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To make your own storm windows, follow the step-by-step instructions, watch the video tutorial, and download the woodworking plans. The acrylic inserts are edged with a soft, patented silicone compression tube that presses into the interior of your window frames to seal drafts. You’ll feel warmer in winter and cooler in summer while saving up to.
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📹 Indow® – Custom Inserts For Your Windows
Indow window inserts are custom-made panels that press into place inside your existing window frame. Made from 100% acrylic …
How do I make my own window insulation?
Bubble wrap, window film, and cellular shades and thermal drapes are all effective ways to keep your windows warm and dry. Bubble wrap, which can be applied by spraying water on windows, provides insulation by capturing small air pockets. However, it doesn’t look attractive and blocks your view. Window film, which allows clear visibility when properly installed, can be purchased online or at home and garden centers. Tape the film loosely around the window’s perimeter and use a blow-dryer to shrink it to fit.
Cellular shades and thermal drapes, which use modern thermal technology, work more efficiently than old-school shades and drapes in retaining cold air. While they keep you warm, they also block light and your view. Overall, these methods offer some protection from the cold but may not be the most visually appealing or practical solution.
What material is used for window inserts?
The inserts are made of lightweight, strong acrylic glazing and are framed by compression tubing for a snug fit. They are pressed into the window frame without the need for nails, screws, or adhesives, ensuring no damage to the frame or use of harmful products. The new pane is virtually undetectable and doesn’t affect the existing window’s appearance, making it ideal for custom-built windows and older homes with poor energy efficiency.
Energy conservation increases to a level comparable to double or triple-pane windows, and may be half or even a quarter of the cost of a replacement window. Additionally, the inserts reduce exterior noise by up to 50%.
What is a compression window?
The Innerglass Compression Window is a vinyl-framed, glass interior storm window that uses Compression-Fit technology to seal tightly, eliminating drafts, condensation, and outside noise. It eliminates the need for a track and provides an airtight fit, even for non-square windows. Installation is quick and easy, with no carpentry required, and these windows do not disrupt existing windows’ integrity.
How to make an internal window?
This document delineates the methodology for the repair of a load-bearing wall, encompassing the stages of planning and marking the opening, the removal of the existing drywall and studs, the framing of the opening, the replacement of the drywall, the finishing and painting of the drywall, and the addition of trim and counter (optional). It is acknowledged that JavaScript may be disabled or blocked by an extension.
What is compression glazing?
Ceramics experience compression when glazes have a lower thermal expansion than the body they are on. A little compression is good, while a lot is bad. The coefficient of thermal expansion (COE) is a measure of how a solid expands and contracts on heating and cooling. If a glaze’s COE is too much, it becomes “stretched on” and develops a crack pattern called crazing. Conversely, when the COE is too low, the glaze is under compression.
What is the best material for interior storm windows?
Temporary and disposable storm windows are ideal for inclement weather or cold snaps. These clear acrylic or film panels fit inside interior window frames and can be installed using heat from a hair dryer. Popular materials include vinyl, fiberglass, aluminum, and wood. Low-E coatings are popular for their energy efficiency and reduced heat transfer. Other glass options include standard three-quarter-inch thick glass panes, one-and-one-eighth-inch thick glass panes, laminated glass, Plexiglass, tinted glass, and tempered glass.
Can I use plexiglass for storm windows?
Window Savers are DIY interior storm windows made of Plexiglas, offering a high-quality, low-cost solution compared to custom-built windows. These windows are easy to install and require no special skills or tools, using an extra-strong, durable peel-and-stick adhesive. They are not sold in stores and come with an unconditional money-back guarantee. The installation process is simple, requiring no special tools or skills.
Window Savers can save 30 to 50 percent on heating and air conditioning bills, making homes or offices quieter, eliminating drafts, condensation, and radiant cold, and slowing the loss of both heated and cooled air.
What is windows compression?
Zipped files are smaller and faster to transfer to other computers than uncompressed files. In Windows, you can work with zipped files and folders similarly to uncompressed files. To share a group of files, combine them into a single zipped folder. To rename a zipped folder, press and hold the folder, select Rename, and type the new name. This allows for easier sharing of files and efficient file transfer.
Can I make my own window inserts?
Interior window inserts are a cost-effective and easy way to reduce heat loss between the inside and outside of a room. They can be made using clear film insulation kits, which are sold at hardware stores. The process involves measuring the height and width of each window, multiplying them to find the square footage needed for the insulation, buying enough lumber to cover the inside edges, and buying enough weather-stripping to go around the insert’s edges.
To build the frame, measure the height and width of each window, multiply the square footage by two, and buy enough 1×2 lumber to cover the inside edges. Cut the lumber to fit the insert’s edges, then reduce the height dimensions and width dimensions to allow space for the vertical frame pieces and weather-stripping. Mark the boards with pencils and cut them with a saw. Assemble the frame by drilling two screw holes at each corner, driving wood screws through the holes, and allowing the glue to dry for 24 hours.
Next, apply the plastic film by applying double-sided tape to the frame’s edges on both sides. Wrap the film over the frame, trim it, secure all outer edges with clear shipping tape, and hold the hairdryer a few inches from the film. Apply heat in sweeping motions and watch the film contract, stopping when wrinkles disappear. Expose the self-adhesive edges of the weatherstripping and stick it around the outer frame edges. Position pull tabs so they can be easily accessed from the inside of the room, and glue a pull tab to two sides of the frame about halfway up. Insert the completed frame into the window.
Are internal windows a good idea?
Walls and doors are often the most conventional way to divide a house or apartment, but they can sometimes be the best solution in small spaces. Internal windows can be both beautiful and practical, helping create more rooms in a small footprint. Examples include Sebastian Bergström’s Stockholm apartment, where he created a kitchen and bedroom out of a single room with glazing in between to allow natural light to flood into both spaces. Gytha Nuttall’s flat also uses a ‘box within a box’ construction to create more rooms hanging from a vast double height ceiling.
Even if not working with architectural constraints, internal windows can be a beautiful addition to a house. For example, a full set of glazed doors can be a great compromise between a fully open-plan layout and something more intimate. For example, Phoebe Hollond’s modern country house added French doors to bring more light into the dark library area.
How do you secure a window from the inside?
Windows are a weak link in home security due to their easy accessibility and potential for burglary. They provide natural light and ventilation but can be easily broken or shattered, making them a tempting target. Most homes have multiple windows, such as ground-floor, basement, and windows near trees or bushes, which can provide hidden entry points. To secure windows from break-ins, there are several effective ways to access your window security needs, such as installing window locks and latches, reinforcing window glass, positioning security cameras, setting up window alarms, installing motion sensors, adding window bars and grilles, and using window security film. By following these steps, you can help protect your home from potential burglars and maintain a secure home environment.
📹 DIY Vapor Compression Refrigeration System
In this video i’ll show how to put together a single-stage vapor compression refrigeration system and explain the theory behind it.
