Radiator Thermal Test Bench Progress

[NaeKuh]

NOOOOOOOOOOOOOOOOO Martin if you dont test the PA as being the king. Im gonna hate you in making me buy more h2o gear!

>:[

[Martinm210]

Thanks guys, that's what keeps me going....

[Martinm210]

Ran a few preliminary tests today.

Here is my string of sensor ready for logging, 4 of them are in my computer that I'll simply disregard, but 14 of them are specifically for my radiator test bench:


My very first test with a target heat load of 100watts, 15watts from the pump, 2 watts lost in my variac and 88 watts from the 300 watt water heater turned down until my "Kill-a-watt" registerd 88.

Takes a while longer to stabilize than I thought, I probably need to run this one again, but it's giving me an indication that at a bare minimum 20minutes of warm up is needed, but 30minutes is even better.

Then I tried a 200 watt run and found my first little glitch. The thermostat on the water heater kicked on mid way through the test...whoops..


Working out the bugs, but the logging is working nicely. My C/W results will be much lower because of heat lost through the tubing and reservoir, but I figured that's ok since a regular system will also. You just won't be able to compare c/w except other tests on the same test bed.

[NaeKuh]

WOW! seriously great work.

BTW sorry martin, i flashed your tec blocks in lc forum. Your pm box is gonna get nuked soon.

[Martinm210]

Hehe.

I was just going to start my 4th run a bit ago by throwing the second 300 watt water heater in there and the darn thing just doesn't thermostat high enough.

So now, I've got the water heater in my lap pulled apart, going to solder a bypass wire to get around the thermostat, must have MORE heat!!...

I think I might bypass all of my heater thermostats, I just want solid power anyhow, just don't want to forget one on, it would probably boil water or start a fire..

[Martinm210]

Finally got a keeper, this is how they should all look:

[systemviper]

Wow, Some great stuff, Now got to kick the brain into OC and try to undertstand the results


As always, thanks for your effort, top notch work!

[Martinm210]

Thanks!

It's not going to mean much until I capture the trends. Right now it's looking like a 10C water over air temperature with the medium speed yates at 1.5GPM is going to fall in the 460-470 range.

Each of the above tests was more for just feeling out how long I really need to let the test run before logging temps and also how long I should log temperatures.

Also adjusting the heat load and plotting out these points will show what sort of curve or line develops. This will tell me how many different heat load points I should test for. So far it's looking pretty linear so testing at 100 watts and 200watts may not really be necessary.

In the end I'm planning to create a tool out of the information where you can estimate your water temperature with some simple pull downs.

[Vapor]

No kidding mcoffey....this is pretty kickass stuff you've got going on here Martin

[rockqc]

So much talent and skill. I'm just amazed at the stuff your able to do and info you provide. I've learned so much.

I think most of the members who post in this section (including myself) would agree.

Great work as always Martin. Looking forward to more results.

[Jedda]

Hope you're enjoying doing it, Martin!
We appreciate your effort.

[Martinm210]

Thanks guys, this is alot of fun.

Always hated just doing pressure drop on wateblocks and not providing thermal stuff in addition, so I'm really happy that now I can do both on the radiators.

Looks like the key is letting the whole system stabilize for around half an hour before making a run.

Here is a 600 watt run, looking even better:


And even though the 100 and 200 watt runs were iffy at best, I plotted a trendline:



I can tell by this that I didn't wait long enough for stabilization for my 100 watt run. It looks to be low by about .2 to .3C.

Anyhow, I kind of like looking at this sort of curve better than normal c/w and heat dissipated relative to flow rate. I'll probably make a series of tests relative to flow rate just to see what the effects are, but since flow rate has less of an impact, I thought it would be nice to see water delat relative to heat dissipated.

The medium speed yates at 1.5GPM and 12V are dissipating really close to 500 watts for a 10C delta.

[Crankyhobo]

Seriosly Badass please keep us all updated!

