WEBVTT - TechStuff Classic: How Refrigerators Work 0:00:04.240 --> 0:00:07.240 Welcome to tech Stuff, a production of I Heart Radios 0:00:07.320 --> 0:00:14.120 How Stuff Works. Hey there, and welcome to tech Stuff. 0:00:14.160 --> 0:00:17.319 I'm your host, Jonathan Strickland. I'm an executive producer with 0:00:17.920 --> 0:00:20.120 I Heart Radio. I almost said how Stuff Works. That's 0:00:20.160 --> 0:00:22.800 my old employer, but no, I Heart Radio and I 0:00:22.920 --> 0:00:26.800 love all things tech. And we're gonna have a really 0:00:27.040 --> 0:00:30.400 cool throwback today. Yep, it's Friday. It's time for a 0:00:30.400 --> 0:00:34.800 classic episode. So we're going to listen to how refrigerators work. 0:00:35.479 --> 0:00:40.960 This episode originally published on March two, thousand thirteen. So 0:00:41.120 --> 0:00:45.560 let's listen to how fridges work. I totally forgot and 0:00:45.720 --> 0:00:49.120 I need to chill out, so let's let's let's hear it. 0:00:49.720 --> 0:00:53.360 We're gonna talk about refrigerators then. And here's the interesting thing, guys. 0:00:53.400 --> 0:00:56.120 If you listen to the episode that Chris Pallette and 0:00:56.160 --> 0:01:00.800 I did quite some time ago about air conditioners, podcast 0:01:00.880 --> 0:01:03.160 is going to sound very similar to that because the 0:01:03.200 --> 0:01:06.200 technology is used in air conditioning systems and the technology 0:01:06.240 --> 0:01:10.120 is used in refrigerators are essentially the same, just one 0:01:10.200 --> 0:01:13.520 is a more small and controlled and um not for 0:01:13.640 --> 0:01:19.039 people usually usually right. No, there's some notable exceptions to that. 0:01:19.880 --> 0:01:22.440 We are not going to talk about those guys, because 0:01:22.440 --> 0:01:26.240 that's creepy and probably belongs in another podcast. Okay, so 0:01:26.400 --> 0:01:29.679 we're not talking about people in refrigerators today, although now 0:01:29.720 --> 0:01:33.720 I can't think of anything else. Um, but no, no, no, 0:01:33.959 --> 0:01:37.120 first let's start with what the definition of refrigeration is. 0:01:37.160 --> 0:01:40.960 So it's defined as the process of achieving and maintaining 0:01:41.000 --> 0:01:44.240 a temperature below that of the surroundings. And the aim 0:01:44.280 --> 0:01:46.760 of it is to cool some sort of space or 0:01:46.880 --> 0:01:51.200 object to a required temperature. Right, because bacteria grow most 0:01:51.320 --> 0:01:53.800 rapidly in this and it's it's called the danger zone 0:01:53.920 --> 0:01:58.960 actually of in between. I now I have a new 0:01:59.080 --> 0:02:02.880 thing filling my head. But okay, yes that I had 0:02:03.000 --> 0:02:08.679 debatably better than than okay, well excellent, but so yeah, 0:02:08.720 --> 0:02:11.679 the danger zone is in between forty degrees fahrenheit and 0:02:11.680 --> 0:02:13.839 a hundred and forty degrees fahrenheit, which is a four 0:02:13.880 --> 0:02:17.160 point four to sixty degrees celsius. And and in that 0:02:17.200 --> 0:02:21.120 temperature range, bacteria really just groove out. They can they 0:02:21.120 --> 0:02:23.600 can more than double in in twenty minutes, and the 0:02:23.720 --> 0:02:28.240 population just explodes. And and bacteria and for things like 0:02:28.600 --> 0:02:32.560 you know, food stuff that that we would consume that's 0:02:32.600 --> 0:02:36.000 not necessarily a great mix that can lead to some 0:02:36.080 --> 0:02:40.320 pretty nasty contamination. It can lead to some really serious 0:02:40.360 --> 0:02:43.840 health problems. And uh, and this is why refrigeration is 0:02:43.840 --> 0:02:46.320 such a big deal. I mean, clearly, before we had 0:02:46.400 --> 0:02:49.240 any kind of refrigeration, we had to look at different 0:02:49.280 --> 0:02:53.079 ways to preserve food. Otherwise, you pretty much had to 0:02:53.200 --> 0:02:56.200 get food from the source and consume it right away 0:02:56.280 --> 0:02:59.200 immediately or as close to immediately as possible. Or you 0:02:59.240 --> 0:03:01.760 had to get so that it would yeah, so it 0:03:01.760 --> 0:03:04.320 wouldn't spoil as quickly, or you had to salt it 0:03:04.520 --> 0:03:08.080 like crazy so that again the salting would would inhibit 0:03:08.160 --> 0:03:13.080 the bacteria from from from reproducing so quickly. And even 0:03:13.120 --> 0:03:17.000 in refrigeration we still have that that process. It's just 0:03:17.120 --> 0:03:19.960 slowed down quite a bit, which is why you cannot 0:03:20.040 --> 0:03:24.200 leave food in a refrigerator indefinitely. It will eventually go bad. 0:03:24.760 --> 0:03:28.120 Um and then just like in that great Far Side cartoon, 0:03:28.360 --> 0:03:31.800 the potato salad will hold up the catchup when potato 0:03:31.800 --> 0:03:36.720 salad goes bad. So the trick here, though, is how 0:03:36.840 --> 0:03:41.400 do you create this cool environment? This this cold environment 0:03:41.400 --> 0:03:47.320 because adding heat two things is easy. Taking heat away 0:03:47.600 --> 0:03:51.680 not as easy, less less easy. And also before I 0:03:51.720 --> 0:03:55.960 get all my physicist friends sending in messages about the 0:03:56.040 --> 0:03:58.880 use of the word heat. I do apologize. We're going 0:03:58.920 --> 0:04:01.440 to be using it in the vernacular quite a bit 0:04:01.560 --> 0:04:05.800 because that's really what everyone's familiar with. But to be clear, 0:04:06.760 --> 0:04:10.880 an object does not possess heat. It has a temperature, 0:04:10.960 --> 0:04:13.440 but it doesn't possess heat. An objects will have internal 0:04:13.520 --> 0:04:16.640 energy as a result of molecular motion, and heat is 0:04:16.720 --> 0:04:21.520 really the description of an energy transfer process. And you 0:04:21.600 --> 0:04:25.280 go from a high temperature object to a lower temperature one. 0:04:25.800 --> 0:04:29.800 That is the basic concept of heat. It's really an 0:04:29.880 --> 0:04:32.720 energy transfer. So when we say, like this object's got 0:04:32.720 --> 0:04:35.400 a lot of heat to it, uh, that's a that's 0:04:35.400 --> 0:04:39.720 a completely colloquial way saying it. So I do acknowledge that. 0:04:39.760 --> 0:04:43.159 I apologize. But if you really want someone who's going 0:04:43.200 --> 0:04:46.760 to be a stickler for science, go bug Robert Lamb 0:04:46.800 --> 0:04:50.320 because he loves that the stuff to blow your mind. Gay, Um, 0:04:50.520 --> 0:04:55.680 Robert's awesome. I love Robert. So, yeah, that's the way 0:04:55.720 --> 0:04:59.160 heat works. Though you have high temperature low temperature, then 0:04:59.279 --> 0:05:02.560 heat moves from the high temperature to the low temperature. 0:05:02.560 --> 0:05:05.760 It does not go the other way around, right without 0:05:05.839 --> 0:05:09.360 without some sort of external force working on the system. 0:05:09.920 --> 0:05:13.599 This is essentially one of the basic laws of thermodynamics. 0:05:13.720 --> 0:05:16.400 And so you've got this, uh, you've got a way. 0:05:16.440 --> 0:05:20.080 You have to find a way of creating a lower 0:05:20.320 --> 0:05:26.640 temperature environment to pull heat from or to for heat 0:05:26.680 --> 0:05:31.080 to transfer from the objects that are inside a refrigerator 0:05:31.240 --> 0:05:35.160 to make them cool. So that's the basis of refrigeration. 0:05:35.240 --> 0:05:37.160 But you know, to get to that point, we had 0:05:37.200 --> 0:05:39.320 to do a lot of stuff and we had to 0:05:39.360 --> 0:05:43.240 understand a lot about physics for this to become what 0:05:43.440 --> 0:05:46.600 we now all kind of take for granted. Yeah, So 0:05:47.240 --> 0:05:50.680 to to get started, I guess we can talk about 0:05:50.720 --> 0:05:53.520 what the predecessor was to the modern refrigerator, which was 0:05:53.520 --> 0:05:56.279 the ice box, right, or you know, going going way 0:05:56.279 --> 0:05:58.920 back in time, you had you had people not even 0:05:58.920 --> 0:06:02.400 making ice boxes, yes, just collecting ice and putting it 0:06:02.440 --> 0:06:04.800 next to stuff. Yeah, or like maybe you know, you 0:06:04.880 --> 0:06:07.599 might have a seller that you'd put ice into, or 0:06:07.640 --> 0:06:10.000 you might just have a hole in the ground, or 0:06:10.040 --> 0:06:12.320 you may just like if you were in a part 0:06:12.320 --> 0:06:16.960 of the world