Transcript: eutectic goop video

[music] Hi. In our last video, we demonstrated a modification that you can apply to a residential freezer and convert it into a blast chiller and it worked. It takes less than an hour to do and it cost less than $50. Now, if you're not familiar with what a blast chiller is, it's effectively a freezer on steroids. They're very popular in large restaurants, hotels, and multi-million dollar homes because they allow you to cool and even freeze food very, very fast. This improves throughput and it actually improves the quality of the food in terms of its texture and its taste if you freeze it very rapidly. The problem with these devices is they're very expensive. They start at a couple thousand and rapidly go up. Part of the explanation is it's a niche item. They don't sell a lot of them. But the other explanation is that they have a very large refrigeration system in order to draw that heat out so quickly. Some of them even have three-phase motors because of the need of the compressor. The fact is the refrigeration system in a residential freezer, whether upright or a chest freezer, is very small. It's essentially designed to keep the food at a low temperature with just a little bit of additional capacity so that if you open the door, you put a few food items in, it can refrigerate them. So, how is it possible that we're able to do the same thing as a blast chiller? And it has to do with the advantage of having a working freezer that's loaded with tens of kilogram of deeply frozen food. So when we place the powerful fan inside of the freezer, we rapidly move the air within the freezer compartment drawing the heat out of the item that we want to blast chill. And that heat, a little bit is removed by that little compressor that could, but most of it ends up being deposited in that large thermal mass of the frozen food. Because there is so much of it and because these freezers typically run at maybe -20 to -25° C, sure they'll warm up a few degrees, but they're still hard frozen. And now whatever you've put in there has frozen or refrigerated. Great. But there's a limitation, you see, because we're dependent on the passive food that's in there as a passive thermal heat sink, basically a thermal mass, you need a lot of it in there. And if you have a lot in there, you don't have a lot of room to do your blast chilling operation. And secondly, if you're trying to put a lot of food in, you're trying to process a number of different foods in there, you're going to gradually and continually warm up the rest of the food inside the freezer until eventually it may start to thaw out. That is why we're going to revisit this because we're working on a much larger project which I will get into near the end of the video. But one of the spin-offs of that project has a very very beneficial use in blast chilling and also has some practical use around the house elsewhere. So that's why I thought it'd be a good idea to cover it. Now the principle is we're going to be taking advantage of phase change. It's a very powerful process. When we were warming the food inside the freezer to chill off a sample, we were depending on the food as a passive heat sink, just a thermal mass. We could have effectively removed all the food and put bricks in there and it would have worked just as well. Phase change is the process where a material, matter, molecules, will change from a solid to a liquid to a gas. When you have a solid piece of something and you want to convert it into a liquid phase, you have to add heat energy. And when you want to convert it from liquid to gas, again, you add heat energy. But the magnitude of the amount of heat is stunning. For example, if I took a sample of ice at 0° C and put it down on the table and allowed it to melt into 0° C water, no temperature change, the amount of heat it would have to absorb from the surrounding environment is sufficient to take that 0° C water and bring it all the way up to boiling. It's huge. Now, ice is a phase change material. It's wonderful. That's why it keeps your drinks cold. When you put ice cubes inside of your drink, the heat is melting the ice and the drink stays cold. The problem is ice melts at the wrong temperature for many of our applications. Another example is say you have a cooler, you're going on a camping trip or a long trip and you take a styrofoam cooler and you load it with frozen ice cream and meat and vegetables and everything that you want to keep cold. And then you'll throw a bunch of cold packs in there and some ice cubes in there and seal it up. What is happening though is as the heat seeps through the styrofoam into the container, everything is simultaneously warming. Nothing's melting. And when the ice that you've added begins to melt, begins to in uh in incorporate the phase change um operation, so is your ice cream. Everything is melting at the same time. If we can make a phase change material that effectively freezes and melts well below the freezing point of ice, we can take advantage in both the blast chiller as well as cooler or anything else that you want to keep deeply frozen in a portable application. Now, in order to do that, we're going to use what's called a utctic solution. Fancy word for salt solution. A utctic solution is a little bit special, but as you can imagine, if you took just a container of water, poured a scoop of salt into it, mixed it up, and put it outside in the winter, when it gets down to about 0° C, it's still going to be liquid. But when you get down to maybe -5° C, it starts to get a little slushy. - 10, slushier yet. And finally, at maybe minus 255 or 30°, it freezes rock hard. The problem is that's too broad a range. The freezer can't freeze the ice completely. It doesn't get cold enough. And when you're trying to keep the uh melting point below zero, some of that ice is actually having to get up to zero in order to dissolve, in order