DIY water block to suit Klondike K16 and Burnins 20 (Bitburner?)

[Defkin]

Water cooling block for multiple boards

I am going to make a single water cooling block to cool either 30 Burnin or 38 Klondike K16 boards.
The strategy is to keep it simple KISS and use off the shelf parts. This is not built yet so any suggestions welcome.

The preliminary plans and CAD drawings below is for a 10 x Burnin board water block (for 30 board size it will be 3 x the length)
 
BOM:
Aluminum rectangular tube 200mm x 50mm x 600mm x wall thickness 3mm
Aluminum flat bar (x2) 160mm x 560mm x 3mm
Aluminum flat bar (x2) 50mm x 200mm x 3mm
Aluminum weld in hose fitting (x2) TBA
Heat sink compound TBA
Heat transfer insulator TBA
Aluminum mesh 10-20mm mesh size.

Welding
End plates fully welded both ends of rectangular tube to make waterproof and then pressure tested - TIG weld.
Heat sink plates to be tack welded in place on both sides of rectangular tube - TIG weld

Heat sink materials
The plan is to put a heat sink compound between the pre-drilled and tapped heat sink plate and aluminum sq tube.
Heat transfer insulator material TIM between the plate and the boards. At this stage I have no idea what i am going to use and any suggestions would be welcome.

CAD files
I will post the CAD files when complete.

Notes:
This is a consolidation of discussions in threads here and here.
Mesh will be stuffed into the aluminum sq tube to increase surface area and create turbulence.

Concept drawing

Heat sink plate render - fit Burning board

Heat sink plate CAD

Aluminum tube render

End plate render

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[grabber]

Keep going, really interested

[wrenchmonkey]

You'll need to create turbulence within the water block. Some sort of baffles, or other system to disrupt the water from just taking the path of least resistance. Adding as much surface area as possible within the tubing, without overly restricting the waterflow will also increase efficiency.

[shapemaker]

You'll need to create turbulence within the water block. Some sort of baffles, or other system to disrupt the water from just taking the path of least resistance. Adding as much surface area as possible within the tubing, without overly restricting the waterflow will also increase efficiency.

From the OP:

Mesh will be stuffed into the aluminum sq tube to increase surface area and create turbulence.

Looks like that's been considered already.

[wrenchmonkey]

You'll need to create turbulence within the water block. Some sort of baffles, or other system to disrupt the water from just taking the path of least resistance. Adding as much surface area as possible within the tubing, without overly restricting the waterflow will also increase efficiency.

From the OP:

Mesh will be stuffed into the aluminum sq tube to increase surface area and create turbulence.

Looks like that's been considered already.

Derp. Not sure how I missed that. Thanks. 

[Defkin]

Some new renders and sketches


K16 Heat Sink Plate



Idea for turning end plates into part of a case.

[Bicknellski]

The design could be easily lengthened for the K16 to create a longer block right? Or would that be a problem pump wise and the distance travelling causing heating at the end of the water block?

Some have plans to use the heat sinks to help give rigidity to the boards when they are daisy chained together in the K16 / K64 Configuration.



]

[Defkin]

Power supply and distribution. Just an idea so far.....

I estimate I am going to be using about 1.2kw@12v so have been looking how to supply and distribute it.

My current plan is to get this 1500w power supply and make a power rail to run along the top of the water block.
I don't have much experience with PCB software so was hoping someone could help out with this. The idea is to sort of staple a heavy duty cable onto a pcb using link wire and soldering it to the tracks. The pcb would just be a repeating pattern totaling about 600mm long so you can snap it off at the required length. The stripped cable would be 'stapled' to pcb both top and bottom.

[Sophokles]

nice design, I like the idea.

what kind and size of fan/radiator are you planning to use for dissipation of 1,2kW?

[Defkin]

The design could be easily lengthened for the K16 to create a longer block right?

Some have plans to use the heat sinks to help give rigidity to the boards when they are daisy chained together.

Off the shelf here you can get the aluminum sq tube 200x50 in lengths of 6.5m
Cannot get flat bar that wide (that i could find) but you can cut sheet (was looking at nesting and getting it laser cut anyhow).