where there was a significant amount of snowfall. Uh, 0:06:17.080 --> 0:06:19.360 we here in Georgia are not in that part of 0:06:19.400 --> 0:06:21.720 the world. We did have some snow the other day, 0:06:22.080 --> 0:06:25.760 I could see a bare trace of it next to 0:06:25.800 --> 0:06:27.680 my steps. Some of it landed in my hair when 0:06:27.720 --> 0:06:29.560 I walked my dog. That was That was about it. 0:06:29.920 --> 0:06:31.640 But if you were in a place where they get 0:06:31.680 --> 0:06:34.360 a significant amount of snow and they're large snow banks, 0:06:34.560 --> 0:06:36.839 then one of the things you might do is store 0:06:36.920 --> 0:06:39.880 some food inside the snow. They're bury it in the snow, 0:06:40.320 --> 0:06:43.440 and just hope that nothing comes along to to grab 0:06:43.480 --> 0:06:45.920 that food. Or Yeah, if if you've got an ice house, 0:06:45.960 --> 0:06:48.200 you can preserve some of the ice with a sawdust 0:06:48.279 --> 0:06:51.280 or wood shavings. Later on, cork was used to insulate 0:06:51.320 --> 0:06:54.560 it for a few months anyway, until temperatures warmed up enough. 0:06:54.800 --> 0:06:58.000 Right right, Yeah, you could. You could definitely slow the process, 0:06:58.160 --> 0:07:01.320 insulated enough from the heat of the outside environment so 0:07:01.360 --> 0:07:05.120 that it would preserve it, you wouldn't lose too much 0:07:05.120 --> 0:07:07.359 in melt off. It took a while before people started 0:07:07.400 --> 0:07:10.680 to figure out the best ways to keep ice from 0:07:10.680 --> 0:07:13.800 from melting too quickly. And it's interesting because just as 0:07:13.840 --> 0:07:17.240 they were really getting getting very good and making sure 0:07:17.240 --> 0:07:21.080 they kept ice uh cold for as long as possible, 0:07:21.160 --> 0:07:25.920 even in hot environments. Uh, that's when the mechanical refrigeration 0:07:26.000 --> 0:07:28.760 technology had started to really take off and it became 0:07:28.840 --> 0:07:32.160 less important. Yeah, and these were happening simultaneously, which is 0:07:32.240 --> 0:07:36.040 really fascinating to me. It was in seven five that 0:07:36.120 --> 0:07:39.000 the first refrigerating machine was produced. I believe it could 0:07:39.040 --> 0:07:41.800 make small amounts of ice in the lab. Yeah. Yeah, 0:07:41.840 --> 0:07:45.840 to to really understand well, first of all, the word refrigerate, 0:07:46.080 --> 0:07:48.120 I found the I found the earliest use of it, 0:07:48.560 --> 0:07:50.920 which was or at least earliest recorded use that I 0:07:50.960 --> 0:07:53.640 could find, which was from fifteen fifty. But it was 0:07:53.680 --> 0:07:57.040 all about using chemicals and water. People were discovering that 0:07:57.080 --> 0:07:59.640 if they added certain chemicals to water for some reason, 0:07:59.640 --> 0:08:01.800 the temper sure the water would drop. So if you 0:08:01.840 --> 0:08:04.560 were to put something in a container of water that 0:08:04.640 --> 0:08:07.800 had this chemical in it, you could cool that's something. Now, 0:08:07.840 --> 0:08:11.160 if that's something was unprotected food and that chemical was poisonous, 0:08:11.320 --> 0:08:13.560 that was not necessarily a great thing. But if that's 0:08:13.560 --> 0:08:15.680 something where I don't know, a bottle of wine and 0:08:15.680 --> 0:08:17.800 you happen to be French, this was a great way 0:08:17.840 --> 0:08:20.840 to cool your wine. And in fact, in the Renaissance, 0:08:20.960 --> 0:08:24.440 these cooled drinks became very popular, to the point where 0:08:24.440 --> 0:08:27.600 if you added chemicals to water it would drop the 0:08:27.600 --> 0:08:30.000 temperature enough that if you put something in it that 0:08:30.480 --> 0:08:33.800 that you could turn on a regular basis, you could 0:08:33.800 --> 0:08:37.120 actually make ice this way. Um. Yeah, so this was 0:08:37.200 --> 0:08:39.600 kind of an early ice maker. Not efficient, not good 0:08:39.640 --> 0:08:42.480 for producing ice on any kind of large scale, but 0:08:42.640 --> 0:08:45.040 it was one of those things that the rich people 0:08:45.200 --> 0:08:47.520 really enjoyed, and really those