Loop Heat Pipe Design: An Evaluation of Recent Research on the Selection of Evaporator, Wick, and Working Fluid

Abstract

Since its invention nearly five decades ago, the loop heat pipe has revolutionized every application requiring cooling or maintaining a constant temperature environment. In this article, its various designs aspects are explored, which include design of the evaporator, wick, and selection of working fluid. Factors such as design guidelines and how they affect the physics of the overall system are surveyed. For the evaporator part, its various designs and their respective applications/operating ranges are reviewed. In the wick section, recent trends on its fabrication and performance enhancement are shown. A special section on how the wick functions is added, with a focus on the study of liquid–vapor meniscus using the thin-film evaporation theory. Attention is also given to the investigations on the various figures of merit used for the selection of the working fluid. For the first time, these figures of merit are categorized with respect to the device physics they represent/simulate. In the end, this review article also touches upon the various creative designs and ideas used to enhance the loop heat pipe performance.