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It on the graph and in the Excel.
Get errors iwhen try to open Excel but downloading with Flashget works fine. |
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Wait a half hour, I'll post something... |
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First measurement.
I have NOT compensated for heat shadowing, something that may be quite significant on the 10x10mm setup. The TIM is SX-25, value is a little higher than I expected, although I haven't checked back my data. I have spent all day calibrating the sensors, from the triple point of water (0.01°C)to boiling point (100°C) and generating Steinhart coeficients for the thermistors. My variation across that range is <0.1° between sensors, two resolution steps. Dimensions for those who want to calculate the heat shadowing effect.: 10x10mm Waterblock surface >> fluxblock sensor, 2.23mm Fluxblock sensor >> FB bottom surface, 2.00mm Die top surface >> Die top sensor, 2.00mm Die top sensor >> die lower sensor, 5.00mm Dimensions to hole centres. All sensors are in 1.5mm holes drilled 6.00mm. Les, you're good. I'm of to kick my heels up. I will be hurting tomorrow. |
Getting errors from that zip file Incoherent.
! C:\...\mcw6000_on_100sqmm_2.zip: Unexpected end of archive ! C:\...\mcw6000_on_100sqmm_2.zip: The archive is either in unknown format or damaged |
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Your zip also will not open.
Again OK with Flashget Think agreement is just as likely to be cancellation of errors as correct parameters. However it is reassuring that effect of die size seems to be accurately predicted. Have sent pm and mailed with bit of Excel. Edit On closer look "effect of die size seems to be predicted(ish)" |
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I conveniently ignored last tine round.and did not see others rushing in However would, if forced with a gun to my head, multiply C/W(Tin) by 1.023 . Attached tentative effort Will think again tomorrow. |
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Got it "arse 'bout tit" Or have I ? Having logic problems : befuddled(not booze). Need more time to get my head round |
Coming to the opinion: That "the shadowing correction" is only required to estimate conditions(Q and fluxboc/TIM interface's T) if a solid-unsensored-block was used.
A sensored-block is used in the test rig and conditions are described by uncorrected calculations. Not happy Help ! |
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I've made a little Femlab model showing an isotemperature plot of the Flux die. The effect of the holes is pretty obvious. (I wonder why I didn't drill all the way through for symmetrys' sake). Looked at like this there is no obvious problem. There is a compression of the temperature isosurfaces but they are rather flat at the height if the hole centre... more follows... |
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...following on
A more comprehensive model of the die. With and without holes: More follows... |
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So far so good.
Have started my own much cruder play, hoping to get my brain to unfuddle Will not interrupt further |
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...continuing. The Femlab model gives a gradient through the die which deviates a little from nominal even without holes I think because of the uneven flux density as it enters the riser from the baseplate. This is probably valid. more follows... |
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...so.
Edit, added calculated Watts error to chart |
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Fine
Then I lose it when looking at the big picture ,shown very roughly. Will have to think my own play through. |
OK at last.
Still to dot some "i"s. That was hard work. dunno why. Ta Jonathan. Where were we? |
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Obviously you can't correct this error with a temperature offset, that is dependent on heat flux. If you add corrections to the hole positions in the calculations (for watts q=k.a.dt/l, for die surface temp t2- (t1-t2)/(l1-l2)*l1), you can trick the equations into giving you the correct numbers. This is what I mean by "effective length" Edit: added comments to chart |
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Maybe I need to add these corrections to the DAQ scripts, I haven't calculated them independently yet. I am not sure how much I trust the FEMLab model for generating these numbers, the above charts are based on it. For sure it is better than anything I can hack up but ... you know. Also my access to FEMlab is limited (by totalitarian licencing) so I try to avoid using it to much for home projects. Plus it crashes frequently on more complex models. Would really appreciate some independent calculations for these corrections Les. I am not sure if the temperature at the die center is the whole story. Attaching Excel for perusal. |
Oh god its magic.
Will peruse Quote:
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Still feeling my way round .
Note the gold bit is 400w/mc Cu ( I use 400 as default) With what are the holes filled ? k appears to be ~214.5, Al? Don't bother answering until have added further queries - which I probably will. |
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k=1, density=1000, heat capacity=1000 Guesses, the results are almost exactly the same with nothing in the holes. The gradient from which I guess you are calculating the k is established more by the temperatures at each end than the material itself. Here's a more comprehensive model raw data result from WB interface down, 0mm is FB/die interface. I have used k copper =392 in this model. Nom gradient 1.65°C/mm. I will use this model I think, it'll save a bit of work despite my reservations expressed above. I'll stick with die, FB centerline temps as well unless something else comes up. I'll have something based on this tomorrow. Edit: Added working for final position corrections |
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I have established sensor position corrections for the whole heat path. (updated attachment above)
As follows with position 0 being the fluxblock-die interface, + towards heatsource: WB-FB I/F -4.005 (reality -4.23) -1.988 (reality -2.00) 0.000 FB-die I/F 0.000 2.081 (reality 2.00) 7.158 (reality 7.00) v v heater. This seem to have had the result of lifting the curve upwards. I will attach a logfile in a wee while, this one was too big for the system to accept |
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I will use
(C"/W")= 1.02670158(C/W) Not given Fbloc any d" |
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:)
A more condensed, cleaner run attached. Uncertainties now are the water temperatures, I have only checked them briefly, not a full on steinhart recalibration. I am seeing odd bumps in the calculated flowrate every now and again, caused by a fluctuation in Water out, not sure what it is, electrical?, don't think it's a blockage, invisible in Water in and PD. Les, what is the laminar-turbulant flow transition flowrate for 10mm ID pipe? I am seeing something at about 4.2lpm which I have seen before but assumed was my pump sequencing , but it is not I have since discovered. My flowrate errors seem to change sign at this point. Visible in the PQ plot. Not so obvious in the attached logfile, clearer with the higher sampling rate. (chart attached) Curious. |
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