THERMAL-HYDRAULIC CHARACTERISTICS OF MICROCHANNEL HEAT EXCHANGER AND ITS APPLICATION TO SOLAR GAS TURBINES

Abstract

ABSTRACT Incorporating "integral method" proposed here, a set of empirical correlations of local heat transfer coefficient and pressure loss coefficient are newly derived based on experiments using microchannel heat exchanger (MCHE) with supercritical carbon dioxide as heating medium and water as coolant. They are expressed in dimensionless forms of polynomial of Reynolds number and Prandtl number. The same correlation of Nusselt number is found applicable to both fluids and its value is almost two times larger than Dittus Boelter correlation. It was also shown that the above form is applicable to a wide range of geometry with the values of constants changed. Accuracy of both correlations is confirmed within 5% errors for MCHE with S-shaped fins in the range of pressures 9~12.5MPa and temperatures 280~390K. Based on the correlations, sizes of heat exchangers are evaluated contained in gas turbine cycle with super critical carbon dioxide as a working fluid applicable to solar power