Experimental study on transitional flow in straight channels of printed circuit heat exchanger

Abstract Experimental study on fluid flow in Printed Circuit Heat Exchanger (PCHE) with straight channels was conducted, with supercritical carbon dioxide (sCO2) and water as working fluid, respectively. The Reynolds number varies from 64.4 to 14160.9. The Fanning friction factors were obtained for laminar flow, transitional flow, hydraulically smooth region of turbulent flow, as well as the critical Reynolds numbers between different flow regions. The experimental result agrees with the theoretical study very well, with a deviation of 4.6%. The critical Reynolds numbers from laminar flow turning to transitional flow and then to hydraulically smooth region of turbulent flow are 2100 and 2700 for the semi-circular channel, respectively. While the values for circular channel are 2300 and 3980. Based on the new developed flow correlations and flow region identification method, modeling of PCHE was made. It is found that the simulated pressure drop with traditional flow correlations has an obvious deviation with the experimental result. It is recommended to use the new developed flow correlations and the identification method for the cases within the corresponding application ranges.