[DavidNJ]

VERY nice graph. Kudos!!!

Now for a shroud and pressure measurement. Without the shroud the whole radiator isn't being used.

The pressure measurement would let us know where it stacks up vs. other fans.

One other measurement would be nice. Ambient air temp other than air in. From Ira's tests it seemed that Air In may be lower then Ambient.

Great work!

Updated:
Looking at the graph again, it is interesting how linear the temperature is for increasing heat load.

Do you have any Panaflo 120x38 M or Ls? The 120x25 SM Yates Loons fall between them in noise (if the published Yates Loon numbers are accurate), yet I would image either would draw more air through the Thermochill rad.

Second Update:

If the temperature differential is that linear with heat load, the interesting graph may be pressure differential (or air flow, on a pq curve either should define a point) on a shrouded radiator with the fan in pull (to take fan dimensions and vortex dynamics out of the measurement) vs. temperature differential. If the temperature differential changes linearly with heat load (less than a 10% variation over a 3x range in your tests), then the air flow to get a specific temperature differential at a heat load could be calculated.

Using a setup like your spreadsheet, and using goal seek as the calculating mechanism, the pressure differential/air flow for a temperature differential could be determined. If pq curves for fans also were in the database, a list of fan/voltage pairs for that pq could be listed, possibly with the sound level for that fan/voltage pair.

[Martinm210]

Yeah, it's going to be even more linear after I get my variac consumption figured out.

I might just pull the variac out of the picture all together, and pick up a 150watt water heater. Then just plan on doing 150 + the pump whatever it works out to be increments. I'm thinking a single point near 150, 300, 600 watts should be enough for triple rads and smaller rads should be fine with 150,300, 450.

I was assuming that the variac only consumed 2 watts, but that's at low voltages, it's closer to 5 or 6 up higher. My second round of 100 watts was also higher coming it at 1.90C.





I'll do some CFM type stuff too, just wanted to get this heat load thing started first.


The fan stuff is coming too. I've only got the medium speed panaflos though. But I've also got some slow speed yates and some of the 38mm 136cfm Scythe Ultra Kazes too that have really good pressure too.

It's all possible, just going to take some time and work. It could easily be a weekend's worth of work just to test one radiator with 4 sets of fan scenarios. As long as a measure actual fan CFM at the same time for now, I can work some other stuff in later.

Take a look at Vapor's fan charts for some good noise vs CFM data.

[DavidNJ]

I think you are making the radiator test way too hard by making it a fan test also. You just need a box you hook to the radiator with enough of a blower that can be create a pressure drop from .01" to maybe .5" across the radiator. I don't know what we have in practice now, however based on the fans I imagine it is in the .05-.1" range.

That would be quick, and neat. Then you can just select the fan with a shroud in pull that will duplicate the pressure drop you want.

BTW, what was your room ambient? Did it differ from air in?

[F1ZZY]

Hi

Long time lurker and 1st post for me here.

Loving your work Martin. It's this kind of effort that finally puts end to (some of) the bickering we see on forums - (like Cathar and his tubing results etc)

There are so many variables available for radiator heatload testing and you are doing a fine job trying to make sense of it. I am particularly loving the dT vs Watts dissipated graphs, I think they are revolutionary. Thermochill have always plotted a fixed 10degC dT.

You do realise that your efforts are going to result in the first full w/c simulator (now that you are adding the thermal assessments too) - Soon your spreadsheet will have to include components and fans used & ambient temps in order to provide speculative temps, ha ha.

Keep busy

[Martinm210]

I think you are making the radiator test way too hard by making it a fan test also. You just need a box you hook to the radiator with enough of a blower that can be create a pressure drop from .01" to maybe .5" across the radiator. I don't know what we have in practice now, however based on the fans I imagine it is in the .05-.1" range.

That would be quick, and neat. Then you can just select the fan with a shroud in pull that will duplicate the pressure drop you want.

