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Title: Porous titanium structures manufactured by selective laser melting for heat pipe applications
Author: Wu, Zhining
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2020
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A heat pipe is an excellent heat transfer device that can be used in many applications such as space, terrestrial industries and electronic and energy conservation. The selection of used metal and working fluid varies depending on the operating environment. The appropriate wick structure used can make it work in any orientations even against gravity. However, conventional manufacturing processes have difficulty in producing heat pipe with complex shape and controllable wick structure, and the capillary lift height is limited for the current types of the wick structure if the againstgravity operating situation is necessary. In this study, Selective Laser Melting (SLM) is used to manufacture full-length heat pipes used in a space application with the wick structure designed and developed by the University of Liverpool based on a unit cell approach. The results show that the SLM process is capable of producing heat pipes with considerable length and the designed octahedral unit cells can provide sufficient capillary force and permeability to make the heat pipe work in space applications. In addition, the relationship between the fluid and thermal properties and characteristics (unit cell size, porosity, and pore size) have been investigated to understand the principle of the heat pipe better. Commercially pure titanium grade 2 (CpTi) and Ti6Al-4V (Ti64) are used as the materials because their excellent machining properties and lightweight are suitable for space application. The capillary lift height is measured using a weight-change method and a height-change method simultaneously to get a more accurate result. The findings of this study indicate that the fluid and thermal performances of the heat pipe are highly dependent on the morphology of the porous structure and the porous structures manufactured by the SLM process can provide bigger capillary force compared with other typical porous structures used in heat pipes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral