Experimental investigation of a novel disc oscillating heat pipe and heat conduction effect on the startup of oscillating motion

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] A new disc oscillating heat pipe has been developed and tested for use in high heat flux applications with a localized heat source. The results show that the heat pipe offers a significant improvement in performance over a copper disc when charged with water or acetone. Despite the improvement, the heat pipe displayed some unexpected behavior. The heat pipe required far more power input to achieve startup than expected, given the heat pipe's small size, and the heat pipe demonstrated much smaller temperature oscillation amplitude than expected. To investigate this behavior, two additional oscillating heat pipes were constructed to test the effect of heat conduction through the adiabatic section of the heat pipe. The results clearly demonstrated that the presence of heat conduction through the adiabatic section of a heat pipe required far more power to startup, between 25 and 275 W additional power depending on the working fluid, condenser temperature, and orientation. The presence of heat conduction through the adiabatic section also demonstrated reduced oscillation amplitude. It was also found that the presence of heat conduction through the adiabatic section of an oscillating heat pipe resulted in better performance than a heat pipe without conduction through the adiabatic section.