Adam Savage’s One Day Builds: Refrigerated Cooling Suit!


Adam Savage here in my cave with my friend, Kipp Bradford. How are you, sir good, and you very good, I’m excited, because we are about to explore a new Vista of cosplay technology now, if you’re a regular follower, you know that I built myself a spacesuit from alien, John Hurt’s suit, and I wore Don the comic-con floor In San Diego in 2012, 2014 in 2014, and I almost got heatstroke wearing basically, what was a quilt with armor attached to it. So the very following year, Chris Hadfield and I walked the floor. In a pair of 2001 spacesuits. The silver clavia suits into which I’d built an integral cooling system, comprised of a bucket of ice water with a recirculating pump and cool shirts, and that worked pretty well.

But Kip among many other things that he has done in his life as an engineer, happens to specialize in extremely tiny refrigeration units and we’re hoping to build one here in the cave today. Small enough for me to use in cosplay so get ready. We’Re gon na get cold, alright, Kip, where, where do we start, there’s a lot of little bits and bobs around the shop? I’M not even sure. I know what this is yeah, okay, so where do we begin Adam?

This? Is that compressor? Okay? Oh! This is the step that does Boyle’s law that yes brings refrigeration and recirculates the this stuff yep our gas, that so what is it?

You compress it when you release it from compression, the temperature lowers corrects and you get the refrigeration, that’s exactly it. So the compressor works, just like any compressor, does there’s a piston inside here. In this case the piston is a rotary piston, so it spins around and as it does so is it a vane pump. These are the vane pocket as a vane pump. It sucks a gas into this inlet, pulls it through the compressor and increases the pressure just like Boyle’s law PV equals NRT.

As you increase that pressure, the heat also temperature goes up because we’re we’re doing mechanical work. We put electricity in here that electricity is what’s doing, that pumping right magnetic field turns the rotor, the rotor, the vein, the vein squeezes the gas we’re doing work on the gas right so just like, if you’re pushing down on a bicycle pump, it can get hot. It gets hot as you’re doing that work, so the energy from your arms is transmitted into the pressure of that gas. So gas gets hot as we do work to it and it gets compressed. We can push that hot gas through another heat exchanger, where we blow air over it and take that heat away and when we take the heat heat away, we’re not just removing heat, we’re actually compressing the gas as well or we’re actually just removing the heat.

Okay. So the pressure, the pressure from this output side stays constant mm-hmm. The temperature is what changes. So we take that constant pressure, gas we blow the air over it and the reason why the pressure doesn’t change is because, even if we take all that heat away, the gas itself is there’s more new gas coming in from the backend. So what happens is not that it changes pressure but changes state.

We go from gas to liquid, I see so because we’re taking temperature out we can fit more gas. In the same volume we can fit more gas in the same volume. Okay, that converts to a liquid and that liquid then goes to the other half of the system where we boil it off, and what waving it off is how we get lower the temperature exactly exactly see, I don’t have a refrigerator works. I’M logged that in my time just a little bit it’s if you’re an engineer, you’ll notice as a reverse Rankine cycle. Okay, a thermodynamic cycle, that’s fully closed loop and we do work with a piston or rotor or some kind of machinery that does that compression.

So we’re putting mechanical work into the system and we go from electricity to mechanical work to thermal, and then we get rid of the thermal and then we reverse and come back on. The cold side boil off turn to a gas and the waste suck gas back. In the inlet – and it strikes me that this is an especially tiny compressor – am i right this is this? Is this? Is this one of the tiniest ones?

This is one of the tiniest compressors, and this has a pretty fascinating story at the first Gulf War. Darpa put out a call for man, portable wearable environmental control system, Oh for just the exact thing we’re exactly working on and they were did an RFP for tiny compressors, yes and two companies, one that RFP and one of those companies is Aspen compressor in Marlborough Massachusetts. These are made in Kentucky. The design of the compressor is a fascinating MIT. Mechanical engineering PhD, of course, of course, makes these incredibly well balanced, super small high-efficiency compact, compressors and when you say well-balanced, that means that the compressor is efficient because it’s not losing any of its energy to vibration.

So when it’s highly balanced, you have a smooth system and all the energy is going where you want exactly, and it means that if you’re, if you’re wearing it you’re, not gon na get all that but vibration on tears. Oh back, it’s not gon na make a ton of noise. If you ever have your shop compressor turn on in the middle of night, and you hear that man, oh, I have to put a timer on apposite wakes, my neighbor’s up exactly yes, I know a normals live upstairs and sometimes we make their lives worse. I don’t know: they’ve never complained about the kind of music. I love the story.

Okay, so the great thing about the DARPA story is that DARPA puts this call out and they get a couple companies that respond to it with these super compacts and compressor technologies, and they quickly realize that putting people in spacesuits in the middle of the desert trying To fight a war is a bad idea right, because if you have any kind of system failure, they’re super compromised right away immediately compromised. But we get this cool technology out of it. And this notion that we can make very compact refrigeration and cooling systems using a portable low voltage DC compressor technology. So the original purpose of this being fighting wars with with people in these crazy suits yeah, not the smartest idea. The result has been, I think, fairly transformative for a lot of medical applications.

I use these for a medevac system that could stabilize people’s temperatures in medevac helicopters after traumatic injuries on their way to a hospital their way humbly. Nothing substantive is getting done. You can actually bring their doctors down, Wow so found some other uses, for it made some fun projects, and the last system I built was the world’s second smallest wearable air conditioner couldn’t quite get it to be. The smallest just got to be the second smallest, and that is currently in a NASA spacesuit simulator, that’s running around somewhere in the world, pretending to be in Mars. Oh simulation space, they’re kind of like what the guys are wearing on high seas.

Experiment. It was the high, so okay, Oh, fabulous fabulous. The the thing we’re gon na build is a replica of the high seas. Basically air conditioner, oh my god, I’m that’s really exciting one. I follow the high seas experimentation project for years.