to melt. A utctic mixture is a very special ratio of a salt and water, very specific that will melt and freeze at one point, a very narrow point. And so by using the right type of salt in a utctic mixture, we can adjust the freezing point almost by the degree. There are hundreds of different types of utctic salt mixtures. What we're going to be doing today is I'm going to be making a utctic mixture that freezes at -15.4° C. So, it's a little bit warmer than the freezer can get to, meaning it'll freeze hard in the freezer. But, as soon as we start to put a thermal load in there and the air starts to warm up to -15°, it begins to convert. It begins to melt and it absorbs the heat. This is nice because it would protect the rest of the food in the freezer from having to absorb all of that heat. And theoretically, you could remove all the food and put a small quantity of utctic frozen containers in there. So, you gain a lot more room in the freezer for the operation of blast chilling and it would still work better. And the same thing would occur in your cooler. Now the mixture or the way that we're going to mix this up involves adding water and in this case ammonium chloride. When we make a utctic mixture of that it will freeze and melt at minus5° 15.4° C. So for the operation the first thing you need to do is decide on a container. What are you going to put this in? Because you're going to make a number of them. And I think a really good choice is these plastic bottles. You get them for bottled water. I drink a lot of sports drinks. This is a Power Aid bottle. Typically, you'll throw them away or you'll put them in the recycling. Just save them because you have a free container. Now, the best way I've found to blend this or mix this is to use a KitchenAid, a mix master. If you use a blender, the highspeed can actually spray out little droplets of salt water that get everywhere. So, it's a bit of a mess. And if you try to do this by hand, you're going to get pretty tired because you have to do this for a few minutes. So, this is perfect with a wire blade in here. Now, one thing you may notice is these small strips here. These are resistive heating elements that you can pick up on Amazon, like eight or 10 of them for about $10, about a buck a piece. And they're hooked up to the small power lab supply. So, I can actually heat the bowl in order to control the temperature of anything that I'm mixing. And I've actually used this in brewing. I've used it in the kitchen. This has been there for about 5 years. It works very effectively. You can buy heated bowls online. But what you'll find is the heated bowls cost about twice as much as the Mixmaster itself. This cost $10 and if you got a power supply, that's all you have to pay for. It works very effectively. Now, the first thing we're going to do is we're going to add a very specific amount of water. This is g of distilled water. And I want to show you something. Hopefully, you can see this and it's in focus. But I'm going to show you that I've preheated this to about 50° or so. And the reason I did that despite the fact that we have the heated bowl is just to make this faster. So I don't have to do all the heating in the bowl. I just put this in the microwave ahead of time. It's just a time saver, but it's not critical. We're going to pour this into the mix master. Then I'm going to turn on the heater and allow it to continue to heat. Now, to the 75 g of water, we're going to add 295 g of ammonium chloride. Now, you can get this in bulk as we have, but even if you buy this, say from Amazon at a little bit higher price, this will cost you about 80 cents if we're trying to produce a budget for how much one of these containers is going to cost. This is about 80 cents of ammonium chloride. Now, one thing that I'm going to show you which is going to be kind of interesting is I'm going to put this in and I'm going to start up the stir. And remember, this was about 50° before we started. I'm going to put about half of this into the liquid. It's not critical. We could just dump it all in, but I just want to show you the effect first. We'll give it a few seconds for some of this to dissolve, not all of it. And then I'm going to show you the temperature again. All right, lift that up. And hopefully you can see this on the other camera. Put in the temp probe. And you can see that we're now down to about 34°. It's gotten a lot cooler from just the addition of about half of the salt. It's an endothermic process. Dissolving the salt actually cools off the water. So that's why we don't start with room temperature water. It end up being freezing cold and it would take a lot longer for the process. So kind of a neat phenomenon. Now we'll let that keep mixing and I'm going to add the rest of the salt. The heater is on right now at about 75 watts. So, this will slowly heat up and then we're going to add the next component. All right. So, let's measure the temperature and see if we're in a good range to add the next component. You can see that we're at about 32 32.5° maybe 33. Okay, that's good. Now, in theory, we're done. You've made a utctic mixture. We could fill the bottle, close it up, and put it in the freezer. But we're going to kick this up a notch. What we're going to do is we're going to add a very small quantity of bentonite clay, 4 g of it. Bentonite clay is actually millions of tiny little crystals. And when you suspend them in the mixture, those crystals provide nucleation sites for the ice when it begins freezing at -15°. And so it further narrows that transition temperature to make it more of a line rather than a broad cone. And so I'm going to sprinkle this in. And we'll let this distribute through here. It'll only take a minute or two. And let's get the speed up a little bit more. Now, while that's distributing, we're going to kick this up one more notch. You see, one of the problems that you have when you have