were the only ones who 0:08:47.520 --> 0:08:50.480 had any chance of getting at it. Um. But yeah, 0:08:51.160 --> 0:08:55.839 it was just before your the refrigerator unit type thing 0:08:55.840 --> 0:08:58.560 you were talking about from the seventeen seventies. Seventeen fifty 0:08:58.600 --> 0:09:02.360 five is pretty much when we talk about the origin 0:09:02.440 --> 0:09:06.320 of the idea. That's when William Cullen made his machine 0:09:06.320 --> 0:09:11.160 with which you used a vacuum UH and UH ether 0:09:11.920 --> 0:09:16.600 to UH to create this UH environment where he would 0:09:16.600 --> 0:09:21.440 put water into a container, put a smaller amount of 0:09:21.440 --> 0:09:25.520 ether in there, put a essentially a vacuum bell jar 0:09:25.640 --> 0:09:27.480 on top, you know, a pump with a pump on it. 0:09:28.360 --> 0:09:31.240 By creating the vacuum, the ether would start to boil off. 0:09:32.080 --> 0:09:34.479 And when the ether was boiling off, when it was vaporizing, 0:09:34.800 --> 0:09:38.520 he noticed that the temperature was going down in the 0:09:38.520 --> 0:09:42.040 water and in fact, by when the ether would continue 0:09:42.040 --> 0:09:45.400 to boil off, the water would start to turn into ice. 0:09:46.080 --> 0:09:48.760 Now we'll talk about why that is a little bit later, 0:09:48.880 --> 0:09:51.800 but this was one of those early observations that started 0:09:51.840 --> 0:09:55.200 to lead people into thinking, you know, if we harness 0:09:55.320 --> 0:10:00.120 this in some way, pretty cool. You're doing it too here, 0:10:02.600 --> 0:10:06.200 there's no way to avoid it. Vocal baumb join us together, 0:10:06.280 --> 0:10:08.800 we will rule the galaxy. Jonathan. We need to we 0:10:08.840 --> 0:10:11.360 need to chill out. Yes we do. Okay, alright, not 0:10:11.679 --> 0:10:14.439 too fast, too fast. You gotta gotta pace yourself here. 0:10:14.800 --> 0:10:19.240 Um So, anyway, this does form the basis. This, this 0:10:19.360 --> 0:10:24.960 idea of vapor pulling out heat somehow, that is what 0:10:25.160 --> 0:10:29.440 was the very basis of mechanical refrigeration. It would be 0:10:29.559 --> 0:10:32.320 quite a while before the mechanical refrigerators would start to 0:10:32.320 --> 0:10:36.319 become a real thing. Uh, I have in eighteen o three, 0:10:36.840 --> 0:10:41.080 you have a Thomas Moore obviously, not that one different 0:10:41.080 --> 0:10:45.520 Thomas Moore UH of Maryland. In fact, he received a U. S. 0:10:45.559 --> 0:10:49.200 Patent for a refrigerator. Now this was not the same 0:10:49.240 --> 0:10:51.560 thing as mechanical refrigerators that would come later. But that 0:10:51.679 --> 0:10:55.320 same year that was when the domestic ice box was invented. 0:10:55.880 --> 0:10:58.680 So three you get the domestic ice box. This was 0:10:59.240 --> 0:11:02.360 usually a wooden cabinet that you would put a block 0:11:02.440 --> 0:11:05.920 of a large block of ice into the top, and 0:11:05.960 --> 0:11:09.600 then you would keep your food and consumables in the 0:11:09.640 --> 0:11:13.640 bottom part of this cabinet, and convection would essentially keep 0:11:14.240 --> 0:11:18.120 because because heat rises and cold sinks, the which is 0:11:18.160 --> 0:11:22.600 which we know is the generalization generalization, yes, but but 0:11:22.679 --> 0:11:26.120 in general in this particular case, yeah, you've got you've 0:11:26.160 --> 0:11:29.160 got the dense the dense cold air going down and 0:11:29.200 --> 0:11:32.760 the and the less dense warm air moving up. Because yeah, 0:11:33.120 --> 0:11:36.559 but we we understand that is a gross over generalization. 