Obviously I revere what those guys have put themselves through and I know the complications of that program, but also I love those suits and are great. I love reading about how much they love their suits, like they fall in love with them. Okay, so what is it for? Obviously this is the centerpiece of this, but how do we start to make our assemblies? So this is our centerpiece and there are two other pieces that we need.

We need a heat exchanger to reject the heat mhm and we need another heat exchanger to absorb heat, one of those heat exchangers. That’S rejecting the heat is going to go from refrigerant, which is a gas in this case to air, okay and we’ll have a fan. Blowing air over that the second heat exchanger will go from liquid refrigerant, as is vaporizing to cool water, and that water will then circulate through your cool shirt. Ah, okay, right so there’ll be a heat exchanger between the right, so it would need like a big aluminum plate. That’S touching the water or something like that, something like that will actually use a stainless steel heat exchanger that will go directly from the boiling refrigerant into the water, oh into it.

Oh okay and we’ll tune the system a little bit so that the water doesn’t freeze or you can also use alcohol instead of water and great. I haven’t money on that even colder. Ah, yes, let’s do alcohol. So, let’s see I love that idea. Aye aye, sir purple will that work.

Isopropyl works. I actually tend to use alcohol with vodka. Oh yeah, great yeah, we’ll send out for a vodka there’s plentiful in the mission to serve and hasten why vodkas great is because it’s non-toxic, depending on how much you drink since I don’t drink, that’s fine! So shall we gather the parts over here? Let’S gather the fire: okay, all right: these are both versions of the same thing.

These are two versions the same thing and we have a big, huge, changer and then a smaller key exchanger. Now the high seats project uses this smaller heat, exchanger mhm and the high seas project is not so noise sensitive mm-hmm. We can have a little bit more noise generated and it doesn’t cause a problem for you, though. I think we want to go with a bigger heat, exchanger, okay and a quieter fan, so the weight is not much different, no there’s fairly negligible, so sure yeah. Listen.

I can accommodate great something this large and then we’re also gon na take two other heat exchangers over the table. We’Ll talk about these two as well, because they’re pretty neat technologies, Aspen compressor, a US company made in US that has just some really nifty technology and it’s hard to get refrigeration components in low quantities most of these companies they don’t sell to consumers or individuals. Now he did not sell the consumers and individuals, but if you go to an HVAC store, you’re, not gon na find compressors like this you’re, not gon na find composed like this right. They sell repair parts of those HVAC stores. So it’s difficult to build the supply chain, knowledge to know where to get this stuff.

These two components are US made. This is a heat exchanger from the company called all coil, which is in New York Pennsylvania, and they make small quantity components great for specialty applications. Like what we’re doing, if I was to go to a company say in China or Thailand, that makes these for refrigerators or air conditioners, the minimum orders gon na be 10,000 units. Okay answer the phone for you: you have to send them a check for 10,000 units and then then they’ll talk right all coils great, because you can order one, oh and to be clear about that structure of this. This is just a wide flat, tube yeah and through which the material passes, and all of this are simply surface area that aluminum meant to shed the heat correct.

Okay, that is super cool, so this is called a micro channel, heat exchanger and it has little micro channels that run along the length of each of these serpentines. So there’s maybe a hundred channels from top to bottom here and we push gas. In this end, the gas flows through and because we’re pulling so much heat out, the gas is a liquid by the time incorrect, the other side erects and it’s freaking cool. That is really really nifty and see all the way. Through this thing and the larger the heat exchanger for a given amount of gas that we’re trying to cool the more surface area, we have to call that gas and the less air that we need to blow over the any given surface Scott it.

So the bulk air flow could be the same, but if the bigger fan I make for a given amount of air flow, mm-hmm, the slower and quieter the fan can get. So if I have a really tiny fan and I’m blowing say Exner of CFM x, / CFM, I have high velocity. It was loud right right if I double the size. I quadruple that surface area and I can reduce the velocity proportionally right and then also have have quieter fan blades, because they’re not slicing through the air. What is okay, so the bigger fan means that it’s quieter right.

Okay, it also means that we can really crank your system up if you want, if you’re like, I need 800 watts of cooling good things to know about the body as we’re standing here right now, we’re not being very active, we’re dissipating about 100 watts of heat. I’M talking about okay, hot light, bulb those incandescent light bulbs. I guess the kids might not know about those yeah, kids yeah, the brightest light bulbs, 100 watts and it got really hot. It got really hot. So and that’s what we’re that’s we’re putting out kind of the same amount of heat over our entire, our entire bodies?

Okay, so it’s a room temperature. This compressor can pull out a couple thousand watts. Really you crank it up to the max Wow. So we’re not going to need to do that to keep you cold, but if you decide that you want to sprint through comic-con’s, doesn’t just crank the knob up and amazing amazing. Okay, I’m just really psyched about so we’ve got a confessor.

We got the heat exchanger that we’re gon na get rid of the heat with and we’re gon na position this above the compressor. Okay, we have a heat exchanger that we’re gon na boil the refrigerant in, and I brought two options here and I think we’re gon na use the larger option for you. Okay, for several reasons. One is, this is a called a brace plate, heat exchanger and it’s stainless steel. We put refrigerant in these tubes, those tubes and water.

Through those tubes, I don’t know don’t fret, but they exchange heat between the two yep freakin cool, and we can attach some fittings to this end, which less blow water through here and then into your suit Wow MPT. It’S actually a not it’s a British straight pipe thread and the reason why Bruce straight pipe threads are used for these is instead of a taper instead of NPT. Okay, so the taper thread is basically a compression stretching fiction fit so you’re literally stretching the metal and tighten that down and that’s great, except once you’ve got that preload. You have to maintain the preload, or else the fitting fails, and if your heating and cooling and heating and cooling and doing this ignition putting a lot of movement and yes and it’s gon na work itself away, it works itself loose and no matter how much the Thread lock you put in that eventually will work itself loose. So amazing, I a made in my book when I was writing the chapter on glue.

