Now this is my favourite kind of napkin maths! Thank you so much for describing this - this is unbelievable useful. At least now we can understand a ballpark upper range of how long it might take under an ideal setup. So really, even with a couple of 300 watt power supplies, and a number of Peltier modules with optimal cooling, we're still looking at a period of time longer than just chucking it in the freezer for 10 mins. I'm glad I didn't continue eking out minor improvements in efficiency! Really appreciate your help here ❤️

Considering he was running those poor cells as hard as he could, and that he didn't provide any insulation, 20% seems a fairly optimistic estimate... I would have guessed 5%, or even less

@@Beregorn88 I'm not an expert on peltier elements so I just looked up typical efficiencies, and 20% seemed to be in the middle of what people were saying, so I went with that.

@@JamiesBrickJams Cool project! I never considered a lego fan ;) Several more forms of thermal loss: Thermal pads are convenient and clean, but nowhere near as good at heat transfer (especially to the ceramic of a peltier module) as thermal grease. You could likely drop the hot side's internal temp substantially with better TIM (Thermal interface material) which would increase your efficiency by an order of magnitude. Even junk thermal grease is typically on par or better than gap pads. Your metal cup is acting as a heat-sink heating the water using the air. It might be that those water blocks just aren't great at transferring heat. Thus, the cold side may be getting far colder than the water. Peltiers are most efficient when the temp difference is minimal so stacking two water blocks on one peltier then a single block on a second peltier may net you some more performance. (so, pump -> top block 1 -> bottom block 1 -> block 2 -> cup. Here where both "block 1"s are on one TEC and block 2's are on a second. Peltiers can actually be quite efficient, but typically at low power at small temp differentials. I have achieved 38%+ with a good test setup and name brand modules. Also, using cheap modules I have gotten to -30+ degrees F. You can use detect radiation and cosmic rays by building a "cloud chamber" with this method.

@@nathanielhuggins9254 True, those thermal pads are pretty useless. Also, could be wrong, but I think they depend on getting hot, at first, to mould themselves around the CPU surface they're usually supposed to be cooling. If you're dealing just with flat surfaces, much better to use thermal paste as you mention. And maybe spring pressure or some elaborate Lego mechanism to keep them firmly pressed onto the heat sink. CPUs use the sort of springs you could do the suspension on a monster truck with, they have power!

Add one of those bricks with holes into the bowl,it will soak up the water and give it more surface area to evaporat

​@@yixuan7043just add bio balls, they add a ton of surface area

Ha I actually kind of like this idea. I'd be interested to know how effective this would be. It'd certainly draw way less power over time

That's what I figured, I did try to wait about 5 minutes to drop the temp, but it seems like the block just refused to get low into the minus figures. I've a suspicion that the block actually heats up the cold side too much, causing it to run way less efficiently. It seems to drop the temp difference it's able to create. But in general I'm sure you're right that a slower trickle passed through it should work better! Or perhaps multiple trips through the system

​@@JamiesBrickJams I have read the comment with the calculations. But my idea for improvements would be a bigger peltier and cooling block, and 2 of those peltiers so you can sandwich the cooling block between them. Still, for proper cooling you need lots of power. Same as with heating. I gues you should look into constructing of a Lego heat pump 😅

Ausome

@@captainevenslower4400 That was my thought too. Sandwich the cooling block and then insulate the exposed sides.

I'm pretty sure you're absolutely correct here, and thanks for confirming what I was suspecting. These things are so inefficient and I'm amazed to see how many silly videos seem to suggest you can make reasonable air conditioners and other ridiculous claims using these. And water seems to be particularly challenging to draw heat from too. Thanks for your comment here 👌

I came here to say the same thing.

@@JamiesBrickJams Pin Me!

