TRANSIENT LUMPED HEAT-PIPE ANALYSES

A transient lumped heat pipe formulation for conventional heat pipes i s presented and the lumped analytical solutions for different boundary conditions at the evaporator and condenser are given. For high temper ature heat pipes with a radiative boundary condition at the condenser, a nonlinear ordinary differential equation is solved. In an attempt t o reduce computer demands, a transient lumped conductive model has bee n developed for noncondensible gas-loaded heat pipes. The lumped flat- front transient model was extended by accounting for axial heat conduc tion across the sharp vapor-gas interface. The analytical solutions fo r conventional and gas-loaded heat pipes were compared with the corres ponding numerical results of the full two-dimensional conservation equ ations and experimental data, with good agreement.