That was one of the hardest parts to write list. You’Ve got to think about what the glues gon na go through. Yes and it’s expanding and cooling, that means it’s gon na work itself away from this or that material. If it’s not the same material property exactly exactly so, we use a straight thread and then the seal is created with a gasket no and that gasket just provides a little bit of preload and if the gasket ever you know, maybe ten years from now the rubber Hardens you unscrew it another one pop another, one, okay, good to go all right. I like this.

This is great, so we hook these components up with some copper tube and there one piece that’s missing here. We use the compressor to put work into the system right and then we exchange heat with this first heat exchanger yeah. Now we have to create some way to reduce the pressure. So we keep the high pressure side high pressure. We have to drop the pressure so that the refrigerant will boil right, so we have liquid coming out of the bottom of this heat exchanger.

We want to blow that liquid off and, if you think about water in space, the vacuum of space mmm is a loan of pressure that water will just boil off and as it does, it will absorb heat right. This is the same thing. We have a pressure low enough that this substance here, which is our refrigerant mm-hmm, will boil at the pressures on the low-pressure side of the system, and this is a new kind of refrigerant that doesn’t add to the ozone hole. That’S correctly, closing like freon used yep. Okay, so this was developed as a replacement to freon in the early 90s and does not destroy the ozone layer and not many people know, but among human beings.

Many crimes, the ozone hole is about to become an ex human cried. Like it’s closed, it’s been closing steadily over the past nine years, as industry has responded, yeah and very occasionally we see blips of rising, rising your factories in China. I think there’s a recent story. I heard that and the Amazon and fires also help you out a tribute to the yeah so but we’re so. How do we create that low pressure system?

So we tried that low pressure system with the copper tubing equivalent of a resistor. It’S basically just a flow resistance that you can either use a small nozzle to create that pressure drop yeah. So you have a high pressure behind a nozzle. You have low pressure in front of the nozzle yeah or we can use a long length of copper tubing. So, Oh any length of pipe will create resistance and friction as the fluid flows through it, and it literally operates exactly like a resistor which does it with electrons, but does it with fluid exactly so?

The whole analogy of electrons to water pressure is actually still works. It’S still tracks, yeah yeah, that’s great. The copper tubing will use the length is going to create the pressure drop and we can change that length that change the pressure drop and that’s gon na have an effect on the temperatures that you’ll feel great. So we’re gon na pick something that will give us a little bit below freezing for you at a high speed setting with compressor terrific, I’m gon na action getting us some vodka in the shop, and I also have a new cool shirt. That’S actually a full body!

Perfect suit and that’s the one I want to try. I bought it’s actually a 1980s British RAF cool suit for high-altitude fliers, but that tubing all feels like it’s good. It’S still like extant and flexible excellent, excellent, awesome, um! Well, you got two that I’m gon na get those broad right right. That’S excellent and the tubing is perfect.

It’S feel its weight hunger than I thought. Oh yeah yeah, that’s great! So there’s some big ones that run out. I haven’t pressurized this, but my cursory inspection led me to believe that it is in pretty good shape. Yeah.

This is expensive and the tubing goes. You know it’s funny cuz. This is the other question I have is. There must be optimizations. You can make for flat tubing that has a greater skin contact, yes and thus a better heat exchange.

So there there is the funny thing. There is a discovery in the early 2000s from some researchers at Stanford, Dennis gran being one of them that you get the best heat exchange through the parts of your body that don’t have hair on them. So your palms soles of your feet your face and you can do more heat exchange through those surfaces than by putting a suit around your whole body. Oh, my god, but I think putting the suit on your whole body creates perceived comfort in addition to actual heat exchange and right, and that’s really important too there couple water pump options. Oh, look at that and this is got ta.

Have a water tank ha ha ha ha, that’s the oh! That’S the size that you need. It doesn’t need to be bigger, don’t need to be bigger than that. So this is the exact size. That’S in the the high seas, suit Wow, Wow Wow, and this is a different one.

This is a different one. That’S a tank and pump built-in ooh, that’s kind of sexy to know I figured you might appreciate that. Oh my gosh. This is amazing, since it as an engineer, I appreciate less complexity, equals more reliability, so I’m inclined to go with the pump reservoir combo. What do you think we should try them both out?

The nice thing is, we can build the refrigeration circuit right and have that be a standalone thing, and then you can and then play around with the options. Okay, long so great, I have the in the CAD right there there’s a little pump. That is right here. Mm-Hmm this is this amazing, British $ 200, really high-quality, high-pressure super quiet water pump and I didn’t get a chance to grab it because I was running late to the airport. Oh we’ll just use the one that I shipped.

This is great. This looks like a kind of almost like a bait pen like yeah. We need some LEDs in there. Yes, okay, so what is the first step for assembly? It’S really the first step for assembly is we want to set the components up, so we’ve got two heat exchangers that we’re gon na need to basically position and then brace some copper tubing into okay, and if we go with the drawings that I’ve made, I think The ideal setup is going to be something along the lines of this okay.

So do you need me to make a bracket, so we can make a bracket or I think, the the process that usually is to do. This is positioning the parts and then figuring out what the copper tubing run should be, and we’ve got a the high seas model that we’re starting with, but we’re gon na use a different heat exchange. I use with high seas, so the high seas system used this heat exchanger, which I haven’t talked about yet okay. I talked about that for a second okay, what’s different between this heat exchanger in this one, it’s a m — thing, two different channels for different liquid right that are kept opposed to each other. Yes, yep and this heat exchanger is a stack of steel plates with some ridges on them, and the steel plates are pressed together, put in a furnace and then the furnace raises like surface mount electronics, almost exactly okay and the that stack.

