VAPOR FLOW CALCULATIONS IN A FLAT-PLATE HEAT PIPE

Steady laminar incompressible two-dimensional flow in a horizontal flat plate heat pipe with an adiabatic top plate was studied. For uniform evaporation and condensation rates, the Navier-Stokes equations and the continuity equation were solved. For radial Reynolds numbers Rer > 1, the velocity profiles were nonsimilar and asymmetrical. At Rer > 10, backflow was observed along the top plate, starting at the end of the condensation zone. At the highest Rer(= 50), the total pressure drop over the heat pipe was more than three times the value found from Poiseuille approximation. However, complete recovery of impulse pressure was found and the additional pressure losses could be fully attributed to increased frictional losses. Experiments with a porousplate model showed excellent agreement. © 1979 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.