Experimental investigation on a loop thermosyphon with three evaporators: Unique startup and oscillation phenomena.

Highlights • Unique instability phenomenon called sudden temperature change is found in the startup. • Sudden temperature change occurs when Δ T between evaporators reaches a certain value. • Oscillation is due to the periodic variation of the flow regime inside the loop. • Frequency is lower and amplitude is larger if multi-evaporator is heated compared with one. • For every two adjacent evaporators, the phases of oscillation are almost opposite. Abstract Loop thermosyphon with multiple evaporators has tremendous potential in applications that involve multiple heat sources. In this paper, a loop thermosyphon with three evaporators is investigated experimentally. Unique phenomena of startup and oscillation compared with common loop thermosyphons are reported. In the startup process, a unique phenomenon called "sudden temperature change" is found. This phenomenon occurs in a temporary state in the startup, when the temperature differences between the evaporators without heating power and with heating power reach certain range (−2.6 °C to 0.8 °C in this experiment). In the quasi-steady state, an oscillation map which shows the range when oscillation occurs is obtained. Compared with only one evaporator with heating power, simultaneous heating on multiple evaporators reduces the oscillation frequency, enhances the oscillation amplitude and sometimes makes it irregular, due to the interaction between the evaporators. Also, for every two adjacent evaporators, the phases of oscillation are almost opposite. [ABSTRACT FROM AUTHOR]