Mitigating thermal stratification in lakes/reservoirs through wind-powered air diffusers

Abstract

Thermal stratification can cause various water quality issues in large water bodies. To address this, a new wind-powered artificial mixing system is designed and experimentally tested for various Savonius rotor combinations (three-stage and four-stage rotors). These turbines directly utilize wind energy to draw air into the water column for aeration, bypassing the need for electrical conversion. The rotor performances were tested in terms of power and torque coefficients. Additionally, these rotors were tested for artificial mixing efficiencies in a specially designed water tank that can mimic thermal stratification typically observed in an actual water supply reservoir. Among the rotors, the three-stage rotor with a 60 degrees phase shift was found to exhibit superior power and torque coefficients, achieving a power efficiency value of 0.14. As for the mixing efficiency, the four-stage rotor with a 45 degrees phase shift excelled in mixing efficiency, reaching 95%.Practitioner Points A new wind-powered artificial mixing system is designed and tested for various Savonius rotor combinations. While keeping the total rotor height constant, the three-stage Savonius rotor class shows superior performance against the four-stage Savonius rotor class in terms of power and torque efficiency. Apart from the rotor performance results, the four-stage Savonius rotors show greater artificial mixing efficiency than the three-stage Savonius rotors. Single-pump/diffuser artificial destratification system exhibits better mixing efficiency than multiple-pump/diffuser systems. A new wind-powered artificial mixing system is designed and tested for various Savonius rotor combinations. The three-stage 60 degrees phase shift Savonius rotor demonstrated the best performance of turbine efficiency. The four-stage Savonius rotor with a 45 degrees phase shift connected to a single-pump system achieved the highest destratification efficiency at 95%. image