BillA, I'm going to have to submit to your l33tness. I was running too many calcs in my head. When I double-checked with my texts and actually took out the calculator, I see you're quite right about the significance of form friction. I still think the tubing is going to be much less important, but if we're going to put fittings into calculations it's pretty damn easy to add tubing as well.
Except . . .
For the sort of tubing sizes we're looking at (around 1/2 inch) and the sort of flow we're going to see (around 2gph) Reynolds numbers will be around the 100s. This is a transitional region, so the Moody diagrams I have - most of which are quite extensive - have no correlation there for friction factor.
Also, do we have pump curves at different temperatures? Viscosity differences will cause huge differences in pump curves at temperature differences any higher than 2-3 degrees C.
Also, gmat:
Quote:
The software will not know about surface area and so on. Every element will be known as a data set of flow/backpressure or heat/flow, or both (for rads and waterblocks).
So for a rad you'll need at least 2 data sets:
backpressure vs flow
total heat transfer vs flow
Of course a problem arises there, air flow.
We can solve this by adding, for example, a heat transfer coefficient vs air flow, then (after fixing air flow) applying the resulting coefficient to the heat transfer vs water flow data.
That means for rads -> we need at least 3 data sets.
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For each rad you need a PQ curve for the water across the rad and the air across the rad.
You also need a heat transfer coefficient vs. flow rate (if BillA means what I think, this is essentially the same as a C/W vs Q plot) between the air and the radiator metal and the radiator metal and the water.
Separating these two effects could pose some difficulty since you need probes on the incoming air and the rad metal as well as the water. You'd probably need to insulate the probe from the air so it was only measuring the metal temperature. Still, as with almost anything, a good experimental method will tell you everything.
So, altogether, 4 data sets for the radiator.
This is so much more interesting than the other two design projects I'm working on.
Alchemy