Thermal and fluid‐dynamic behaviour of double‐pipe condensers and evaporators—a numerical study

Abstract

This paper deals with a numerical simulation of the thermal and fluid‐dynamic behaviour of double‐pipe condensers and evaporators. The governing equations of the fluid flow (continuity, momentum and energy) in both the tube (evaporating or condensing flow) and the annulus (single‐phase flow), together with the energy equation in the tube wall, are solved iteratively in a segregated manner using a one‐dimensional, transient formulation, based on an implicit step by step numerical scheme in the zones with fluid flow (tube and annulus), and an implicit central difference numerical scheme in the tube wall, solved by means of the Tri‐Diagonal Matrix Algorithm (TDMA). This formulation requires the use of empirical information for the evaluation of convective heat transfer, shear stress and void fraction. Two criteria to calculate the location of the points of transition between single‐phase and two‐phase flow are tested. An analysis of the different parameters used in the discretization is made. Some illustrative results corresponding to the solution of a condenser and an evaporator using two different working fluids (R–12 and R–134a) are presented.

Citation

Escanes, F., Pérez‐Segarra, C.D. and Oliva, A. (1995), "Thermal and fluid‐dynamic behaviour of double‐pipe condensers and evaporators—a numerical study", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 5 No. 9, pp. 781-795. https://doi.org/10.1108/EUM0000000004087