You can see these these kind of channel formed channels and the the way this bottom plate is a pan. All the rest of these plates have that same pan feature okay, so you stock all the highs up, mm-hmm and the pans alternate refrigerant water, refrigerant water. For the water, the brazing process is, is you could do this with a torch yeah, but doing it in a furnace gives you good uniformity. This heat exchanger is also steel plates, but these are flat steel plates with and they didn’t have. The channel have been etched.

So those plates are thin enough that we can use actually processes, and this is then vacuum furnace bonded and the bonding process involves heating up. You put it a dissimilar metal bracket around it and that similar bracket. When you heat this, the steel expands more than the bracket does so as the steel is expanding. The bracket creates a compressive force that diffusion bonds, the layers of steel together, good god, with with Wow. So we we can etch micro channels in using photo lithography processes that are super precise.

We get a much smaller, more compact unit that isn’t doesn’t quite have the capacity of this, but you can see is that’s an impressive. The small thing heat exchanger is something that can cool down a human body that is, is rated at 800 watts of cooling. Some believe this is rated about 1.2 kilowatts of cooling and – and this is so efficient because you can get high amounts of precision in the etching process and that’s a lot of flow through it. Even though it’s really tight a lot of float.

A lot of surface area for exchange right right right, the surface area is everything, surface area is everything, and the difference in price of these is also pretty funny. This is maybe 40 $ 50 get them made in a factory overseas. This is about $ 400. So 10x difference in costs. Okay, I see super super cool technology from one-off projects, those those aren’t crazy price points, but for any business venture that is variant difference.

You really have to have a need for using something that size we’re going to use this mostly because we can put threaded fittings on right and make it really easy to interface directly with your suit and pump and when you’re holding this up here. And this goes with this, I would love to know if these pipes can be there. While I have a lot of room for to put in, let’s say, fake place for a space suit, this space will be a premium, so I’d love to keep that dimension. This X dimension as narrow as possible, assume we can cut these a little bit tighter, we’re not gon na cut them we’re gon na bend, though okay great, so I’ve got some metal benders too, and some flames tools who we need those and Bend. You know the copper tubes around so it’ll create a nice flat profile.

Okay, we’ll keep everything in a line, and that way we can get our refrigerant out to our heat exchanger. So we go out of the compressor and we go up to the top to of the heat exchanger that way notice the gas works its way back and forth and gets to condense down to liquid the liquid drops to the bottom and then the bottom comes out And then goes to the bottom of this heat, exchanger, okay, where we boil up so we end up with a gas at the top okay and then alright. So there’s a direction to this. There is a direction – okay, yeah and then to mount this to this, I’m assuming we need a little bit of some bracket j –. Is that correct right?

It’S will be good. We can zip tie up, but brackets are gon na be better okay. Ultimately, I have endless numbers of spacers and our little nuts and bolts, and even all thread should be needed after we get everything positioned the way we want we’ll mount it on a fixture, great 80/20, a piece of wood just so that we can braise it yeah. Once it’s braised it’ll hold the stuff together, then we can make sure to measure and create a bracket that holds everything in to your suit. Fabulous, don’t put any strain on the join them to copper, joint because aluminum, copper joints, they’re delicate they’re, very delicate.

Oh that’s! Lovely yeah, it’s it’s soft and I can guarantee that I’m not overloading the joint right right right notice that it’s it stays straight as it comes out of here right. I got most of the bend and that’s important because we didn’t stress exactly at all exactly because if we lose these connections, brazing copper to aluminum is one of the hardest things I’ve ever tried to do. I want to think about it. Don’T even want to think about.

It succeeded better people than me. It conveys this John all right, I’m gon na up a tube, that’s gon na come out of the compressor and it’s gon na need to get into here right. So if I flipped like that, and then it comes in the top, I can come out and beyond up in the top okay. That seems great. So that makes that easy.

Okay and then the tube that comes out of the bottom is going to go into our expansion valve, so we’re gon na have something like this come in here we’ll have a coil of some of this and, like I said, the length will determine the temperature that Determines to the temperature are the length of this tube, which gives us the pressure drop. Okay, the speed of the compressor, which tells us how much gas we’re moving, how much mass of past a certain point right and then the amount of refrigerant that we have in the system. So we want to balance those three things and we’ve got some tools to do that. Okay, how do we braise this to this? Does that get braised or is it a pressure fence?

That’S gon na be braised we’re gon na braise, all this stuff together. So, do we need to machine some specific, copper, little couplers yeah, you know we could machine them or we could just take a pair of pliers and crimp. The soft copper tubing down around this. Oh really yeah and that’s do and then you just fill some amazing material. You know that I do it just want you to see the cool that day that I did invest in full retail rack or both of these, but I’m all about the simplest possible fusion.

Doesn’T know that I have this is good to know one of the funny things about this tubing. You saw how easy it was for me to bend yeah by hand. Yes, this. There are two styles of copper tubing for refrigeration, there’s drawn tube and then there’s an eel tube right. The drawn tube is pretty rigid right because it’s been mechanically drawn yeah.

It means it’s work, hard work, hardened yeah, the anneal tube after you draw it even baked. So and the steel is release all of those tensions of the crystals from inside yes, and it’s super bendable and it’s really fun to work with. So you don’t need College to talk engineering. We should not mention how many degrees I have. I have zero three.

I an honorary degrees which are worth just as they’re worth. Nothing actually did believe it or not. I I think that the out of school education for me has been so much more informed. So my background is: I have a mechanical engineering right right right. This is all thermodynamics and, what’s really really fun about this is yeah I’ll make fun of my education, it’s a fantastic education, and I it is certainly extremely well, but when I took thermodynamics in college, I couldn’t tell you what all these parts were, how they worked.

