Numerical and experimental studies of flow field and heat transfer for high temperature exhaust gas over in-line tube banks

Flow field and thermal-hydraulic characteristics for outside tubes of a recuperator were studied numerically and experimentally. Calculations are carried out for an in-line tube bank up to four rows deep under the conditions of uniform tube wall temperature. Fluid flow is incompressible, two-dimensional and turbulent. The radiation effect was considered between the tube wall and the working fluid for evaluating the outside performance. Because of high emissivity which the tube wall and exhaust gas had, radiant heat transfer was not negligible in this study. Streamline, isothermal lines through the whole tube bank, local and average Nusselt numbers, and friction factor are presented. The numerical results of Nusselt numbers show that the radiant heat transfer can run up to about 28% of the whole heat transfer. The numerical result is in good agreement with the experimental data within 5%.