Flow Characterization of a Pulsating Heat Pipe through the Wavelet Analysis of Pressure Signals

Roberta Perna, Mauro Abela, Mauro Mameli, Alessandro Mariotti, Luca Pietrasanta, Marco Marengo, Sauro Filippeschi

Research output: Contribution to journalArticle

Abstract

Pulsating Heat Pipes are two phase passive heat transfer devices characterized by a thermally induced two phase oscillating flow. The correct detection of the dominant frequencies of such oscillations is fundamental to fully characterize the device thermofluidic operation but the studies available in the literature are very heterogenous and results are often discordant. In this work, the concept of dominant frequency in Pulsating Heat Pipes is thoroughly discussed and defined analytically. The wavelet transform is used to characterize the fluid pressure signal in the frequency domain varying the heat power input at the evaporator and in the condenser zone of a full-scale Pulsating Heat Pipe tested in microgravity conditions. During the slug-plug flow regime, the dominant frequencies falls in the range 0.6–0.9 Hz, showing an increasing trend with the heat load input. The Cross-Correlation reveals that the two signals at the evaporator and at the condenser are very similar. Finally, the instantaneous angle of phase is calculated and lies between 310 and 360 deg. This value can be physically interpreted as a repeatable time shift between the two signals that can be used to evaluate the flow local mean velocity (0.09–0.13 m/s) constituting a valuable alternative to the visualization techniques.

Original languageEnglish
Article number115128
JournalApplied Thermal Engineering
Volume171
DOIs
Publication statusPublished - 27 Feb 2020

Keywords

  • Pulsating Heat Pipe
  • Frequency
  • Wavelet Cross Correlation
  • Flow velocity
  • Wavelet cross correlation
  • Pulsating heat pipe

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  • Activities

    67th European Space Agency Parabolic Flight Campaign

    Luca Pietrasanta (Participant)

    16 Nov 2017

    Activity: EventsEvent

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