Investigation of a loop heat pipe to achieve high heat flux by incorporating flow boiling

Abstract

• A loop heat pipe incorporating flow boiling is proposed for high heat flux dissipation. • The device combines the virtues of LHPs as self-driven and flow boiling as high heat transfer limit. • An injector serves as a pump and provides liquid for a boiling chamber. • The boiling chamber achieves a heat dissipation capability several times higher than the evaporator. A loop heat pipe incorporating flow boiling (LHPFB) was proposed to meet the heat dissipation requirement of high heat flux devices. A boiling chamber was arranged for high heat flux dissipation, where flow boiling was realized. An injector was designed to serve as a pump without introducing any moving parts and extra energy consumption. Moreover, the heat transfer performance of the LHPFB was investigated under various operating conditions, and its operation mechanism was revealed by visualization study. The results indicated that the vapor coming from the evaporator was the driving source of the injector, whose entrainment characteristics provided a large amount of liquid for the boiling chamber. The boiling chamber performed satisfactorily and achieved a heat dissipation capability several times higher than the evaporator. It was also found that higher heat sink temperature resulted in higher operating temperature and lower heat transfer limit of the boiling chamber, with the maximum heat flux of 103.3 W·cm −2 and 87.8 W·cm −2 at heat sink temperature of 5 °C and 35 °C respectively. Compared with the conventional loop heat pipes, the LHPFB had substantially higher heat transfer limit. Therefore, it is a promising device for high heat flux dissipation.