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On Fri, 2005-01-14 at 10:44, Jerry Hey wrote:
> Believe me when I say that until TODAY I thought the EWP was dead in
> the water. That makes me about 2 years behind. All I knew was what I
> read on ACRE. (That is a scary sentence.) I checked EWP in the
> archives and read about three hours worth of messages going back to
> around Oct. 2002. If I had ten more hours, I could read them all.
> And I will read them as soon as I can. In the meantime, is anyone
> interested in briefly bringing me up to date. Thanks, Jerry
Jerry, I was looking at the flow numbers that Todd provided a while
back, and comparing them with the numbers that Davie's Craig provided to
me. Todd said that he cleaned up the flow in his system as much as he
could manage, and it looked like he did a good job.
>From the best I could tell, Todd only has about 9psi of head pressure.
The calculations I've seen coming from the ACRE list are all based on an
assumption of 30psi. Todd was getting sufficient flow on only the
battery and with cold well water. In the air the alternator is usually
operating, driving up the system bus voltage. And if the water isn't
getting warm, you have much bigger problems. Warm water is less viscous
and easier to pump than cold water. As the EWP is somewhat sensitive to
input voltage and all pumps are responsive to fluid viscosity, he'd be
getting more actual flow under normal circumstances than from what he
test.
The calculations from the ACRE list that I've seen are also predicated
on 30gpm flow. 30gpm is a nice safe number, but is not an absolute
necessity. The number can easily drop IF you're willing to design for a
higher temperature drop across the radiator. In fact, for the same
amount of radiator and heat removal, a lower flow rate WILL result in a
higher temp drop up to the point where you get steam in and water out
8*)
It's just like Leon said earlier, if you lock yourself down to the wrong
assumption, the resulting logic and calculations arent' worth the
electronics they're posted to the list with.
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