Different aspects of geometrical optimization for compact heat exchangers

In this study a two dimensional, steady state and incompressible laminar flow for staggered tube arrays in crossflow is investigated numerically. The study is based on a patented (APU, UK May 2001) compact heat exchanger design using implanted vortex generators on the internal flow, and change of fluid momentum in a turbulent jet on the external flow side. A finite-volume method is used to discretize and solve the governing equations for the geometries expressed by a boundary-fitted coordinate system. Solutions for the Reynolds numbers from 20 to 200 are obtained for a tube bundle with 10 longitudinal rows in different tube arrangements of ES, ET, and RS each with nominal pitch-to-diameter ratios of 1.33, 1.60 and 2.00. Different performance parameters which are used commonly to compare different heat exchangers are investigated and the performance parameters which account for pressure losses as well as occupied area are defined. The variations of these parameters with inlet Reynolds number and different nominal pitch-to-diameter ratios for different tube arrangements are also indicated. The optimum tube layouts for the studied flow and geometry ranges are shown as well.