Temperature Oscillations in Loop Heat Pipe Operations-- a Revisit

Abstract

The oscillatory behaviors sometimes observed in Loop Heat Pipe (LHP) operations can be shown as the byproduct of the system (like all other dynamical systems) operating in certain unstable regimes. A LHP operational stability theory based on an linearized approximation was first introduced in 2014 focusing on the criteria for the appearance of High Frequency Low Amplitude (HFLA) and Low Frequency High Amplitude (LFHA) temperature oscillations for "unforced" external conditions (i.e. the power input, sink & ambient temperatures remain constant). In the current paper, the nonlinear effects shall be taken into consideration to reveal the transient behaviors of the LHP temperatures after the oscillations appear. In addition, test data from several LHPs are used to verify the updated theory.