Experimental verification of advantages of the S-shaped fin configuration was examined by Nikitin for use in a recuperator of a supercritical CO2 gas turbine cycle [2] and by Ngo as a hot water supplier of a residential CO2 heat pump system [3]. More specific comparisons between numerical and experimental results were made by Utamura and Nikitin for a recuperator [4] and a hot water supplier [5] with S-shaped fins. The deviations between numerical and experimental values were within experimental uncertainty or 5%, which is sufficiently small to conclude that numerical