Part 1: Lec2
Class Problem 1: The chilled water system for a 25-story building has a pump located at
the ground level. The lost head in a vertical riser from the pump to an equipment room on
the 25th floor is 9.144 m of water, and the pump produces 76 m of head reversibly. What is
the pressure (P1) on the suction side of the pump for a pressure (Pe) of 55 kPa (gage) to
exist in the riser on the 25th floor? Assume 3.70 m of elevation per floor & water density is
ρ=997 kg/m3.
Assumptions: It is reasonable to assume the kinetic energy (k.e.) change
(∆C2)/2≈0 between any two points is small as most of the fluid kinetic energy
is converted into either pressure or head to climb the 24 floors.
Solutions: (Provided in this lecture note- Self Study)
Problem formulation
Hloss=9.144 m, through vertical water supply line
Ze-Z2= ∆Z= 24*3.70= 88.8 m
H= total head= P/(ρ.g) + C2/(2.g) + Z
H2-H1= head developed/produced across pump= 76 m
Pe = 55 kPa
m1 = m2 = me= continuity
Determine: P1 = ?
Class Problem 2: (to be worked out in next class)