During the operation of parallel evaporative micro-channels, system instability may occur in terms of cyclical fluctuations at a long period. This is due to the co-existence of the liquid phase flow at high mass flux and the two-phase flow at a lower mass flux among different parallel channels under the same total pressure drop. For a system at constant flow-rate pumping, with a pressure regulating tank, and a constant heating pre-heater, the system may experience severe alternations between these two states of boiling and non-boiling with a period of minutes. This cyclical system instability has been modeled. In the model, the existence of the liquid phase flow happens at conditions of inlet subcooling and low surface heat flux that the boiling inception is hard to occur. Accordingly, the system instability criteria are established in terms of a System binary states parameter S and a non-dimensional surface heat flux, which is normalized with the boiling incipient heat flux. This model has been validated experimentally.
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System Instability of Evaporative Micro-Channels
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Lee, HJ, & Yao, S. "System Instability of Evaporative Micro-Channels." Proceedings of the ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. Volume 3: Combustion, Fire and Reacting Flow; Heat Transfer in Multiphase Systems; Heat Transfer in Transport Phenomena in Manufacturing and Materials Processing; Heat and Mass Transfer in Biotechnology; Low Temperature Heat Transfer; Environmental Heat Transfer; Heat Transfer Education; Visualization of Heat Transfer. San Francisco, California, USA. July 19–23, 2009. pp. 301-310. ASME. https://doi.org/10.1115/HT2009-88217
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