Experimental study of a high-capacity dual compensation chamber loop heat pipe at different orientations

Dual compensation chamber loop heat pipe (DCCLHP) is a promising technology for future avionics cooling. In this work, the effect of orientations on the steady state and startup performance of a DCCLHP with kW class heat transfer capacity was investigated experimentally. Experimental results show that for high capacity DCCLHP, the variation of condenser performance at different orientations is a decisive factor in system performance, which could result in up to a 50 % decrease or 10 % increase in the heat transfer limit. In addition, the lack of condenser performance could also have a potential negative impact on the startup performance. By establishing a method to analyze the operating temperature, the authors provided an in-depth analysis of the related mechanisms. The effect of gravity could change the force condition and therefore the thickness of the condensate in the condenser, which in turn affects the condenser capacity and the working fluid temperature flowing into the compensation chamber. As a result, for practical applications, it is necessary to focus on the installation of the condenser to avoid the orientations that tend to cause the increase in the thickness of the condensate film, such as the condensate flow inside the condenser was opposite to gravity. The research content of this paper could deepen the understanding of LHP technology and contribute to the realization of application in acionics cooling in the future.