Influence of Operation Parameters on Thermohydraulic Performance of Supercritical CO2 in a Printed Circuit Heat Exchanger

Abstract

The performance of recuperative printed circuit heat exchangers is critical in supercritical CO2 (sCO2) power generation applications. This article presents a three-dimensional numerical model of sCO2 flowing in a printed circuit heat exchanger and investigates its thermohydraulic performance under different operation conditions. The simulations employ the standard k-ε turbulent model, and consider entrance effects, conjugate heat transfer, real gas thermophysical properties and buoyancy effects. The heat exchanger operation parameters cover mass flux from 254.6 to 1273.2 kg/m2s, inlet temperature 50–150 °C and outlet pressure 100–250 bar on the cold side, and 300–500 °C and 75–150 bar on the hot side. Results show that increasing CO2 mass flux leads to a significantly increased heat transfer coefficient, a slight increase in temperature difference between the hot and cold CO2, as well as larger pressure drop and lower friction factor on both sides. Increasing the cold CO2 pressure, decreasing the cold CO2 temperature, and increasing the hot CO2 temperature result in a higher heat transfer rate of the heat exchanger. Increasing the CO2 temperature on each side causes increased pressure drops on both sides. Increasing the CO2 pressure on each side reduces the pressure drop on each side.