Numerical study of the thermohydraulic performance of printed circuit heat exchangers for supercritical CO2 Brayton cycle applications

Abstract

The printed circuit heat exchanger is currently the preferred type of recuperative heat exchanger for the supercritical CO₂ Brayton cycle due to its highly compact construction, high heat transfer coefficients and its ability to withstand high pressures and temperatures. This paper employs a three-dimensional numerical model to investigate the thermohydraulic performance of supercritical CO₂ flow in a printed circuit heat exchanger. This numerical model considers entrance effects, conjugate heat transfer, real gas thermophysical properties and buoyancy effects. The inlet temperature and pressure are 100 °C/150 bar on the cold side and 400 °C/75 bar on the hot side while the mass flux is varied from 254.6 to 1273.2 kg/(m²·s). The overall performance of the heat exchanger and comparisons of local heat transfer and friction pressure drop with predictions from the empirical correlations are presented and discussed. Overall, this paper provides useful information that can be employed in the design of recuperators for supercritical CO₂ Brayton cycle applications.