Miniature loop heat pipe with a flat evaporator

ABSTRACT
The classic design of a loop heat pipe usually includes a cylindrical evaporator design, where the heat generated at the wall has thermal/hydraulic contact with the surface of a cylindrical porous wick structure. Such a design is characterised by good technological and physical bases and well-proven theory. It is capable to solve many tasks in various applications.
But also attempts to design a loop heat pipe with flat interfaces between the heated wall and wick are of practical interest for applications, for which the effective heat input to a cylindrical evaporator surface is hardly or not realisable, or for which the mounting surfaces require a contact over a flat surface. World wide there is only limited development of flat-evaporator loop heat pipes:Hence this study can be called a novelty. Besides of technological development the basis for physical modelling of such loop heat pipe should be elaborated.
One possible approach, based on the method of idealised elements for pressure and temperature prediction, is presented.
INTRODUCTION
The majority of loop heat pipe (LHP) designs utilises a cylindrical evaporator, in which the “heat generating” wall has good contact to the cylinder surface of the porous wick body. Such a design has a good technological and physical basis and is supported by a well-proven theory,allowing to apply such a configuration to execute many practical tasks. Anyhow, attempts to design a loop heat pipe with a flat “heating wall-wick” contact surface are very scarce [1], but certainly of practical interest for applications where the effective heat inputs to cylindrical evaporator surface are hardly or not realisable, or where the mounting surfaces require the contact over flat surface only. Also the study of adapting the main known design principles and techniques to a flat heat transfer arrangement is a very interesting subject of research.