An analysis method for exergy efficiency of wind turbines based on experiment and simulation

Abstract

ABSTRACTThis paper discusses the result of the exergy efficiency analysis of direct-drive wind turbines by obtaining the exergy loss and destruction characteristics as well as the law of influence of every original factor on the dynamic change in the exergy efficiency. After proposing an exergy balance equation for wind power systems, a mathematical model of exergy analysis is constructed. Based on this model, the exergy utilization rate was improved by considering unavoidable exergy destruction. At first, the exergy loss characteristics were obtained using particle image velocimetry technology and the exergy destruction characteristics were obtained using simulation of finite volume method. Then, by combining the result of experiment and simulation, it was found that the exergy loss rate reached the maximum value at a tip speed ratio of 4.5–5.0. The exergy destruction rate was weakened between 10 and 15 degrees. The maximum value of exergy efficiency rate was 0.38, corresponding to exergy loss and destruction rate of 0.58 and 0.06. Finally, five factors were analyzed to determine the exergy efficiency influence weights. These were as follows: slot type = 0.30813, air gap length = 0.28471, yaw angle = 0.13637, the tip speed ratio = 0.04116, and matching characteristic = 0.25250.