First, I think your website is probably the best on YouTube for inventing/engineering discussions that show the actual process of trial/evaluation/retrial of ideas. Keep up the excellent work. However, a few points that are likely also being made by other commenters: Soldering propane connections is unsafe and prohibited by the gas code (at least where I’m from). The connections at the end of your evaporator/heat exchanger are very sketchy. The wetted surface area of your soldered joint is very small, and will be subjected to substantial thermal stress. Don’t be surprised if it starts to leak. If you rebuild it, I would strongly reccomend you use a reducing tee instead of a 90. You can find models that are AxBxB sized where you can have a sidearm and one through connection at the smaller tubing size, with the second through connection larger. You then file/grind/drill out the stop inside the smaller through connection and can run your smaller tubing right through the tee. This allows a full sized brazed or soldered joint on all three pipe connections. The home distilling community has lots of examples of condensers made this way. You might also want to consider using a small brazed plate exchanger instead of a tube-in-tube. You can get these quite cheaply in the usual spots online, and they’re often rated for refrigerants and their working pressures.
13:55 – Copper work-hardens, so your straightening of the coil to thread the other one through would have already hardened it, made it more difficult to re-coil (in addition to the added internal pipe). Annealing (heating and quenching) isn’t really an option here either with 18ft of straight pipe, so you often need to be frugal with your manipulations, lest you end up with some really stiff pipe.
A little while back, I repaired a -50c cryocooler. It uses a 1/3hp pump similar to the first one you showed and a custom blended refrigerant I couldn’t find any details on. One major mistake was that measuring the evaporator pressure at the compressor gave inaccurate pt chart results for the minimum temperature observed. After a lot of trial and error, it was discovered that measuring the pressure at the meters’ entrance to the evaporator more accurately predicted the observations. A pressure gradient is formed inside the tubing. In normal hvac applications, this gradient is not an issue as the goal is higher efficiency, and the ‘exact’ boiling point is almost irrelevant. But for your application of mathematics, I believe it should be accounted for. There is a post on sciencemadness about it. I hope your success continues, and I really enjoy the articles you’re making. Stay safe
To get the centre pipe through the heat exchanger, you might want to send a flexible piece of plastic through first, then attach the copper. That way you can `pull` the copper through and it will be much easier. To clean the `fuel` type propane up, I have a tank that contains a few pounds of activated charcoal, I transfer a quantity of of propane and let it sit for a day or so. This will absorb most of the stenching agent. This is needed for a long term unit as the stencher is rather corrosive to some materials. Lastly, the soft solder is not suited to long term operation in a unit like this. Some people think it`s not suitable for the pressure, this is incorrect though. The real reason that it is not suitable is that after many cycles of hot, cold, it begins to crack. You will most likely see this effect where the layer of solder is thickest, like in the connection to the capillary tube. Great article series, perusal with interest!
I really can’t find words to express how amazing you are in so many aspects Since my childhood, I have been working in the refrigeration and air conditioning departments for nearly thirty years. I know very well and appreciate the enormous amount of effort that you have made in these experiments. Much more than wonderful I would like us to meet, but there are many obstacles, but I will write to you by mail, and this is my pleasure and happiness I was impressed, enjoyed and honored to see you My sincere wishes for all success and I would like if I can help you Sorry for the inaccuracy of the expression, I use a translator👍👍👍
You probably already know this, however you didn’t mention your flow configuration in the article. Make sure you’re running all your tube-in-shell heat exchangers in countercurrent flow for best heat transfer. This series is fantastic and extremely high quality, I look forward to seeing the end result.
A few notes, from someone currently going to school for this: – Install your filter dryer last and change it as close to every time the system is opened as possible. Installing a filter dryer should be a very quick hot potato sort of operation, you get the pipes lined up, swaged or flared and ready, and right after popping the filter dryer caps off you stick it into the pipes and start brazing or tightening. There should also be zero temperature drop across the filter dryer (within your measurement margin of error), a temperature drop indicates the filter dryer is clogged or otherwise producing a resistance to flow. That dryer spent way too much time open to atmosphere and is unlikely to have much dry dessicant left, especially if you blew air through it testing the cap tube in that one clip – Solder, no no no. Solder can’t be trusted with the sort of pressures you’re working with. You should be using brazing rod, and learning to make flare fittings will do wonders for the ease of disassembly and modification of your system – Awesome work on the calculations for your capillary tube! All that homework you did is the only reason this is working at all. – Pulling a vacuum before charging is, like super duper important, not just necessary. For best results, pull a vacuum below 500 microns of mercury (about .67 mBar), break the vacuum (let <1 bar of pressure in) with an inert gas (ideally nitrogen), pull another vacuum to below the same level, break it with refrigerant, then pull a third vacuum before charging. That's what's done in industry to reliably eliminate all moisture that can reasonably be removed - That tube-in-tube HX for the cascade system is sketchy, to say the least. I'm very curious what sort of ridiculous pressure drop you have across it, the uneveness in space between the tubes is going to make all sorts of weird constrictions and pressure drops. An evaporator should have the same pressure throughout the whole thing, maybe a couple pounds' pressure drop at the very most, you'd do well to stick a pressure gauge on either side of that evap - In the industry when we hook up to a system we measure what we call superheat and subcooling. Superheat is how many degrees above its boiling point vapor warms up in the evaporator after boiling, subcooling is how many degrees below its boiling point liquid cools to in the condenser. For instance, at 21:03, you just described 15 degrees C of subcooling, which is really quite a lot of subcooling, I'm taught to generally look for about 10 F/5 C of subcooling, so your condenser was performing quite well. Your evaporator got as cold as it was going to, without knowing the outlet temperature I can't tell the superheat but it was probably also quite high, I'm taught to look for 10-20 F based on application. Looking at a cap tube system, high subcooling and high superheat is generally a massive red flag for undercharged, that setup might have just needed more gas to perform better. With cap tubes, charge until the desired superheat is reached, for your application that's probably 3-4 C under load. - The compressor is cooled by the cold vapor refrigerant coming back through the suction line. Your compressor didn't overheat because the condensor didn't reject enough heat, the condensor rejected tons of heat, the compressor overheated because at such low pressures it barely got any refrigerant to cool itself with and what vapor did come back was likely highly superheated. Issues with mixing and matching compressors and refrigerant aside, also a sign that the system could have taken more charge - I don't even want to know what became of what charge was in that AC unit when you bought it to harvest its organs. Whatever happened to it, that was probably all illegal, if you live in the U.S. and aren't EPA 608 certified it was definitely illegal. Not judging, just a heads up - Second setup: I see 15ish F subcooling and 5ish superheat, high-ish and somewhat low respectively. Condenser is very slightly starved and the evap is bordering on flooded. A flooded evap is fine to see in no-load conditions without the second stage built yet, especially with a few degrees left to protect from sending liquid back to the compressor. Once it gets a load on it and your superheat starts going up your compressor might stop getting cooled as effectively and overheat, though. - I think you've done this whole article charging passively, but I'm not sure. Just in case you've been opening up your propane bottle with the system off, weighing in a charge and stopping at that, you can charge with the system running by hooking the low side up to your container and metering it in. Should ideally be done with the system having reached its thermal equilibrium so you can charge based off good measurements. - The cooling power calculations are gonna be off by more than you expect, just that little bit of condensation on the beaker is actually a ton of heat leaking into it. Good news! Your calculation is definitely an underestimate. Very cool! Also kind of concerningly dangerous but you're definitely doing your research. Interested to see where this goes. Edit after sleeping on it: Lost in trying to transfer knowledge, was, holy shit! This is really impressive, you've really done your homework. I'm almost only squawking about danger because of the solder rather than brazing, God only know I've done stupider. Keep at it!
