A study on energy and fluid flows for a novel photoelectrochemical reactor developed for hydrogen production

Abstract

A numerical study of a new photoelectrochemical (PEC) cell for hydrogen production is performed to investigate energy and fluid flows in particularly removing the adhering bubbles on the surface of the electrodes. The proposed ratio of the electrodes’ surface area is taken as 2.6:1 of the photocathode to the anode. The total surface area of the dome photoelectrode and the disc anode is designed to be 1680.2 cm2 and 645.4 cm2. The developed reactor primarily consists of two cylindrical compartments made of acrylic glass with good absorptivity to allow the maximum wavelengths to pass through. The sunlight is supplied from a solar simulator on the top cover of the PEC cell. The governing equations of the proposed model include Navier-Stokes equations, energy equation, and the radiative transfer equation (RTE). The COMSOL package is used to perform the fluid flow simulation for two different models. Two different COMSOL modules are utilized to solve the governing equations, including Laminar flow and heat transfer in solids and fluids. Also, all electrochemical equations are investigated by the Engineering Equation Solver (EES). The velocity contours, streamlines, temperature contours, and pressure lines are presented and discussed. The present results indicate that the electrolysis and solar to hydrogen (STH) efficiencies are found to be 26.70% and 5.17%, with a mass flow of hydrogen at 66.3 × 10−9 kg/s. A comprehensive parametric study is performed to find the best-operating conditions of the studied PEC reactor. Furthermore, the highest STH efficiency is obtained as 7.3% at a solar incident flux of 400 W/m2. The hydrogen mass production rate can be generated of 132.7 × 10−9 kg/s at a solar incident flux of 1200 W/m2.