Abstract: This study proposes a novel concentrated solar-driven methanol steam reforming hydrogen production system that integrates photothermal conversion with reactor thermal management through a symmetrical Fresnel reflector array. The system comprises 14 Fresnel reflector units forming a 1.2 m long concentrating module to achieve a theoretical concentration ratio of 11.56 and optical efficiency of 84.3%. A three-dimensional multiphysics coupling model was established using ANSYS Fluent to simulate temperature distribution, flow field characteristics, and component variations within the reactor under standard test conditions (1000 W/m² irradiance). Numerical results demonstrate that the concentrator delivers a stable thermal flux of 600 W to a 400 mm × 20 mm focal plane, maintaining a thermally stable zone (560 ± 45 K) across the reactor's rear 30 cm section with a temperature gradient of -4.6 K/cm and effective reaction space utilisation of 75%. Mass transport simulations reveal distinct reaction phases: the initial 0-8 cm section serves as a methanol phase-change preheating zone without hydrogen production; the 8-32 cm central section constitutes the primary reaction zone with 82.6% methanol conversion; and the terminal 32-40 cm section exhibits reactant depletion, reducing conversion to 11.4%. Under 1000 W/m² irradiation, hydrogen production reaches 0.36 NL/min with 64.2% mass fraction at the outlet. The study confirms effective thermal compatibility between Fresnel concentrators and tubular reformers while identifying challenges in terminal reaction stagnation and flow field disturbances. Future work will combine experimental validation to optimize system parameter matching and flow regime control to provide critical data for engineering applications.

Key words: solar hydrogen production, methanol steam reforming, fresnel concentrator, multiphysics coupling, numerical simulation