Channel wise displacement-velocity-frequency analysis in acetone charged multi-turn Closed Loop Pulsating Heat Pipe

• Published in: Energy conversion and management 2019-09, Vol.195, p.367-383
• Main Authors: Patel, Vipul M., Mehta, Hemantkumar B.
• Format: Article
• Language: English
• Subjects: Acetone; Circulation; Closed loops; Displacement; Engineering; Flow pattern; Flow visualization; Frequency; Frequency analysis; Frequency distribution; Heat pipes; High speed cameras; Multiphase flow; Multiple steady-states; Oscillations; Parameter identification; Pattern analysis; Pulsating Heat Pipe; Recovery zones; Synchronism; Synchronization; Thermal management; Thermal performance; Two phase flow; Velocity; Vertical orientation
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2019.05.014

•Visual experiments are performed on nine-turn acetone charged CLPHP.•Multiple steady states and recovery zone are observed and analyzed.•A flow pattern transition criterion based on velocity is proposed.•Channel wise displacement-velocity-frequency analysis is performed.•Thermo-hydrodynamic characteristics of a CLPHP are synchronized and quantified. Pulsating Heat Pipe (PHP) remains a contemporary research interest due to its promising merits in the field of thermal management of various engineering applications. Thermal performance of a PHP is greatly influenced by various operating parameters. Heat input is one of the significant parameters that alter the intricate two-phase flow physics in a PHP. The present research is aimed to explore channel wise intricate thermo-hydrodynamic characteristics as a function of heat input (10 W–200 W) and its influence on the thermal performance of nine-turn acetone charged Closed Loop PHP (CLPHP). Filling Ratio (FR) is kept as 50% and vertical bottom heating position is considered. Flow visualization is carried out using a high-speed camera (Photron FASTCAM Mini UX100) and images are processed on Photron FASTCAM Analysis (PFA ver. 1.2.0.0) software. Flow patterns, shape of meniscus, liquid-vapor volume fraction, circulating/oscillating characteristic based on channel wise bubble displacement and velocity-frequency distribution are investigated. Synchronization of hydrodynamic characteristics with thermal performance parameters is performed. Multiple steady-states and recovery zone are identified and analyzed. A flow pattern transition criterion based on velocity is proposed. The trend of displacement-velocity-frequency with heat input is developed. The present quantified analysis will be helpful to design and develop CLPHP based engineering applications.