Bubble generation in oscillating heat pipe

In the previous models of oscillating heat pipe (OHP), only the evaporation and condensation in the liquid–vapor interfaces were considered as phase changes. Thus, only a simple sinusoidal oscillating motion of liquid slugs and vapor plugs was produced due to the small driving force. From our visualization results, the motions of liquid slugs and vapor plugs are very random and very different from the previous models. We observe that the bubble generation and growth phenomena are one of the reasons of the random motion of liquid slugs and vapor plugs. This means that those bubble generation and growth phenomena provide the large driving force. The velocity of liquid–vapor interfaces is accelerated suddenly when the TS (tube-size) bubbles, bubbles with the diameter equals to inner diameter of tube, are generated. The visualization results show that the TS bubbles will generate if the velocity of liquid slug is lower equal 0.2 m/s. The small bubble generation, before TS bubbles are generated, is ignored because they do not provide the large driving force. The model of TS bubble generation and growth is made by considering those visualization results to describe those phenomena.