Comparative Analyses on Freezing Risk and Novel Anti-Freezing Structure for PCHEs As SLNG Vaporizer

Facing high pressure, low temperature, volume weight limits and marine conditions, the printed circuit heat exchanger (PCHE) has piqued the interest of numerous individuals and become an important component of ship fuel gas supply systems (FGSS). This study proposes a new cross counter flow (CCF) PCHE, selects the double bank plate as the investigation unit, and uses ANSYS Fluent 2021 R1 to numerically simulate the vaporization of supercritical liquefied natural gas (S-LNG). The thermal hydraulic phenomena of counter flow (CF) and CCF configurations were studied, the critical flow rate when the vaporizer fails was determined, and the risk of freezing under different S-LNG flow rates was analysed and compared. The results show that the CCF PCHE demonstrates outstanding heat transfer capabilities, which can improve heat transfer by 4.5 % compared with CF PCHE. Its overall performance can be improved by about 4.6 %. CCF PCHE also performs well in the effectiveness of vaporization and anti-freezing capability. Its effectiveness of vaporization is improved by 1.4 %-3.4 %, and the icing ratio in the same channel can be reduced by 5 % to 19 %. This study lays the foundation for the application of PCHE in S-LNG vaporization and provides valuable guidance for PCHE anti-freezing design.