Design and Optimization of a Wind Turbine for Rural Household Electrification in Machakos, Kenya

Abstract

Machakos is an area characterized by low wind speeds in the range of 0.5 m/s to 5 m/s with an annual average wind speed of 3.5 m/s. Maximum power generation from wind requires the appropriate design of the conversion system. In this study, two HAWT rotor blades were fabricated using Styrofoam and aluminium with a pitching mechanism to maximize power. The system was tested in a wind tunnel environment at a wind speed range of 0 m/s−20 m/s. RPMs and torque were measured and then used to calculate the TSR and power coefficients at different pitching angles. Energy optimization was performed by varying the pitch angles from 0 to 40 degree and rotational speeds, blade shape, and also a variation of blade materials. The analysis of tip speed ratios showed positive skewness implying high potential for significant energy generation at low wind speeds. At the rated wind speed of 5 m/s, Styrofoam blades performed optimally at a pitch angle of 20 degree with a tip speed ratio (TSR) of 2.1 corresponding to a Cp of 0.465. This translates to 238 W of power. Aluminium type performed optimally at a pitch angle of 15 degree with a TSR of 1.9 corresponding to a CP of 0.431, a power estimate of 220 W. These findings showed that Styrofoam blades were more effective and thus suitable for application in wind systems. The understanding gained from this study could be useful to the HAWT research community and can be extended to the turbine designs for small-scale microgrids and utility applications.