Experimental investigation and numerical prediction on heat transfer performance of a high speed radially rotating heat pipe

Abstract

A CFD model considering the saturation pressure difference inside radially rotating heat pipes (RRHP) was proposed to reveal the heat transfer characteristics. To validate the model, copper-water RRHPs were designed and experimented. These experiments were conducted under equivalent centrifugal accelerations ranging from 100 g to 1500 g, with heat inputs varying from 40 W to 240 W. The centrifugal force has a significant influence on heat transfer in the evaporator, leading to the observed of two different working states in the RRHP: forced convection and pool boiling. An unstable transition state may be observed between these two states. As the rotation speed increased, the occurrence of pool boiling gradually suppressed and the heat transfer performance of the RRHP decreased. At 100 g, the minimum thermal resistance was 0.1792 K/W and at 1500 g the minimum thermal resistance slightly increased to 0.2369 K/W. The numerical results showed demonstrated strong agreement with the experiments, with an overall error below 10 %. Subsequently, a working condition diagram was included to provide a dimensionless description for the RRHP heat transfer behaviours based on the Weber number and Bond number. Finally, the heat transfer performance of RRHP under centrifugal accelerations ranging from 2000 g to 1000 g was simulated. The results indicated that even under 10000 g, RRHP can still maintain the thermal resistance at 0.2527 K/W. And the model can be used to further investigate the potential application of different RRHPs in high-speed rotating machinery.