What they did, I can just tell you, the math behind what what they’re supposed to be doing right right and the gap between that theoretical knowledge and then understanding not just like. Why do we have a capillary tube right, but what these parts are, how you put them together? That gap was pretty big in closing that gap. Not only did I take that theoretical knowledge and then the practical knowledge and rigid, but it gave me a very deep appreciation for how these systems work and how you optimize them ago. I behave and I think that’s something special – that we really need to get more engineers learning the practical sides.

They see that and get more of the technicians understanding a little bit more of the science on Mythbusters. We frequently had trouble when we call up one of the world’s experts in the field. We were trying to explicate because they’d be so much of an expert at the one thing they knew, but they couldn’t discuss with us how it crossed correlated to this other part of the store right and nothing exists within its own frame. It’S all reaching out to deal with other frames, and so we found the polymaths the people with more wide ranges of experience, much more able to talk to speak to and adjust between multiple fields. It’S it’s amazing, the contexts that connect something like this and how much knowledge of this context really really helps put those pieces together.

Like okay, I see a compressor, I know what it does and then I know the physics of what’s happening. So I understand what goes on inside the exchanger and what changes when I speed the compressor up or slow it down or change the diameter of the capillary tube or change refrigerants from say our 134a, which is freon. It’S not only. Every change affects multiple other systems. Yeah, and so it’s not just a simple of move this – and this happens – it’s all these cascading.

If I can change the chemistry of the refrigerants and that changes, everything else in this is Wow and understanding what those effects are or change. The speed of the fan and, what’s gon na happen, how much liquid refrigerant do. I have left over when the speed of the fan goes up. Amazing, all those things are connected. Well, I figure it doesn’t matter how far it goes in no yeah okay.

So then the bend comes about here, yeah you could start bending there and because we’re just gon na want to clear the fan and I’ll stay in line with the IC I kind of want to be in line with that valve at the bottom yep. Oh it’s. This is the best stuff to work with so then once we have that, and I think I can actually come in even tighter yep and then this comes around here and comes that way. Wow it looks like I actually cut it. I think you have excited it’s just about the perfect size Wow, because if you didn’t, we could fudge it a little bit because we’re gon na do the same thing.

We’Re gon na insert this into the mouth of the compressor, since that’s a quarter-inch, don’t pull that out yet okay. So the reason why this has the plugs in it is that the compressor has a oil, that’s a Palio ether oil mm-hmm and that oil absorbs moisture and, as it absorbs moisture, it creates an acid and that acid over time will eat away at the insides of The components so we don’t want to so I’m gon na cut this down by half inch cuz. We don’t need more than that just a little bit far oh yeah yeah yeah, and how much copper to to steal brazing experience. You have hmm some, oh I’ll, do the first one I’ll tell you know the stuff that I use for everything is stay bright, silver solder, so we I’ll grab stay still 56 over 60 still 56, which is a high silver content. Phosphorous bronze, brazing rod, the high silver is, we always use it in special effects.

Cuz, it’s strong! It’S really strong and it’s just about the only really sensible way to create the copper to stainless steel bond and I uh I was doing it to UM. What did i buy? Oh those stainless steel, chrome, doesn’t actually desert brass and then chromed balls and I’m able to to braise brass to them nice right through the chrome, yeah, that’s really nice. That is pretty awesome.

So we’ll do that to copper to stainless here and so we’ve got that connection. I think that’s gon na look nice yeah. We, the bottom of this, is going to come out and we’re going to go into the capillary tube and will basically spiral this down and come into the bottom. The heat exchanger here so we’re gon na take a little quarter, inch pipe and make a straight stub to come out and we’ll crimp that stub will crimp this into here. All right will crimp is stub into here, so we’re kind of what we’re doing right now is setting up all the brazing we’re going to exactly.

If we don’t do a great job cleaning, the copper tubing, those little copper filings will flow through the system and end up in the compressor. We don’t want that to happen, so we use this filter dryer, which has a little filter on the inside and I’ve. Have these made at a factory custom-built for me so that it’s got the right diameter to slip right on there and for our capillary tube to slip right in there? If we didn’t have that, then we’d have to create fittings that make all these things fit together. So this will make it a lot easier, perfect and that’s really cleaned out with a three sixteenths reamer excellent.

So this atom is, I brought a couple. Filter drives cuz, I didn’t remember which size we’re going to need, but this has one the perfect fitting I’ll just slip right on there and we’re gon na slip. That here same thing now we’re gon na have a maybe 30 to 32 inches of tube coiled. That will go from this point here down to this point here: okay and the really nice thing about that. Bender that you have is, you can do clean hundred and eighty degrees.

Yes, that’s nice, yeah, okay! So then, so then we’re just gon na do 180. Full Bend yep from from right about here, yep, I’m, no copper dust in there. So perfect. Look at that right!

There! Okay! So then that goes there yep! So that’s that’s it! Those are the P really yeah!

Oh wait, but then there’s this. It goes to do. Yeah, so the rule like said we’ll have this: this one’s gon na go here, yep and then the coil is gon na come out, see how this is so nicely sized if it really really sexy. The only thing that we’re gon na do that’s gon na be tricky, is, and by tricky I mean slick and also difficult great is we need a fitting to be able to add refrigerant and a fitting so that we can measure the performance of the system? Okay, so does that mean we need a little T of copper?

You know we could use it T of copper, but what I’ve found is that we can cheat a little bit and we can drill a hole into the side of the copper th and we’re gon na braise this in okay. What that ends up looking like. So this joint mm-hmm is kind of uh. Oh that’s, crazy! Yeah didn’t do that.

I did this way closer to the copper yeah we’re not gon na. Do it that close, because I think I probably got lucky there. There’S no reason to expect accuracy from drilled holes on them, Fe so having Center drilled that we have a really clean hole. Now, that’s lovely, get a nice fit there. Oh yeah, oh good!

