標題: Bubble characteristics in time periodic saturated flow boiling of R-134a in a narrow annular pipe due to heat flux oscillation
作者: Chen, C. A.
Lin, T. F.
Yan, Wei-Mon
機械工程學系
Department of Mechanical Engineering
關鍵字: Time periodic saturated flow boiling;R-134a;Bubble characteristics;Heat flux oscillation;Mini-channel
公開日期: Nov-2016
摘要: In this work, experiments have been conducted to investigate how the imposed time periodic heat flux oscillation affects the bubble characteristics of saturated flow boiling with refrigerant R-134a in a horizontal narrow annular pipe. The test section for the horizontal annular duct consists of an outer pipe made of Pyrex glass and an inner heated copper pipe, intending to facilitate the visualization of boiling processes. A cartridge heater is installed inside the inner pipe to provide the required heat flux to the refrigerant flow in the narrow annular duct. In particular, attention is focused on the time periodic saturated flow boiling characteristics affected by the mean levels, amplitudes, and periods of the heat flux oscillation. The results show that the bubble departure diameter, bubble frequency and active nucleation site density are found to oscillate periodically in time as well and at the same frequency as the imposed heat flux oscillation. Furthermore, in the boiling the resulting oscillation amplitudes of the bubble parameters, such as the bubble departure diameter, bubble frequency and active nucleation site density, get larger for a longer period and a larger amplitude of the imposed heat flux oscillation and for a higher mean imposed heat flux. (C) 2016 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.07.020
http://hdl.handle.net/11536/134051
ISSN: 0017-9310
DOI: 10.1016/j.ijheatmasstransfer.2016.07.020
期刊: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
Volume: 102
起始頁: 1150
結束頁: 1158
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