BTW, what was your room ambient? Did it differ from air in?

Yes, but that wouldn't capture real world fan hub effects for folks that don't use a shroud, which I would esimtate is the larger majority of users.

I'm more interested in capturing something that is useful and easier to understand for people.

A CFM base flow chamber would have to be a large facility too, I just don't have the space where this little bench I'm using is very simple and small.

It'll work out..


I don't understand what the ambient vs air in question really is. air temperature is extremely sensetive and if I measure room ambient 10' away it really has very little correlation, measure it on the floor and it's probably cooler than air in, measure 6' up it's higher. Air temps are really really sensetive and different everywhere, that's why I've included 8 individual air in sensors to average out the mess of differences.

[nikhsub1]

Very nice Martin! This is exactly the sort of testing i begged Bill Adams to do, but he went with the 10C water/air differential instead which is much harder to decipher. You realize the can of worms you've opened though now right? Each test should include various air and water flow rates...

[bobo5195]

Care to plot your results as Time vs the LMTD

http://en.wikipedia.org/wiki/LMTD (the countercurrent one).
Cold stream = Air
Hot stream = Water.

The excel formula for it would be
with Wi being water in, Wo being water out Ai being air in and Ao being air out.

=((Wi-Ao)-(Wo-Ao))/Ln((Wo-Ao)/(Wi-Ai))

should be pretty much a straight line of results or a nice *slighty* smooth curve.

Edit
Oh and a scatter plot of (Wi-Wo)/(Ai - Ao). For a period of constant air and water flow rates.
The amount that this is a scattering of points vs a straight line (use a trend line intersecting at 0) is the value of "crapiness" for want of a better word of the experiment.

This should be varying with heat load.

Edit 2
Also that value call it K, or by its real name ratio of thermal heat capacities.

K=(Wi-Wo)/(Ai - Ao)

Would tell you fan CFM exactly (depending how good your apparatus is) if you varied Fan speed. Which would also tell you radiator flow resistance.

[DavidNJ]

Yes, but that wouldn't capture real world fan hub effects for folks that don't use a shroud, which I would esimtate is the larger majority of users.

I'm more interested in capturing something that is useful and easier to understand for people.

A CFM base flow chamber would have to be a large facility too, I just don't have the space where this little bench I'm using is very simple and small.

It'll work out..


I don't understand what the ambient vs air in question really is. air temperature is extremely sensetive and if I measure room ambient 10' away it really has very little correlation, measure it on the floor and it's probably cooler than air in, measure 6' up it's higher. Air temps are really really sensetive and different everywhere, that's why I've included 8 individual air in sensors to average out the mess of differences.

People who don't spend $10 and 30 minutes to build a shroud aren't really trying to leverage the numbers for the best performance: thermal or acoustic. Making tests that hamper radiator performance and don't provide numbers for people looking to tune thermal performance are equally lacking.

Isn't the goal for people to start designing their systems better rather than institutionalize bad design?

Ira's tests indicated that the higher speed air as it is sucked into the radiator has a lower temperature than ambient. That difference is a function of the effectiveness of the system in creating a pressure differential across the radiator design of the radiator. Failing to take it into account can make a more effective setup look less effective.

Taking the air temperature say 12-24" from the radiator should reflect the ambient temps around the radiator without any cooling affects from the fast moving air.

if you use a shroud (which Thermochill even sells for their units, which come with mounting holes) it may be very interesting to compare a PA120.3 to a BIX 360 with fans in the 20-30dbA range.

[gojirasan]

I think you are making the radiator test way too hard by making it a fan test also.

No. He is doing it right. Remember that test where the Thermochill was soundly beaten by the HWLabs GTX but only above 1200 RPM with a certain Yates fan? This is the first test in the English language where we might see such results duplicated, finally dethroning the PA120.3. It seems clear that nothing can beat the thermochill at very low CFMs/pressures. But the real question is how low exactly. If this can happen at a low enough sound level, then it will really be something very significant for most of us. This isn't SPCR. Not everyone here cares about utter silence. But most of us don't want a jet engine roar either.

