Vapor flow analysis in partially-heated concentric annular heat pipes

The steady-state laminar and incompressible vapor flow in four partially-heated concentric annular heat pipe (CAHP) is studied. The governing equations are solved numerically, using finite volume approach based on collocated grids. The first order upwind scheme and the QUICK scheme are used in the numerical solution. The vapor pressure distributions and velocity profiles along the annular vapor space are predicted for a number of test cases in the range of low to moderate radial Reynolds numbers. The results show that in a partially-heated annular heat pipe, as the radial Reynolds number increases, a number of recirculation zones may be created at both ends of the evaporator and condenser sections. The size and location of the recirculation zones are predicted and their effects on the performance of an annular heat pipe are discussed qualitatively.