scholarly journals Study on liquid film formed with liquid column oscillation in pulsating heat pipe (Measurement of liquid film thickness using forced oscillation system)

2019 ◽  
Vol 85 (879) ◽  
pp. 19-00307-19-00307
Author(s):  
Masayoshi MIURA ◽  
Haruki ARAI ◽  
Takaaki OGURA ◽  
Hiroyuki ITO
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Heat Pipe ◽  
Forced Oscillation ◽  
Liquid Column ◽  
Liquid Film Thickness ◽  
Pulsating Heat Pipe ◽  
Oscillation System

Liquid Film Thickness of Oscillating Flow in a Micro Tube

2011 ◽  
Author(s):  
Youngbae Han ◽  
Naoki Shikazono ◽  
Nobuhide Kasagi
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Two Phase Flow ◽  
Liquid Film Thickness ◽  
Working Fluid ◽  
Oscillating Flow ◽  
Phase Flow ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Flow Systems

Oscillating flow is encountered frequently in many two-phase flow systems such as pulsating heat pipe, refrigerator with reciprocating compressor, etc. Thickness of liquid film formed between the tube wall and the vapor bubble is one of the crucial parameters to develop two-phase flow systems using micro tubes. However, liquid film formation and variation of oscillating flows are very complicated phenomena coupled with acceleration, deceleration, evaporation, condensation, etc. In the previous research, liquid film thickness in accelerating flow under adiabatic conditions was measured and compared with the correlation developed under steady condition [5]. In the present study, liquid film thickness in decelerating flow in a micro tube is investigated under adiabatic condition. Circular tubes with diameter, D = 1.0 mm, is used. Laser focus displacement meter is used to measure the liquid film thickness. Two-phase flow is obtained by introducing air from the open end of the test tube. Ethanol is used as a working fluid. At small capillary numbers, the effect of deceleration is negligible similar to the trend under accelerated condition. As capillary number increases, liquid film thicknesses in decelerated conditions become larger than the predictions of adiabatic steady correlation. However, liquid film thickness does not exceed the critical thickness at Re > Recrit. It is considered that liquid film thickness is affected by the altered velocity profiles in the liquid slug ahead of air-liquid interface according to accelerated or decelerated condition.

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