One thing: it’s really important to always remember to take your Schrader cores out before brazing, yes, because the o-rings, always that makes things bad the decision. As always, we can fuck the flux. This we’re not really, if we’re doing copper to copper and it’s fresh, clean, copper. Like this flux is optional, oh, I didn’t realize that got a little bit of an orange tail. I want to try to get that to be a little bit.

Okay, that’s pretty good yeah! It’S a nice little! It’S that will keep that joint clean. It’S really important to flex this joint, because we’ve got the dissimilar metals coming together and the flux is what’s going to allow the brazing material to flow in between the metals effectively. So we want to get good coverage on the surfaces and it’s going to make all the difference, so that should fill that material up clean, that up to make sure we get some good flux coverage again and then we’re gon na heat.

This sucker up secret here is: we want to heat up the copper first and the stainless steel last how’s it going you here just for that part. So this is the copper to stainless brazing, and this is a tough thing. Yes, this is the tough thing, so we hit up the copper, because the copper conducts heat a lot battery well and it’s just gon na pull the heat I give away and I’m just gon na keep stroking the copper whistle until it flows, and then I grinding Again, I just get the stainless a little bit make sure we get good coverage dude and we got a really nice clean joint. That’S awesome! You can see how uniform that so you’re actually feeding nitrogen in here, while you’re doing it yep any.

We shut that down. Now you can examine cuz. I actually uh fills us with nitrogenous abstentions: everything air, Oh nitrogen, that often just sits there very cool. So that’s one joint and the only thing I’m gon na do is it’s right here now we’ve made that joint. I want to make sure that we flow through here yeah, because if I screwed up, that’s never good, so we should get the puffs there.

We go. Oh cuz, you can see it step out there yeah. If I fed too much rolling the target I’ll clog it up, I’ve done that once yeah I’ve got about a hundred fifty systems and it’s like: let’s never do that again and so now, you’re gon na do the same thing again with this one yeah. Alright, it’s always terrifying brazing stuff, there other stuff, that’s been braised, yeah yep. Fortunately, oh I see you needed the goggles that day that shielding yeah I mean this is it’s it’s really not that hot of a flame but ya, know it’s good practice, because the oxy rig will make you blind for a day.

Yeah pay attention all right. That looks good, so should be really uniform. Some of that is definitely flux. It’S always good to clean the flux off and make sure that that’s do you need a certificate to do that. You need the hydro oxygen yeah.

Okay! I think I’ve got some yeah. So that’s that’s the stainless to copper and we can take advantage of these fittings once they’re braised in to fill the system with nitrogen amazing, so we’re gon na have this sitting here, we’ll pop that into the and it’s slightly long in case yeah. Well, I, instead of cutting out, I just bend it up a little bit cuz. It’S it’s so much easier right right right once we’re yeah, you should roll it yeah we can roll it.

We can. We can work with this straight piece here, mm-hmm, so the we’re at that point where we can look at the last couple steps. I always do the compressor last, partly because the compressor has the oil in it, but also because we can get everything else set up and if anything has to get tweaked, we can tweak it and then the compress will be the last joint to make. So there. The next joint we can do if you want rest that tube on top of the compressor.

You know the next joint will do is the coming out of here and then going down into here. Let me just dunk it in a glass of water right. Exactly is it hygroscopic we’ll pull water back into the holes yeah? Okay, so we want to get it up quickly, so we’ll hook it up while we’re still pretty warm and I’m doing all the brazing with the high silver content material. Just because we can it’ll look pretty when there’s just a little in the back yeah see so I’m just gon na make sure it’s got coverage good.

It’S like that puppy on here, oh and then we want to measure out. I could do these separately, but we’ll do at the same time. Okay, guys stay selves. Why the heck not Oh use that as the SAS nice. How can I do this part that looks really fun?

There’S this kind of thing. Thank you for letting me play. One part for inches off the end. We can split an unsupported supersoft. That’S perfect!

Oh whoops! Oh yeah! Sorry, I should probably close up first there you go excellent, so we’re gon na stick this in here mm-hmm get a little scotch brite and then once we get everything set up. The last thing we’ll do is unspool. It insert it in there and close everything up.

I guess, and just a straight up tube filled with desiccant right yep and there’s a little mechanical filter, strainer filter on it as well, so you’re not doing anything but just improving the desk it by getting it hot right right. Nice wedding. Give that good wedding make sure there’s lots of extra in there. So I try to avoid getting you. That’S all right.

I can take it all right and then one of the things again I’ll do is make sure that I’ve got good flow and I didn’t plug in a hole. So I’m gon na hold my finger over that. You know and then ya feel that oh yeah, oh nice, yeah careful about breathing in that nitrogen yeah. Are you kidding just an asphyxiant right? That’S exactly exactly it!

So we’re pretty good shape. The final three joints to do. I think we’ll do the compressor now and then the last one will do. Is this okay? So so now we actually want to pop out the plugs and the faster.

We do yeah this one. The better works. Three perfect. Now we hit it. Okay, just a little bit cleaning there, then this one will take a little sneak it around like that, but more maybe we’ll stick it underneath like that, and that goes that’ll go there.

So you want to put such bright that these are the other two tricky joints, because heating up a painted compressor right with oil in it. Yes, it’s always it’s fun and ok, that’s the steepest that one’s going yeah. So again, we could just do regular because it’s so clean because it’s clean and copper to copper, but it I think you’ll enjoy the shiny silver finish along the braze joints. So now there’s a fun bit where we can put pressure through here. We should get something out of here and they’ll, put my finger on here yeah and then that will pressure right here, yep see here that the little click in the compressor I’m hearing something leaking somewhere yeah.

That leak is right here. Oh that’s that yep! That’S put my finger here. Oh this tells me we have a complete circuit, wait so yeah, that’s awesome! We’Ve pressurized!

