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Here is a .GIF that illustrates both our points. At
zero flow, the pump shaft horsepower is less than at rated flow, but all the
energy is going into heating the water.
I believe that the reason Davies Craig claims that
they save a lot of horsepower, is because at high rpm, the pump is not running
at its high efficiency point. It is clear from the successful EWP tests of Todd,
that the actual energy required to pump the water is small. So if DC is correct,
then they are using the high rpm point for the "horsepower saved".
Bill Schertz
Tracy
Wrote:
All true. But my point was that there is
still *less* shaft HP required to turn the pump when the thermostat
restricts the flow through the pump and we are not wasting engine HP by
having a restriction in the circuit as is occasionally claimed. True,
the pump is operating in a less efficient part of its operating curve, but
do we really care?
Tracy
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