Energy Programs: Circumferential Heat Transfer and Pressure Drop in Tube Arrays with a Low-Lateral-Pitch Ratio in Crossflow

摘要

An investigation has been conducted of the pressure drop and circumferential heat transfer about banks of large diameter (4-in. OD) tubes in crossflow. The tube banks are representative of configurations that were proposed for Ocean Thermal Energy Conversion systems whose heat exchangers use arrays of multipass horizontal tubes. Water flow is by gravity down through the tube banks. The tube arrays that were tested consisted of two staggered configurations: (a) with a pitch ratio of 2.63 by 0.59 (lateral-to-longitudinal pitch ratio proposed for prototype heat exchangers) and (b) with a pitch ratio of 2.00 by 0.59 (proposed for a core test model). Also tested was an in-line configuration with a pitch ratio of 1.44 by 1.19, which was considered a possible alternative prototype configuration. The pressure drops across the banks were consistent with those reported in the literature for configurations having large longitudinal pitches. The circumferential distribution of the heat-transfer coefficient was uniform for the tubes in the interior of the bank. The circumferentially averaged values of the heat-transfer coefficient were slightly higher than those predicted.