0:11:36.600 --> 0:11:40.080 But for the purposes of this podcast, it's effective enough. Yeah, 0:11:40.120 --> 0:11:41.640 you keep that ice on top. You have a like 0:11:41.679 --> 0:11:44.199 a drip tray on underneath, because hey, that ice is 0:11:44.240 --> 0:11:47.880 melting um, and so you would collect the water which 0:11:47.880 --> 0:11:49.800 you would not just pour into the top where it 0:11:49.800 --> 0:11:52.600 would magically become ice again. Essentially, once that ice was gone, 0:11:52.600 --> 0:11:54.839 you had to go out and buy more ice. And 0:11:54.880 --> 0:11:57.640 actually the ice trade was really huge right around that time. 0:11:57.640 --> 0:12:01.160 In eighteen o six, I think Frederick Tudor began his 0:12:01.160 --> 0:12:04.880 his ice empire. He was called the Ice king Um 0:12:04.920 --> 0:12:07.679 when he started cutting chunks out of the Hudson River 0:12:07.760 --> 0:12:10.640 in various ponds around Massachusetts and then exporting it as 0:12:10.679 --> 0:12:13.800 far as China and Australia, in India and India. Yeah. 0:12:14.120 --> 0:12:18.199 Also what's interesting is that India was the way the 0:12:18.240 --> 0:12:20.120 way they were producing ice in India at this time 0:12:20.200 --> 0:12:25.120 was through a process called nocturnal radiative cooling. Right, I 0:12:25.160 --> 0:12:27.440 was reading about this this it took me a while 0:12:27.480 --> 0:12:30.320 to grasp how that work. I still did not understand it. 0:12:30.360 --> 0:12:31.880 So I mean what I what I understand that basically 0:12:31.920 --> 0:12:34.880 they were doing was putting water in shallow clay trays 0:12:35.000 --> 0:12:39.560 and setting it outside under the open sky overnight and 0:12:39.600 --> 0:12:43.000 then in the morning ice would be there. Yeah. What 0:12:43.000 --> 0:12:47.160 what essentially is happening is that the uh it's there 0:12:47.240 --> 0:12:49.480 is another physical process going on here. But you've got 0:12:49.520 --> 0:12:53.000 you've got a tray of water outside. The sky needs 0:12:53.040 --> 0:12:55.400 to be clear because what's happening is the heat is 0:12:55.520 --> 0:12:59.920 radiating from the water out into the atmosphere and escape 0:13:00.280 --> 0:13:03.480 that way. Now, if there are clouds, then the heat 0:13:03.520 --> 0:13:06.800 can radiate back down too, because it's like an insulator. 0:13:07.200 --> 0:13:09.440 It'll it'll end up insulating the earth and you end 0:13:09.520 --> 0:13:15.560 up you don't get us. But otherwise, even if the 0:13:15.559 --> 0:13:19.800 the ambient temperature outside is still right around freezing or 0:13:19.840 --> 0:13:22.920 just above freezing. You can still freeze water that way 0:13:23.440 --> 0:13:25.439 under a clear sky. It also helps if it's a 0:13:25.520 --> 0:13:28.360 very dry climate. Right. And and from what I understand 0:13:28.360 --> 0:13:30.599 that it's important that it's a that it's an earthenware 0:13:30.720 --> 0:13:33.959 tray because that way you get some of them, well, 0:13:34.240 --> 0:13:37.360 you have to have that insulated effect there as well. 0:13:37.480 --> 0:13:40.079 It's the earthen tray and there's usually hay underneath it, 0:13:40.120 --> 0:13:43.040 some kind of compressed Yeah, so it's it's interesting that 0:13:43.040 --> 0:13:45.600 that was the way that India was producing ice, but 0:13:46.320 --> 0:13:49.400 that was not a very again, a very efficient way 0:13:49.400 --> 0:13:51.360 of producing ice. You couldn't produce a lot of it, 0:13:51.520 --> 0:13:55.720 and uh there was a big demand. So Tutor was 0:13:55.800 --> 0:14:00.280 really raking it in by harvesting ice in the United States, 0:14:00.320 --> 0:14:03.080 just natural ice. Not he's not producing it in any 0:14:03.160 --> 0:14:05.560 mechanical means. He's actually going out and digging it up, 0:14:06.480 --> 0:14:09.720 packing it in wood shavings and that sort of stuff, cork, 0:14:10.040 --> 0:14:12.000 that kind of thing, shipping it to the other side 0:14:12.000 --> 0:14:14.480 of the world, and making huge bank off of it, 0:14:14.640 --> 0:14:16.760 huge bank. And I want to mention that also right 0:14:16.800 --> 0:14:21.880 around this time, in UH seven, ammonia was first liquefied 0:14:22.000 --> 0:14:25.080 in a laboratory, right, which will becoming point um, So 0:14:25.240 --> 0:14:27.280 just keep that in your heads for a second and um. 0:14:27.280 --> 0:14:30.320 And then also in eighteen o five, right before Tutor 0:14:30.360 --> 0:14:34.240 began his big ice trade, um Oliver Evans described did 0:14:34.240 --> 0:14:38.120 not create, but described a closed at their vacuum refrigeration system. Yeah. 0:14:38.160 --> 0:14:42.160 So this is the same sort of