Experimental investigation on the heat transfer characteristics of axial rotating heat pipes

The heat transfer performance of axial rotating heat pipes was measured under steady state at rotational speeds up to 4000 RPM, or a maximum centrifugal acceleration of 170 g, and heat transfer rates up to 0.7 kW. A cylindrical and an internally tapered heat pipe with water as the working fluid were tested with different fluid loadings that ranged from 5% to 30% of the total interior volume. The measurements were used to characterize the effects of rotational speed, working fluid loading, and heat pipe geometry on the heat transfer performance. The internal taper on the condenser was found to significantly increase the heat transfer rate compared to the cylindrical case. A comparison between the test results and predictions from previous models showed that natural convection in the liquid film at the heat pipe evaporator plays an important role in the heat transfer mechanism at high rotational speeds.