Abstract:
Pico hydro is one of the most appropriate and an economical way of providing electricity for rural areas anywhere in the world, where there is sufficient hydro energy potential. The present technology trend in relation to Pico hydro uses a domestic centrifugal water pump as the turbine. In this process, standard pump units are used as a low-cost alternative to conventional turbines to provide stand-alone electricity generation for isolated houses and remote communities who do not
have electricity. Considering the high cost and unavailability of suitable axial flow pumps, the centrifugal pumps are used as turbines. Deferent types of impellers for the turbine were designed, fabricated and tested. These impellers were developed by changing the number of vanes, vane angles, diameter of the impeller, type of impeller (closed type, semi open) and vane thickness. Brake load testing was carried out for those
impellers to check their performance to be used as turbines. Efficiency of an existing impeller when used as a turbine was 13% and maximum mechanical
output power was 69 W running at 700 rpm, 4.0 1/s flow rate and 18 psi pressure head. The newly developed impellers, which were made of fiber reinforced plastic (FRP), reached a maximum mechanical output power of 130 W, running at 1000 rpm, flow rate of 4 1/s, pressure head of 21 psi and the efficiency was 22%. It is envisaged that the efficiency could be further improved beyond 30% by increasing the flow rate. Further research and development is done to optimize the impeller design.
