Development of a two-dimensional thermal network model for performance prediction of printed circuit steam generators

• Two-dimensional thermal network model is developed for PCSG simulation. • Developed model can predict 2D steady-state behavior of a PCSG with cross-flow. • Input convention for channel arrangement information is introduced. • Heat transfer and pressure loss were higher in serpentine-type than Z-type PCSG. • 2D model can reflect important aspects of PCSG design that 1D model cannot. Printed Circuit Steam Generator (PCSG) is a promising candidate for Small Modular Reactors (SMRs) due to its high heat transfer area per unit volume. PCSGs generally have two-dimensional flow channel arrangement, which often involves cross-flow heat transfer. To accurately predict the thermal behavior of such PCSGs, we developed a method incorporating two-dimensional thermal network each for the fluid layers and wall surface layers for the primary and secondary sides. Correlations are obtained using Computational Fluid Dynamics (CFD) for the Fanning friction factor and Nusselt number for semicircular straight channels for 800 ≤ Re ≤ 200,000 and 0.8 ≤ Pr ≤ 3.0, and conductive thermal resistance for fixed parallel and cross channel geometries for the solid thermal conductivity ranging from 12 to 24 W/m∙K. The model is applied to predict the performance of a Z-type PCSG and a serpentine-type PCSG. The serpentine-type PCSG yielded 21.8 °C higher steam temperature but approximately ten times of secondary side pressure loss compared to the Z-type. Limitations in the conventional one-dimensional method was investigated, proving the necessity of the proposed two-dimensional model.