of mechanical system 0:14:42.200 --> 0:14:46.920 that would eventually become what we use in refrigerators, most refrigerators, 0:14:47.080 --> 0:14:52.680 I'm saying refrigerators in general, but there are different types. Yeah, well, 0:14:52.720 --> 0:14:55.920 we'll mention a few, but but the we're focusing on 0:14:55.920 --> 0:15:00.000 what most of us have available in like in our kitchens. Uh, 0:15:00.400 --> 0:15:04.280 and maybe our basement if Okay, I'm not gonna go 0:15:04.320 --> 0:15:08.880 back there. It's dark base to a dark place. Voco 0:15:08.960 --> 0:15:11.920 bomb really early on, I'm very fond of that of 0:15:11.960 --> 0:15:15.400 that documentary American Psycho. Okay, that's fair, All right, guys, 0:15:15.480 --> 0:15:17.320 we're gonna take a quick break. I'm gonna go raid 0:15:17.360 --> 0:15:29.040 the fridge and we'll be right back in. This is 0:15:29.080 --> 0:15:34.840 interesting that the Michael Faraday was working again with liquid ammonia, 0:15:34.880 --> 0:15:39.480 and that's when he started realizing that liquid ammonia, which 0:15:39.960 --> 0:15:43.160 ammonia is naturally at room temperature is a gas, right, 0:15:43.200 --> 0:15:47.240 because it boils it at like negative twenty seven degrees fahrenheits. So, 0:15:47.240 --> 0:15:49.920 so to to liquify it, you have to compress it. 0:15:49.960 --> 0:15:52.360 You have to pressurize it to make it a liquid. 0:15:52.600 --> 0:15:55.440 And he realized that when it went from liquid back 0:15:55.480 --> 0:16:00.520 to gas, it caused cooling and so again and another 0:16:00.560 --> 0:16:05.760 important part of this mechanical refrigeration. Now, in one a 0:16:05.840 --> 0:16:09.600 German physicist by the name T. J. Cbeck discovered that 0:16:09.640 --> 0:16:13.760 if you have two junctions of dissimilar metals kept at 0:16:13.840 --> 0:16:18.680 two different temperatures, it induces electromotive force or electric currents. 0:16:18.680 --> 0:16:20.720 So what that means is that let's say that you 0:16:20.800 --> 0:16:23.760 have a junction of a copper wire and an iron wire, 0:16:24.040 --> 0:16:26.640 all right, and then you have a second junction where 0:16:26.680 --> 0:16:29.520 the iron wire is attached to a second copper wire. 0:16:30.120 --> 0:16:33.000 And let's say you were to heat up that, uh, 0:16:33.280 --> 0:16:37.320 that first junction, and cool down the second junction, perhaps 0:16:37.320 --> 0:16:40.040 put some ice on it, you would actually induce electricity 0:16:40.200 --> 0:16:43.520 to flow through that wire. Now that's important because in 0:16:43.600 --> 0:16:48.640 eighteen thirty four, uh Peltier discovers that if you do 0:16:48.760 --> 0:16:52.560 the opposite, if you put electricity through a series of 0:16:52.560 --> 0:16:54.760 wires that have these kind of junctions on one side 0:16:54.760 --> 0:16:56.600 will heat up and the other side will cool down 0:16:56.800 --> 0:16:59.800 exactly and then by up to I think forty degrees fahrenheit. 0:17:00.000 --> 0:17:03.680 It all depends on what kind of material material you're using. UH. 0:17:03.720 --> 0:17:07.640 In fact, this sort of is called the Peltier effect. Actually, 0:17:07.960 --> 0:17:11.119 but this sort of effect is dependent upon the types 0:17:11.160 --> 0:17:15.560 of metals or or materials you're using and UH their purity. UH. 0:17:15.960 --> 0:17:19.719 If you're using pure metals, the effect is pretty small, 0:17:19.920 --> 0:17:22.760 so small as to not be very useful. It's interesting 0:17:22.760 --> 0:17:25.239 in the laboratory setting, but not terribly useful. Also, if 0:17:25.240 --> 0:17:27.679 you're using pure metals, they tend to be very good 0:17:27.920 --> 0:17:32.240 thermal conductors, which means that that that difference in temperature 0:17:32.280 --> 0:17:36.159 will not maintain itself for very long. You will eventually 0:17:36.440 --> 0:17:39.160 have the the heat will move from the high temperature 0:17:39.200 --> 0:17:43.040 to the low temperature and balance that out. UH. Meanwhile, 0:17:43.160 --> 0:17:45.520 if you were to use an insulator, then you wouldn't 0:17:45.560 --> 0:17:49.000 get the effect, so it would take years before anyone 