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Water Block Design / Construction Building your own block? Need info on designing one? Heres where to do it

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Unread 01-27-2003, 12:40 PM   #376
Roscal
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Pay attention to what I said BB2K..

I gave you the hottest T° in copper so point in the middle of the die BUT T° distribution isn't equal on the die , it's "concentric" so a T° average (less than higest T°) must be calculated on whole die surface (as BillA die it's not T° constant on the die, in reality it's different because of components into the die, L2 heat more than other die units so T° distribution is "random").
This average could change between 2 blocks... The 4° are not real because it's an savage extrapolation (?) to 70W to 100W I done in my mind (not the real geometry too)

Take care about T° because all is "perfect" in a simulation (no TIM, perfect contact, etc..), depends on my reference too...It's a prediction !!
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Unread 01-27-2003, 12:58 PM   #377
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Thank you, Roscal!

I understand that the temperature distribution (or heat source) from the die is not "even", although it is simulated to be that way.

Not to worry, I took your "4 deg C" estimate as a rough estimate. I am assuming that the process that you used to make the estimate, is the same as for WhiteWater, so the results should be "somewhat accurate".

I also understand that this is a simulation, and that there are a number of variables that are not taken into account. As you pointed out yourself, my channels are perfectly square cut, when really, there will be a slight curve, from the wear on the endmill. Also, the center cross is not square cut, there's a very small curve, also as a result of using an endmill.


All: yesterday, I started to work on the geometric calculations of the inlet opening, in order to determine the proper/optimal size of the nozzle. Due to unavoidable circumstances, I won't be able to complete those calculations this week, and next weekend looks grim...

Hang in there... it's coming!
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Unread 01-27-2003, 03:47 PM   #378
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Roscal,
According to your initial simulation, what is better? WW or Radius? This would be interesting to see.
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Unread 01-27-2003, 04:37 PM   #379
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WW, by 4 deg C. (assuming that the simulation is similar).
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Unread 01-27-2003, 06:41 PM   #380
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Here's a pic of the part of the res that was troubling me:

The top (white) piece is the threaded adapter. The middle (grey) is the trimmed polypropylene barb. The bottom is the 1 1/2 clear polycarbonate tube (with electrical tape, to protect it from scratches).

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Unread 01-27-2003, 06:41 PM   #381
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...and here's the pic...
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Unread 01-27-2003, 06:42 PM   #382
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The polypropylene was (is being) replaced with a nylon one, which glues very easily now.
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Unread 01-27-2003, 06:44 PM   #383
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Here's one of the inner tube's elbow, mounted.

As it turns out, my measurements were off: the inner tube (straight) wasn't long enough. It has since been taken apart, and rebuilt (Good thing that Goop is easily removed!)
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Unread 01-28-2003, 10:17 AM   #384
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WOW! Those simulations are incredible! Mastering that kind of software is a really powerful tool for the block maker. Isn’t there any “CFD for dummies” one?

Maybe this is too much asking Roscal, but are you interested in doing a simulation for another radial microchannel design I’ve made? I can provide a 3d model in the format you ask me. Details of it can be fount at this thread.

Ben, maybe the water can be forced to that central corner by going deeper with the intake pipe into the base.
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Unread 01-28-2003, 10:56 AM   #385
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Quote:
Originally posted by nicozeg
Ben, maybe the water can be forced to that central corner by going deeper with the intake pipe into the base.
Now why didn't I think of that?:shrug:
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Unread 01-28-2003, 01:08 PM   #386
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Adjusting depth and reducing diameter could do the trick, but finding an optimal that doesn’t cause a severe flow drop could be difficult.

To avoid modifications to the main fins it could be easier to cut slots on the pipe end at 45º. The interference with the tips of the third fin level could be milled out in the base, as it doesn’t affect the structure.
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Unread 01-28-2003, 01:33 PM   #387
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Yep! It actually takes care of two problems.

I'm still going over the nozzle dimensions, and the inlet/outlet ratio of different areas within the block, to get to an actual nozzling effect. (Not terribly accurate, as it doesn't account for hydraulic equivalents, yet...).

