Performance characteristics of cylindrical heat pipes with multiple heat sources

A steady-state analytical model for cylindrical heat pipes subject to either constant heat flux or convective cooling is presented. The proposed model couples two-dimensional heat conduction in the heat pipe's wall with the liquid flow in the wick and the vapor hydrodynamics, and is capable of modeling multiple uniform heat sources (evaporators). A parametric study on the effect of axial heat conduction in the heat pipe wall was carried out. It was found that the exclusion of the effects of axial heat conduction in wall can result in an overestimate of the pressure drops in heat pipe by about 10%, depending on the heat pipe specifications. A simple method was developed to predict and quantify the criteria for the importance of the axial heat conduction in the heat pipe's wall. A significant saving in computational time is achieved by use of the proposed analytical model compared to full numerical simulations. The developed model provides a useful tool to evaluate the capillary limit of the cylindrical heat pipes and can be used for optimization and design applications. (C) 2011 Elsevier Ltd. All rights reserved.