Man you nailed everything regarding using propane in the system. One thing that may have an effect on the performance is the oil circulation that the rotary compressor has. During its normal operation some oil leaves the compressor and can get stuck in the evaporator and changes the performance of it. One way to check is to have a sight glass on the inlet of the compressor as it should be mostly vapor and not too much oil. Its like having an inside look into the system on whats actually going on inside the copper pipe. Not sure if this was already taken into account but a piston compressor typically has less oil circulation overall. Great article and look forward to the next ones.
Bro, these vids are like CRACK to me, every time I see you’ve posted a new article I instantly binge and rewatch it a couple times for good measure ☺️ Aside from your epic and super interesting project, all the refrigeration knowledge you’re pumping directly into my eyeballs is seriously informative, and I’m now finally starting to understand why my first air conditioner unit failed with the entire thing feeling 80 deg C on the outside with the lack of noise waking me up deep in the night when I panicked from the external plastic casing temperature and immediately turned the thing off. I haven’t dated turn it back on ever since, and I was fiddling with the starter capacitor because I though that was the cause of the issue, but now I’m starting to doubt that. Thanks to your articles I really feel like I’m finally learning enough about this topic to be able to fix the thing myself in the future (I hope!!). thanks for your epic vids, AWRRRRRR MATEY! I really appreciate all the effort and hard work you out into these super educational articles of yours! ♥️
HVAC Tech here. You can switch “gears” by having three capillary tubes at different lengths in parallel with a valve that isolates each tube for up to 6 “gears” by opening and closing certain tubes at certain times. However, this is a lot more convoluted and expensive than simply just using a regular TXV. However, using a regular TXV is difficult because you’re doing something without any engineers or refrigerant knowledge, so you won’t know exactly what model of TXV you’d want (they change based on the cooling load required and the expected operating pressure range of a particular refrigerant). Your best bet is to get an EXV which uses an electromagnet to turn a magnet inside to open and close the metering device. This has an advantage that you can test where you want the EXV seated at which stage of cooling, and program it with an raspberry pi or an arduino. You’ll be able to trial-and-error it to where you want it to be for a given load.
I’m taking thermodynamics right now in college. I really love the class and the math that comes with it so perusal this and seeing someone design a refrigeration cycle is awesome. It really helps show how what I’m currently doing in school applies to real world design challenges. This was really cool to watch. Phenomenal job sir!
12:37 shouldn’t the flows be going in opposite directions? The on-screen graphic shows the flow going in the same direction. Counter-flow heat exchange is what enables you to get the most heat exchange. Parallel flow heat exchange will only ever approach meeting in the weighted average temperatjre of the two (with heat capacity considered), but counter-flow heat exchangers have the possibility of heating the target fluid hotter than the outlet of the heating fluid.
14:17 Take a look at this arrangement of tubing for a VCC system in a modern regenerative VCC refrigerator, linked below. In this design, the capillary tube itself is used in the heat exchanger, and the heat exchanger is in a counter-flow arrangement, which should yield higher efficiency. I linked straight to the timestamp where the coaxial capillary tube and gas return tube (which is effectively a heat exchanger) is explained. Modern refrigerators explained (timestamp links to introduction of the coaxial capillary tube + evaporator vapor return tube, which acts as a recuperator. Hot condensate is used to warm up cold vapor/cold vapor is used to cool down hot condensate, making the whole system more efficient, as less refrigerant needs to be evaporated to cool the remaining refrigerant to your target temperature. ) youtu.be/7NwxMyqUyJw?t=301 This arrangement would save you a good bit of flow friction losses, and would perhaps perform better than the design you showed in this article.
Idea for the capillary tube: You could put a few taps in it like you would for a transformer. That’ll give you a couple of “gears” to switch through. ie: Every couple of turns you could attach a valve and then depending on the length you want, open that valve. it’d be a bit of work but it would give you some variability.
I made myself a cooler with a rotary compressor for cooling cpu-s, I also have 2 stage cascade with ethylene but was bought already made. It cools to -113°C on the evaporator so my cpus are at -100°C at load. If you want to buy ethylene it is 1800€ for 18kg so I can`t wait how to make one 🙂 good job on the article and have a good day, B
Something I recommend doing differently here is not to solder (as appears being done), but to braze instead, preferably with silver rods. For a more permanent/less experimental system I also recommend flushing tubes and part while brazing them with inert gas (N2 is cheap and easy to get) to avoid corrosion on the inside of the tubings as that is the stuff that might eventually block your capillary tube. Notwithstanding this I love the articles 👍🏻👍🏻👍🏻 and particularly this one as it threw me back to my highschool days when I built cascade systems to cool my CPU and overclock… I commented on your last article with a recommendation to do a R290/R1150cascade system – I wonder whether you had seen this ☺️
Out of respect, I want to note some of my ideas came to my mind while perusal: -Could use excessive dripping water in AC to use as evaporative cooler on the condenser side, to further increase the efficiency of an AC unit -Might use a bicycle or football needle-valve inside a tube as a junk alternative for evaporator tubing Last but not least, I’m an electrical engineer, and can’t help but thinking about this project: +For AC units average COP=3 (mine is R134a), which means it uses say 500w electrical power gives д-heat of 1500w. +ThermoElectric Coolers (TEC Peltier) have written efficiency of 50%. Then; If you made a special evoporator from silver-plated copper, that’d touch to TEC, finely grinded (5000 fine sand for ex) and liquid metal as thermal paste to further increase the efficiency, you’d have a reactor that uses 500w compressor, gives 1500w д-heat, and peltier would generate 750w in theory.
Fantastic article. Warms an engineers heart to see a project conducted with proper regard for the science principles and associated mathematics. Even better to hear an American accent wrapped around SI units! Mr, you got it all goin’ on! 🙂 And seriously, great article. I’ve worked a few heat pump designs myself and my only question about your technique is your soldering is using soft solder; is that really strong enough and long lasting enough for the task at hand, and does it not soften a bit at your higher temperatures where the pressure is also higher? I use silver solder and nitrogen gas in the tubes to stop scale forming in the tubes. It is a pain but those joints are stronger than the tube! Now, to find the promised next article…. and to say; thanks for sharing.
