Optimization of capillary structures for inverted meniscus evaporators of loop heat pipes and heat switches

Loop heat pipes (LHPs) and other two-phase heat transfer devices are used in the thermal management of electronic devices with high density of heat dissipation. In these two-phase thermal devices, the key component is the capillary structure (CS) that pumps the working fluid using the capillary forces generated by the meniscus, which are formed due to evaporation. The evaporator’s performance depends greatly on the internal structure and external configurations of the CS. However, there is not enough experimental and theoretical data on the optimization of the capillary structures of evaporators. This paper covers some important aspects of the CS design for evaporators working in an “inverted meniscus” scheme and proposes a methodology for analysis and selection of the CS pores size for LHP, flat heat pipes and heat switches, aiming for maximum heat transport capacity. Based on this methodology, two examples of capillary evaporators have been designed and evaluated.