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https://hdl.handle.net/2142/83925
Description
Title
Developing Adiabatic Two-Phase Flow
Author(s)
Bowers, Chad D.
Issue Date
2009
Doctoral Committee Chair(s)
Predrag Hrnjak
Department of Study
Mechanical Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Language
eng
Abstract
In order to understand the characteristics of the adiabatic development of two-phase flow this study was performed using H2FC-CF 3 - 1,1,1,2-Tetrafluoroethane (R134A) as a working fluid in three different transparent tubes. The flow was visualized using a high speed camera. To better (faster and more objectively) analyze the flow, a technique was developed to determine the separation distance using a statistical method known as Change Point Analysis. The distance at which the phases become separated can be an important parameter in design of inlet tubes to evaporators. A method for determining the void fraction from the visualization results was developed and presented. This method allows for a local, instantaneous or time averaged, void fraction determination in Stratified, Intermittent, and Annular flows and could conceivably be implemented into an online void fraction determination. Qualitative examination of these images allowed for the determination of the distinct regions of flow development: Well-Mixed, Separating, Separated but Developing, and Developed regions. Dynamic examples of transitions between flow regimes in the process of flow development were also presented; specifically, transitions from Stratified to Intermittent flow.
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