The impact of relative dynamic-pressure losses and other factors on overall power demand and energy savings
The pattern of pressure drop through a system during off-design conditions is critical for centrifugal-pump and fan applications and even more so for systems employing variable-frequency-drive (VFD) control. Typically, the assumption that, based on the affinity laws, relative electrical-power demand is changed following the variation of relative flow rate, which is raised to the power of 3, is made. However, this assumption is correct only when overall system relative pressure differential changes in direct proportion to relative flow rate, which is elevated to the power of 2.
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