Design Changes to Archimedes Screw Turbines to Improve Energy Generation

Abstract

Over the past two decades, Archimedes screws have transitioned in use from pumps to turbines, specifically in wastewater treatment facilities, and have exhibited slow growth in ubiquity. The major challenge with Archimedes screw turbines (ASTs) is their high cost, low energy generation, and subsequent low return on investment. Studies over the past decades have focused on optimization of screw performance, via the maximization of efficiency at specific flow rates. However, given that wastewater treatment facility flow rates vary diurnally, and ASTs are often shut off during low flow at night, it is imperative that designs that accommodate for these daily flow rate drops be created. This thesis searches for such a design, but only finds one design with moderate improvements at lower flow rates. This thesis also found that increasing the number of blade turns rather than increasing the number of blades, could present a more cost-effective method of maximizing efficiency. The final finding verified that though bucket fill was important for Archimedes screw pumps, it had little impact on the performance of ASTs.