The experimental investigation on thermal performance of a flat two-phase thermosyphon

Electronics cooling has become a key factor for improving the performance of electronic devices. An effective thermal spreader can achieve a more uniform heat flux distribution and thus increase heat dissipation in heat sinks. Two-phase thermosyphon is highly effective thermal spreader. In order to observe boiling and condensation phenomena, a transparent two-phase thermosyphon was prepared for observation and study. The characteristics of phase change heat transfer were experimentally investigated. The performance of the two-phase thermosyphon with different working fluids was measured for different heat fluxes. The experimental results show that it has the ability to level temperature and produces a very uniform temperature distribution in the condensation surface. The impairment of cooling condition on the external side of the condensation plate worsens the performance of the two-phase thermosyphon. Throughout the tested heat flux range in our experiment, the two-phase thermosyphon with water as working fluid has a better performance than that with ethanol as working fluid. We also studied the ability of the grooved evaporation surface to increase boiling heat transfer. Our experiments prove that the two-phase thermosyphon with a grooved evaporation surface has a much better performance due to the increased heat transfer at the evaporation surface. By comparing the thermal resistance of a solid copper plate to that of the two-phase thermosyphon, it is suggested that the critical heat flux condition should be maintained if two-phase thermosyphon is to be used as efficient thermal spreaders for electronics cooling.