Numerical investigation on thermal hydraulic performance of supercritical LNG in PCHEs with straight, zigzag, and sinusoidal channels

Printed circuit heat exchanger (PCHE) has semi-circular micro-channels with high thermal performance and is widely used in the oil and gas industry, refrigeration, and other fields. PCHE is seen as the most promising technology in LNG-floating production storage and offloading due to its high efficiency and compactness. In this study, the local and global thermal-hydraulic performances of different PCHEs using supercritical LNG and liquid nitrogen were investigated by a numerical method. Shear stress transport k−ω turbulent model was used to determine the numerical solutions in the PCHEs. The PCHE channel shapes included straight, zigzag with different sharp and round corners (R = 1.0, 1.5, 2.0, and 3.0 mm), and sinusoidal shapes. The flow separation and recirculation around the corner inhibit the heat transfer and increase the pressure drop. The smoothness of bend corner is conducive to heat transfer and leads to the reduction of hydraulic resistance. The sinusoidal channel can reduce the pressure drop by 8.3% and increase heat transfer coefficient by 2.9% compared to the zigzag with sharp corner channel at a constant mass flow rate of 2.0 × 10^–4 kg/s. To find the best comprehensive performance of PCHE channel shape, an evaluation index reflecting the heat transfer and flow capacity was monitored depending on the mass flow rate in the range of 1.0 × 10^–4 kg/s to 5.0 × 10^–4 kg/s. The results show that the sinusoidal channel at a mass flow rate of 3.0 × 10^–4 kg/s has the best thermal-hydraulic performance with a range of 7.2–45.8% higher than others among the PCHE configurations.