Thermal performance of rotating two-phase thermosyphon disc

Abstract

This experimental work examines the thermal performances of rotating two-phase thermosyphon disc (RTPTD) using centrifugal forces to drive vapor–liquid circulation at sub-atmospheric pressures with cooling applications to electrical rotor machineries. Boiling flow images, boiling/condensation heat transfer rates and the composition of total thermal resistances (Rth) for the RTPTD are examined at rotor speeds of 250, 500, 750 and 1000rev/min with four sets of boiling numbers (Bo) and condenser thermal resistances (Rth,con) at each rotor speed. Experimental conditions in terms of Bo, Rth,con and relative centrifugal acceleration (Ω) are in the respective ranges of 70–153, 0.065–0.25KW−1 and 4.3–70. While both boiling and condensation heat transfer rates are raised by increasing rotor speed, heat transfer properties over the evaporator and condenser of present RTPTD are respectively improved and impeded by raising Bo. Due to the combined Bo and Ω effects on each constituent thermal resistance of Rth, the total thermal resistance of the present RTPTD is reduced by increasing Bo and/or Ω. Empirical correlations determining the boiling/condensation heat transfer rates and the evaporator pressures as well as Rth that permit the evaluations of individual and interdependent effects of Ω, Bo and Rth,con are generated to assist engineering applications.