, well, somewhat hilarious because then you’re actually using your 00:22:08.649 --> 00:22:11.250 refrigerator to cool you down and you know what? 00:22:11.250 --> 00:22:12.580 I approve! 00:22:12.580 --> 00:22:14.760 Not in any practical way, of course. 00:22:14.760 --> 00:22:16.120 It’s absolutely silly. 00:22:16.140 --> 00:22:20.500 Your refrigerator made that ice by pulling energy out of water and dumping into your kitchen. 00:22:20.500 --> 00:22:23.400 But technically it would work at least a ‘lil bit. 00:22:23.400 --> 00:22:28.769 But in general these desktop personal coolers are only sometimes able to do anything at all. 00:22:28.769 --> 00:22:32.920 It depends entirely on where you live and also varies day to day. 00:22:32.920 --> 00:22:37.700 Now just because I’m not a total jerk about these things, I have in fact tested this in a few scenarios. 00:22:37.860 --> 00:22:43.600 And while I think that sure, it provides a cooling effect, it’s not the miracle product 00:22:43.600 --> 00:22:48.520 that you HAVE TO BUY that all of the ads out there are proclaiming them to be. 00:22:48.520 --> 00:22:53.020 And how on Earth this little thing managed to get all these five star reviews is … 00:22:53.020 --> 00:22:54.760 Suspicious! 00:22:54.760 --> 00:22:58.860 And also, right now, these are horribly overpriced! 00:22:58.860 --> 00:23:04.480 It is literally a computer case fan, a hunk of cheap plastic, and a bit of paper 00:23:04.480 --> 00:23:06.760 with a tiny control board for everything. 00:23:06.760 --> 00:23:11.980 It’s powered over USB and they don’t even give you the courtesy of providing a power supply. 00:23:11.980 --> 00:23:17.720 These should cost no more than $25 and even then, that’s a lot for what it is. 00:23:17.720 --> 00:23:21.340 Plus, the water absorbing material should be replaced periodically. 00:23:21.340 --> 00:23:25.420 It gets gross over time, and do any of these companies provide replacements? 00:23:25.420 --> 00:23:26.980 Who knows! 00:23:26.980 --> 00:23:32.260 Keep in mind also that by adding humidity you’re making your air conditioner work harder. 00:23:32.260 --> 00:23:36.440 Getting water to condense removes heat energy that we can’t feel - 00:23:36.440 --> 00:23:38.159 that’s the whole latent heat bit. 00:23:38.159 --> 00:23:42.700 So if you have a lot of moisture in the air, your air conditioner needs to run longer to 00:23:42.700 --> 00:23:47.380 provide the same amount of cooling thanks to all that water that’s condensing on the evaporator. 00:23:47.380 --> 00:23:51.800 Using a mini-swamp cooler in an already-humid place makes your struggling air conditioner 00:23:51.800 --> 00:23:56.519 struggle even more (though admittedly, not much given the small amount of water this 00:23:56.519 --> 00:23:58.929 thing is capable of putting out over a day). 00:23:58.929 --> 00:24:01.009 So - these things. 00:24:01.009 --> 00:24:02.200 Are they a scam? 00:24:03.520 --> 00:24:08.620 Well, they just barely pull off a no on a technicality. 00:24:08.620 --> 00:24:12.300 I mean, calling it an air conditioner is an outright lie. 00:24:12.300 --> 00:24:20.720 But if they’re sold as “personal cooling devices” then… well yeah I suppose that’s technically true. 00:24:20.720 --> 00:24:25.060 But they’re only useful in certain places and certain situations. 00:24:25.060 --> 00:24:29.480 This is not a personal air conditioner, and while I wish it was as easy as 00:24:29.480 --> 00:24:33.540 Just Add Water! I regret to inform you that it is not. 00:24:33.540 --> 00:24:36.880 If you’d like to take a little test drive of this concept, 00:24:36.880 --> 00:24:41.799 I’d suggest you make your own evaporative cooler to see if it would even do anything for you. 00:24:41.800 --> 00:24:45.960 You could probably just glue a few kitchen sponges to a dinner plate in an upright position, 00:24:45.960 --> 00:24:47.640 with a bit of space between them, 00:24:47.649 --> 00:24:51.160 add some water so the sponges absorb it, and put that contraption in front of a small 00:24:51.160 --> 00:24:56.080 desk fan and get way more cooling than this thing could ever hope to produce. 00:24:56.080 --> 00:25:01.240 Any time you see a cooling device for sale which doesn’t require either a hose for 00:25:01.240 --> 00:25:05.540 exhaust or actual installation, it’s not an air conditioner. 00:25:05.540 --> 00:25:11.420 There has yet to be a device you can just plop on your desk and actually get air conditioning from. 00:25:11.420 --> 00:25:13.340 In fact, that’s impossible. 00:25:13.340 --> 00:25:18.960 So while I can’t quite call this a useless device, it’s alarmingly disingenuous, 00:25:18.960 --> 00:25:21.080 terribly overpriced, 00:25:21.080 --> 00:25:23.880 and almost always not worth your time. 00:25:23.880 --> 00:25:24.880 Thanks for watching! 00:25:24.880 --> 00:25:29.760 This is now, I believe, the third time I’ve explained the refrigeration cycle without 00:25:29.769 --> 00:25:33.169 actually making a video specifically about it. 00:25:33.169 --> 00:25:38.340 It really is a remarkable achievement of humanity, and heat pumps are going to become increasingly 00:25:38.340 --> 00:25:42.580 common and important as we move into the age of electrification. 00:25:42.580 --> 00:25:46.590 For sure you’ll be seeing a video about that before too long, and I think then we’ll 00:25:46.590 --> 00:25:50.680 get into the real nitty-gritty like all those terrible refrigerants we used to use 00:25:50.680 --> 00:25:53.580 and how we can move forward with grace. 00:25:53.580 --> 00:25:56.420 But for now, le bloops. 00:25:57.320 --> 00:25:59.720 ♫ disingenuously smooth jazz ♫ 00:26:01.600 --> 00:26:03.860 But swamp is just one syllabo… 00:26:04.740 --> 00:26:06.060 syllabo… 00:26:06.060 --> 00:26:07.920 But swamp is just one syllabo… 00:26:08.440 --> 00:26:09.679 syllable! 00:26:09.679 --> 00:26:11.640 I said “syllabo”... twice now 00:26:11.640 --> 00:26:14.480 Now the energy it picked up from cooling the process…. 00:26:14.480 --> 00:26:17.100 From the cooling process… 00:26:17.100 --> 00:26:18.820 uugghghhg 00:26:18.820 --> 00:26:19.400 But! 00:26:19.409 --> 00:26:21.920 I think it will help to illustrate why these 00:26:21.920 --> 00:26:23.780 .... oh I need it here, ha! 00:26:24.400 --> 00:26:25.860 In fact, fun fact! 00:26:25.860 --> 00:26:28.660 [clink as the nozzle hits the table] The… shoot. 00:26:28.660 --> 00:26:31.940 And if you’re not interested in this part, go ahead and skip to here. 00:26:31.940 --> 00:26:33.400 But, I think it will help to… 00:26:33.400 --> 00:26:35.590 that’s right in front of my face, that’s a bad idea. 00:26:35.590 --> 00:26:40.860 The air that comes from this feels a little bit cooler than the air coming from an ordinary fan, but 00:26:40.860 --> 00:26:41.960 not my much. 00:26:41.960 --> 00:26:43.360 Not My much. 00:26:43.360 --> 00:26:45.380 It’s not MY much it’s YOUR much! 00:26:46.760 --> 00:26:49.480 The way these things are marketed? 00:26:49.480 --> 00:26:51.900 Not cool. 00:26:51.900 --> 00:26:55.420 Oh I regret not working that into the script somehow. 00:26:55.420 --> 00:26:58.880 But now it's the secret end joke, so yay!