K16 is 100x100 so you could fit 2 across a 200m tube with no tolerances. So 2 mounted either side is 4 per 100mm. 6.5m length could in theory hold 260 boards. My concern here is 260x40w=10.4Kw can enough water flow through the block to cool that many boards?

I do not know how good the heat rejection on the tube will be yet but a am comfortable with my 38 x K16 on one block.

The K16 Modular Design is a 4x4 16 boards (400mm x 400mm no tolerances). You could stack two 200x50 water blocks one on top of each other?

[Bicknellski]

The design could be easily lengthened for the K16 to create a longer block right?

Some have plans to use the heat sinks to help give rigidity to the boards when they are daisy chained together.

Off the shelf here you can get the aluminum sq tube 200x50 in lengths of 6.5m
Cannot get flat bar that wide (that i could find) but you can cut sheet (was looking at nesting and getting it laser cut anyhow).

K16 is 100x100 so you could fit 2 across a 200m tube with no tolerances. So 2 mounted either side is 4 per 100mm. 6.5m length could in theory hold 260 boards. My concern here is 260x40w=10.4Kw can enough water flow through the block to cool that many boards?

I do not know how good the heat rejection on the tube will be yet but a am comfortable with my 38 x K16 on one block.

The K16 Modular Design is a 4x4 16 boards (400mm x 400mm no tolerances). You could stack two 200x50 water blocks one on top of each other?

Lots of different variables here...

Thing is those with larger orders of boards would like a modular system for water block I think... so if you can come up with a design that could do say a 4 x K16 that be better than an individual unit in terms of putting these units together. I will leave it there and see what you can think of and what is possible. Personally going with forced air but so many would be interested in water blocks even on single boards I think but not sure how much benefit you get for a single K16 as I think forced air can pretty much handle it given what we see with the original Avalon. You market I think would be farmers.

K64 is 200mm x 200mm that is the largest board I think BKKCoins said he would even bother with.  Typically most will get a K16 or 100mm x 100mm what I was drawing was 4 x K16 daisy chained in a linear format which is possible.  Heat sinks can be extruded to fairly large lengths and make the Klondike into a Bar... if you like

[Defkin]

nice design, I like the idea.

what kind and size of fan/radiator are you planning to use for dissipation of 1,2kW?

I have reconditioned radiator out of a V8 and as for the fan I have not decided yet. If I had a backyard I would hire a trenching machine and dig a 10mx10 square 1 meter deep and bury a couple of loops of PEX piping.

[yoyobob19]

i think after the asics have been mounted we should call the thing the bit saber

[Defkin]

I have an update on my project.

I have been looking at doing away with the welding and using ABS plastic caps and clips.

In the images below is what I intend to 3d print. There will be a 40x40 square tube running inside the block to supply water to the other side off the 200mmx50mm rectangular tube (water block) so hoses are connected at same end.
The 6mm flat bar will be held in place by the clip and a 16x16 channel either side clamped together with M8x110mm bolts, I figure 1 clamp set every 3rd PCB. Flat bar to be drilled and tapped and PCB secured by M4x10mm nylon screws.

[Ente]

We have similar designs on our tables, so I thought about hijacking contributing to the topic?

..quoted from the Klondike thread:

-collecting numbers in this post here-

1) Junction to chippackage 0.001K/W
2) Solder layer between chippackage and board 0.01K/w
3) Board with 25 vias 3.8K/W
4) Thermal paste between board and aluminum 2.5K/W

Watercooling:
5a) X mm aluminum
6a) Aluminum to water
--> I'll simplify this to "T_alu = T_water"
7a) Radiator with/without fan to air 0.25K/W


Aircooling:
5b) Heatsink with/without fan to air 0.5K/W


2w per chip
5x5mm for 2) and 3)
somewhat larger area for 5a) 6a) and 5b)



This tutorial was posted earlier, it has almost all answers already:
http://www.electronics-cooling.com/2004/08/thermal-vias-a-packaging-engineers-best-friend/

1) Silicon to chippackage: 0.001K/W

2) As shown on the thermal imaging here:
https://bitcointalk.org/index.php?topic=190731.msg2043405;topicseen#msg2043405
I calculate with a delta of 7K between chip and board (62°C and 55°C respectively).
This assumes the soldering and boardsetup is comparable between Avalon and Klondike.
--> Nah, 3.5K/W is waay too high. The tutorial says 0.008K/W, 0.01K/W seems more realistic here. We don't use the length of the board for heat transportation, but the thickness!