a container like this and it's trying to cool off the inside of a freezer or a cooler is that all of the heat has to enter from the outside. If you've ever taken a jug of water or apple juice and taken it out of a freezer, you can leave it on the counter for a while and what you'll find after a couple of hours is that the outside will have a layer of water around it and you still have a big cube of frozen material in the middle. The reason being is that water is a poor thermal conductor and as a consequence all of the heat entering from the outside melts that ice first and now you have a partial insulation of the ice inside. The outside surface is going to end up being well above the freezing point of water. We don't want that. We want the entire container to be acting in concert so it's all freezing and melting at the same point. We need a thermal conduit system. Now, the first thing that occurred to me was to use something like a metal wool, copper wool, aluminum wool, steel wool, stainless steel wool. Tear it off and force some of this in there to act as a as a highway system for the heat. Not a good idea. Part of the reason is that copper, aluminum, and steel will rapidly corrode in the saline liquid that we're working with. And although stainless steel is much more resistant, it has a very low thermal conductivity. So it kind of inhibits its action. The best material to use if you want to go up to this upgrade is to add carbon fiber. Now this is chopped high modulus carbon fiber. You can get this on Amazon for maybe about $10 a pound. And we're going to be using about a 20th of a pound here, but I don't know if you can see this easily on the camera right here, but I'll show it over here on this camera so that you can see that there are these individual little ribbons. These are called 1 or 2 cm segments of carbon toes. This is where they take all the fibers, they lay them out, they roll out these fibrous ribbons that can then be used to make a composite material. Well, they get trimmings, they get edges, and they can even take the full ribbon and chop it up for you. So, you don't have to do this. You buy it in this form. Now, this is simply 20 g of carbon fiber. It's very, very dispersed. And we're going to add this to the mixture because number one, it's immune to saline solutions. Number two, it has a pretty darn good thermal conductivity around 60 or 70 where stainless steel is down around 20 and aluminum and copper are a couple of hundred. You can actually get ultra high modulus carbon fiber that will cost you about 20 times as much and has a thermal conductivity up around diamond. But we don't have to go there. This works just great. And the low density actually has another advantage that I'll cover in just a second. Now, one trick though is that if you saw those little uh ribbons, they're held together so we don't have just a pile of hairs in here with a sizing. This is what they call the weak adhesive that they put between the individual fibers so that they stay in a ribbon format. There's only a couple of milligs of that sizing present. But what that sizing does is it needs to be removed in order for us to distribute and produce millions of tiny little fibers that give us the enormous surface area to interact with the liquid. So I'm going to begin adding this and you're going to see an interesting phenomenon happen. The reason I measured the temperature ahead of time was that even though the sizing, which is usually either a polyester or an epoxy resin, is not soluble in water, the abrasive action of all the mixing. And a warm temperature will tend to mechanically remove about 95% of it from the surface. And that will have a very profound effect on what you see in a few minutes. Now, an important thing though is you don't want to add this to a solution that's over 40° C. That will actually cause the sizing to cure and then you're going to end up with little carbon gumballs floating around inside of your matrix. So, you do want to make sure that you don't overheat it. And I'll confirm that by just turning this off and doing another temperature measurement just to make sure I'm not getting too aggressive here. So about 35° 35.5 35.7. It's getting close. So, I think what I'm going to do is just turn off the heater and allow it to continue the process without any outside heat. That way, it won't get hot enough that we're going to end up with the glue. This will take a total of about 10 minutes. All right, let's take a look. As you can see, those tiny little fragments have now thickened up into these kind of hairy blobs and separated away from each other and absorbed a fair amount or essentially surface absorbed a fair amount of the liquid. But that brings up a second problem. One issue with the metal um wool is that it's far denser than the salt solution. Carbon fiber has a density of about 1.6 g per cubic cm. The salt water has a density of about 1.2 g per cm. So pretty close, but not exactly the same. If we cycle these bottles repeatedly, freeze thaw, freeze thaw, eventually that carbon will start to sink down toward the bottom so that it's not effectively interacting with a fair volume inside of the container. We want it to stay fixed. So, the last ingredient we're going to add is a jelling or thickening agent, zantham gum. Now, we're not using the sodium polyacrylate that we used in the video for the laser defense shield as well as the upcoming microwave defense system because sodium polyacrylate will not gel in a saline mixture. Zantham gum is perfectly fine. So, I'll put this back in, start the mixer up, and then I'm going to sprinkle in 12 g of Zantham gum. And again, the exact recipe will be in the description below the video, so don't worry. We'll let this go for about 5 minutes and then we'll be all set. All right, let that go. All right. Fow, eat your heart out. As you can see, this stuff looks like something the cat left on the