Interesting
Interesting
Two factors that may or may not be worth considering are compression and friction.Quote:
Originally Posted by Cathar
Air will get slightly compressed entering the radiator, then heated to up a maximum of the water inlet temperature, then decompress on exit thus lowering exhaust temperature.
Dunno if there is any noteworthy friction coefficient at these airspeeds, if there is it could heat the exhaust past water inlet temp.
Not relevant. It starts at standard pressure, and leaves at standard pressure.Quote:
Originally Posted by Fairydust
Besides, even if it was relevant, the pressure changes we're talking about are just 100-120Pa (from the results), or ~1/1000th that of atmospheric pressure. The amount of temperature rise from that size of pressure change, starting at a standard atmosphere pressure would be absolutely miniscule.
Also, frictional heat from the airflow wouldn't show up in the calculated heat dissipation, since that's calculated purely from the water delta and water flow-rate. Air-flow friction warming the air up would make the air hotter, yes, but only hotter above the amount required to absorb the rated heat-load from the water.
Sorry brainfart, thought the last posts were about a measured exhaust temperature but after re-reading everything i see it was just calculated values.Quote:
Originally Posted by Cathar
This thread makes me realize how dumb I am. I don't understand most of the mumbo jumbo here. Thanks Marci and Cathar . . .
same here:(Quote:
Originally Posted by DarthBeavis
This reminds me a great deal of the so-called "open letters" from Dolby Laboratories and DTS regarding Dolby's claim that their lower-bitrate AC-3 encoders could somehow produce superior quality than DTS's encoders at about one-third the bitrate -- which is about the most unimaginably arrogant claim imaginable, as both encoders utilize practically the same means of data compression (primarily based upon psychoacoustics).
Of course, Koolance has been even more bold and misleading than I could have imagined. It's both an angering and humorous situation in some ways, but also certainly somewhat saddening.
An aluminium rad would have to be slightly bigger due to strength weight ratio of aluminium, you need more of it for the same strength then you would say copper or brass.
Psst. Listen. It's easy. You can even fool yourself.Quote:
Originally Posted by DarthBeavis
When reading the posts, nod slowly, raise your eyebrows slowly. From time to time mutter "Ah, of course." and "I see."
Look for tables of information, or summaries, read those. The rest of the stuff look at the big words and pick up keyphrases.
To kid on the rest of the forum ask questions like "Ah, but would the [keyphrase] have any impact on this?".
If Cathar, Marci, Hwlabs, or any of the experts posts and says they made a miscalculation or a mistake, quote that post and say "I was thinking that myself, but I didn't want to be rude and point it out"
If for some reason someone springs you, and catches you talking nonsese and corrects you, reply with "Sorry, that's what I meant to say".
It works a treat!
Actually, you're really not supposed to understand because you haven't attained legendary status. You are still part of the n00b caste and are not qualified to comment. Your role is to accept whatever is said at face value.
The conditioned response should be: "I see" and "of course" and you are expected to adopt what is said as gospel because the truth is dispensed by legends. After all, unless they specifically admit to a miscalculation, they are never wrong because they are industry pioneers and they know what they are talking about, even though you don't understand a word.. refer to my previous comment about not having attained legendary status.
[Old post ^ , sorry]Quote:
Originally Posted by Cathar
What if, for aluminium based radiators, aluminium based waterblocks are used?
If we assume that people know mixing metals in a loop is "dangerous", a test could be done with an all copper loop, and another with an all aluminium loop.
Perhaps such a test would result in far too many variables to comprehend, brand A copper waterblock will no doubt perform different then brand B aluminium waterblock, but this way the aluminium loop will not suffer from the added coolant as much.
Because of the very good properties of copper (and maybe a bit of history), copper is the way to go if you want to watercool.
Your very good post about tube dimensions (and how the end results don't differ much) might be applicable to the properties of radiator materials as well? Given the wall thickness between water and air medium, how much do different metals of a radiator actually contribute to the overall cooling performance?
[On a side note: I am willing to admit that I want to build a watercooling loop using a reserator 2 and a zalman gtx waterblock... will be my first, but decided to go with that because 130W VGA and silent don't go together air cooled]
omg... that's what I do :eek:Quote:
Originally Posted by Halk
Anyone notice that ever since this "test" was released that the [H] forums have imploded?
They must be taking it [h]ard over there...;)
Don't worry, it was from the server upgrades over the weekend :clap:Quote:
Originally Posted by ranker
Ahhhh.....I see the impact of what you are referring to. I was thinking that exact same thing myself, that was the keyphrase I meant to say.Quote:
Originally Posted by Halk
I like your style, I just do...Scots don't mess about, do they?
ranker lolz.
thanks marci. Always happy to see a manf. putting up specs.Quote:
Originally Posted by Marci
K & C are interchangable when in that format as the scale of the units (as opposed to the absolute value) are identical.Quote:
Originally Posted by MaxxxRacer
I wonder if Koolance has seen this thread or is planning a response. HWlabs, will your company be posting a rebuttal to their test like the previous time?
Been out for a while, work mostly...
Some friends from Aluminum radiator supply industry gave us some tidbits to consider.
Alloys are usually based on AA3003 for CAB (controlled atmosphere brazing) but modified for better structural and corrosion resistance by additions of Mg ,Cu and Zn.
Claddings - AA4343 or AA4045 typically.
Thermal conductivity influenced greatly by alloy type, typically 0.4 cal / cms Deg. C. (that's only about 167 W/m-K)
So looking at things, its not pure Aluminum as nor are the thermal characteristics as dramatically different as they would like people to believe.
And if for anything else, the alloy owes corrosion resistance to a helping of copper.
MPE, or multi-port-extruded tubes, used in the Koolance radiators have wall thicknesses typically of 0.25mm, and huge liquid-side pressure drop characteristics.
