WIND ENERGY SYSTEMS - Cd3wd

Chapter 7—Asynchronous Loads 7–5
Figure 2: Diagram of piston pump. (Courtesy of Dempster Industries, Beatrice, Nebraska.)
D = AL p f m 3 /s (1)
where A is the cross sectional area of the piston, L p is the length of the stroke, and f is the
number of pump cycles per second.
The volume capacity of the pump is given by
Q v = D(1 − s) m 3 /s (2)
where s is the slip. The slip is a measure of the losses due to leakage around the packing and
through the valves. For a well built pump, slip is probably between 0.03 and 0.05, increasing
as the pump wears.
Example
A piston pump has an area A of 0.01 m 2 and a stroke of 0.2 m. The manufacturers data sheet
lists a recommended maximum operating speed of 50 cycles per minute. The slip is estimated as 0.05.
What is the pump volume capacity?
Q v = D(1 − s) =AL p f(1 − s) =(0.01)(0.2) 50
60 (1 − 0.05) = 1.58 × 10−3 m 3 /s
Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001