The nozzle was always meant to be a "drop-in" solution, so that I don't have to build a new top each time I want to test a new configuration. With the notches, now I don't have to worry about it spinning out of position.

I'm not too worried about how deep the nozzle can go within the channels: I'm aiming to focus the flow within the bottom half of the channels, so the top half is "free game".

The inner tube's inner diameter (ID) is 5/8 inches. Whatever the solution, it'll have to fit in there.


Another thing that's been bugging me: it seems that people don't get the use of 8 bolts on the top: as Paul Vodrazka put it, 4 aren't enough to ensure an even clamp. That may or may not be true, but I am not a mechanical engineer, so I'm opting for "more than 4". Since 6 is awkward ( 5 and 7 even more so), and would be a hard fit within the confined area of the block (because of the o-ring, which has already been reduced to 1/16, for the same reasons), I opted for 8, spread equally, with a 22.5 degree "twist" to make maximum use of the tiny available area outside the o-ring.

(So Bill, if you're still reading this, it wasn't for aesthetics).
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Unread 01-28-2003, 03:33 PM   #388
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Just realized something in your design:

Water always prefer to flow through the wider path. Case 1 is your actual situation, the 1 mm channel at the corner seems too narrow. If you cut the corner of the fin the situation improves a lot, focusing more flow at the key spot. Cases 3 & 4 are just variations.
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Unread 01-28-2003, 03:52 PM   #389
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Quote:
Originally posted by nicozeg
Just realized something in your design:

Water always prefer to flow through the wider path. Case 1 is your actual situation, the 1 mm channel at the corner seems too narrow. If you cut the corner of the fin the situation improves a lot, focusing more flow at the key spot. Cases 3 & 4 are just variations.
In three I'd make the center fin with more of a longer point to it if at all possible. That way your not accidentally forcing the water past the next fin. Trying to help.
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Unread 01-28-2003, 03:59 PM   #390
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That's correct, but if the area of the inlet (or its hydraulic equivalent) is less than the outlet, then the coolant should "shoot" down, hitting the baseplate.

I ran some calculations earlier, and this "ratio" (inlet to outlet) actually varies greatly, from 0.2 to 1.5, for diameters ranging from 0 to 3/4. There's kind of a linear progression, but not completely. It was an old calculation though, based on inlet tube diameter, and exiting channel area.

In the simulation, there weren't any flow seperators, so the coolant hit the top of the fins, instead of the baseplate. The resulting disturbance causes the water to ignore the deadspot, at the corner. If you look at the first graph, you can see a red spot (high speed), righ on top of the fin. I believe that that hot spot actually acts as a flow restriction.

I was looking at this earlier, and if I use a nozzle that's 1/4 inch diameter, that would address exactly what you wrote about. The exiting channel area ratio is favorable (for the water to shoot down). Now I just have to calculate the resulting pressure drop, and recalculate the channel exit's hydraulic equivalent, and double check all my calculations...

Here's a pic of the 1/4 diameter:
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Unread 01-28-2003, 04:04 PM   #391
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Quote:
Originally posted by SysCrusher
In three I'd make the center fin with more of a longer point to it if at all possible. That way your not accidentally forcing the water past the next fin. Trying to help.
Not possible: the channels cannot be cut in a width less than 1 mm: all channels are cut to 1 mm.

But thanks for the suggestion!
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Unread 01-28-2003, 04:36 PM   #392
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Quote:
Originally posted by bigben2k
Not possible: the channels cannot be cut in a width less than 1 mm: all channels are cut to 1 mm.

But thanks for the suggestion!
If it was possible i think it would work, which I don't think it is now that I think about trying to mill less than 1mm. If the pressure from the nozzle is strong enough it should take care of that though.

How about cutting a 1mm X through the fins in the center that criss-cross each other?
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Unread 01-28-2003, 04:43 PM   #393
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Quote:
Originally posted by SysCrusher
How about cutting a 1mm X through the fins in the center that criss-cross each other?
That would be a design compromise.

As I stated earlier (somewhere along with those graphs...), Radius suffers because the fins aren't all connected. I made the decision to leave the center 4 ones connected, and it appears that it does makes a difference.

