Thermal performance investigation of vapour chamber heat spreader

Velardo, J 2019, Thermal performance investigation of vapour chamber heat spreader, Doctor of Philosophy (PhD), Engineering, RMIT University.

Document type: Thesis
Collection: Theses

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Title Thermal performance investigation of vapour chamber heat spreader
Author(s) Velardo, J
Year 2019
Abstract The seemingly endless development of integrated circuits has seen a dramatic increase in the usage of electronic devices over the past few decades. It would be difficult to imagine life without devices like computers, laptops, tablets and mobile phones to name a few. Yet all of these will unavoidably generate heat during operation. Removing this heat in an acceptable manner has been the subject of much research and development in order to cope with the ever increasing electronic demands. Two-phase heat transfer devices generally form part of the thermal management system for many electronic devices due to their excellent performance and passive operation. Of these two-phase heat transfer devices, the vapour chamber acts like a heat spreader which can effectively transfer heat from concentrated sources to larger sinks. The intention of this research was to perform an experimental and numerical investigation into vapour chamber heat spreaders. The experimental investigation consisted of the development of a vapour chamber with both sintered powder and mesh structures for the evaporator wick. This composite wick was designed such that the inherent strengths in each wick structure could be better utilised. An experimental setup was also developed to measure thermal performance. Through detailed measurements, spreading resistance was determined. It was found that the vapour chamber had superior performance to that of a solid copper heat spreader with reductions of up to 50% observed in spreading resistance. Further measurement of the vapour chamber temperature distribution highlighted some interesting heat transfer mechanisms that governed performance. Thereafter, a simple numerical model was introduced. It assumed that all heat transfer mechanisms were conduction based and thus the detailed aspects of two-phase heat transfer were replaced in favour of simple conduction mechanism. Through this model, which was validated against the solid copper heat spreader, the effective thermal conductivity of the vapour region was determined for a number of cases. It was found to be a function of heat source size, with reduced heat source sizes leading to reduced values for effective thermal conductivity of the vapour region. This value has been rarely explored in the literature however it provides useful information to designers of thermal systems which use vapour chambers. Some of the intricacies of this value were explored in further detail. Finally, an investigation was performed into the composite evaporator wick structure using the numerical model. This investigation helped determine practical guides for wick structures and provided suggestions for improving thermal performance of the vapour chamber. The overall research presented here will help in the continued development of the vapour chamber so that they can better achieve future demands.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Engineering
Subjects Energy Generation, Conversion and Storage Engineering
Keyword(s) Thermal management
Vapour chamber
Spreading resistance
Effective thermal conductivity
Electronic cooling
Two phase heat transfer
Wick structure
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Created: Tue, 26 Nov 2019, 12:40:59 EST by Adam Rivett
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