Final exama nd answer to Micro Hydro power plant

1. College of Engineering
Final Examination
ME ELEC 2 – Micro- hydro Powerplant
1st Semester, AY 2020-2021
December 10, 2020 ;100:00 am -2:00 pm
NAME : _____________________ Date :___________
Student No.__________________ Score:__________
Directions: Choose the most appropriate answer. Submit the screenshot or image
copy of the solution to the LPUB portal.
1. A centrifugal pump has an 8-inches diameter suction line which reads 10-inches of mercury
vacuum. The discharge is 6-inch in diameter and has a pressure 3 ft. above the vacuum gage of
30 psi. If the discharge is 3 cu.ft./sec. And bhp is 36, determine The total dynamic head
A.
B.
C. 63.38 𝑓𝑡
D.
2. What is the Efficiency of the pump in number 1
A.
B. 59.9 %
C.
D.
3. Water from an open reservoir A at 8 m. elevation is drawn by a motor-driven pump to an open
reservoir B at 70 m. elevation. The inside diameter of the suction pipe is 200 mm. and 150 mm.
for the discharge pipe. The suction has a loss of head three times that of velocity head in the 200
mm. pipe. The discharge line has a loss of twenty times that of the velocity head in the discharge
pipeline. The pump centerline is at 4 m. Overall efficiency of the system is 78%. For discharge
rate of 10 L/s, find the power input to the motor and the pressure gage readings installed just at
the outlet and he inlet of the pump in kPag. What is the Head loss at suction side?
A. 0.015498 m
B.
C.

2. D.
4. What is the head loss at discharge site.
A. 0.3266 m
B.
C.
D.
5. What is energy equation between tank A and 1
A.
B.
C.
D. 39.02375 kPA
6. What is the energy between tank 2 and 3|
A.
B. 650.2783 kPA
C.
D.
7. What is the energy equation between tank A and B
A.
B.
C.
D. 61.6579 m
8. Output power of the pump
A.
B.
C.
D.6048. 6402 Watts
9. Power input to the motor
A.7754.6669 Watts
B.
C.
D.
10. Water from a reservoir is pump over a hill through a pipe 450 mm in diameter and pressure of
1.0 Kg/cm2 is maintained at the summit. Water discharged is 30 m abover the reservoir. The
quantity pumped is 0.5 m3/s. Frictional losses in the discharge and suction pipe and pump is
equivalent to 1.5 meters head loss. The speed of the pump is 800 RPM. ; What amount of
energy must be furnished by the pump in KW?

3. d= 450mm = 0.45m
P1 = 1 kg/cm2
= 98 kPa
Q = 0.5 m3
/s
Z = 30 m
hf= 1.5 m
A.
B.
C. 0.625 m3
/s
D.
11. If the speed of the pump was increased to 1000 RPM, what are the new values of discharge,
head, and power?
A. 321.754 kW
B.
C.
D.
12. A 10-inch pipe which carries a flow of 5 cu. ft. per second branches into a 6-inch line, 500 ft. long
and as 8-inch, 1000 ft. line. The friction factor is 0.022 for both pipes. Find the flow rate in the 8-
inch line.
L1 = 500 ft
L2 = 1000 ft
f = 0.022
D1 = 6 in
D2 = 8 in
m = 5 ft3
/s
A.
B. 2.96 (ft^3)/s
C.
D.
13. A pump is to deliver 80 gpm of water at 140 deg.F with a discharge pressure of 150 psig. Suction
pressure indicate 2 inches of mercury vacuum. The diameter of the suction and discharge pipes
are five [5] inches and four [4] inches, respectively. The pump has an efficiency of 70% while the
motor efficiency is 80%. Determine: Water horsepower of the pump;
Given:
𝑄 = 80
𝑔𝑎𝑙
𝑚𝑖𝑛
𝑃𝐴 = 2 𝑖𝑛𝐻𝑔𝑣
𝑃𝐴 = 150 𝑝𝑠𝑖𝑔
 𝑃
= 70% 𝑜𝑟 0.7
 𝑚
= 80% 𝑜𝑟 0.8

4. A.
B.
C. 5.202 ℎ𝑝
D.
14. Brake horsepower of the pump;
A.
B. 7.432 ℎ𝑝
C.
D.
15. Power input to the drive motor;
A. 7.432 ℎ𝑝
B.
C.
D.
16. Combined motor-pump efficiency.
A.
B.
C.
D. 55.99%
17. A submersible, multi-stage, deepwell centrifugal pump, 300 GPM capacity at 3450 rpm is
installed in well where the static level is 120 feet below the fround level. Drawdown at 300 GPM
flow is 10 feet. Pump is installed 27 feet below static water level. The centerline of pump
discharge pipe is 3 feet above the ground 1 level. The centerline of well is 3 m. horizontally away
from centerline of storage tank. Total friction loss in piping is assumed to be 6 feet. Calculate the
total head developed by the pump.
A.
B.
C. 147 ft
D.
18. If each stage of the pump can develop a head of 36 feet, how many stages are in the pump.
A.
B.
C.

5. D. 4 stages
19. Calculate the brake horsepower of the pump if the pump efficiency is 74%.
A. 15.06419016 hp
B.
C.
D.
20. A submersible multi-stage, centrifugal deep well pump 260 gpm capacity is installed in a well 27
feet below the static water level. Drawdown when pumping at rated capacity is 10 feet. The
pump delivers the water into a 25,000 gallon capacity overhead storage tank. Total discharge
head developed by pump including friction in piping is 243 feet. Calculate: Brake horsepower
required to drive pump if each impeller develops a head of 38 feet at 3,450 rpm.
A.
B.
C.
D. 2.497444605 hp
Prepared by:
Engr. Charlton S. Inao
Faculty – BSME
Reviewed and validated by:
Dr. Nestor C. Camello,
BSME-Department Chairman
Approved by:
Dr. Conrado I. Dotong
Dean, College of Engineering