@Hyperspace Pirate Granted this is a low TRL as of now and you are still figuring out what works, let alone polishing it, **BUT**: Can you optimize this for Off the Shelf (OTS) Parts / “Clean” Design? Basically what you did with the 3D Printed Parts but on Steroids. Use reliably sourced OTS parts, have there be like a pallet sized (heck even (plastic) pallet mounted) module for each “stage” and have the fittings all in a standard spot, then make a “shell” enclosure if you are feeling REALLY fancy? It would be a PILE of work, but i feel that if you get this project working, then do that, we could have an Open Source, Modular Refrigeration System that could be used as is for a water chiller etc, or be cascaded like you are doing and get cryogenic levels of cold! Granted again this is asking a lot, and worse case scenario others and i could iterate of tour work, but i feel like that would be an AMAZING application of this project. That’s my rant lol, and thanks for reading this far. What do you think of all this?
It’s probably in the charts somewhere (“read the fucking manual” moment), but at what level would using CO2 as the Refrigerant make sense? I know it is used commercially, and is kind of the “latest and greatest” / non Fluorocarbon/ Chlorocarbon / CFC options, along with Ammonia, Butane/Ethane, and DME. I haven’t taken an HVACR class yet though, and don’t remember the papers, so does it require obscene pressure and/or stainless steel or inconel pipes? If not that would be a great option. Cheap and Non-Flammable.
About the ethylene side: since your cooling efficiency is bad, keep in mind that the cold (ethylene) stage compressor is going to be dumping its entire heat budget into the hot (butane) stage if you use a sealed compressor unit. So your hot stage cooling power needs to be at least as much as the cold stage total power. And good luck finding a liquid lubricant that doesn’t freeze at -100C (in the cold stage evaporator) or boil at room temperature. An oil separator doesn’t really matter here if your lubricant has turned into a gas anyway and is spread through the whole line. Oh, also, maybe just stick the whole hot stage evaporator in a cheap styrofoam cooler for now? Its way easier than having to foam and tape everything. Also also, you might find that those $2 mylar emergency blankets are a lot more manageable than aluminum foil. I used those two things to make a passive sky freezer that gets down to -40C at night when it isn’t too humid.
Bubble the propane through a sodium hydroxide solution chemically binds to and removes mercaptan and other sulfides. Then dry the propane with a desiccant. Caustic soda wash and Sulphur making stable salt, sodium sulphate. Store bought propane is probably dirty with heavier hydrocarbons. You may want to chill the tank and only use only the light stuff that boils off first.
IDEAS PLEASE?????? I’m wanting to make a small lightweight system to use on a race car to cool the intake charge for more power and safer combustion. I can tell you intake temps can reach °500 at its highest & are usually 200 or less. It only needs to cool the charge for 15 seconds at most & has hours to recover if needed… ideas?? My water to air works great but I want better. Also I’m now flowing nitrous or Co2 through the intercooler venting it to atmosphere. I want a system that is easy to use over and over… Help me….. I love to play with science lol.. IDEAS???????
28:00 BTU: ~ This is the units refrigeration technicians use but from an engineering perspective it’s “kind of annoying”. It feels like you’re being a bit facetious here. This actually never happened and I am so grateful – where I would have to answer a question with units involving BTU’s. It does not matter how well I know principles of heat transfer or thermodynamics, making it through all the unit conversions and getting the right answer was a crap shoot for me with the odds heavily stacked against me.
the airflow across the condenser has to be a specific amount, overcooling it will screw up the distribution of liquid. You can effectively make the system act overcharged or undercharged by varying the subcooling. Subcooling always has to be at least few degrees, but a ton of subcooling will need to be taken into consideration elsewhere as it screws up the pressure ratio.
This is amazing, and is exactly what I need for a air to water heat exchanger. But before I get to excited please let me know if it is possible, I am building a rally car an i am using water to air cooling for the turbos, and have been asking myself if I could some how get that water to be cold with a modified AC system… Do you think I could achieve some decent air cooling
At 15:01 you could have just used the fitting you’ve got your hose on threaded into the FIP you brazed on but you decided to put 2 adapters to go back and forth in the middle… When you could’ve used one braze on service fitting to go straight to your hose. The part of my that works in refrigeration is like bro why, but my diyer self loves the simplicity of it
You might like R-1270 better, you can get it at the hardware store as yellow bottle torch fuel. I have a freeze dryer that will do -40C from ~23C ambient. If I run it in cold weather (-10c) then it will pull below -55C if I have vacuum in the chamber. I also made a blast freezer from a broken dehumidifier that I had to -46.8C the other day. I want colder but I don’t see how unless I start something crazy like trying to condense ethane out of natural gas. And I could only run that in the winter, and at great peril. One problem with such low evaporator pressure is that the compressor wants to overheat real bad. I am water cooling the bottom of the compressor to cool the oil which helps. There’s a reason those home freeze dryers have a reputation for compressors failing… it’s far from ideal to have a 60-80C temperature differential. I found propylene was good for about 5C or 7C lower temps than propane with the same cap tube and compressor. Another kind-of-decent is air dusters. It’s basically a drop-in for R-12. Less flammable than propane but not as cold. ALSO: Dump that 1/4 tubing and get some 3/8 for your low side. Something else you might find lovely: a sight glass! I like to put mine right on the end of the liquid side between the filter drier and the cap tube and position it at an angle so you can see if the system is getting liquid, liquid/vapor or only vapor. Experimentation has shown for me that the coldest is liquid/vapor something like 50/50 so the vapor bubbles don’t allow the stream to accelerate but there is less total refrigerant because of the bubbles.
Wouldn’t it be better to have opposite flow rate in the Coaxial heat exchanger? I mean that would give you a much more stable temperature difference as the warmed up gas would cool the ‘hot’ gas on the condenser inlet side and towards the outlet side of the condenser both would get cooler (the refrigerant in the condenser from cooling and the one in the evaporator from being fresher) – don’t feel bad if you gotta correct me, I’m happy to learn if there’s a mistake in my thought process ✌️
If you can crush the tube to make a connection then you can also squeeze the tiny tubeing to create finer control on the expansion valve. I got a question on these soldering connectors. My impression on hvac job is it requires blazing than soldering due to higher sealing capacity requirements. Soldering is probably only good for a short time test?
Since you’re already measuring the inlet and outlet temperature of the cooling water on your evaporator, why not do your heat transfer calc with that? Power = mass flow x Cp x deltaT Also, use an antifreeze mix so that you don’t ice up inside the heat exchanger, but you probably knew that. Pre mix is nice since the thermal properties are well published.
I’ve really enjoyed this series on cooling, thanks! One question for you: did you purge the air in the system before pressurizing it with propane at 15:25? I’m guessing you did but didn’t show it in the article. If not, I imagine it’s probably okay (24:1, extremely overrich mixture), but personally I’d sleep a little better knowing there wasn’t any oxygen in there at all.
