Investigation on the Performance of Pico-hydro Generation System ...

addition, the estimated maximum power will be used to
verify the efficiency of the pico-hydro system.
C. Battery Charging Ability Test
This test is carried out to determine the ability of the
pico-hydro system to store energy. Thus, a 9.6V,
700mAh, Ni-cad rechargeable battery shown in Fig. 1 has
been tested. This type of battery is normally used for
robotic and radio/remote control toys.
Fig. 1 A 9.6V, 700mAh Ni-cad rechargeable battery pack
3. Results of Performance
A. Open Circuit Test
The open circuit test results in Table 1 show the water
pressure level, rate of water flow, open circuit voltage and
generator speed within 24 hours test.
TABLE 1 OPEN CIRCUIT TEST RESULTS
Time
Speed
(rpm)
Voltage
(V)
Pressure
(psi)
Water Flow
Rate (l/s)
1.00 am 1601 71.8 18 0.240
2.00 am 1602 70.9 18 0.240
3.00 am 1604 71.9 18 0.240
4.00 am 1600 70.1 18 0.238
5.00 am 1597 69.3 18 0.238
6.00 am 1432 66.5 17 0.238
7.00 am 1410 64.4 17 0.236
8.00 am 1318 60.2 15 0.232
9.00 am 1300 60.0 15 0.232
10.00 am 1250 57.2 15 0.230
11.00 am 1246 56.9 15 0.230
12.00 pm 1105 49.8 13 0.225
1.00 pm 1320 60.9 15 0.232
2.00 pm 1257 58.6 15 0.230
3.00 pm 1320 60.3 15 0.232
4.00 pm 1307 61.5 15 0.232
5.00 pm 1282 59.2 15 0.232
6.00 pm 1257 58.3 15 0.230
7.00 pm 1250 57.3 15 0.230
8.00 pm 1192 54.9 15 0.225
9.00 pm 1197 55.3 15 0.225
10.00 pm 1243 56.4 15 0.230
11.00 pm 1240 56.0 15 0.230
12.00 am 1256 57.4 15 0.230
Fig. 2 Voltage versus time
Fig. 3 Water pressure versus time
Fig. 4 Water flow rate versus time
The recorded data are plotted accordingly in Fig. 2, 3
and 4 to ease the observation of the water energy potential
within 24 hours. In general, the open circuit voltage is
directly proportional to the generator speed (refer to Fig.
5) [7], thus, it is utmost interest to observe the voltage,
water pressure and water flow rate trend rather than the
generator speed. It can be noted in Fig. 2 that the
generated open circuit voltage is dependant on the
pressure and flow rate of the consuming water distributed
through pipelines. However, water flow rate seems the
most dominant parameter in controlling the voltage level
as water pressure did not change significantly within the
24 hours period. Since voltage has close relationship with
power, these results provide initial information that the
pico-hydro system follows the general output power
equation of a hydro power system [6]:
P out
= 0 . 74 × P × Q × g × η
(1)
Where,
Pout = Output power (Generator output)
P = Pressure (psi)
Q = Water flow rate (liter/second)
g = gravity (9.81 m/s 2 )
η = efficiency