Ｓ字型フィンを有するマイクロチャンネル熱交換器に関するＮｕｓｓｅｌｔ数相関式

Abstract

An advanced microchannel heat exchanger (MCHE) with S-shaped fins can realize high heat transfer performance and reduced pressure drop performance. Simulation calculations by the three-dimensional computational fluid dynamics (3D-CFD) code were examined for a MCHE with S-shaped fins using carbon dioxide (CO2) as the working fluid in the wide range of inlet pressure and temperature conditions, which are from subcritical conditions to supercritical conditions. From the numerical results, a Nusselt number correlation was obtained using multivariable analysis. The standard deviation between the correlation and numerical results was 6.1%. A MCHE test piece with the same flow channel configuration as that for numerical simulation was manufactured, and experimental verification of the thermal-hydraulic performance of the test piece was examined. The heat transfer performance of the test piece was calculated using the Nusselt number correlation and was compared with experimental results. Numerical heat transfer performance showed good coincidence with a deviation of 2.5%. The conditions used in numerical simulation include the conditions of a recuperator and an intermediate heat exchanger of CO2 gas turbine cycle. Using the obtained Nusselt number correlation, designing these heat exchangers becomes easier.