At 8:15 If your turned of system if filled with “a saturated mix of liquid and gas” then you compressor would be trying to compress liquid, which it can’t ? My HVAC guy says, at rest the system is all gas and there should only be liquid on the pressure side, none in the suction side. Also you mention charging into the low pressure port, but here too I think you have to be careful charging with the system enabled, if your gas doesn’t all evaporate before it reaches the compressor it could kill the compressor. Usually the system is charged by weight roughly and then final charge is slowly added while measuring TX temperature and I believe for most system it’s 12F but my memory is getting very blurry here with regards to the exact TX charging procedure.
I would use an EXV as your throttling valve. I built a system kinda similar to yours (R290 + bldc compressor actually) using one and a couple electronic pressure sensors to control, and it worked out quite well. I am able to easily match the compressor spec sheet COP at their test conditions (COP=3.5+) with cooling power ~1kw. They are exactly like normal stepper motors, so are pretty easy to control with an Arduino etc. Just make sure you have some sort of failsafe so you notice if the control loop causes pressures to go out of wack (manual gauges like you have should be fine).
Nice article, I really like when a people make their own equipment for refrigeration/hvac, several years ago I read that the rule of thumb for max compression ratio is 1:10, out of that your efficiency is out of range, that’s why cascade systems are used for deep freezing, as side note: deep freezing use R23.
Lots of comments so I’ll keep it brief. – Cool project well explained but don’t reinvent the wheel. See tube-in-tube condensers made for marine HVAC or water-cooled commercial ice makers. These may well suit your application as an evaporator. Brazed plate heat exchangers work well for evap. or cond., but not w/o careful engineering. A cheap automotive R-134 TXV would save you a lot of headaches trying to adjust cap tube length, will also give much faster pull-down from hot. – Ester oil has the lubricity of water but is speced for current refrigerants that don’t like real oil. Refrigerant grade mineral oil would be better w/ Propane. PAG oil is not for electric compressors (dissolves insulation). – You need to determine the charge under load. No measurements are meaningful w/ no load on the evaporator. – Keep the compression ratio (in AC land that is: P absolute Cond / P absolute Evap) under 7 for less heat/longer comp. life. Lower is better. 5-6 is OK. – Commercial propane is not a clean (pure) gas and may not be dry (wonky pressures and may form frost inside the Evap. blocking it) Use a big molecular sieve dryer. – Mount that condenser fan back 1″-2″ in an enclosed shroud to get even air flow (or use the fan and shroud designed for the condenser) – Source: A career designing oddball thermal things for industry/military. I’ll be following this.
This is the best article I’ve seen on the subject, and I’ve watched many. I had to make a coaxial tube heat exchanger a number of year ago… On straightening tubing: Grab one end with a vise, grab the other end tightly in a drill chuck, pull HARD and turn the drill a few revolutions until the tubing is straight. Don’t overtwist the tube. Cut off the mangled ends. Annealing the tubing should not be necessary. Putting one tube inside another is quite easy when both are straightened. I learned this method from an electrician who used it to straighten solid copper wire. 🙂
at around 15:00, you should pull a vacuum on the system before filling and also add a valve at the end of your fill line. Let propane out to evacuate any air in the line, then connect and fill the system. I’m not sure how much it will impact your performance but it should avoid ice crystals forming inside the loop.
Usually r600a(isobutane) not r600(n butane) is used in residential/small commercial fridges. MO and I think AB oil dissolved in r290 along with POE. R134a sometimes has PAG in automotive. Different refrigerants are compatible with different oils. Just make sure if you are getting to super cold temperatures that you aren’t flooding the compressor with liquid refrigerant otherwise it can damage the compressor since liquid is generally incompressible and it will remove the oil from the compressor Great article!
I really appreciate this whole deep dive into esoteric cooling technologies and seeing how you’re going about modifying stuff. I’m a big proponent of DIYing glycol chillers for homebrewing and I usually just take a whole AC unit and bend it for my purposes. I’ve been thinking about ways to get creative with using liquid cooling to eliminate the fan noise, or… oh shit I just realized that fridge hot coils are passive! That’s a huge benefit for doing some DIYing on what I’m planning…
Nice, keep great work going, this brings fond memories of my DIY propane and R404-system builds for computer CPU/GPU cooling. Just few questions – why not use standard commercial plate HX and to save on work time and improve efficiency? Also you’ll need oil separator and bypass path for second stage to avoid freezing oil and overheating compressor. -6C without insulation sounds like not enough cooling power. Efficiency of cascaded system is not great, so it’s always good to have some cooling power headroom.
I’ve looked at making a cascade cryocooler like this before. What turned me away from it was the high amount of gaseous storage space for the ethylene, methane, and nitrogen loops. Propane is nice because it is liquid at room temperature and moderate pressure. But ethylene doesn’t have a liquid phase below 8C, methane below -80C, and nitrogen below -145C. So to store it at room temperature, these have to be a gas, meaning terribly low density. Not impossible, just a pain to deal with.
Interesting to see someone now days fumbling through this! Long ago in the 1960’s I did my fumblings and built a cascade air liquifier, first stage using a 7 1/2 HP Copeland compressor with 3 pounds of R13-B1 refrigerant. The second stage used a 4 HP carbon dioxide compressor with R14 refrigerant. Both compressors had to be water cooled. The unit would liquefy about a liter of liquid air every two hours. I’m not sure how you will get usable amounts of liquid air with such small compressors and without water cooling them. For your first stage, use an open frame automotive compressor so you can use water cooling on the head. For your second stage, use a SCUBA compressor. These have an open compressor so you can water cool the second or third stage head. (SCUBA compressors are 2 or 3 stage)
Plumbers putty/silicone for threaded refrigeration lines? No. Use either leak lock or blue monster Teflon. Leak lock is meant for threaded refrigeration joints it comes in a blue squeeze tube. Also, when using Teflon tape you must put the tape on the same direction as the threads. If you go the other way the threads will push the tape right off the joint when tightening
I scrap HVAC units for some of my jobs and have hundreds units from split systems, package units, mini splits, window units, I separate all parts and am waiting for a high price on copper to sell. If you need anything, I have literally anything HVAC. If you pay shipping, I’ll give you anything you want.
Many years ago my 87 Grand Marquis developed a refrigeration leak ( R-12 ). After three expensive trips to three different A.C. “Specialists” it still required Monthly recharges of (Then Very Expensive) R-12. I built my own set of recharge lines and began using very cheap Propane. The car NEVER was parked inside a closed space and it never leaked inside the car. Worked like a charm. The leak was somewhere under the hood and so small that there was no danger of explosion.
You did a lot of research for this project. Thank you for mentioning that you evacuated your system, that was stressing me out, lol. One thing I would like to point out, you should measure the suction line temp and compare it to your saturation temperature. You want to make sure that you have at least a couple of degrees higher (a residential AC with a fixed metering device would be around 10 to 18 degrees or so depending on load) to make sure you’re not sucking liquid refrigerant into the compressor. Compressors don’t like that much. Fun project.
