Exergy analyzing of a horizontal-axis wind turbine in different conditions based on the BEM method

In this study, a horizontal-axis wind turbine based on the first and second laws of thermodynamics in different wind speeds and pitch angles is analyzed. The blade element momentum (BEM) theory coupled by the exergy equations was implemented to model the wind turbine at wind speeds from 6 to 15 m s(-1)and three different pitch angles 5 degrees, 10 degrees, and 20 degrees. The aim of this study was to evaluate the effects of metrological variables such as wind speed, temperature, pressure, and relative humidity on the exergy efficiency of the wind turbine in different pitch angles. It is found out that the wind turbine has been affected more by wind speed compared to other metrological parameters and the highest exergy efficiency is 42.8% at wind speed 12 m s(-1)and pitch angle 5 degrees. Also, it is shown that the rising of pressure changes and relative humidity decreases the exergy efficiency for all wind speeds and pitch angles. Increasing the relative humidity from 0.001 to 0.015 and pressure changes from 100 to 240 pa can decrease the exergy efficiency 1.76% and 1.26% at the wind speed of 8 m s(-1)and pitch angle of 20 degrees, respectively. In contrast, temperature has a positive impact on the exergy efficiency in the same condition and is able to increase the exergy efficiency 2% by changing from 5 to 35 degrees C at wind speed of 8 m s(-1)and the pitch angle of 5 degrees.