Ah that's really interesting, thanks for your comment! I do have a lot of these modules, so perhaps running 6 of them at half power might work? Might have to invest in a few of those larger water blocks and attach multiple units to it

@@JamiesBrickJams And a few other things, you don't need that beefy water blocks nor your silicon pads. Both of them increasing temperature mass and the time, in the end. Also, if you want to squeeze as much COP as you technically can - you should isolate all your cold side from the ambient, and definitely start to use double-sided glass, cuz you should keep the already cooled liquid as far as you can from ambient temperatures. And definitely, pouring more energy into peltier modules isn't a great idea too, because from their poor efficiency, let's say 20%, remaining 80% are gonna be heat, so more power you're make them chug - more heat they gonna release, and heat losses doesn't give a flying fk where's your cold side. Because of that, peltier modules is really useful only in car can chillers, because they're too weak to actually cool them, but their power output is viable to keep them at the same temperature (and with insulation of the box as well...)

Aw thanks, really enjoy comments like yours 😊 Will try to keep the ideas fresh!

"Lego" not "Legos"! The plural of Lego is Lego! Ask the Danes.

exactly what i was thinking

Finally someone thought about thermal paste

nah, thermal paste is overkill for how little heat is being moved.

@@ameteuraspirant I think 40 watts of heat on a small piece of ceramic will get hot. That's like a CPU working at 25% capacity

That'd be quicker than the Peltier device for sure! But I tested putting a can in still water (and not moving the can), and it takes a fair bit longer. Also when the water is sitting in something for a while, the water heats up rapidly, so the drink can't get as cold. I'd imagine your best alternative is just chucking your drink bottle into a bucket of ice or ice water. But I enjoy overengineering things 😁

Not a bad idea, I could give that a try!

@@JamiesBrickJams and as i now looking at the device i would also recommend to use something like a CPU cooler(like that one in the beginning of the video) because they have heat pipes wich spread the heat more efficiently,so the whole surface area is used for cooling and not just a small point. For your application i think you could scavange the heat sink from a old GPU like the gtx670 because they are really flat and have a large surface area so it will fit in your current design without major changes

@@JamiesBrickJams another idea is to go for water cooling but for that you will need a radiator wich further complicates the device. I think just dumping the hot water in a large bowl filled with water could also work since you are only running the peltier at 17w

Please use thermal paste like arctic silver 5 or Thermal Grizzly Kryonaut, it pains me to see the thermal pads instead of pasteeee @@JamiesBrickJams

Oh that's so cool, I'll see if I can find something like that for inspiration. I guess an ice bucket would work well if you can pump it over the can

Thanks a lot man, love your videos too!

"We were sucking and blowing at the same time" 💀

"Both sucking and blowing at the same time"

Ah that's interesting, I could certainly give it a try with thermal paste and a larger block. Cheers for the suggestion 👌

That's cool, I wondered if those little fridges were just Peltier modules in them. And you're probably right, I'd imagine a cooling bag is much more effective. Certainly quicker

Thanks for joining, and I appreciate your comment. I'll continue to keep my voice down for future vids 😉

I guess I could also put ice in or around the drink cup too 😅

Woah you can use toothpaste?? Haha that might actually be worth a try

That's a good idea - I actually did try different speeds, allowing 10 minutes to slowly pump the fluid, and it did bring the temp down by 4 degrees. But still not enough for it to be worthwhile. Probably quicker to just put it in the freezer 😅

Ooooh that's a cool idea, I like it! 😁 That sounds pretty straighforward

Hmmmm that might not be a bad idea, cheers for the idea. I see no reason why I couldn't run the cooling beneath the module and extract heat from above. As someone else noted, it might even be worth using water to cool the hot side!

