Thermal Aging Analyses of a Gearbox oil Used for Wind Turbine Nacelles

Abstract

Abstract The original gearbox oil (typed CALTEXMEROPA 320) used for wind turbine was heated for 96 h at 155.0 °C in air to simulate the thermal aging process. By thermogravimetry (TG) experiments in air, the thermal stability of the gearbox oil and the oil heated after 96 h were compared. The Advanced Kinetics and Technology Solutions (AKTS) tool was used to explore related thermal aging effect. The results demonstrate that the thermal decomposition processes of the gearbox oils can be divided into three stages, with major mass loss occurring in the second stage. The maximum mass loss rates are -12.0 %/min (0 h) and -13.0 %/min (96 h). The S value (combustibility index) of original gearbox oil (7.35) is higher than that of preheated oil for 96 h (6.70). The thermal aging curve of gearbox oil presents an inverted L-shape, the thermal aging rate is faster in the first week and then gradually slows down. Practically, the fire risk of gearbox oil in the initial application stage is the highest to induce a potential burning process in an unwanted high temperature (say, higher than 270.0 °C based on TG results) environment.