Transient characterization of flat plate heat pipes during startup and shutdown operations

Analytical models for predicting the transient performance of a flat plate heat pipe for startup and shutdown operations are developed in this work. These models can be utilized separately for a startup or a shutdown operation, respectively. The two models can also be combined together to simulate the thermal performance of a flat plate heat pipe in cyclical startup and shutdown operations. The transient temperature distributions in the heat pipe walls and wicks are presented in this work. The results reveal that the thermal diffusivity, the thickness of the wall and the wick, and the heat input pattern affect the heat pipe time constants. The wicks create the main thermal resistance resulting in the largest temperature drop in the heat pipe, thus substantially influencing the performance of the heat pipe.