A Numerical Study of Fluid Flow and Heat Transfer over a Bank of Flat Tubes

Abstract

The present study considers steady laminar two-dimensional incompressible flow over both in-line and staggered flat tube bundles used in heat exchanger applications. The effects of various independent parameters, such as Reynolds number (Re), Prandtl number (Pr), length ratio (L=Da), and height ratio (H=Da), on the pressure drop and heat transfer were studied. A finite-volume-based FORTRAN code was developed to solve the governing equations. In all, 10 modules were considered in this study. The flow is observed to attain a periodically fully developed condition downstream of the fourth module. The nondimensionalized pressure drop decreases monotonically with an increase in the Reynolds number. In general, the module average Nusselt number increases with an increase in the Reynolds number. The results at Pr ¼ 7.0 indicate a significant increase in the computed module average Nusselt number when compared to those for Pr ¼ 0.7. The overall performance of the in-line configuration for lower height ratio (H=Da ¼ 2) and higher length ratio (L=Da ¼ 6) is preferable since it provides higher heat transfer rate for all Reynolds numbers except for the lowest Re value of 25. As expected, the staggered configurations perform better than the in-line configuration from the heat transfer point of view. Also from the heat transfer point of view, equivalent circular tubes perform better than flat tube banks. However, the heat transfer performance ratio was always greater than 1, signifying that from the pressure-drop point of view the flat tube banks perform better than a tube bank with equivalent circular tubes.

Effect of tube spacing, fin density and Reynolds number on overall heat transfer rate for in-line configuration

“…Table 2 presents the comparison of the average Nusselt number ( Nu ) for two-dimensional of in-line arrangements between the present study and Bahaidarah et al [27]. The geometrical parameters of the tube configuration are presented in Table 2.…”

“…Flat tubes are vital components in various technical applications like modern heat exchangers and automotive radiators. Even though many researchers have devoted their work to study the fluid flow and heat transfer over objects of various shapes, flat tubes have not been investigated as much [6,7]. Flat tube designs are a recent addition for use in automotive air conditioning evaporators and condensers.…”

Heat Transfer and Pressure Drop Prediction in an in-Line Flat Tube Bundle by Radial Basis Function Network

“…The numerical model was validated with some of the previously published standard problems. The comparison between the code results and Bahaidarah et al [3] is shown in a previous publication by Tahseen et al [26].…”

“…Tube bundles are widely employed in cross-flow heat exchangers, but the design is still based on empirical correlations of heat transfer and pressure drop [1,2]. Heat exchangers with tube banks in a cross-flow are of great practical interest in many thermal and chemical engineering processes [3][4][5][6]. Flat tube designs have been newly introduced for use in modern heat exchanger applications such as automotive radiators.…”

Analysis of Laminar Forced Convection of Air for Crossflow over Two Staggered Flat Tubes

“…For the same reason, vibration and noise are expected to be less pronounced in flat tube heat exchangers compared to circular tube heat exchangers. Reports on air flow over a bank of flat tubes are limited, except for the recent study by Bahaidarah, Anand and Chen (2005) in which two-dimensional numerical, steady, laminar, incompressible flow over a bank of flat tubes are researched for both in-line and staggered configurations.…”