0:17:49.040 --> 0:17:50.959 would find a way to make that useful. But that 0:17:51.119 --> 0:17:55.000 is used that that same technique is used in some 0:17:56.640 --> 0:17:59.159 little portable refrigerator things like the kind of stuff you 0:17:59.240 --> 0:18:03.440 might plug in to your your car outlet. Sure. Yeah. 0:18:03.560 --> 0:18:05.800 Basically you just get a whole bunch of these junctions 0:18:05.800 --> 0:18:07.560 set up. You put the hot ones outside the unit, 0:18:07.640 --> 0:18:11.800 the cool ones inside the unit. Fridge. Yep, that's exactly it. 0:18:12.320 --> 0:18:14.879 So so spoiler alert, that's how that one works. But 0:18:14.920 --> 0:18:16.840 we thought it i'd be interesting to talk about that, 0:18:17.040 --> 0:18:19.639 But that's that was what caused was the basis of 0:18:19.640 --> 0:18:22.199 that sort of refrigerator. UM. And that same year, in 0:18:22.200 --> 0:18:26.720 eighteen thirty four, Jacob Perkins developed a vapor compression cycle 0:18:26.800 --> 0:18:29.920 refrigerator using either. So you got a lot of people 0:18:29.960 --> 0:18:34.200 working on patent for it. Happened that year and h 0:18:34.280 --> 0:18:36.840 eighteen forty four you had John Gory proposing an air 0:18:36.880 --> 0:18:41.600 cycle refrigerating machine for making ice. UH eighteen fifty you 0:18:41.680 --> 0:18:45.560 had Rudolph Clausus who said heat can never pass from 0:18:45.560 --> 0:18:48.119 a colder to a warmer body without some other change 0:18:48.119 --> 0:18:50.960 connected there with occurring at the same time. This is 0:18:50.960 --> 0:18:52.840 what I was talking about at the top of the podcast. 0:18:53.160 --> 0:18:57.000 It's kind of a rewording of the second law of thermodynamics. 0:18:57.560 --> 0:19:02.000 It's related to that. So that's one of the principles 0:19:02.080 --> 0:19:05.439 that guided refrigeration as well. UH. In eighteen fifty one, 0:19:05.440 --> 0:19:08.400 our buddy John Gorey from back when he had proposed 0:19:08.400 --> 0:19:11.520 that air cycle refrigerating refrigeration machine to to create ice. 0:19:11.680 --> 0:19:14.760 In eighteen fifty one, that's when he got the another 0:19:14.840 --> 0:19:19.119 patent for mechanical refrigeration. And in eighteen fifty five Alexander 0:19:19.200 --> 0:19:22.560 Twining starts his first commercial ice making plant using vapor 0:19:22.640 --> 0:19:26.760 compression refrigeration. We'll explain what that is in more detail 0:19:26.920 --> 0:19:31.080 in a little bit. Eighteen fifty six, commercial refrigeration begins 0:19:31.080 --> 0:19:35.800 in industries like brewing and meat packing. Now, commercial refrigeration 0:19:35.840 --> 0:19:39.760 did not necessarily mean they were using mechanical refrigeration. They 0:19:39.760 --> 0:19:42.560 could be using natural refrigeration, as in going out and 0:19:42.600 --> 0:19:45.879 buying lots and lots of ice and packing stuff in it. Um. 0:19:45.920 --> 0:19:48.080 It's interesting to me that brewing picked up on this 0:19:48.160 --> 0:19:51.119 really quickly, like like the brewing companies were like, we 0:19:51.240 --> 0:19:54.440 want beer that tastes good. It's as though alcohol technology 0:19:54.480 --> 0:19:57.800 is something that drives industry in some way. Yeah, the 0:19:57.840 --> 0:20:03.520 meat packers were slower to follow, which is disturbing. Spoiled 0:20:03.520 --> 0:20:05.679 meat was something everyone was used to write. But and 0:20:05.720 --> 0:20:08.800 if you're drunk enough, you don't care. Okay, got it, 0:20:08.920 --> 0:20:11.440 I understand now as someone who does not imbibe alcohol, 0:20:11.480 --> 0:20:13.280 it was just completely foreign to me. But I don't 0:20:13.320 --> 0:20:16.520 eat meat either, so what do I care? Um. Also, 0:20:16.640 --> 0:20:18.920 we're no longer in the eighteen fifties, as it turns out, 0:20:19.119 --> 0:20:21.640 But yeah, meat pagging was slow to adopt this technology, 0:20:21.720 --> 0:20:24.600 but it did start it back in the eighteen fifties, 0:20:24.960 --> 0:20:27.920 and the majority of plants wouldn't switch to mechanical refrigeration 0:20:28.000 --> 0:20:30.480 until about nineteen fourteen, and by then you were