Numerical Investigation on the Two-Phase Flow Boiling Thermal Management for the Silicon-Based Bipolar Plate of a PEMFC

Cooling channels in proton exchange membrane fuel cell (PEMFC) bipolar plates are commonly arranged in parallel and connected by inlet and outlet manifolds. Under high heat flux, uneven flow distribution among parallel channels can lead to non-uniform temperatures and local hot spots, weakening thermal management reliability. To address this problem, this study develops a vapor–liquid two-phase computational fluid dynamics model to investigate flow-boiling cooling in a silicon-based bipolar plate. The Mixture multiphase model is combined with a user-defined phase-change source term to simulate water boiling in parallel channels. The thermal performance is evaluated using the temperature difference across the plate and a mass flow-rate non-uniformity index. The effects of four factors are systematically quantified, including inlet–outlet layout, inlet incidence angle, tube diameter, and inlet subcooling degree. Compared with the parallel inlet–outlet configuration, the central-side inlet–outlet arrangement reduces the plate temperature difference from 5.00 to 2.33 K. Increasing the inlet incidence angle worsens flow distribution uniformity, and the non-uniformity index rises from approximately 0.002 at 0 degrees to approximately 0.052 at 90 degrees. Reducing the tube diameter improves both flow distribution and heat transfer, and a 1 mm tube diameter produces the most uniform temperature field, with a plate temperature difference of 0.7 K. In addition, a saturated inlet condition rapidly establishes the two-phase region and maintains a plate temperature difference of 0.7 K, whereas the temperature difference increases to about 9 K when the inlet subcooling degree reaches 8 K. Within the investigated geometry and operating conditions, a central-side inlet–outlet layout with a 0-degree inlet incidence angle, a 1 mm tube diameter, and a saturated inlet condition provides the best overall temperature uniformity for PEMFC bipolar-plate thermal management.