Thermal Analysis of a Water-Filled Micro Heat Pipe With Phase-Change Interfacial Resistance

Abstract

The progressive evaporation and condensation processes in a micro heat pipe, with which high heat fluxes at the liquid–vapor interface are associated, render it a device of high thermal conductance. By coupling the phase-change interfacial resistance model with a mathematical model based on first principles for fluid flow and heat transfer, the axial temperature variations of the liquid and vapor phases as well as those of other field variables are characterized and analyzed. The findings provide a well-defined exposition of the validity of uniform-temperature assumption for the liquid and vapor phases in the analysis of micro heat pipes. In conjunction with the acquisition of liquid and vapor temperature profiles, the heat transfer characteristics of the evaporation process can be analyzed. The local evaporative heat transfer coefficient and heat flux are evaluated. The results indicate that both heat transfer coefficient and heat flux are of considerably high values, confirming that the heat transport capability of a micro heat pipe is dominated by the phase-change heat transfer at the liquid–vapor interface.