getting 0:20:30.520 --> 0:20:34.080 into a really like a booming time of refrigeration. But 0:20:35.200 --> 0:20:39.000 backtracking just touch. In eighteen fifty nine we had a 0:20:39.359 --> 0:20:43.440 Ferdinand car of France who developed an ammonious slash water 0:20:43.480 --> 0:20:48.240 refrigeration machine. Eighteen sixty eight you had Peter van der Wide. Uh. 0:20:48.520 --> 0:20:52.639 He patents thermostatically controlled refrigeration systems. That's going to be 0:20:52.640 --> 0:20:56.160 important when we get to the modern refrigerator. Eighteen seventy 0:20:56.359 --> 0:20:59.680 Carl Lynn publishes a paper called the Extraction of Heat 0:20:59.720 --> 0:21:03.240 at Temperature by Mechanical Means, and he designs the first 0:21:03.240 --> 0:21:08.560 practical portable compressor refrigeration machine in eighteen seventy three. Uh. 0:21:08.600 --> 0:21:11.280 In eighteen seventy seven, that was the peak of the 0:21:11.359 --> 0:21:15.400 ice trade so in the US that it hit its peak, right, 0:21:15.480 --> 0:21:19.720 and the late eighteen seventies, the United States was exporting 0:21:19.840 --> 0:21:24.159 almost almost a quarter of a million tons of ice 0:21:24.240 --> 0:21:27.960 to other countries. So uh, yeah, a lot of ice 0:21:28.040 --> 0:21:32.879 leaving the United States. Um, and uh it's interesting to 0:21:32.920 --> 0:21:36.159 me that at this point where the ice trade is 0:21:36.280 --> 0:21:40.080 at its peak, but mechanical refrigeration is already in its infancy. 0:21:40.560 --> 0:21:46.680 The only reason that mechanical refrigeration even started to take off, 0:21:47.480 --> 0:21:50.639 it wasn't because the technology was getting great. It's because 0:21:50.680 --> 0:21:55.080 the ice trade was starting to encounter problems. Once it 0:21:55.119 --> 0:21:58.520 gets to about the eighteen nineties or so, Like, if 0:21:58.560 --> 0:22:02.600 the ice trade had not encountered problems, then even with 0:22:02.680 --> 0:22:06.480 the technological advances in mechanical refrigeration, we may not have 0:22:06.520 --> 0:22:10.720 seen refrigerators in the United States for another you know, 0:22:10.720 --> 0:22:14.800 I don't know, four or five decades, but so yeah, 0:22:14.840 --> 0:22:20.160 and that what happened with was that as people were 0:22:20.720 --> 0:22:25.040 essentially mining ice, you know, cutting away ice from these 0:22:25.200 --> 0:22:30.480 rivers and ponds, they were starting to uh exhaust the 0:22:30.600 --> 0:22:35.320 clean sources of water and so more and more of 0:22:35.359 --> 0:22:38.280 the ice. The demand was was growing, right, and the 0:22:38.320 --> 0:22:41.359 supply was diminishing, not that we were running out of 0:22:41.640 --> 0:22:43.720 lakes and rivers and stuff. It's just the demand was 0:22:43.760 --> 0:22:46.440 so great and great that there wasn't enough to go around. Yeah, 0:22:46.440 --> 0:22:49.240 there's not there's only that are frozen and the Hudson 0:22:49.359 --> 0:22:51.320 is really big and stuff. But yeah, I mean when 0:22:51.320 --> 0:22:53.479 you're talking about a quarter of a million tons, right, 0:22:53.800 --> 0:22:56.199 so you're talking about tons of ice that might have 0:22:56.240 --> 0:23:00.960 things like sewage in not so great when you're using 0:23:01.000 --> 0:23:05.000 it in the meat packing industry as not maybe not 0:23:05.240 --> 0:23:10.239 such a big advantage over spoiled meat. Um. Yeah. So uh, 0:23:10.840 --> 0:23:13.400 it's because the ice industry was starting to have these 0:23:13.440 --> 0:23:17.280 issues that we began to see the rise of mechanical refrigeration. 0:23:18.520 --> 0:23:21.200 One was when a trade journal called Ice and Refrigeration 0:23:21.320 --> 0:23:24.920 began to publish. Nineteen o four was when the American 0:23:24.960 --> 0:23:28.639 Society of Refrigerating Engineers was founded. By the way the 0:23:28.640 --> 0:23:32.920 American Society of Refrigerating Engineers, I learned, was about engineers 0:23:33.160 --> 0:23:35.720 who were experts in refrigeration. It was not a society 0:23:35.720 --> 0:23:39.680 that would actually refrigerate engineers. Because the way it was 0:23:39.720 --> 0:23:43.720