A model of the capillary limit of a micro heat pipe and prediction of the dry-out length

A model for fluid flow and heat transfer in a micro heat pipe of any arbitrary (polygonal) shape is presented utilizing a macroscopic approach. The coupled non-linear governing equations for the fluid flow, heat and mass transfer are developed based on first principles and are solved numerically. The performance and the capillary limitations of such a device are analyzed in detail. The profile of the radius of curvature is used to predict the onset of the dry-out point and the propagation of the dry out length. A method is developed to estimate the dry out length as a function of system geometry and process variables, e.g., heat input and inclination. The model predicted results are successfully compared with the experimental results from a previous study. The general nature of the model and the associated parametric study ensure the wide applicability of the model.