We’Ve got pressure all the way back through our evaporator the cold side. Yeah we’ve got pressure through the compressor, we’re actually pushing nitrogen through the compressor. Through this heat exchanger through the filter, dryer and then out, the capillary tube, which we will then hook up to here – this is the last braze connection we have to make, and then you have a fully completed circuit, we’ll put that in a bucket of water. Yep. Will pressurize with nitrogen make sure there are no bubbles?

Okay and then we know I’ve. We have a sealed system, we can pull vacuum on it. So incredible and then this is where the water circulates yeah. This is the business end. That’S the business end, so electricity in here cold out of here at this point, everything is ready to go.

So all we got to do is bend this down and start it in here and use the pipe cleaner. Also to make you stiff being out any authorization, since we’ve done all the brazing under dry, nitrogen yeah, it keeps the dryness make sure that we don’t get any water in the system. Any water in the oil, the nitrogen part, is nice because we can get it instantly. It prevents an oxidation inside during the braze. It prevents the heat oxidation from causing like this kind of flake.

Can you see on the outside? Oh that would end up. That comes amazing, the flow right that ends up inside right and that that material, the oxidized copper just clogs the oil and over time it might take ten years it might take one year, but over time. If you got enough of it right, it caused the system to fail, unroll it like this and then do a kind of a twisty twist yeah and ice. Have it come down like that exactly and then it just would sit like that to me.

Is kind of nice perfect that seems like cheating. It is so. I have got a little bit of motion, so I know that I didn’t crimp down on the tube itself, so I just closed this off and if you look at the end, you know there’s enough of a gap there. All I got to do is fill that with Ray’s materials and then we’re good this guy. This is pretty easy joint because there’s not a lot of copper here.

Just on the end, just like that, nice, amazing and fast that is done. We have a fully built system now should be all done with the brazing part and we’re ready leak test. Oh it’s time to leak test, it’s time to leak to us. Okay, so now you need a bucket. No, we need a bucket of water all right kid.

This is what happens when you ask a science communicator for a bucket that should yeah that should hold the whole thing. I think we’re gon na have a little displacement. I may need to add a little on top. I don’t want to get any water in the Schrader’s, because that water can right then potentially get entrained in the system. So I close these would have a nice gasket on the inside oh nice, and take use this one to fill.

So we take our nitrogen. I nitrogen attached that we’ve got a Schrader’s in now and we’ll do a pressurized bubble leak test: okay, where, oh, why see will pressurize it and put it in to see if it’s coming out anywhere so we’re now at 200, psi of nitrogen? May I not yell! We do that it’s got excited you good to get excited she’s very important, we’re gon na disconnect this line. Oh so now it’s still under pressure, so still under pressure.

We have because of the Schrader exactly, and this is why, having the Schrader’s in number one, I know that had a straighter and now because I pressurized it. Let me do this and if that’s coming out of that right now, just coming out of there yeah hmm interesting, I don’t think that’s a leak in the heat exchanger a leak in the heat exchanger yeah. That’S a pinhole heat exchanger leak! Well, all of my brains. Don’T sit good, do you want to try and braise that one should try to braise that shut?

Okay, that looks good, damn all right? Okay, let’s cross their fingers and hope that we do it’s. These are lost free fittings or Loas fittings. Amazing. I was amazed when I found out you could do that by using hydraulic quick, connects with pneumatic systems, yeah yeah yep, all right.

I just put it up to about 300 psi. So, okay really will we should see something immediately if I did a good job? Yes, I’ve never done that before first time ever that Wow dude. That was an awesome effect now I just want to make sure we get all of this underwater. Let me put this cap on first, oh yeah.

There you go sorry! Thank you. Nope no worries. Thank you perfect, and I see no leaks coming from anywhere yeah amazing dude. That was that’s.

You know, nuts our day could have gone any which way in the making or we’re done by the end of the day that it’s awesome. So do we leave that in there for a while yeah we’re good? We okay have a lottery system test done now, does leak test done. You have a hermetically sealed system, as we know – oh my god, and the next two steps, we’ll pull out a vacuum to remove all the nitrogen okay and we will oh and then we fill it with the thing we fill it with Bertrand. We’Ve got that so we’ll pull vacuum to remove the night, remove the nitrogen.

We will fill it with a little refrigerant hook up the electronics fill it with more refrigerant walls running and then you’ll have a perfect system. Amazing inside my gauge set right now, I’ve got a a very high vacuum that I’ve pulled over the weekend and we’ve hooked up a can of automotive, our 1:34, which is the refrigerant we’re gon na use for this, and you have to be certified. Yes, plumb. This is X, so I have certified a universal EPA: HVAC certification. Under normal circumstances, we would use in any real HVAC work – a 30 kilogram, okay, big bar a 15 kilogram tank right, a big bottle in the case of a system like this.

We’Re really only gon na put about 30 grams 40 grams of refrigerant in okay, so it doesn’t make sense to have 15 kilograms when we only need 30 grams as an alternative. This little tank of refrigerant here for automotive purposes, is 340 grams, so we’ll end up using 20 % of this bottle, or instead of like 2 % of a really big bottle. That’S awesome: we’ve had to make a little juryrigg connector together, automotive bottle and the automotive can tap through to our standard refrigeration fill line, and we braised that in the other day, the other time so I’ve purged any air out of my refrigeration line and ready to Fill this, so we always fill the suction side, which means adding refrigerant to the blue line. Okay, and to do that, I’m gon na make sure I always start off making sure my valves are closed. This one I can have open because we’re gon na add refrigerant.

Here we’ve zeroed out our scale. I want to know how many grams we put in okay, it’s helpful to understand how the system is behaving and at this point is pretty simple. We open this up. We know what’s up and we’re gon na squeeze the trigger. To add more bread, so we’ve now added a starting refrigeration charge of let’s see how many grams we’ve gots three whole grams of refrigerant.

