According to the structural characteristics and heat transfer characteristics of single-loop oscillating heat pipe, a comprehensive mathematical model with consideration of gas-liquid two-phase flow, heat and mass transfer, phase change in the oscillating heat pipe is established.Selecting ethanol and water as the working fluid, and numerical simulating the oscilla-ting heat pipe by using Vof method, the gas-liquid phase change in the running process of oscillating heat pipe is studied.The results show that the heat transfer performance is related to the latent heat of vaporization, and the OH...