Pump Chractaristics

1.0 Objectives: To establish a set of pump characteristics, at constant and variable speeds, using three types of pumps: positive (single cylinder double acting pump), displacement reciprocating pump, the centrifugal pump (horizontal), and the gear pump. Still we only used the reciprocating pump and the centrifugal pump. Furthermore; to compare under identical speed conditions the performance characteristics of each pump.

2.0 Theory: The primary function of pumps is not only the transportation of fluids, nut also to add energy to the transported fluids. Different types of pumps are designed to process fluids under variable engineering conditions. Calculations of pump characteristics: •

Water power = ρgQH*10-3 (kW). Where; o ρ: is the density of water (kg/m). o g: is the acceleration of gravity (m/s2). o Q: is the volumetric flow rate (m3/s). o H: is the head gain meter of water and equals; P/ρg*10-5. o P: is the delivery pressure – the suction pressure (bar).

•

Brake power = 2πSmLR*10-3 (kW). Where; o Sm: is the motor speed (rev./s). o L: is the brake load (N). o R: is the torque arm radius = 0.15 (m).

•

Overall efficiency (η) = water power / brake power.

Note that for the centrifugal pumps, the volumetric efficiency (ηv) = recorded volumetric flow rate (Q) / calculated volumetric flow rate (Qc). • The calculated volumetric flow rate, for the reciprocating pump, can be found as follows: •

Qc = 2nt(A-B)Sp*10-6 (m3/s). Where; o n: is the number of teeth in each gear = 12. o t: is the axial length of the teeth = 0.0413 m. o A: is the area enclosed between the adjacent teeth and casting = 0.00000054 m2. o B: is the area enclosed between teeth tips when they are about to come out of the mesh = 0.00000055 m2. o Sp: is the pump speed (rev./s).

3.0 Calculations & Results: Table 1; Centrifugal Pump Readings, @ 10 rev./s speed

Time (s).

Mass (kg).

21.00 24.00 26.00 31.50 36.00

5.00 5.00 5.00 5.00 5.00

Spring force (N). 11.58 11.77 10.79 10.40 10.59

Suction pressure (bar). 0.00 0.00 0.00 0.00 0.00

Delivery pressure (bar). 0.10 0.20 0.30 0.40 0.50

Table 2; Centrifugal Pump Readings, @ 15 rev./s speed

Time (s).

Mass (kg).

16.00 17.00 18.00 19.00 20.00

5.00 5.00 5.00 5.00 5.00

Spring force (N). 13.73 13.83 13.93 14.32 14.52

Suction pressure (bar). 0.00 0.00 0.00 0.00 0.00

Delivery pressure (bar). 0.40 0.50 0.60 0.70 0.80

Table 3; Centrifugal Pump Readings, @ 20 rev./s speed

Time (s).

Mass (kg).

12.00 12.50 13.00 13.50 14.00

5.00 5.00 5.00 5.00 5.00

Spring force (N). 18.64 18.84 19.03 19.23 19.52

Suction pressure (bar). 0.00 0.00 0.00 0.00 0.00

Delivery pressure (bar). 0.70 0.80 0.90 1.00 1.10

Table 4; Reciprocating Pump Readings, @ 15 rev./s speed

Time (s).

Mass (kg).

13.50 14.00 14.20 14.00 14.00

5.00 5.00 5.00 5.00 5.00

Spring force (N). 8.04 8.83 10.79 14.72 18.84

Suction pressure (bar). 0.00 0.00 0.00 0.00 0.00

Delivery pressure (bar). 0.50 1.00 2.00 3.00 4.00

Table 5; Reciprocating Pump Readings, @ various speeds.

ω (rev./s).

Time (s).

10.00 12.00 14.00 16.00 18.00 20.00

20.30 17.20 15.00 13.00 11.70 10.50

Spring force (N). 9.42 9.81 10.01 10.40 10.59 10.99

Suction pressure (bar). 0.00 0.00 0.00 0.00 0.00 0.00

Delivery pressure (bar). 1.50 1.50 1.50 1.50 1.50 1.50

Constant speed calculations for the reciprocating pump: Table 6; Reciprocating pump, @ speed of 15 rev./s:

Water power (kW). 0.02 0.04 0.07

Brake power (kW). 0.11 0.12 0.15

Overall efficiency (ηo). 0.18 0.33 0.47

Volumetric efficiency (m3/s).

61.73 59.52 58.69

Delivery pressure (bar). 0.50 1.00 2.00

0.11 0.14

0.21 0.27

0.52 0.52

59.52 59.52

3.00 4.00

0.16

0.14

Water power (kW).

0.14 0.12

0.11 0.1 0.08

0.07 0.06

0.04

0.04

0.02

0.02 0 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Delivery pressure (bar)

Chart 1; Delivery pressure VS. water power.

0.3

0.27

Brake power (kW).

0.25

0.21

0.2

0.15

0.15

0.12

0.11

0.1

0.05

0 0

0.5

1

1.5

2

2.5

3

Delivery pressure (bar).

Chart 2; Delivery pressure VS. brake power.

3.5

4

4.5

0.6

0.52

Overall efficiency.

0.5

0.52

0.47

0.4

0.33

0.3

0.2

0.18

0.1

0 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Delivery pressure (bar).

Chart 3; Delivery pressure VS. overall efficiency.

Volumetric efficiency (m /s).

62

61.73 61.5 61 60.5 60

59.52

59.5

59.52

59.52

59

58.69

58.5 0

0.5

1

1.5

2

2.5

3

3.5

Delivery pressure (bar).

Chart 4; Delivery pressure VS. volumetric efficiency.

4

4.5

Constant speed calculations for the centrifugal pump: Table 7; reciprocating pump @ speed of 10 rev./s

Manometer head (Hm). 1.019400 2.038700 3.058100 4.077500 5.096800

Water power (kW). 0.002400 0.004200 0.005800 0.006300 0.006900

Overall efficiency (ηo). 9.343700 18.383200 30.069800 41.607100 51.019000

Volumetric flow rate (m3/s). 0.000238 0.000208 0.000192 0.000159 0.000139

Table 8; reciprocating pump @ various speeds.

Brake power (kW).

Input torque (N.m).

0.0888 0.1109 0.1320 0.1568 0.1797 0.2071

1.4126 1.4175 1.5009 1.5598 1.5892 1.6481

ω (m/s).

Volumetric flow rate (m3/s). 0.000246 0.000291 0.000333 0.000385 0.000427 0.000476

10.00 12.00 14.00 16.00 18.00 20.00

25

Pump speeds (m/s).

20

15

10

5

0 0

0.00005

0.0001

0.00015

0.0002

0.00025

0.0003

0.00035

Volumetric flow rate (m /s).

Chart 5; Volumetric flow rat VS. Pump speeds.

0.0004

0.00045

0.0005

25

Pump speeds (m/s).

20

15

10

5

0 1.4

1.45

1.5

1.55

1.6

1.65

1.7

Input torque (N.m).

Chart 6; Input torque VS. Pump speeds.

25

Pump speeds (m/s).

20

15

10

5

0 0

0.05

0.1

0.15

Brake power (kW).

Chart 7; Brake power VS. Pump speeds.

0.2

0.25