Fluid Flow Note Chapter 7
Fluid Flow Note Chapter 7
Fluid Flow Note Chapter 7
CHAPTER 7
ROTATING EQUIPMENT
OUTLINES
Introduction
Types of Pumps
Performance of Pumps
Types of Compressor
Performance of Compressor
INTRODUCTION-PUMPING OF FLUID
a)
b)
a)
b)
c)
d)
e)
TYPES OF PUMPS
Reciprocating Pumps
1. PISTON PUMP
The
diaphragm
pump
has
been
developed for handling corrosive
liquids
and
those
containing
suspensions of abrasive solids.
It is in two sections separated by a
diaphragm of rubber, leather, or plastics
material. In one section a plunger or
piston operates in a cylinder in which a
corrosive fluid is displaced.
The movement of the fluid is transmitted
by means of the flexible diaphragm to the
liquid to be pumped. The only moving
parts of the pump that are in contact
with the liquid are the valves, and these
can be specially designed to handle the
material.
B. ROTARY PUMP
high-viscosity
GEAR PUMP
LOBE PUMP
2. CAM PUMP
6. SCREW PUMPS
SCREW PUMP
Mechanisms:
1. Fluid enters the centrifugal pump
to the center of the pump impeller.
CENTRIFUGAL PUMP
DISCUSSION
(20 MIN)
ADVANTAGES OF RECIPROCATING
OVER
CENTRIFUGAL PUMP
PERFORMANCE
OF PUMPS
PERFORMANCE OF PUMP
V2
V2
z
g 2 g
g 2 g
out
in
Water horsepower;
W
shaft Tshaft
Efficiency W
W
gQH
water horsepower
water horsepower
pump
W
bhp
Tshaft
shaft
Shut off
H=0
Q=0
H required hpump,u
P2 P1 2V22 1V12
( z2 z1 ) hturbine hL ,total
g
2g
1.
2.
3.
4.
H required H available
PUMP CAVITATIONS
CAVITATION
NPSH
NPSH
2
g
g
pumpinlet
Minimum NPSHrequired necessary to avoid cavitations
in the pump.
EXAMPLE 8.2
TYPES
OF COMPRESSOR
PERFORMANCE
OF COMPRESSOR
In practice, it is not possible to expel the whole of the gas from the
cylinder at the end of the compression; the volume remaining in
the cylinder after the forward stroke of the piston is termed the
clearance volume. This clearance will have a significant effect on
the work done per cycle.
The volume displaced by the piston is termed the swept
volume.
Therefore the total volume of the cylinder is made up of the
clearance volume plus the swept volume.
The clearance c is defined as the ratio of the clearance volume to
the swept volume.
COMPRESSION OF GASES.
COMPRESSION OF GASES
TOTAL VOLUME
1
V1 V4 Vs 1 c c
P
Where,
Vs= volume swept
c= clearance percentages/ratio
= isentropic ratio
TOTAL WORK DONE ON FLUID PER CYCLE
P2
P1Vs
1 P1
P2
1 1 c c
P
COMPRESSION OF GASES
P2
P1V1
1 P1
P2
nP1V1
1 P1
1
n
EXAMPLE 8.3