It looks like you don't have the top rated fans though, Martin. Isn't there anyone who can contribute a few San Aces or some Scythe S-Flex Fs or Zalman ZM-F3s or Noctua NF-P12s? I do have a few of those San Aces you could borrow, but I only have one each of the Zalman and S-Flex. Actually I was thinking about scoring some of those medium speed Ultra Kazes. The problem with the Noctuas is I think they are too slow. They need to be overvolted or something. They would be great for this radiator showdown though.

[nikhsub1]

While I see your point of testing with shrouds, not all rad mfgrs have them... this would mean that Martin would have to MAKE a shroud for EVERY rad he tests... single fan, dual fan, tripple fan, quad fan ETC. Do you see the nightmare in this proposition? Plus, shrouds affect performance very differently on different rads, it is NOT LINEAR at all. The more densely packed the FPI, the more a shroud will help. A shroud on a PA rad is almost pointless.

[bobo5195]

Ira's tests indicated that the higher speed air as it is sucked into the radiator has a lower temperature than ambient.

I'm not sure that is possible from a thermodynamics POV given the conditions of the test.

Higher air speed would remove heat from the sensor faster if it was being warmed up though.

I have also never heard or seen it mentioned in textbooks or such. Good old Prof Kaynes would have brought it up.

[Martinm210]

I'm not sure that is possible from a thermodynamics POV given the conditions of the test.

Higher air speed would remove heat from the sensor faster if it was being warmed up though.

I have also never heard or seen it mentioned in textbooks or such. Good old Prof Kaynes would have brought it up.

Thanks and thanks for the equations, you're always making me dig my old reference manuals out and keep an eye on the equations.

First up I'm trying a few repeatability tests just to see that, then I'll play around with some other data concepts. The data is all there, I've been capturing with each test about 2,000 rows with 14 column of temperature data (logged every second) along with a timestamp and RPM), so there are plenty of numbers to play with.

Here is a sample of 40 or so rows of the 2000 or so I'm collecting in just one run:
http://img519.imageshack.us/img519/6...prelim8qu2.png



Yeah the colder inlet vs ambient doesn't make sense to me either either, it was probably just error in the thermometers. If anything I've usually measured warmer temperatures at the inlet that's caused by recirculation of the exhaust. This is a big issue with alot of rear and top case mounted setups, my own system I was able to cut about 3C off by simply channeling air to exit and keep away from the inlet. In the end I don't find value in ambient, if the setup is done right ambient will equal Air In. Air in is what matters for heat exchange.

Even though I'm pretty impressed with these Dallas sensors, I still don't trust them for more than a few tenths of a degree and it's not uncommon for two sensors only a few inches apart to read as much as 1 degree difference. It's really amazing how much air temperature changes in such a small amount of space. After all air is considered and insulator, so it's not like measuring water and it's very high specific heat capabilities. Lots of sensors and logging for very long periods of time are the key to accurate air measurements is what I'm finding.

Also on the shroud vs. no shroud, I plan to do some controlled experiments to see if I can extract some good correction factors for a shroud vs. no shroud. I'm thinking on correction for 40mm hubs (25mm fans) and one for 55mm hubs (38mm fans) should be adequate, then you could adjust results for either shroud or no shroud.

If folks have the opportunity to see what those shroud performance results are, then they can decide for themselves if the effort is worth the hassle.

To keep the shroud design concept simple and easy for just about anyone, I'm thinking I'll try evaluating the effects of a shroud made from old 25mm fans with the motors snipped out of them. I could also play around with pull/pull, push/pull, etc. All of those difference scenarios where a flow chamber would only evaluate a shroud like condition, so it's not as flexible.