Quote:
Originally posted by Skulemate
It's just some messy nomenclature on Since87's part. The dp is really the flow resistance for the component, as a function of the flow. The term he's calling the flow resistance, Rf is really a constant, needed to shape the parabola.
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Yes. I'm an electrical engineer. My formal training in fluids consists of about a week during freshsman Physics in college. Virtually everything I know about fluid flow comes from the forums so my nomenclature is definitely sloppy.
Quote:
Originally posted by bigben2k
Let's put it to the test, with some data I've extracted from Bill's roundup:
Using the "Surplus"'s curve, I extracted the following info:
dP @ 2.0 gpm: 1.6 psi
dP @ 1.5 gpm: 1.0 psi
dP @ 1.0 gpm: 0.3 psi
(a rough extraction, but let's take a look!)
Ignoring the units,
using the first set of numbers, Rf = 0.4
using the second set of numbers, Rf = 0.44
using the third set of numbers, Rf = 0.3
Hum...:shrug:
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Per Bill's suggestion I did similar for some of his most recent data. I chose to do it for my HC since it was the most restrictive and allowed me to get the most accurate dP numbers off the graph.
I printed the graph, and used digital calipers to get as accurate data as possible off the graph. My results:
dP = 0.71 @ 12 lpm, Rf = 0.00493
dP = 0.32 @ 8 lpm, Rf = 0.00500
dP = 0.092 @ 4 lpm, Rf = 0.00575
Pretty good match at high flowrates. Less good for low flowrates.
The following graph illustrates the effect of modeling my HC with two different waterblocks, and using both 0.005 and 0.00575 for Rf.
Fairly small errors IMO. (Especially when you consider the C/W change associated with the difference in flowrate.)
But, like I said, the techniques I suggested were for quickly doing "good enough" analysis. This is not the way to get the most accurate results.
If someone understands the limitations and can make use of my suggestions, great.
I didn't really expect my suggestions to enable you to do more useful analysis than you already do Ben.