Building Exhaust Recovery, A Small Scale Wind Turbine Design

Abstract

Small-scale wind turbine design is a growing field as larger utility turbine wind recovery sites are nearing saturation. We present a complete method for the design of small, application-specific turbines based on the blade element theory. This thesis consisted on the design, manufacturing and wind-tunnel-testing of the rotor of a small turbine for wind energy recovery. A complete redesign loop allowed for the implementation of lessons-learned from the first prototype, in terms of both structural deformation and root twist starting torque, on the second prototype that was thoroughly tested for aerodynamic performance in the wind tunnel. The design process was focused on a novel motivation: the recovery of energy from building ventilation exhaust. Building exhaust systems present a unique opportunity for energy conversion based on how air is moved using a system of exhaust fans and the inefficiency and costliness of those systems. This thesis approaches this problem from a theoretical, computational and experimental perspective, with the goal of producing a practical prototype to validate the design and manufacturing process. The design takes the theoretical-optimum characteristics from blade element momentum theory. The design is renewed after computational modeling, while exploring various manufacturing techniques. Prototype development and testing is used to further understand the operation of the system and optimization in preparation for the final design. A final prototype, based on experimentation on the first design, was built and tested in the wind tunnel, providing experimental performance data for real life power generation and operating conditions evaluation. This data also allows for comparison against the design values in order to validate the design-build-test process.