Oscillation characteristics of self-oscillating boiling cooler with a moving part such as bellows are experimentally investigated. Two oscillation behaviors are observed when heat flux is increased. At low heat fluxes, the frequency is kept almost unchanged and the amplitude is increased. At high heat fluxes, the frequency is increased and the amplitude is almost unchanged since the liquid working fluid reaches the end of the boiling surface. It is also shown that average operating pressure corresponds to the applied pressure on the bellows. In addition, critical heat flux and heat transfer coefficient are increased as the applied pressure is increased.