I'll leave it to you gentlemen for now to see what the implications are.
Will pop in from time to time with more info and results once the radiators arrive and the testing is done.
Ok, well I can add some maths on the impact of the brass wall.
If we're using 16mm wide tubes, and the copper fins are 0.07mm thick (fairly typical for traditional cores), then every fin has 2 contact points with the brass tube of 0.07x16=1.12mm², or 2.24mm². Now, if we've got a 12x12cm core, that has 12 tubes and 13 finned regions, of 16fpi, that 75fins per region, or 75x13=975 fins. That means 2184mm² of surface area between the tube walls and the copper fins, or 0.002184m².
Brass has a thermal conductivity of 159W/mK. The walls of the tubing are 0.2mm thick. The thermal resistance of the walls to the fins is therefore:
((159 / 0.0002) * 0.002184) W/mK, or 1736W/K.
That's 0.00058C/W
i.e. For a 200W heat-load, the tube-fin interface is contributing 0.115C to the water temperatures.
Okay, so there's some solder there too. Typically around 60W/mK, but nothing like 0.2mm thick of it though. The fins are pushed against the tube wall when the solder melts and holds them there. The solder-gap is miniscule. 0.05mm would be over-stating it. Still, even if we were totally pessimistic, we could say that the solder bridge is doubling the tube-fin C/W, so of our 200W heat-load, ~0.23C of the water temp rise would be due to the tube-fin thermal junction.
The best 12x12cm radiator with an extremely high speed fan blasting will get a C/W of around 0.03C/W, or a water-temp rise of 6C in total for a 200W heat-load.
i.e. Our tube-wall thermal impact is just 0.23/6 = 3.8% of the total thermal problem. As fan speeds decrease, so will this impact become an even smaller proportion.
i.e. The best that we could ever hope to achieve over a brass/copper radiator would be a 3.8% improvement given a 100% thermally perfect wall-fin material & interface, and even then I was being generous with some of my assumptions.
All this talk of 35-45% is pure tripe.
Depending on the precision of the solder bath attachments on a tube mill, the thickness of the solder cladding should be anything from 0.015-0.025 mm.
Then there is of course the difference between lead and tin's thermal conductivity but both are negligible in this application.
In response to the negligible gains possible comments made by Cathar (who I have mad respect for, took me forever to do all those maths myself) I have to ask if the issue could be slightly improved by using a different formulation-something like ambronze, or nickel silver (those are just examples, I know their acoustical properties, not their thermal properties)...
I understand that one of the issues is that we are still limited by what the radiator can absorb in order to dissipate, and that is governed by the thermal capacity of the metal. Is there a metal that would serve as an even slightly superior conductor that is available in some quantity? There's always pure copper, but that may/may not be cost effective, but I'm wondering if there are other metals worth pursuing...
Reason I ask is in the musical instrument field (where I spent a long time) new alloys have really changed the ability to influence the sound of instruments-andone of the reasons is that they heat up faster and hold that temperature, evening out tuning issues due to expansion/contraction. Beryllium bronze and ambronze are both in that category, and there's more work in sterling silver, gold, and platinum due to that as well.
Meh, I'm divorced from my books, but I hope I made that understandable...
More copper in an alloy is often touted to have higher conductivity but lower structural rigidity and for tubes, alloys need to be correctly done to enhance corrosion resistance.
Going to pure copper tubes, would have tubes become 3+ mm thick just to avoid dog boning, wherein the middle section of the tube across its width collapses, preventing proper tube to fin adhesion.
So whatever gains you wish to obtain, at least for the extreme PC application, would be mitigated by the thick tube width, i.e. high air pressure drop.
Okay, so let's model for the worst case scenario then.Quote:
Originally Posted by hwlabs
The worst thermally conductive solder is 32W/m-K. (soft lead solder)
Let's assume the worst case scenario of 0.025mm thickness for all fin-tube joins.
((32 / 0.000025) * 0.002184) W/mK => 2795W/K or 0.000358 C/W
Add that to our previously calculated tube-wall thermal resistance of 0.00058C/W
So we get a total tub->fin thermal resistance of 0.000938
Once again, applying that to our 120mm radiator with a ~200cfm fan on-board, we get 0.000938 / 0.03 => 3.1%
Okay, so following the worst-case scenario at every point, and using the worst-case scenario of an insanely high fan-power, the brass-tube->solder->copper fin impact is just 3.1% of the total problem.
For more typical slow-spinning PC fan powers, it's more like 1% of the total thermal problem. i.e. insignificant and justifiable.
I think that once again this highlights the nature of the automotive industry focus on the problem not being applicable to the PC water-cooling focus.
The auto-motive industry dealing in 3-30m/s air-flow speeds through a radiator, while the PC application is dealing with 0.3-1.0m/s air-flow speed typically. At 30m/s air-flow speeds (~1000cfm actual through a 12x12cm area), the brass->solder->fin approach could potentially be as bad as 20% of the total thermal problem, and this is where a brazed aluminium radiator of superior thermal conductivity in the tube->fin interface would start to win over the copper approach.
I think that this just shows that any company who continues to apply automotive industry principle to PC water-cooling is completely failing to grasp the huge differences between the two applications.
Worse, any company that uses automotive industry testing to justify their design decisions for PC water-cooling are completely and utterly wasting their time. Worse still, any company that attempts to use such in marketing and advertising is not only wasting the time of the customer, but is polluting the marketplace net-clue factor with misguided, misleading, misinformation.
There's been a lot of that going on around here lately and in the WC'ing in general. I'm hoping that all established and reputable companies and individuals, including those that participate on this forum speak out about this and call those individuals and companies out for their unethical behavior.Quote:
Originally Posted by Cathar