So we’ve got about three grams in a system. The pressure has gone from high vacuum up to 55 psi, and this is when we can start the compressor, since we no longer have the system under vacuum. We have some minimal refrigerant charge in the system. We can spin the compressor and it can do some work once we get the compressor moving, we’ll continue to add refrigerant until we see a couple different values up here on here, so I’m gon na grab two other clamps, so we can watch the temperatures. So this first clamp I’m putting on the suction side of the compressor, okay, and what this is going to tell me.

This is really fundamental measurement. We’Re gon na be boiling refrigerant off here and the refrigerants gon na come through this heat exchanger and as it’s absorbing heat, we can measure the temperature when it gets to here. Okay, we’re also measuring the pressure at this point, so at a given pressure, we’re gon na have a given boiling points of given temperature for water. Water boils at 100 degrees, the gas that’s the steam that’s generated can be hotter than 100 degrees. The water itself right can never be hotter than 100 degrees Celsius, 212 Fahrenheit at sea level, but we can change the pressure like.

If you go to Colorado you’re a higher elevation, which means you can have a different boiling point in different temperature. So we can modulate those boiling points. Oh, I changing the amount of refrigerant in the system and changing the speed of the compressor, fascinating, so look at them that can change overall, how fast it can go through cooling cycles and how much it can cool and also how efficient the system is. I never realized it was an adjustable set of values with it. Yes, I just thought you put it under pressure and boiled it off, and in that change you got cold, but that’s, but your with part of it.

Different pressures yield right right right, oh my god. So we can adjust those pressures and temperatures and we’re gon na adjust them to make the system really efficient and also give you the right amount of cooling amazing so right because there’s an optimal relationship between the values. Exactly that’s exactly the case. So okay gon na go ahead and make sure this is all ready and if you feel this, actually no and you probably get a little cold that should be cold mmm-hmm. These cans are not the best.

These fittings leak a little bit. So I see I want to make sure that we’ve keep our pressure up here and now we can basically spend the compressor now. Okay, this control board is ready to go, but I’m gon na take a little shortcut here, which is, I don’t know why I write to the compressor. We can wire the right right to the compressor, I’m hoping that my software is still running on our little Arduino board, but we’re gon na plug in 24 volts hook up Larry turn this off rounds no go ahead. I don’t mind plugging things in while they’re on.

It’S all low voltage, yeah, nothing to be afraid of here all right so because that second we’ll see, if that turns on and if it doesn’t, then we should wire directly in whoa there. It goes so that was a great check system, yeah that it was going through to make sure it was finding everything it wanted to find exactly and now the compressors running, I’m gon na keep adding refrigerant, okay and I’m gon na watch these temperatures. So this is the temperature that we’re boiling at right. So I want the warm side of this to be warm enough, that we can reject heat and the cold side cold enough that we can absorb you tonight. This is getting warmer excellent yeah.

It’S definitely getting colder right down at the bottom here, where the oh yeah boiling is taking place, that’s gon na be the coldest spot. Other thing we can do is if you have a jumper, I think we’re gon na jump the 5 volts directly to the speed setting, so that I don’t have to plug my Arduino in all right sneak that in here there we go 77, a fan on here. We can start to get rid of some of that heat. Okay, oh yeah. This is getting nice and hot on the hot side.

Okay, so now you need a third um power supply before when we weren’t taking heat away, the cold side was cold, but it was not as cold as is now now we’re getting rid of that heat. The cold side is extremely cold to the point. Where we’ve got a layer of ice forming on all these once we hook add them up. We will get a load so we’ll start taking Adams heat away into this system, and then, when we crank it back up to full speed, Adam will get cold quickly outlet into the top one, because we want to go okay flow. We want to have right, cold refrigerant, going up and we want to have the water going down that way.

You’Re gon na get the most effective cooling fastest, and then it comes out of me into into yes into there. Yeah it’s pumping out a lot. Isn’T it? Oh, that seems like right. We should let’s crank it up, we’re going it that slow speed here.

So you crank that fan and we’re gon na go yeah. I was thinking it didn’t feel like it was getting any colder, but now it is, I mean I’m definitely feeling cooling all over. I loved it. This 1975 Royal Air Force cool suits still totally functional they’re fast. We can go before you feel in it.

Like the moment, you did that I’m feeling a difference. Yeah that seems to be one of the limiting factors and how cold we can get yep yeah. I can feel the conspirators we’re circulating, so we definitely need a more powerful pump. Yeah dude check me out. I’M getting cold; this is the most elaborate way to get cold in most the United States right now, if you just walk outside there’s, also helping it sink in how incredible it is that NASA built us all into their space students write something fully.

Everything here is in a self-contained spacesuit, along with oxygen and other stuff going on and other telemetry. Oh yeah again, I always understood how the system worked, but seeing its level of complexity is kind of amazing in the vacuum of space. Dealing with temperature is really tricky because you can’t conduct temperature away by by having air, that’s cold or hot right right. You’Ve got solar radiation, that’s bringing a lot of energy onto people and then you’re, giving away photons out in the space. So there’s these trade-offs of of heat flux, this that NASA had a system that kept kept astronauts cool by actually boiling off a gas and dissipate a liquid in space and basically just vaporizing it.

And as you do that you can, you can have a lot of phase changes happening here right. It’S changed, absorbs energy, absorbs heat and tah-dah you’re managing temperature. Now I feel, like I’m standing outside oh yeah great day, I’m starting to get real cold. It is actually, I think, we’re hitting some good at some point. You can look at the thermal image.

Oh yeah, that’s awesome! Yeah! You can see the lines on your body where the FLIR is picking up all the cold tubes. That’S spectacular, I think, that’s what I would call a successful test of the mini refrigerator that Kipp designed and we built here because it has me freezing and I want to say cut so we can wrap it. I can get on some normal speed clothes so cut.

Really noticeable it’s moving, I mean it’s moving to heat yeah man and if we crank up the the pump yeah you’re gon na, that’s pretty awesome.

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