This was like when I hear people speak another language and every now an then I hear one English word. Now I’m looking at the fridge like it’s gonna steal some of my beer and make up a reason ( that I’ll believe ) why it “evaporated ” I’m usually scared of people that speak more that a few syllables, why the hell I thought this would be a good article after a night out I don’t know ( it was entertaining) can’t wait to get back to my job as a bureaucrat
Excellent! I’m running a similar project and the difficulty is really the tuning of the system. Therefore why have you disqualify so quickly needle valve? It takes a really long time to tune capillarity tube. One of the only DIY LN2 successful proof of concept I found on YouTube used a needle valve! It was a JT system loaded with 300 bar of N2 and he explained he choosed needle valve because he was afraid to clog capillary tube! Would love to hear you thoughts about that 😊
Wow, I wanted to do this exact project and you saved me a bunch of money with trial and error 😅. Just one thing on the test water, there may be a stationary boundary layer forming on the surface of the tube wall that you’re not accounting for and which causes additional insulation. It would form almost instantly. This is why continuous freeze crystallisers use scrapers on the tubes. Edit: ..hence, even more reason for a lower than expected COP
It’s 4:13 am. I just woke up from a crazy dream with sleep paralysis where I was trying to save my dead pet from the evils of pet sitters and going on a trip and coming home and leaving my luggage on a bus and almost forgetting it. The worst part was the pet was almost dead and i had to climb a 99 stair tower where I apparently lived, to comfort it where all of a sudden a blue light came down and blasted him into the sky. I literally said what the F*** and then tried waking up but couldn’t move my body, Thought I’d share 😂
this is exactly how they process electric inhibiting oil for power transformers. 2 stage vacuum pump, close to near perfect vacuum, pumps, heaters, and a chamber with screens it slowly flows down. you generally want less than 10ppm water, otherwise it slowly starts to ruin the insulation. when transformers leak, they aspirate atmosphere which has water (usually have a bottle of dry nitrogen feeding 1 or 3 psi to prevent this
As a Hvac, I myself. perusal all the research you did to make this little unit work. And your calculations and Matthew used to come up with ballpark figures. I got you very close.. To dial it in there was just one formula you were missing. Because it was a cap tube system using superHeat to get the charge exactly correct. But with your system airflow is King.. also knowing the correct airflow over evaporator and condenser. Too much airflow for the BTUs to be displaced in the air passes so fast over the fence it actually does less work.. Too little airflow and efficiency drops way down. If the airflow is wrong over the Evaporator or the condenser . When you attempt to take your superheat measurements, they will be wrong.. you will get a measurement, but it will be based off the wrong airflow over the condenser or evaporator that messes up the formula for coming up to the right charge for the desired effect. But even having wrong airflow in wrong charge, you still keep playing come up with some sort of result that actually works . Compressor might have to work harder the system Majus consume more power in ratio to the amount of work. It’s actually doing.. Excellent article very impressed .
Thanks for sharing this project. I’m building a monoblock air to water heat pump to heat domestic water and water for hydronic in floor heating. The heat pump evaporator and condensor are outside so the R290 refrigerant is not a “fire” hazard.The danger of propane in a refrigeration system is exaggerated. It’s a hermetically sealed system. Even if it were to leak off over time, the leak would most likely be undetectable. If you are concerned about flammability you should remove the natural gas line from your house. You remove the air from a new system (mostly N2) because it’s non-condensable at the temperatures and pressures of the R290 system. Obviously it also contains O2, and could form an explosive mixture with propane but is also non-condensable. It’s usually a good idea to purge with pure N2 and then pull and hold vaccum before introducing any refrigerant.
I have no problem with you using propane in an engineering test-mule. But these refrigerants are explosive and the government has mandated their use in refrigerators over global warming concerns, and now people’s fridges are springing evaporator leaks which are igniting (apparently on the switch contacts for the ice makers) and exploding with the force of a about a stick and a half of dynamite. It’s an awful idea, and r-134a shouldn’t have been banned until a PATENT FREE replacement was available.
You got the relation between drive power and compression ratio wrong. Rather than compression ratio, mass flow is proportional to the drive power. If the suction pressure increases the drive power increases since the mass flow is increasing. This is why air conditioning compressors have a much stronger motor than a freezer compressor for the same swept volume. If you would use a freezer compressor for air conditioning you will severely overload the drive motor. The other way around it won`t be as efficient as it can be but it will work. If you want a very versatile expansion valve get a stepper motor expansion valve, they have unipolar motors and can be driven very easily. The can be salvaged from inverter mini split units or bought from aliexpress for cheap(search for electronic expansion valve). A Arduino can do the superheat control no problem.
18:40 superheat! superheat is important for compressor life. its a necessary evil. high superheat, indicates not enough refrigerant, and with no superheat you will flood the compressor with liquid refrigerant. the refrigerant vapour cools the windings in the compressor, so not enough refrigerant (high superheat) will damage the compressor and it will get crazy hot your suction line “should” be sweating all the way back to the compressor. this generally indicates you have adequate refrigerant for compressor cooling.
Please buat project menggunakan metode air asin,, di Indonesia ada yang membuat tapi saya belum dapat pejelasan secara ilmiah. Project yang saya maksud adalah membuat frezer box tapi menggunakan metode air asin, yang dimana evaporator di rendam dalam air asin yang bersikulasi . Air akan mencapai titik dingin ±-30 tapi air asin tersebut tidak membeku, metode ini bagus untuk membuat blok Ice for fish di pasar . Thanks before
I was perusal and wondered did you pull a vacuum on the system to remove the air? I didn’t see that part but as an automotive technician i know that if you don’t remove air it takes up valuable real estate that the freon needs. Filling a system with freon without removing the air “works” but removing it all then filling with freon only into a vacuumed out space is better for the system. I’m trying to make something and stumbled on this which was super helpful. I’m also in FL maybe we can chat I have some questions. Thanks
I did mine with a dual compressor setup… I completely winged it out of boredom but it works. First stage chills it and the second chills it further allowing it to form LOX. I just feed either pure tanked oxygen or use regular air ran through zeolite to “scrub” it. Not sure how pure it is but it’s highly energetic. Mixed with kerosene and it burns amazing
1:39 First vacuum cannot exist inside an expanding universe. What is pushing the expansion? Only pressure gradients between spaces that are divided by a solid material can exhibit what is referred to as vacuum. Secondly, Newtonian laws of force and motion when applied to the angular velocity of a rotating spherical body, when crossed by an implied gravitational force that pulls toward the center mass of the body produces a force vector graph that shows angular velocity at a 90* right angle to gravity unopposed at the poles that changes incrementally at each latitude from 90* unopposed to directly opposed at the equator of the spherical body. The only place where both forces could find balance. Newtonian laws of force and motion predict that if Earth were a spinning sphere with gravity pulling towards its center of mass all unrestricted water on its surface would necessarily have to follow the vector angles produced to the equator and then upward to the point where gravity’s fixed and angular velocities increasing forces were equal, but since angular velocity increases with radius it will overtake gravity at some point and propel the water out in a disk and off of the Earth. Thank you.
