Experimental and numerical study of water single-phase pressure drop across an array of circular micro-pin-fins

M.S. University of Hawaii at Manoa 2011.Includes bibliographical references.This thesis includes a study that investigates pressure drop associated with water liquid single-phase flow across an array of staggered micro-pin-fins having circular cross-section. The micro-pin-fins are micro-end milled out of oxygen free copper and have the following dimensions: 180 micron diameter and 683 micron height. The longitudinal pitch and transverse pitch are equal to 399 microns. Seven water inlet temperatures from 23 to 80 °C, and seventeen maximum mass velocities for each inlet temperature, ranging from 159 to 1475 kg/m2s, were tested. The test module was well insulated to maintain adiabatic conditions. The experimental results were compared to those from a micro-pin-fin array having similar size and geometrical arrangement but with pins with square cross-sectional geometry. The circular micro-pin-fins were seen to yield a significantly lower pressure drop than the square micro-pin-fins, between roughly two to three times less. The present experimental results were also compared with the predictions of several friction factor correlations, all of which poorly estimated the experimental data. The experimental results were also compared to a three-dimensional numerical analysis which showed good agreement. Finally, a room temperature (23 °C) numerical study of the effect of pin height to diameter ratio was conducted for six different ratios, ranging from 1:1 to 18:1 for seven different Reynolds number, ranging from 20 to 800. The results matched findings in previous studies on height to diameter ratio effects