carpet. It's this mushy kind of stringy, very strange. Nobody would eat this kind of texture. It's just fowl. So, what we're going to do is we're now going to load the bottle because we've basically made the complete mixture and we're ready to go. Now, to get it in the bottle, it's not difficult. Take a goodiz funnel and place it in the bottle and get a dowel rod that you can pass through here because this will not drain spontaneously. Take a couple of scoops of the stuff science and then your dowel rod. And you can just sort of push the stuff through. It's not bad. It'll take a little while. I'm going to visit this a little later in the video. Now, as you're filling this, you don't want to overfill it. You want to fill it to about 90% of its capacity because like any ice or water-based freezing, it will expand when it freezes. And so, a extra 10% of volume inside the container will give you that room without bursting the container. So, don't get too aggressive. Go about 90%. And you push it through here. Now, I think you get the idea. So, I'm not going to keep you watching water boil, but this takes a few minutes, but it isn't difficult. And you can get this done relatively quickly. I'm not going to finish this here because I think I've made the point and I actually want to retain some of the material in here because I'm going to show you something interesting in just a little bit. But effectively, you would then take this when it's filled up to the top like this, put the lid on, and now you have your utctic solution with a freezing point around -15° C. You put it in the freezer, it gets rock hard and it will do everything that you want it to. So, now that I have demonstrated how to make it, now I'm going to demonstrate that this actually works. All right. Now, before I open this, because that's actually going to start the test, I want to show you something. We're going to be doing three samples. One is going to be just a container like this of distilled water. One is going to be a container filled to 90% with the mixture that we just made. And as an interesting control, I'm going I have a third container in there that has been sitting in the freezer for many hours. And it contains the contents of one of these cold packs, the things that you'd normally buy on Amazon, put it in the freezer, and put it in your chiller. And what I did is I simply cut them like this. And you'll see that it's a jelly like mixture that's sitting inside of here. And it's pretty stiff. It's pretty rubbery, but you can get it to come out. This is almost certainly sodium polyacrylate because of its clear nature. kind of gross. But that is what we're going to have in the third bottle just to see if there's any difference between what we made pure water and see if it has any benefit other than the fact that it's in a package. So, I'm going to open this up and you can see I've got the three bottles that we're going to be testing over here. This is the utctic mixture. We'll put this over here. This get this out. Is the pure water. And this is that weird gel that we got from the packet just filled up. And it expands a little bit more. so it looks a little fuller. Now, because I've taken them out, we should start the timer. And then I'm going to plug these on. We're going to get these all set up. And then we're going to show you the temperature and what to watch for over the next couple of hours. So, utctic mixture, contents of the gel pack, distilled water. All right, we've got everything hooked up. This is looking pretty stable. Pretty stable. We're at a minute 42 now. Just keep your eyes peeled. This particular meter is hooked up to the um the super freeze. This is hooked up to the uh gel and this is hooked up to the water. The water will be going in here and that represents the second number 11.9. All right. So, we see you in a little bit. [music] >> [music] [music] >> All right, that took a little while, but as you can see now, the utctic mixture is heated up to minus 2.6° and these are slowly beginning to move beyond the freezing point. And because this has been running so much colder for a long period of time, it's actually absorbed more heat. So eventually when we get to room temperature, this will probably get there first simply because we've absorbed more heat because it's been running at about 14° colder than these which have been running around zero. So we'll give you a detailed analysis of this in just a second. All right, so let's look at a graph of the data that we just acquired. And to lay this out, you can see that on the horizontal axis on the bottom, that's time. And if you look at the vertical axis on the left side, that's temperature. And you'll see the three lines that trace out the temperatures of the different samples uh highlighted with the dots and the lines that run through them. The black line, which is black, is the bottom line, and the gel and the water are uh identified by the green and the blue lines. Now, the first thing to note is that our freezer operates at about -20° C. And so, you might wonder after a whole day of freezing why all of the samples didn't start out at minus20. This is uh a little bit of a a glitch due to the thermometers themselves. The thermal probes that we have inserted in each of the bottles are completely metallic, including their cables. And they're relatively thermally conductive. And so when they extend out of the top of the bottom, out of the top of the bottle, they will absorb some of the room heat, which modifies the temperature of the prob's outer casing and elevates the baseline temperatures for each of the three samples. because the probes are identical in each of the samples. This differential between the minus 20 where we were probably running uh initially and the actual measurements though is consistent because of the identical monitors. So let's take a look though at the actual data. You'll see the first two lines