Radiators and Fans - Page 5

BillA · 05-06-2003, 06:57 PM

Roscal
the last test is yours
reversing the inlet/outlets on a Chevette core at 2gpm yielded a (very nominal) 0.005psi (~ 3 or 4cm H2O) difference
perhaps of interest to the analytically inclined, not even slightly to a user
(if you knew which direction was better it would not be worth crossing the hoses)

Since87 · 05-06-2003, 11:26 PM

Some further torturing of Bill's latest data...

I took a subset of the data ( ID's from 6.1mm to 11.18 mm, and flowrates from 3.783 lpm to 11.35 lpm) and graphed dP vs ID for the four flow rates included.

I used log scale for the dP axis because it can clarify (exaggerate?) patterns in the data.

Then I 'normalized' the four curves by dividing out flowrate^2 for each.

The black line I 'painted' in (actually something a bit less sloppy) is what I was inclined to use as a barb factor.

But I really disliked that 8.89mm ID number, so I just plopped 9.89 mm in instead. I really liked the results with 9.89, but I decided to take a look at the Imperial measurement and saw that it was 0.375". (or 9.525mm)

Here's the second graph redone with 9.525mm in place of 8.89mm.

I'm much happier now.

Too late at night for me to be coming up with an equation though.

Les,

How do you generate those polynomials from a set of data points? Is that something Excel can do?

pHaestus · 05-07-2003, 12:04 AM

click on data in the graph to select. Right click, add trendline, choose the type of line to fit. Then in the options check "show equation" and "show r^2" or something like that

Roscal · 05-07-2003, 04:24 AM

BillA > Thank you for the test

. Which way was better :enter small tank or big tank??

It's a pity that difference between the 2 tanks of the chevette rad was so small , much difference should probably appear in a rad like that (at left) :

Since87 · 05-07-2003, 10:45 AM

Just a quickie.

For each ID, I averaged the dP/Q^2 value for the four flowrates I'd graphed earlier to get a single data set.

Since87 · 05-12-2003, 11:50 PM

I've played around with my experimentation spreadsheet to incorporate Bill's barb data.

The latest simulated vs measured comparison:

I assumed 0.25" ID barbs for the Big Momma.

I've tweaked all the fudge factors a bit.

There is still an overhead factor, but it is only 61% of its former value.

I will update the user friendly spreadsheet tomorrow and make it available for download.

bigben2k · 05-13-2003, 08:59 AM

If you're interested, here are my results, for Fedco# 2-304:

dP of heatercore @ 0.5 gpm: 1.5" (0.054 psi)
dP of heatercore @ 1.0 gpm: 4.0" (0.14 psi)
dP of heatercore @ 1.5 gpm: 8.5" (0.31 psi)
dP of heatercore @ 3.5 gpm: estimated, 4.48 psi

Not terribly accurate, procedure described here.

Since87 · 05-19-2003, 11:12 PM

Ok, I finally got the new version of the spreadsheet done.

A (color distorted) screenshot:

The main changes are:

Accounting for inlet and outlet ID in determining the pressure drop.

More detailed usage notes, and some background information on the spreadsheet.

The pie chart, which is handy for visualizing the impact of barb ID on the dP of the heatercore.

05-07-2003, 04:24 AM	#104
Roscal Cooling Savant Join Date: Apr 2002 Location: North of France Posts: 198	BillA > Thank you for the test . Which way was better :enter small tank or big tank?? It's a pity that difference between the 2 tanks of the chevette rad was so small , much difference should probably appear in a rad like that (at left) : Last edited by Roscal; 05-07-2003 at 04:35 AM.

05-13-2003, 08:59 AM	#107
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	If you're interested, here are my results, for Fedco# 2-304: dP of heatercore @ 0.5 gpm: 1.5" (0.054 psi) dP of heatercore @ 1.0 gpm: 4.0" (0.14 psi) dP of heatercore @ 1.5 gpm: 8.5" (0.31 psi) dP of heatercore @ 3.5 gpm: estimated, 4.48 psi Not terribly accurate, procedure described here. __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101 Last edited by bigben2k; 05-20-2003 at 08:56 AM.

05-06-2003, 06:57 PM	#101
BillA CoolingWorks Tech Guy Formerly "Unregistered" Join Date: Dec 2000 Location: Posts: 2,371.493,106 Posts: 4,440	Roscal the last test is yours reversing the inlet/outlets on a Chevette core at 2gpm yielded a (very nominal) 0.005psi (~ 3 or 4cm H2O) difference perhaps of interest to the analytically inclined, not even slightly to a user (if you knew which direction was better it would not be worth crossing the hoses)

05-06-2003, 11:26 PM	#102
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Some further torturing of Bill's latest data... I took a subset of the data ( ID's from 6.1mm to 11.18 mm, and flowrates from 3.783 lpm to 11.35 lpm) and graphed dP vs ID for the four flow rates included. I used log scale for the dP axis because it can clarify (exaggerate?) patterns in the data. Then I 'normalized' the four curves by dividing out flowrate^2 for each. The black line I 'painted' in (actually something a bit less sloppy) is what I was inclined to use as a barb factor. But I really disliked that 8.89mm ID number, so I just plopped 9.89 mm in instead. I really liked the results with 9.89, but I decided to take a look at the Imperial measurement and saw that it was 0.375". (or 9.525mm) Here's the second graph redone with 9.525mm in place of 8.89mm. I'm much happier now. Too late at night for me to be coming up with an equation though. Les, How do you generate those polynomials from a set of data points? Is that something Excel can do?

05-07-2003, 12:04 AM	#103
pHaestus Big Player Making Big Money Join Date: Aug 2001 Location: irc.lostgeek.com #procooling.com Posts: 4,782	click on data in the graph to select. Right click, add trendline, choose the type of line to fit. Then in the options check "show equation" and "show r^2" or something like that

05-07-2003, 10:45 AM	#105
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Just a quickie. For each ID, I averaged the dP/Q^2 value for the four flowrates I'd graphed earlier to get a single data set.

05-12-2003, 11:50 PM	#106
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	I've played around with my experimentation spreadsheet to incorporate Bill's barb data. The latest simulated vs measured comparison: I assumed 0.25" ID barbs for the Big Momma. I've tweaked all the fudge factors a bit. There is still an overhead factor, but it is only 61% of its former value. I will update the user friendly spreadsheet tomorrow and make it available for download.

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