Design and Performance of a Gravity Water Fed In-Duct Crossflow Turbine for Hydropower Generation

Abstract

In Kenya, 70% of households are connected to the grid; however, the consumption of electricity, among households, has reduced by 30%. To address power accessibility inadequacy, especially in rural areas, and develop an appropriate in-duct hydropower (HP) generation system, several horizontal crossflow turbine prototypes were designed based on the field survey data collected from existing pressurized water supply ducts. An assessment carried on water supply schemes in Makueni County led to gathering and mapping required data that included; pipelines of diameters ranging from 50 to 200 mm, water pipe slopes of lengths ranging from 40 to 800 m, slope elevation heads between 14 and 183 m, and 33 potential HP sites with HP production capacity between 0.59 and 23.63 kilowatts. Various horizontal crossflow turbines were designed, fabricated, and tested for HP generation performance. The designed horizontal crossflow turbine has specifications that include a 0.99 mm diameter (D_o) impeller that rotates clockwise, 12.5 mm blade radius of curvature, 0.7033 turbine efficiency, turbine inner diameter of 30 mm (D30), 10 blades (B10), 100 mm diameter pipe, turbine speed of 2210 revolutions per minute (RPM) and production of 5.92 V at a head of 6 m hence making a turbine designed and designated as D30B10. It provides savings on power cost to the extent that in 7.5 years’ time, an institution would have saved enough funds to install a new station. On the basis of these findings, it was concluded that in-duct power generation technology is a promising energy harvesting system for rural communities. HP from ducts provides a paradigm shift to the rural communities’ source of energy and its use, hence reducing the use of firewood for cooking, which is at 89% and effectively reducing deforestation. More studies are recommended to prototype a full-scale product of the D30B10 turbine to improve technologies for harnessing HP from existing gravity water ducts.