Investigation of a solar hydrogen generating system design for green applications

This study presents a unique dome photoanode design that can harvest the maximum delivered sun rays over the daytime due to its specific dome design to enhance the solar to hydrogen energy efficiency and improve the hydrogen mass generation rate. The photoanode and cathode domes are placed in a potassium hydroxide electrolyte inside two cylindrical vessels. The coupled electrochemical, exergy, energy, as well as fluid flow analyses, are conducted to examine the proposed photoelectrochemical cell designs using both COMSOL and Engineering Equation Solver software packages. The electrochemical process equations are simulated extensively to investigate the impacts of changing the illuminated electrode surface area, quantum efficiency, solar radiation intensity, and photocurrent density upon the corresponding energy efficiency as well as hydrogen generation rate. The thermodynamic balance equations are also developed to predict the exergy and energy for all inputs and outputs. The impact of electrolyte flow circulation on the oxygen bubble formation is formulated in a way to prevent the bubble coverage phenomenon. The numerical results showed that the hydrogen mass generation rate and solar to hydrogen efficiency are 26.16 mu g/s and 4.38%, respectively, which happens at 600 W/m(2) of solar irradiance, 10% quantum efficiency, and 569 cm(2) illuminated electrode surface area. The maximum mass-based hydrogen generation rate and the overall energy efficiency, which are found to be 55.20 mu g/s and 6.69%, are achieved at a 800 cm(2) illuminated photoanode surface area, a 600 W/m(2) solar radiation intensity, a 3.3 mA/cm(2) current density, and a 10% quantum efficiency.