Transient flow phenomena observed in heat pipes

The flow field in heat pipes is discussed in terms of fluid dynamics, and experimental results are presented. Experiments were performed in wickless vertical heat pipes in which fixed amounts of air were introduced as a noncondensible gas. Water or a water-alcohol mixture was used as the working fluid, and temperature distributions along the condenser section and the pressure were measured. The effects of the introduction of a noncondensible gas are explained, and output signal data from hotwires placed in the heat pipes are presented.