Quote:
Originally posted by bigben2k
It is definitely a good design.
It's a shame that the channels had to be so wide. I'm sure it would have been interesting to test this with tighter fins.
Optionally, one could braze very thin strips of copper, in that design.
There is an ideal fin spacing and thickness, as well as height. It's calculable, but it's not obvious.
Good work.
BTW, (I asked in another thread), did you consider running the test from side to side while plugging the middle barb? I believe that the middle barb, if it wasn't completely plugged, could alter the results. If you could replace the middle barb with a plug, that would be ideal.
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So wide?! 1mm? Some people are never satisfied!
Micro-channel theory basically calls for 0.7mm-1.3mm wide channels. I'm smack bang in the middle 'cos unless I went to EDM, it's not really feasible to get the channels any thinner with conventional machining. Much more expensive to get into EDM territory.
Near as I can tell though with my simulator, 0.8-0.9mm wide fins with 0.6mm wide channels is where it's at (optimal). We can go smaller but get to the point of rapidly diminishing returns. Would expect about a 0.5C improvement in that config over my current 1.0/1.0 config. Optimal channel height is dependent upon the water velocity, which of course depends on the number of channels and flow rate. Have to juggle a few balls here to figure it out, but basically 4-6mm channel height is a good choice for a "general" solution, possibly dropping down to 3mm height and boosting pump pressure and flows to get the water whipping through, which will really pick up its performance.
Currently the block is a result of a set of trade-offs to work with conventional pumps and attempts to explore the limits of what's possible in most people's water-cooling setup when all we do is change the block. The design can be refined to more closely approach "the ultimate" using the above guidelines. Whack on a cross-sectional nozzle under the inlet barb to get good jet flows impinging down into the hot sections too, and we'd start to see something significantly better (another 1-2C again), but it all hinges on the pump.
That's my theory on "The Ultimate". Oh, I forgot, we'd have to work up an optimal base-plate thickness for each die size too. The actual target heat load will also impact various aspects of the design such as base-plate thickness and channel height. "The Ultimate" is a highly strung piece of work carefully crafted to do its job for only a specific application. Throw it at a different application and it will cease to be "The Ultimate".
Back to your other question:
I tried the side-to-side option and will do so again, and plug up the central barb properly with some blu-tak (putty).
I'll give it a burl tomorrow.