Experimental investigation on SCO2-water heat transfer characteristics in a printed circuit heat exchanger with straight channels

The supercritical CO2 Brayton cycle (SCO2-BC) is proposed to be used as the concept of fast cooled reactor (FCR), which is a typical application in the 4th generation reactors. The recuperator and cooler, which acted as important components in SCO2-BC, are required for long-term operation especially at the high pressure condition. However, the traditional shell-and-tube heat exchanger, which already has mature fabrication technology, is not appropriate in the developing miniaturized thermal system because of its low compactness. In the present paper, the compact printed circuit heat exchanger (PCHE) with straight ribs is manufactured by the photochemical etching technology and the diffusion bonding method independently. Then, the thermohydraulic performance of PCHE is tested on the SCO2-water experiment platform. Considering the difference of thermal properties of working fluid, the comparison of thermal and hydraulic performance between SCO2 and water in the tested PCHE is studied at the same mass flow rate, which shows that the SCO2 has better heat transfer capability than water fluid. Further, the heat transfer rate and pressure loss of PCHE are investigated at different SCO2 operating pressure, which indicates that the PCHE has better comprehensive performance when it operates at higher pressure condition. Meanwhile, the extreme operating condition due to the pseudo-critical point of CO2 working in the PCHE is analyzed comparing with the normal operating condition. The results show that the comprehensive performance of PCHE is significantly reduced nearly 17.6% when operates at the transcritical state. The heat transfer correlation of PCHE with straight ribs is fitted by experimental data in both the supercritical and transcritical states in order to simplifying design process. (C) 2017 Elsevier Ltd. All rights reserved.