or the top two lines, the green and the blue are relatively rapidly warming and increasing towards 0°. Because they are below their freezing point, they are simply passive thermal masses, essentially the same as a brick or a lump of wood. They are simply absorbing heat and warming up. When they eventually get to the point where they begin to melt and we get phase change, they stabilize. All the additional heat that's coming in from the outside is simply converting that ice into liquid water. And so it remains very close to the freezing point of water all the way through the test. You'll also not notice how similar the gel and the water are. The gel simply contains approximately 1% of sodium polyacrylate as a gelling agent. It doesn't do anything to alter the freezing point of the water that is bound up in the gel. And so that's why they operate similarly. It also means that cold packs that you place in a cooler or in something that you want to keep cold are literally just encased ice so that they're not making the internal components wet, but they're not more effective than just using ice cubes. The other interesting thing you'll see though is on the bottom the utctic mixture is at its phase transition temperature very soon after it comes out of the freezer. And because it is converting the solid ice into water, it remains stable just like the gel and the water do, but at a substantially lower temperature, the utctic freezing/melting point. And it remains so for approximately 5 hours until eventually all of the ice has been converted into water. And now, just like the gel and the water mixture, it's beginning to warm up as a thermal mass. in this case as a liquid thermal mass while the first two were warming up as a frozen thermal mass. And eventually when we got to the very end of the graph, the utctic mixture is approaching the freezing point of the water. But the important component is the fact that we are obtaining a far lower melting and freezing point which is advantageous for all of the applications that I brought up earlier in the video. Now, one little thing that I did notice in the whole process was the fact that using the stick loading technique, it works, but it's kind of annoyingly slow. And so, as a consequence, I built something this this is a vacuumass assisted bottle loader. And it's pretty neat. You'll see what happens here. I'm going to plug this guy in. Reach back here to do it. Basically, what this consists of is a heavywalled plastic tube that has a vacuum pump hooked up to the lid, which seals down on here like this. And then what we do is we place one of the bottles inside of the container, put the lid back on, and then we'll put the same funnel in the top like this, which inserts into the bottle. So when I turn on the pump, the only way for air to get into the system is to go through the funnel, into the bottle, out along the edges, and eventually out into the pump. Let me show you how effective this is. We're going to take some of this goop and start placing it in here. It's kind of an organic sound, but as you can tell, this is far faster than using the stick and saves a lot of time. So, I think I made the point. This would easily allow you to fill a bottle in 30 seconds or so. Now, some of you are going to say, "Okay, kind of neat, neat concept." But the point is, you're going to build this whole structure in order to save time by loading up a few bottles with a dowel rot. I agree that probably would be a waste of time unless you have a lot of bottles. And this is just one bag. And this has to do with the big project that we're involved in that I'm going to talk about on Sunday because if you want to fill up hundreds of bottles, saving that time is going to add up very quickly. Something I mentioned when I was talking about utctic salt mixtures is that I said you can vary the freezing point of the water by using different salts or even mixtures of salts. What I didn't say is that it always lowers the melting and freezing point of water. You can actually get utctic mixtures on with common salts that will freeze above 0° Celsius. Now, you may wonder why the heck would you ever want to do that? Well, that is the project that I'm going to go into in a lot of detail. I'll get the principles. I'll give the engineering and the explanation for what we're doing in the upcoming live stream that we're going to be having on Sunday, this coming Sunday at 6:00 p.m. Eastern time. But in the meantime, what I will do is I'll give you a good hint. What do you think is the output temperature from an air conditioner? So, with that, I want to thank you very much for watching. And if you liked what you've seen here, please just take a couple of seconds, it doesn't cost a penny, and subscribe. And if you take a few more seconds and you give us a thumbs up [music] and a comment, all three actions will induce YouTube to distribute our videos to a [music] broader audience. And the bigger we get, the more we can do and the more frequently we can do it. And if you really like what we [music] are doing, we'll put a link to our Patreon that directly support the channel and [music] have enabled us to avoid those annoying inter video promotions that most content creators have had to resort to and we want to keep it that way. In addition to that, we do provide some extra perks for our content uh for our Patreon uh supporters and those benefits will become clearer on Sunday when I talk about some of the things that we're going to be doing in the future. In any case, I really thank you very much for for watching the video. We don't make any money from any of these videos. We take all of the money that comes in and [music] we spend it on projects. The reason we do this is because we think that what we're [music] doing is very important and it's a heck of a lot of fun. So, [music] in the meantime, stay safe, have fun, and we'll see you Sunday night. [music]