@@JamiesBrickJams oh and water in Ireland isn't free, to quote Uisce Éireann, aka Irish Water, "it's a precious resource that we're all responsible for". Although, given the number of mains repair work jobs logged on their website, Irish Water is pissing it into the ground due to a complete lack of maintenance over the years, especially the years before the Irish government's failed attempted to privatise the national water supply, using their Garda thugs, in an attempt to introduce yet another stealth tax on its citizens. ✊🇮🇪✊ 🇮🇪✊ 🇮🇪

True, and that's one of the main reasons I don't want to waste water. Having lived in South Africa where it is a scarce resource, I really don't like the idea of being frivolous with it. But not having a number appear on a bill makes it feel sort of 'free' 😅

@@JamiesBrickJams Not to bitch too much, but the Irish Government is like do as we say, not as we do. You have that pillock Eamon Ryan telling all us plebs to walk, cycle, use public transport, or get small electric cars, while he drives around, alone, in a VW transporter. The level of hypocrisy just keeps getting higher and higher, like 100/10 high FFS

😂

A few folks have suggested this, so I'll definitely give that a go, cheers!

I'm only realising this properly now 😅 Someone did the maths, and there is an absurd amount of thermal mass to pull from a drink

and I guess you could have a light spray of mist -which improves everything

Ooooh I like that idea! So water cooling the hot side? Damn I should have tried using those water blocks on the opposite site too. Great idea, I'll give that a try for sure

That does seem like it would have been a good idea - cheers for the suggestion!

Thermal paste is definitely an option, I could try that 👌

Hmmmm I wonder if that works?

Ha I wish I could work on these more often, but life is always so busy 😅

Not a bad idea to perhaps keep the fluid running in loops until it's cool enough 👌

Haha it's certainly possible, but it'd likely be the world's most inefficient AC unit 😅 and would have an absolutely insane power draw for it to work

@@JamiesBrickJams Just need some wd-40 and it will lower the friction of lego, but yeah it will be a bit hard, considering the pressure necessary

That's not a bad idea!

That seems to be a common recommendation so looks like I'll have to give that a try, thanks!

Haha she's been a useful old thing. Does yours still get any action?

@@JamiesBrickJams only on special occasions

I've actually made a few of those in the past, but never made a video out of it. Cheers for the suggestion!

@@JamiesBrickJams how many pounds were they

Good lord 😂

yes

Yeah you're absolutely right here. I tried driving them at different voltages, and at a certain point, they create so much heat, they totally overwhelm the cooling capacity. I've been wondering if using those aluminium water blocks on the warm side might do a better job of drawing heat out, allowing that temp dif to grow? Might be worth a test, along with some thermal paste

@@JamiesBrickJams Using a cooling loop with the aluminum water blocks would be incredibly effective, but you're not going to be able to get the air pressure necessary to cool the typical radiator out of lego fan blades. Have you already tried pairing back down to using the 1 peltier, and also using some thermal putty (not thermal paste)? Thermal putty is way more effective in this case, since thermal putty doesn't require continual compression to perform it's best, but still neatly conforms to the surface like thermal paste (most thermal putties also have a lower minimum temperature than paste, so either way you'll at least want it for joining your cup to the peltier), and you can use putty to join the two individual heatsinks as 1 big heatsink without having to redesign the lego frame you already built. If you really want to go the direction of liquid cooling but also still lego, you could build your own diffusion cooling tower, since that wouldn't require air pressure, just air volume (which just requires a fast fan blade rather rather than a specifically shaped, rigid fan blade). You could even use lego to make a diffusion frame to hold layers of cloth between the fan and the water basin (this'd be your airating medium). Janky, a pain to clean, and you'd probably have to vinyl wrap the outside of the tower if you build it out of lego too, but it's the most fun, lego compatible solution I can think of.

Wow thanks for these suggestions, I really appreciate the thought and effort 😁 I've just ordered some thermal putty to use for future experiments. I quite like your idea of a Lego diffusion tower. I'll need to do a bit of research to fully understand how that'd work, but thanks for the coil suggestion!

I wish I could say that was intentional 😂

Hmmm I wonder if spinning in the freezer would help it cool faster? I guess in theory it might actually! Cool idea