Numerical analysis of the solar reactor design for a photoelectrochemical hydrogen production system

Heat transfer in a photoelectrochemical (PEC) hydrogen generation reactor system is studied numerically. Four different reactor designs are investigated in this work. Solar irradiation is spectrally separated into short and long wavelength parts depending on the energy band gap of the photoelectrode. The short wave energy is directed to the anode to generate electron and hole pairs, and the long wave energy is used for heating the reactor. Results indicate that the use of the excess long wave energy by careful reactor design can effectively increase the system efficiency. Comparing designs 1 and 4 under 6000 W/m ² irradiation and a quantum efficiency of 30%, the enhancement of the solar-to-hydrogen efficiency is respectively 12.7% and 18.2% for electrodes with E _g = 2.1 eV and 3.2 eV, such as Fe ₂O ₃ and TiO ₂. Effects of several parameters on the PEC hydrogen reactor system are discussed in details.