Operating Limits of Oscillating Heat Pipes

This paper describes the experimental analysis of the operating limits of oscillating heat pipes. An oscillating heat pipe with check valves was used to eliminate the effect of amplitude shortage of oscillatory flow. The existence of a limit of the operating temperature and the maximum heat load is confirmed and it is shown that the limit of the operating temperature exhibits strong dependence on heat load. The result is discussed by comparison with the pressure oscillation and heat transfer characteristics and it is suggested that the limit of the operating temperature is stimulated by the increase in necessary flow rate due to the decrease in latent heat of evaporation with a rise in temperature. The pattern of increase of pressure oscillation with heat load governs the variation in the operating limit