Factors affecting oscillating motion and heat transfer in an oscillating heat pipe

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] As demand has grown for thermal management solutions, interest in passive heat transfer devices such as heat pipes has grown as well. In particular, oscillating heat pipes (OHP) have shown the capacity to handle high heat loads and heat fluxes. However these devices are still a relatively recent development, and there is much that has yet to be understood. The current investigation studies the effects of heat conduction, channel layering, transient process, and wicks on the oscillating motion and heat transfer in an OHP as well as the oscillating motion influence on the flow field in a liquid plug. The results show that the heat conduction effect can improve overall performance as well as dampen temperature oscillations. The wicking structure effect was found to aid low power operation while neutron imaging shows that short circuiting of the fluid through the porous wall can be an issue with the concept. Increasing the number of channel layers was found to improve overall performance, including the ability to transport higher heat fluxes, and the use of interconnected layers was shown to decrease the effect of gravity. The study on pulsed heating shows that the OHP can start up in very short time and offers a significant improvement over a copper spreader. Computational fluid dynamics software is used to model oscillating Taylor flow. It is shown that the oscillating motion creates significant recirculation zones that should improve the heat transfer performance within the OHP.