Study of crossflow cooling and heating of air via an in-line elliptical tube array heat exchanger.

摘要

In current study, airside heat transfer and flow characteristics of an elliptical tube array heat exchanger were experimentally investigated by examining the effects of Reynolds number on Nusselt number and pressure drop coefficient.; In a thermal wind tunnel, the air-cooling and air-heating experiments were conducted via an array of 18 elliptical tubes (each 300 mm long) with their 31.7 mm major axis parallel to the air crossflow. The tubes, minor-to-major axis ratio of 0.3, were evenly spaced by 6.1 mm airgap. The array was placed in a 300 x 300 mm2 and 600 mm long test section. Water entered the bottom tube, jig jagged through the array, and exited at the top tube. Two temperature settings, constant air and water inlet temperatures and constant air and water inlet temperature difference, were applied. The airside Reynolds number (Rea), based on the approach air-velocity and streamwise major-axis length of the tube, was varied between 10000 and 36000, while that for waterside (Rew) based on mean water-velocity and inner-hydraulic diameter, altered from 1100 to 7300. (Abstract shortened by UMI.)