3) 5x5mm area with 5x5 grid of vias, each 0.3mm diameter.
Bottom layer is 1 oz. copper
electronics-cooling says 3.8K/W with a 5x5 grid of vias (at 2mm spacing though, ignored)

4) https://en.wikipedia.org/wiki/Thermal_grease says 0.5K/W @ 12.6cm², which calculates to 2.5K/W for our 5x5mm area.

5b) I randomly found a value of 0.3K/W for a CPU-cooler with a fan. Let's calculate with 0.5K/W for our non-sophisticated DIY solution.

7a) Found 0.21..0.35K/W for a 12cm radiator. The larger the radiator, the wore heat gettin' rid of. I'll use 0.25K/W here, although this value is pretty random - can be reduced at will with more/larger radiator.

..I'll calculate a bit with those values later.


Ente

I am an engineer with a background in aerodynamics/fluids and am capable of performing Heat/CFD simulations. Is there any way I can contribute to the heat sink/dissipation design. I can't promise anything but I can try if I had more understanding of what the goals/design are.

Awesome! :-)
Quick question about watercooling:
How about building a simple aluminum "box" from 5mm aluminum, no fins or similar, and screwing the K16s on that? We could use both sides of the cooler and it would be pretty easy to build.
I guess even with a low waterstream it should cool the board enough?
Cooling the water with a big radiator and a fan, outside, 35°C outside-temp worstcase.
With a few dozen watt per 100cm² this should be a piece of cake for the actual cooler?

Your gut-feeling is enough for me now :-)
(Else we might migrate to the K16 DIY thread)

Ente

So the water is running through the inside of the "box"? The largest problem with any setup like this is making sure that there is conduction between the chips and aluminum to the water. There will be no convective cooling in this setup (such as blowing air over the chip without any heat-sink). I also wouldn't consider setting something like this up along with a radiator and fan as "easy" unless you already have this stuff around. But I would have to see a design to make sure I understand what you are talking about.

Edit: OK, I've seen a design similar to what you are talking about. So, these current designs are placing heatsinks/aluminum housing on the underside of the board... how is heat being conducted from the thermal pad on the chip, through the board, and to the heatsink/aluminum? If it is just silicon then there may be a conduction/heat-transfer issue. It seems that this QFN design isn't really made for external heat dissipation.

About silicon-to-heatsink: I collected some numbers here:
https://bitcointalk.org/index.php?topic=190731.msg2295823;topicseen#msg2295823
My conclusion is we'll be in the 10 to 15 degree ballpark, difference between junction and coolingmedium.

Yes, normally we want some turbulence in the water, for quick mixing of the fresh, cold water with the heatsink and warmer water.
In our setup, where we ultimately cool the water with room-temp air, I am sure there will be no thermal gradient over the whole setup at all! I.e. the water going into the heatsink and the water coming out will be the same temperature, in equilibrium. And with such low power over such a high area - I am sure such a minimalistic waterblock is enough. Having a potent enough radiator, with a strong enough fan, is a totally different story though ;-)

So. Who can tell me anything about running a bit of water over flat aluminum, which is heated with <50w per 100cm²?

Ente

So, my goal is to have an even easier build. Ideally from stock material, with "household machinery" needed only.

Any hints?

Ente

[tom_o]

Yep, mixing aluminium and copper in the same loop is a no no with plain water, the de-electric effect will turn it into a battery and ruin the blocks and radiators. Most radiators are made of copper, they're much thinner too!



As for getting more surface area but mostly much more turbulence you could use some of this rolled up and put down the tubes, aluminium mesh.

[O_Shovah]

I also design water cooling systems.
and will add my 2 satoshi and constructions in time somewhere at the end of july.

Using anodised aluminium never brought up problems
in my cooling systems.

[chanberg]

Please use regular G1/4 threads for the waterblock, that way i can customize my setup with the already abundant fittings market!~

[cardedon]

Why you don't use a furnace for make this kind of items?
So you don't need to weld and you can also use recycled alluminium

[iANDROID]

Watching!