2016 journal article
System Efficiency of Miniature Horizontal-Axis Wind Turbines With and Without Gear Transmission
JOURNAL OF ENERGY ENGINEERING, 142(1).
AbstractIn this paper, two miniature horizontal-axis wind-turbine systems (MHAWTs) with and without gear transmission consisting of commercially available off-the-shelf components were designed for harvesting energy from ambient airflow to power wireless sensors. The basic performance of the MHAWTs was tested at various wind speeds (2–8 m/s) and resistive loads (10–500 Ω). The maximum output powers of the MHAWT with and without gear were 8.6 and 11 mW at the wind speed of 4 m/s, which suggested that both MHAWTs enabled powering low-power wireless sensors in natural airflow environment. To analyze the system efficiency and predict the optimal resistive load of the MHAWTs, an equivalent-circuit model was used. According to this model, the maximum system efficiency of the MHAWT system was predicted to be 14.8%. The actual maximum system efficiency of the MHAWTs with and without gears was tested as 8.4% and 7.5% at the wind speed of 8 and 6.5 m/s. In addition, the predicted optimal resistive loads of the M...