[Alchemy]

For airflow, might as well keep the pressure drops and airflow in inches water and cfm, which is how most data is given. [edit- sentence fragment removed - meant to cut&paste into next paragraph, sorry]

Since all this data will be given in terms of empirical equations, it makes no difference what units things are in so long as they're consistent - it's not like any unit conversion need be done so we can run semitheoretical methods or anything like that.

I'd say go for whatever units the experimental data is given in. BillA would probably be best in deciding what units those are.

BillA, on your site, how do you measure C/W? My indication is that it is the same as 1/hA, the inverse of the heat transfer coefficient mutiplied by the area of transfer.

For a waterblock, then, the C/W would be the difference in temperature between the CPU die and the average temperature of water in the block divided by the heat load. This is consistent with what you are doing, right?

Also, for the fittings issue, I still maintain that it's easiest to ignore the effects of tubing and fittings on the assumption that the person setting up the system will be doing his best to reduce their effects to be very small compared to the wb and radiator.

If everyone wants to include them, it will complicate the system pretty impressively because the k values will be needed for all fittings and the roughness factor will be needed for all tubing. You'd need to include a Moody diagram with at least a dozen or so best-fit correlations and, once all this was done, you'd need to iterate enough to form a PQ diagram for every possible fitting and every possible length of tubing. Then that PQ diagram must be fit like all the others so it can be combined with the WB and rad PQ diagrams so that it can then be combined with the pump curve, generating flow rate.

The k values are totally empirical and can be different even between two equally sized, seemingly equally-shaped elbows, for example. It is likely the k values for tees and elbows will be about the same, but I wouldn't be sure yet since I don't really have experience with simple fluid dynamics on this scale size.

Going this far you'd probably want to have delta-P considerations for bends and curves in tubing, which will be on a similar scale to elbows. These particular correlations I don't know off the top of my head, but I'm fairly certain even the Bernoulli equation could lead someone else to a theoretical equation.

All of this can be done if everyone wants.

It seems to me the project requires two significantly different parts - one using components to determine flow, the other using components and flow to determine an overall heat transfer coefficient. Seeing Joe was so kind to give us a forum, might we start making threads for each particular fascet of the project?

And, as futRtrubL says, should we look into considerations with pelt devices? Adding them would require consideration of temperature difference at any given heat load and voltage/current, but once that was done you would know the temperature of the hot side and the total heat leaving it, allowing one to run the heat transfer part of the simulator as if the hotside of the pelt were a CPU. Then the delta-T determined between the hotside and ambient would have the delta-T of the pelt to determine CPU temp.

The pelt part, I think, would require a third thrust of the simulator.

Once this is developed, I think ProCooling is going to gain a great deal of publicity among watercooling hobbyists.

Quite exciting, really.

Alchemy