Investigation of temperature oscillations in a novel loop heat pipe with a vapor-driven jet injector

A novel loop heat pipe with a vapor-driven jet injector (LHPI) shows excellent heat transfer performance. However, high-amplitude temperature oscillations are observed at low heat loads. In this study, a LHPI with transparent compensation chamber is designed and tested to reveal the mechanism of temperature oscillations. The relations between the internal flow and temperature oscillations are investigated by visualization study, and the results show that high-amplitude temperature oscillations are caused by the intermittent liquid supply of the compensation chamber. Meanwhile, the temperature oscillation characteristics of the LHPI under a variety of operating conditions are also studied. Five operation modes of the LHPI are classified as start-up failure mode, high-frequency/low-amplitude oscillating mode, low-frequency/high-amplitude oscillating mode, overshoot mode and smooth mode. Furthermore, a low filling ratio can eliminate the low-frequency/high-amplitude oscillating mode and is therefore conducive to the stable operation of the LHPI, but it elevates the operating temperature under high heat loads. In addition, increasing the sink temperature can also suppress temperature oscillations.