Study on CO2 – water printed circuit heat exchanger performance operating under various CO₂ phases for S-CO₂ power cycle application

Abstract

The supercritical CO2 (S-CO2) power cycle is receiving worldwide attention as one of the promising advanced future electricity generation technologies. Since the S-CO2 power cycle can achieve high efficiency with simple system configuration, the role of compact heat exchanger becomes more important to achieve smaller system footprint. As an example of successful compact heat exchanger, the printed circuit heat exchanger (PCHE) was recently suggested for the S-CO2 power cycle application due to the capability of enduring high pressure difference while providing large heat transfer area within a small volume. However, the S-CO2 precooler operates very close to the critical point of CO2 where the conventional design methodology may not be suitable due to substantial variation of the thermo-physical properties near the critical point. Thus, in this paper the design and operation issues of PCHE as the precooler are addressed. In this study, the verification of developed PCHE core design code and experimental test results are presented. The test conditions were 26–43°C and 7.3–8.6MPa in temperature and pressure, respectively. In terms of non-dimensional numbers, the Reynolds number range is 15,000–100,000 and the Prandtl number range is 2–33. Friction factor and heat transfer correlations were developed with the experimental data and computational analysis for the future PCHE design as a precooler in the S-CO2 power cycle.