A novel transient thermohydraulic model of a micro heat pipe

•Transient thermal numerical model is presented for a micro heat pipe.•Governing equations for the transient state were derived by the thin liquid film theory.•Predicted performance variables were analyzed during the whole transient process.•The model was validate by experimental results in the literature.•Influence of the input variables on the transient simulation was investigated. A transient analysis model for predicting the heat and mass transfer performance in micro heat pipes is presented in this paper. The mass, momentum, and energy equations were separately applied for the vapor and liquid phases to predict the physical performance of the transient response more effectively. As a result, the axial distributions of the mass flow, pressure, and temperature were obtained for the vapor and liquid in a micro heat pipe. In particular, the profile of the liquid–vapor interface was obtained with liquid thin-film theory using the augmented Young–Laplace equation. Consequently, the interfacial areas for heat and mass transfer were predicted and incorporated into the governing equations of each phase. The analytical model was validated by comparing its solutions with experimental results. The discrepancy between the experimental and numerical results for the temperature difference between the evaporator and the condenser was less than 0.5 °C, which represents moderate accuracy.