It's not an option, but again, thanks for the input
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Unread 01-28-2003, 04:52 PM   #394
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With an 1/4 nozzle, your effective intake area is going to be really small, about 12mm2, cause the fin area has to be substracted. I'd go for a bit wider nozzle, plus the tip removal.
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Unread 01-28-2003, 04:57 PM   #395
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Quote:
Originally posted by bigben2k
That would be a design compromise.

As I stated earlier (somewhere along with those graphs...), Radius suffers because the fins aren't all connected. I made the decision to leave the center 4 ones connected, and it appears that it does makes a difference.

It's not an option, but again, thanks for the input
Looks and sounds like it's directing flow better with them connected then. That and alot of the heat is directly over the center. With the X cut through it would just direct the flow straight into the center fin in each quarter hindering flow. Bad idea. LOL Well it sounded good at the time!

Thats the problem i'v been having with mine. The best I can get out of it is 10C delta. If I connect my sink faucet to it it does 6Cdelta easy with no difference between load or idle. Does that count? LOL
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Unread 01-28-2003, 05:07 PM   #396
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Quote:
Originally posted by nicozeg
With an 1/4 nozzle, your effective intake area is going to be really small, about 12mm2, cause the fin area has to be substracted. I'd go for a bit wider nozzle, plus the tip removal.
That's about right.

The area of inlet for a 1/4 nozzle is 31.67 mm^2. Take out the center fins (1.5 by 6.35 twice, minus 1.5^2)...31.67-16.8 is... about 15 mm^2 for inlet area (minus those tiny tips). That's about the equivalent area to a 3/16 nozzle, but it needs to be recalculated for its hydraulic equivalent: it's actually more restrictive than a round nozzle.

17/32 is another good nozzle size. Anything 3/8 or less would also work well, theoretically, but anything in between is a no-no:shrug: (I charted everything in 1/32 increments)
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Unread 01-28-2003, 05:31 PM   #397
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Damn imperial units! How much suffering has to be for kids to learn that in school! I needed to grab a calculator to know wich one is bigger, 3/8 or 17/32

Four small L shaped jets has to be very diferent than a similar area round one, but I don't think standard tables can tell the difference, You'll have to deal with brute aproximations and safe margins. :shrug:
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Unread 01-28-2003, 05:43 PM   #398
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Quote:
Originally posted by bigben2k
That's about right.

The area of inlet for a 1/4 nozzle is 31.67 mm^2. Take out the center fins (1.5 by 6.35 twice, minus 1.5^2)...31.67-16.8 is... about 15 mm^2 for inlet area (minus those tiny tips). That's about the equivalent area to a 3/16 nozzle, but it needs to be recalculated for its hydraulic equivalent: it's actually more restrictive than a round nozzle.

17/32 is another good nozzle size. Anything 3/8 or less would also work well, theoretically, but anything in between is a no-no:shrug: (I charted everything in 1/32 increments)
3/16 is what i'v been working with and using in my current block im using now. It's restrictive but doesn't seem to hurt flow to badly. Temps are not bad. With out it my temps jump a bit by 2-3C. You have to find a size that overcomes the restriction of your fins. That seems to be the hard trial and error part for me.
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Unread 01-29-2003, 09:00 AM   #399
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Quote:
Originally posted by SysCrusher
3/16 is what i'v been working with and using in my current block im using now. It's restrictive but doesn't seem to hurt flow to badly. Temps are not bad. With out it my temps jump a bit by 2-3C. You have to find a size that overcomes the restriction of your fins. That seems to be the hard trial and error part for me.
Thanks for sharing your experiences!

"finding a size that overcomes the restriction of your fins" is the biggest obstacle for me, but I'm confident that I can resolve it.
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Unread 01-29-2003, 04:59 PM   #400
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Quote:
Originally posted by bigben2k
Thanks for sharing your experiences!

"finding a size that overcomes the restriction of your fins" is the biggest obstacle for me, but I'm confident that I can resolve it.
Keep at it! I enjoy watching other people's ideas evolve and learning from them.
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