Thermal-hydraulic analysis and design of printed circuit heat exchangers for KAIST Advanced Pyro-SFRs

Abstract

The printed circuit heat exchanger (PCHE) has advantages such as operation in wide temperature range, high effectiveness, compactness, high structural integrity and reliability in comparison with the existing heat exchangers. Through this dissertation, the most suitable channel type for the intermediate heat exchanger (IHX) of KAIST Advanced Pyro-SFRs (KAPS), which is an advanced integrated reactor, was determined.We devised and evaluated the following three channel configurations: the Straight PCHE, the S-shape PCHE and the Zig-Zag PCHE. These three types were compared with respect to pressure drop and demanded surface area by design methodology. As a result, in case of the pressure drop, while the Zig-Zag PCHE had the excessive pressure drop, the pressure drop of the Straight PCHE was lowest among three PCHE types: pressure drops in a supercritical CO2 (SCO2) channel for a 12 module case are 247,574 Pa (Straight PCHE), 585,570 Pa (S-shape PCHE) and 2,889,321 Pa (Zig-Zag PCHE). The Zig-Zag PCHE was calculated to give the minimum required wall surface area while the S-shape PCHE needed the largest surface area among the three PCHE types: the required wall surface area are 10,824 m2 (Straight PCHE), 14,081 m2 (S-shape PCHE) and 5,502 m2 (Zig-Zag PCHE) when 12 modules of PCHEs was applied to KAPS. As the maximum surface area to be manufactured for a SCO2 channel with 12 modules of PCHE is 12,503 m2, the Straight PCHE with 10,824 m2 satisfied the required wall surface area requirement. In the total cost calculation, pump operating cost was the dominant one. Therefore the PCHE with the lower pressure drop showed the lower total cost under the same module number. We found out that 12 modules of Straight PCHE showed the lowest total cost among the three candidate designs for KAPS operation according to the design methodology.We conducted the CFD calculation using fluent to validate the design methodology. The CFD analysis estimated 200,896 Pa and 10,824 m2 for the p...