State-of-the-Art Experimental Studies on Loop Heat Pipes

Abstract

The present study provides a concise overview of the main feature evolution of Loop Heat Pipe (LHP) designs, in particular on the evaporator/compensation chamber, based on experimental studies published between 1998 and 2010. It presents a synthesis of results on LHP performances at steady-state, and observations related to the LHP dynamic behaviours, as start-up or oscillating behaviours. The objective of this review is to gather as much information from the LHP experimental studies so as to provide a database, and thus promote the development of tools for understanding and predicting the LHP behaviors. The review shows some omissions in the LHP description and in the results presentation that makes these data difficult to use for further studies. This review should promote some coordination for future experimental works on LHP.

Thermal Tests and Two-Phase Phenomena Observations in a Transparent Experimental Loop Heat Pipe

“…The understanding of the origin of temperature oscillations in LHPs and of operating conditions, which cause them, is another challenging issue. As explained by Launay and Vallée (2011), three types of temperature oscillation regimes have been reported in the literature: (i) ultra-high frequency temperature oscillations (period less than 1s), caused by the formation of liquid slugs in the condenser or the vapour line, (ii) high frequency low amplitude oscillations (period of few seconds or few minutes) caused by the inability of the vapour front to find a stable position inside the condenser, and (iii) low frequency high temperature oscillations (period of few hours), which may appear in case of large evaporator thermal inertia, low heat loads and cold sink temperatures. In many experimental studies, these temperature oscillations are recorded using non-intrusive thermocouples implemented along the LHP wall.…”

The Study of Novel Self-Rewetting Fluid Application to Loop Heat Pipe

“…In 2011, Launy et al [8] sorted out the literature on the theoretical prediction and parameter discussion of loop heat pipes over the years. The paper pointed out the selection and filling amount of the working fluid, the material of the capillary structure, the parameters and geometric dimensions, the temperature and the heat sink temperature.…”

Characterization of Wick Evaporators through the Behavior of the Specially Designed Condenser

“…Any optical measurements are not possible since the LHPs are visually closed systems. Unfortunately, it makes it difficult to distinguish the evaporator's capability while it is affected by other elements [1].…”