Love all your articles, especially the cloud chamber. I was curious if you could assist me. You want something could but if I wanted to hear water instead with propane how would one accomplish that? Of course water heater exchanger for the condenser coil but how do i find the math for his to heat it and what size device is needed. I suppose starting with old AC units is a good first start.
Worked in a cryogenic shop for a number of years. On the low temp side, the dryer was the largest source of water contamination in the system. This can be solved by chilling a second dryer, equipped with isolation valves and a bypass valve, to a low temperature. Once the system has run for a while, all excess the moisture will be in the chilled dryer. The isolation valves closed, the hypass opened and chilled dryer can then be removed (while still cold) from the circuit and you will have a very dry system. Having said all this, the above may be overkill for what you are trying to do.
with a stirling engine you can go down to minus 200°c, and you don’t need to add refrigerant gases or liquids, they operate on ambient air! go see the work of the philipps company! with a stirling engine if you turn in one direction you can go down to minus 200°c, and if you turn in the other direction you can make it a heat pump and go up to 800°c
Freon is not R134a by definition. Freon is a brand name from dupont that made the first R12 and R22 or Freon12 and Freon22. Its like saying a car is Mercedes, a not the other way around. 😅 R134a is the replacement to R22. (Used for Cooling) R404A is the replacement to R12. (Used for Freezing) R32 replaced R410A (Used for heat pumps) And both R134a and R404A are being fased out due to enviromental protection. R449a replaces R134a. R452A replaces R404a On cars a lot of new airconditioners is seen with this “semi-flamable” refrigiant: YZ1234 and some like it. Thats crazy stuff… And then theres the “natural refrigiants”: R290, R600 and R744. (Propane, isobutane and Co2) these are seen more and more due to their low-toxicity to the enviroment.
I second the other comments around measuring superheat and sub cooling. That’s the typical way one measures the appropriate charge level in a system. Basically the sub cooling is the amount by which the refrigeration lowers the temperature of the condensed refrigerant below the the condensation temp. And the superheat is the amount above the evaporation point for the low pressure side the system heats the gas. The advantage of a thermostatic expansion valve is that it controls the superheat to a narrow range for a given refrigerant, assuming you can find one for propane. I believe there are also electrically controlled valves used in modern automotive systems. I think in your case though you want absolute minimum temperature so you want a lower superheat and maximum subcooling on the hot side. You should also flow the refrigerant in the exchanger in the opposite direction to ensure the end of the flow of the secondary stage is the minimum temp.
I am NOT trying to be a smart ass, honestly. Why not just empty the 134a from the window shaker AC unit, and then fill the system with propane and when done, test the system? Last summer I fixed my first Automotive AC in my truck, then I attacked 1 of my Duo-therm rooftop units on my 1993 Unihome Grand Villa 40ft. Screaming Jimmy motor-home. I am the proverbial newby of AC. I was unable to complete either RV park repair without tons of reading to understand the basics of AC, and close to fifty hours of University of YouTube. Before fixing either I purchased a 5000btu shaker at Walmart-$150CAD all taxes in: Back-up unit.
Freon as it turns out has been used for R12, R22, AND R134A. Freon was originally and is still best known as R12. R134A is typically just called by its number. I came with pitchforks to say you were wrong, but yiu weren’t. However putting it there against R134A is misleading at best. Sewing the seeds of confusion unnecessarily.
Stop calling refrigerant “Freon”. Freon is a manufacturer not not a substance. That’s like calling all electrolyte waters, Gatorade. R-134a is 1,1,1,2-Tetrafluoroethane, a hydrofluorocarbon gas. Freon is a generic manufacturer, extremely common misconception. Even before the use of 134, r12 and r22 were called “freon” because that’s who made the refrigerant.
Very cool. I think an externally equalized TXV is critical to the longevity of this project though. You figure, we’re after the phase change and only the phase change for cooling, then a small superheat to prevent flooding. Too little returning, compressor can’t cool and discharge gets above 225 degrees. Too much returning, it could contain liquid and wash oil from the bearings. In fact on a capillary tube system, in HVAC we charge refrigerant based on one single metric- suction superheat at design conditions. I think you need another pressure gauge at the inlet of the evaporator. Your gauging saturation at the very end of the evaporator run, after a significant frictional loss. What iif further up the pressure doesn’t equal 0, but 20? That’s a much higher temperature pressure relationship and from that angle heat exchange might be ok. Household propane contains additives for smell btw, not sure if that plays nice with the polyolester oil. It may also coat and insulate the copper. This could then become exacerbated if oil begins to migrate because of the low load, collecting and worsening the problem. It will also have at least some effect on the condensing pressure, maybe small but maybe not. This will be a cascade system so the load may keep the lines clean. Typically evaporator approach (or the delta between evaporator saturation and fluid leaving the secondary loop) would be no more then 10 to 20, though on big chillers it’s 0-2. In HVAC we size air cooled condensers to run 20 over ambient with the expectation that the last 20% containing pure liquid.
@Hyperspace Pirate: Hello, I like your 5,000 Volt Power Supply apparatus. Can you build a few pieces of just the HV transformer for me. I will pay by the piece and for the postage (to US location). Let me know how much you want to charge per piece. I can pay you through Paypal (or other if you like). Thanks!
For cascade cooling and with ethylene on stage 2, you will need an TXV for stage 1, do you intend to have a stage 3 with methane?. I would go with a 12000BTU R22 compresor for stage 1, and 6000BTU stage 2, and 3. And us cascade cooling for each stage at the output of compressor (first with air heat exchanger and than cascade with previous stage)
I was thonking….. 1. Why didnt you just use a scroll compressor .. they are said to be the most efficient for any application. and sometimes come with variable speed controls. They also have higher compression and ability to cycle gas with little power consumption. 2. You could have used the A/C unit as-it-is… instead of pulling out all parts you could just replace the evaporator.. with your custom one… 3. Dont Die….
Ok where to start…First if thats supposed to be butane regular butane just an off the shelf can used to fill up lighters will not work as a refrigerant. I know pretty much everybody here knows all these things but one more point there is no way in hell that itty bitty $1 motor would compress any gas to work as a refrigerant.
Hey, that’s a really cool article. I just got another question and I’m happy about everybody helping out. I want to replace the R134a in my car with R290 (propane) due to the lower boiling point. Background story: That car originally came from a nothern climate but I moved way south and in the summer it’s very very hot and very humid and the AC that originally came with that car just doesn’t keep up with the excess amount of water that it needs to remove from the incoming air and also the temperature on the vents is far from comfortable. The car wasn’t sold where I moved so there’s no stronger version and I don’t want to get rid of the car either as my assignment here is for 3 years and then I’ll take it back home. Long story short Intention: As the boiling point of R290 is lower than of R134a my idea is to thereby lower the evaporator temperature and improve the efficiency of my AC. I don’t worry about freeze protection on my AC as I have the engineering software on that car and I can code different temperature and also different pressure limits for the car to accept. That wouldn’t be the problem for me. I just lack the knowledge about ac systems and refrigiration cycles. Currently my evaporator temperature is at 18-21°C and there’s a rather strong stream of condensate dripping from underneath. Yes the system is charged correctly. The problem is a temperature of close to 50°C and a dew point of over 30°C . Is there anything I can do without major mechanical changes? Another idea would be a different crank pulley for more rpm/belt speed at the ac compressor.
