A TIM C/W number.

[Les]

Originally Posted by Incoherent

Thank you for the offer Les.

Would you have any particular suggestions? I have not really been paying close attention to the pump threads so I have no real idea of what is capable of what. I note that Cather has been busy but am not sure that is quite pertinant for this scenario.
I do like quiet.

Ugh
The only pump I see in Sweden is Danger Den
Seems a bit pricey at 895Kr
Maybe someone will offer a pump for 460Kr (£35) ?

[BillA]

I could send a MCP650 but I'm not so sure it is a 'good' pump for testing

what is the service to which the pump is to be put ?
if to provide the flow in a controlled circuit a larger pump would be preferable to overcome the losses from the instrumentation 'bits'

[Les]

Originally Posted by unregistered

I could send a MCP650 but I'm not so sure it is a 'good' pump for testing

For £35 I think Incoherent would think a very good pump

[BillA]

Les, you do not need to pay for a pump that I provide to Inchoerent as I too am a fan of his work
I'm not sure that the D4 is the pump he wants though (nor the relationship of quiet to testing ??)

[Les]

Originally Posted by unregistered

I'm (nor the relationship of quiet to testing ??)

Kiwis always play quiet cricket

[Incoherent]

Originally Posted by Les

For £35 I think Incoherent would think a very good pump

I would.

Originally Posted by unregistered

...the relationship of quiet to testing

Really there isn't any, except that the testbed is right below the bedroom and the tester is easily distracted.
At the moment I have an extremely quiet pump (Hydor Seltz S30) in series with a not so quiet pump (Hydor Seltz L30), when I need the higher flow I switch one or both on as needed. Currently I adjust flow with a valve on the pump outlet. I have been fairly careful to keep restriction to a minimum in the circuit, for example the water temperature sensors provide less restriction than the hose itself (10mm I.D. silicone). This requires heavy insulation but I have been working with the limitation of weak pumps.

[Incoherent]

The System is in a shambles right now, water regulation on the outlet sensor, a pump rattling like a Kiwi batters' wickets, wires everywhere and heater resistance drifting due to an overheat but I could not resist.
Made new base to fit the P4 mounting system and did one unoptimised mount of the MCW 6000.

PRELIMINARY, lots of salt please.

Bill I really like that SX25 grease. This block kicks the shit out of the sphere PD-wise.

The new base will let me mount a load measuring/alignment system which may or may not work, the excel models say yes to the electronics but FSR (Interlink) repeatability is untested.

Bedtime.

[Les]

I like
Copy and paste from your Excel
Your green line is in within "Old Trafford"of my bodged extrapolation of Bill's worK(yellow)

[lolito_fr]

hrmm, looks close!
and the gap would decrease with a smaller die(?)

looking forward to some multiple mount testing...

[Incoherent]

Originally Posted by lolito_fr

hrmm, looks close!
and the gap would decrease with a smaller die(?)

looking forward to some multiple mount testing...

I think the whole ensemble would move up with a smaller die. The C/W number really should be C/W for x area. I am not sure if the response would be that linear, it should be but mounting pressure is never going to be the same in terms of force/area...
Although I am working on it.

Question about your prediction Les. What water temperature are you calculating the delta T against? in, out or average. I remember seeing somewhere that the average was the thing to use but it did not strike me as logical. I am using T in. (Actually by mistake I didn't just now, will compare this)

Bill I think your moon bet would be safe. I am having a hard time regulating the water temp with varying flow rates and pump power levels. It's still quite OK but not the 0.01C I was getting in a static situation.

[BillA]

as the wb is a heat exchanger, the LMTD is probably the most strictly correct
the LMTD is only ever so slightly different than the avg, with our deltaTs insignificant
where I have only one temp I'll use the intet temp

[Les]

Originally Posted by Incoherent

Question about your prediction Les. What water temperature are you calculating the delta T against? in, out or average.
.

Inlet,.or rather, have not included allowance for rise in temp.
Strictly an average should be used.
Probably, as Bill says, the LMTD .
I use the Wolverine series pdfs for my understanding of heat-exchangers.
ch1_3 covers LMTD.
When sorted out my Excels will post an allowance

[Incoherent]

Originally Posted by Les

Inlet,.or rather, have not included allowance for rise in temp.
Strictly an average should be used.
Probably, as Bill says, the LMTD .
I use the Wolverine series pdfs for my understanding of heat-exchangers.
ch1_3 covers LMTD.
When sorted out my Excels will post an allowance

I am very curious because of this:




++!

Wow.

[Les]

Yes "water out" is a bit.close to predicted "water in"
But sure is only accidental.

