Five locally fabricated turbines with 3, 5, 7, 9 and 11 flat blades were locally fabricated and tested in conjunction with a vertical penstock of diameter 0.0762 m and nozzles of diameters 0.0158, 0.0212, 0.0266, 0.0343 and 0.042 m in a simplified Pico hydropower system. This study is an aspect of an ongoing work aimed at ultimately implementing the system for small power generation. The turbines were mounted at the foot of an overhead reservoir 6.95 m high. A 1.11 kW pump was used to recycle the water downstream of the turbine from an underground reservoir to the overhead reservoir, and a 3.9 kVA alternator used for the on-load tests. The turbine was linked to a 3.9 kVA alternator by a belt drive of pulley ratio of 6:1. The mean rotational speeds of each turbine and alternator shafts, volume of water displaced, and voltage developed were measured for each nozzle diameter. These data were used to compute flow rate, shaft and electrical power, and efficiency for each operation. Dimensionless flow, head and power coefficients as well as specific speed were computed and functional characteristic curves relating plotted. The turbine with 11 blades developed the maximum voltage with the nozzle diameter of 0.042 m and the least voltage for 0.0158 m diameter nozzle. The corresponding estimated power output computed using the manufacturer’s specifications on the alternator was also highest and the mean maximum efficiency based on the estimated power output was 0.4482. This indicates that the larger nozzle diameters combined with the turbine with higher number of flat blades favour beneficial system operation. The results indicate good potential for the system as a simple, environmentally friendly and decentralized small power generation system that can contribute to the current energy mix in Nigeria.

The basic operational parameters of a simplified Pico hydropower system were investigated using five locally fabricated turbines with 3, 5, 7, 9 and 11 splined blades in conjunction with a vertical penstock of diameter 0.0762 m and nozzle of diameters 0.0158, 0.0212, 0.0266, 0.0343 and 0.042 m. Water from an overhead reservoir 6.95 m high was discharged through the penstock to the turbines one after the other and recycled to the overhead reservoir using a 1.11 kW pump. For the on-load tests, a 3.9 kVA generator was linked to the system by a 6:1 pulley ratio belt drive. The mean rotational speeds of the shafts of each turbine and generator, volume of water displaced in the reservoirs and electrical quantities were measured for each nozzle diameter, while the shaft power, flow rate and efficiency were then computed. Dimensionless flow, head and power coefficients, and specific speed were computed and a functional characteristic relating them developed. The turbine with 11 blades developed a maximum voltage of 238 V with the largest nozzle diameter and a minimum voltage of 2.3 V with the smallest. The corresponding estimated power output computed using the manufacturer’s specification on the generator were 1765.96 W and 7.613 mW respectively. The mean maximum and minimum efficiencies based on the estimated power output were 0.8797 and 0.0007 respectively. This basically indicates that the larger nozzle diameters combined with the higher number spline blades favour good operation of the system. These show that the system has the potential of being a simple, environmentally friendly and decentralized small power generation system that could potentially contribute to the improvement of the Nigerian energy crisis.