Hi i love your work and I have a suggestion, maybe you should try to use an arduino to manage the needle valve. If you use a geared steppemotor like the “28BYJ-48” slow but precise and loads of torque for the application, I think you can gauge the pressure before the needle valve and after the needle valve, feed the data into an arduino PID loop and based on that regulate the needle valve. you can even add a 220V relay for the compressor, temperature probes, and a display.
12:38 if you reverse the flow in one flow path. This will be a counter-flow heat exchanger, which is much more efficient. With equal mass flow rates, equal CPs, no phase change, and a sufficiently large counterflow hear exchange would have your stage 2 condenser outlet temperature equal to your stage 1 evaporator inlet temperature. (Instead of the stage 1 evaporator outlet temperature with parallel flow). Since there’s a phase change and pressure drop, things are harder to predict, so some experimentation may be best. 27:58 this diagram shows counterflow, which is “correct”
Wait, has anyone jumpped on you for how Freon is a trademark that covers multiple refrigerants? several of them predate R-134a & are banned. When I ran auto parts delivery in the late 2000s if someone ordered refrigerant they got R-134a, and if they ordered Freon they got a couple “are you sure?”s and a bottle of R-12. that only happened once, still not sure it was legal.
just some quick notes from a guy who is almost finished with hvac school and tried tried this too : – Make sure your superheat is not to low or too high, low superheat will ruin vales because the compressor tries to compress liquid… happent to me… – too high superheat will result in a high discharge tempeture, also the oil will degrade and the motor will get damaged however Rotary compressor run pretty hot, still try to stay below 80C – Superheat is just how mutch you heated the Vapor beyond the boiling point lower = better COP = higher safer for the compressor (not too high tho) – if you start to use higher power compressors try to use a TXV for the first stage you can find a cheap danfoss T2 Valve for probably 30 bucks r22 valves or 407c work pretty good with propane dont forget the orfice tho, howover the charge needed is mutch higher then normaly, also you need a Collector or a “reciever” to always have the correct amount of refigerant in there they can regulate betwin 10C and -40C just fine – Becarful when unbrazing the pipes propane or Etheline will boil out of the oil and Cach fire Please keep going with the series i cant wait to see how you make ethylene, Gretts from the EU!
I have about 3 months before I (hopefully) leave my country for a new bachelor in Itally, and I was looking for a fun project like this while I still have access to cheap material and tools at home country and this looks like real fun 🥲 and as I mentioned earlier, this stuff can be found super cheap here! like I found a 3/4 hp compressor for around 10 USD 😁😁
You didn’t mention it, so I thought I would, but wet insulation is bad. Unless your aluminum foil is sealed (which, no.) every time you run it, you’re condensing water in the insulation filled part. This is why HVAC insulation is closed cell foam: closed cell foam is inherently sealed (kinda) so you don’t have to deal with the very bad insulating properties of liquid water. Short story shorter: use pipe foam on the whole evaporator or half of it is just wasting energy.
Great work, but a couple of things: compressors are designed for different evaporator temperatures. Using an AC compressor (high temperature ~4°C) for an evaporator that is ~40°C is not very efficient. You should use a low temp or extra low temp compressor. The other major issue is superheated and subcooling considerations. The more subcooling in the condenser, the less efficient. The more superheat in the evaporator the less efficient. We need to maintain some of both, but it is more efficient to do it with a heat exchanger between the liquid line and suction line.
Using a dryer to remove the smell of propane? Hell no, this thing will live outside! Lol Also its important to note he probably broke the law by venting those R401a window AC units to build this. Lol dont try this at home. Lastly why doesnt he use a heater to remove the ice???? You know like they do in store freezer units or properly spaced fins on the evap OR a timer for defrost cycling?? Lol Seems a bit odd sense he’s already using plently of power to build this thing…
It looks like you have too much refrigerant. The frost line should go no further than half way past the suction receiver, that’s a big part of your cop problem. That and you are using capillary tubes instead of thermal expansion valves. If you want to get low temperatures then you need to use high pressure gasses. You could also try an auto cascade. If you need any advice I have studied thermodynamic engineering and worked on ultra low temperature systems using things like liquid helium in the low stage, I usually used R508B in my designs. Don’t forget you need an oil separator and expansion tank on low temperature if you don’t want it to die.
Many years ago, befor I had internet, I was thinking of setting up an ac for my house useing a 500 or 1000 pound propane tank. All I really knew was what I knew about the properties of propane from my chemistry books and the basic ac works. For cooling the returning hot gas, was thinking of a putting unit into a water tank and having a pump run water over a tower or waterfalls. Water is 300% better at removing heat than air and water would also use evaperative cooling, used keep replacing loss. The large propane tank also has alot of surface to lose heat. Rather than propane going into to centrol air system, perhaps move a cooled alcohol into the house system. It was something that I thought about, but would unlike do, but if I watch this over a few time…?
You can buy liquid phase heat exchangers meant for AC applications See the Adam Savage refrigerated suit one day build article for an example of this. Now granted, that one is really small, but the bigger ones aren’t that expensive either. In my opinion, that is the easiest way of going about cascading refrigerant loops
I wonder if this guy realizes that, starting around 1:23, he completely debunked the ball urf / outer space meme. I mean, surely he’s not going to sit there and explain how in “outer space” “the water would cool down, freeze, then continue boiling and cool through sublimation” and then in the same breath claim that earth is a ball, where a positive pressure atmosphere butts up against the near-perfect vacuum of ‘outer space’ and somehow all it takes is the mythical force of ‘gravity’ to prevent water and other gasses from freezing, boiling, and sublimating. These scientism acolytes and their silly religion. lol
I did refrig, for 30 years, with the suction line frosting back to the comp, you are flooding refrig, back to the compressor, the valves can’t handle to much of that, the liquid going in to the compressor will pull oil out of the comp. usually causing a comp failure, how to charge a cap tube system, add refrig, till you get frost back to the comp, and then start removing a little at a time, you will see the frost line move back to the evaporater, that is the correct charge, but you are not removing the cold from the evap…. it all has to work together… make sense…. I use to work on cascade systems for hospitals…. they would run -30F to minus 50F for sterilizing…
at 12:35 you showed a heat exchanger but your flow is backwards 2 flows in opposite directions create an extreme gradient with high efficiency theoretically 100% heat transfer but 2 flows in the same direction mix temperatures with a maximum efficiency of 50% and a shallower gradient that must be much longer to achieve similar speed