Vapor and liquid flow in an asymmetrical flat plate heat pipe" a three-dimensional analytical and numerical investigation

Abstract--In this work, an analytical and numerical study was carried out for the steady incompressible vapor and liquid flow in an asymmetrical flat plate heat pipe. The pseudo-three-dimensional analytical model employs the boundary layer approximation to describe the vapor flow under conditions including strong flow reversal and the method of matched asymptotic expansions to incorporate the non-Darcian effects for the liquid flow through the porous wicks. The coupling of the liquid flow in the top, bottom and vertical wicks is also included in the model. In the numerical study, a finite element scheme based on the Galerkin method of weighted residuals was used to solve the full set of nonlinear differential elliptical equations of motion and the continuity equation for the three-dimensional vapor flow. The analytical and numerical results for various injection Reynolds numbers are presented. The three-dimensional effects are discussed and lhe results show that a three-dimensional analysis is necessary if the vapor channel widthto-height ratio is less than 2.5. Very good agreement was found between the analytical and the numerical results. While showing, qualitatively and quantitatively, the pertinence and the effects of various physical parameters, the analytical results are quite useful for practical engineering purposes by providing an effective and rapid prediction method for the flat plate heat pipe operation. ~5 1997 Elsevier Science Ltd.