A solar methane reforming reactor design with enhanced efficiency

Highlights: • The thermal efficiency increases from 71% to 76.02% with the cutoff wavelength coating. • The peak-to-mean flux ratio decreases from 5.42 to 3.07 with CPC device. • The solar-to-chemical and thermal efficiency reach 59.16% and 76.02% at 850 °C and 1 atm. • Methane conversion rate is 83.95% at temperature of 850 °C with Ni as catalyst. We report an efficiency-enhanced solar methane reforming reactor design, featuring cutoff wavelength coating over quartz window for incident solar energy, a compound parabolic concentrator (CPC) device for thermochemical performance enhancement and reticulated porous ceramics (RPC) structure of Ni/CeO₂-ZrO₂ used as the catalyst. A numerical model combining Monte-Carlo ray-tracing (MCRT) method with finite-element method (FEM) is established to evaluate the effectiveness of this reactor design. The simulation results show that the cutoff wavelength coating (with threshold wavelength of 2400 nm) helps to reduce 80% radiation heat loss from within the reactor at the cost of only 1% incident sunlight loss during transmission at a typical reforming temperature of 850 °C. The performance of the reactor is numerically investigated under different reaction conditions with wide ranges of temperature, solar power input and steam-to-methane ratio. Results show that ${\eta }_{\text{solar}-\text{chemical}}$ (solar-to-chemical efficiency) can reach 39.98% and 59.16% without and with 90% heat recovery, respectively, and $X_{{\text{CH}}_4}$ (methane conversion) is 83.95% at reforming temperature of 850 °C and pressure of 1 atm. The new reactor design could considerably increase the utilization efficiency of solar energy.