Have allowed for water temp rise and is with reference to inlet temperature
Used Kryotherm but not sure whether they use "average DeltaT" or LMTD

.

Will extend to below 1lpm when locate my original "h(effective)" sums - probably tomorrow

[Les]

The model:
The 281pin MCW6000 considered as 16channel(1.62x9mm) ,2mm fin on a 60x60x5mm bp with 6mm(ID) inlet.
Used Flomerics(D=0.006, H=0.009, r=0.015 to calculate "h(convection)"
Converted "h(convection)" to "h(effective)" using Kryotherm
Converted "h(effective)" to *C/W(isothermal)" using Waterloo
Converted *C/W(isothermal)" to C/W using Kryotherm

Originally Posted by Incoherent

.. it should be but mounting pressure is never going to be the same in terms of force/area...
.

Probably should only matter for C/W(TIM) values.

Edit Replaced the Hemisphere-wb data with the initial MCW6000 data

[Les]

Compared with your new data and eyeballed Billa's
Same 281pin modeling technique used for both.

[Incoherent]

I think I need to refine and further verify my flow-rate calculation.

I am trying to get the mounting pressure measurement incorporated and calibrated along with pressure drop. I am running out of DAQ channels, might need to sacrifice the fluxblock middle sensor.

[Incoherent]

Some data from the differential pressure measurement. Finally got it running, seems to be making sense. The sensor is not designed for water (I am skint) but I don't need the water in direct contact to get a reading and I am able to log it.







I am deliberately showing raw data, it gives a good idea of my noise levels. With averaging this can be cleaned up a bit. Note the increase in noise above 4lpm, this is the Hydor L30 which is rattling, it is very visible in the pressure drop measurement.

Also note that this (the dP) is not calibrated, it is the nominal transfer curve of the differential pressure sensor with an offset. I am using a low resolution DAQ channel for convenience, I think it is sufficient, gives me ~0.13kPa resolution (0.013m H2O).
No major clashes with existing data for this block I think.

[Incoherent]

Bumping this to make it easier to find. Will post some TIM data shortly.

[Incoherent]

I have been doing a bit of work. I have replaced some thermistors, recalibrated, remeasured the fluxblock after some lapping, fine tuned the placement of thermistors within the fluxblock and tweaked my realtime calculations to take into account the heat shadowing effects of the sensors and their holes.
I am now fairly confident that I am able to get reasonably consistant readings from the setup.
Since I generate a waterblock C/W number by extrapolation, I am able to get a number independent of the value of the TIM by assuming that the TIM joints at either end of the fluxblock are the same since I measure and calculate the joint between die and FB and remove it from the WB number.
This relies on me getting a good mount. Since I have made many mounts of this waterblock, I am now pretty familier with its performance so I am able to see if I have made a good mount by checking that my calculated C/W is correct. I tighten the mounting screws under power and am able to see the measured WB and TIM C/W in real time while I am doing this. When the WB C/W is correct and the TIM is at a minimum (within the mounting pressure limits, a spring compression distance) I know that I am either good on both TIM joints or equally bad on both. I choose to believe that it is unlikely that one would get both interfaces equally bad at the same time. I can see a difference - if the WB C/W is high, then the WB-FB interface is bad, if it is low then the Die-FB interface is at fault. This relies on a bad joint being caused by uneven pressure tilting one of the interfaces. Anyway, details...

(This reads incoherently, I will fix it tomorrow)



This shows my performance over six mounts. (It's actually good over a damn sight more than just six) The Shin Etsu 765 grease (and 751 actually) is extremely viscous and seems to go hard when you move it or put it under pressure. A non-Newtonian dilatant behaviour. I had terrible difficulty in getting any decent mounts at all with it. This shows in the chart. Apart from this one thermal compound, I am pretty happy with the repeatability I am able to get.

The following numbers represent what I have been able to get from several different thermal greases. I would caution people not to draw too many conclusions from this. The numbers are Short term values and do not show effects of TIM settling over time and power cycles. They also represent only the behavior under a given pressure (~20kg over 144mm^2), NOT a given thickness. Meaning essentially that the more viscous the grease, the higher the thermal resistance. Depending on the application, the value will probably change. (Think IHS, where there might be a measurable gap between die and spreader)



A simple chart for what is tens and tens of mounts, megabytes of logfiles and repeated remounts.

Edit: Manners. Big thanks Colin at Arctic Silver for providing the Arctic Silver greases and Bill for the Shin Etsu and a pump, and the waterblock.

Excel sheet attached for those interested.