| Use of concentrated solar energy as a source of heat for thermochemical splitting of hydrogen sulfide is an intriguing method of storing solar energy in the form of hydrogen and sulfur while eliminating the costly environmental burden of disposing of a waste product formed during processing of petroleum, coal and natural gas. The major technical challenge is the design of the interface between the solar source and the chemical reactor. This study is to examine and characterize a porous bed, alumina reactor under various operating conditions. The study uses a one-dimensional, steady state model to predict the hydrogen production rate per unit area, the temperature profiles in both solid and gas phases and the composition profiles in the gas. The coupled, first-order, ordinary differential equations of the model were numerically solved by using a program called SIMPLER. Firstly, the exploration of the problem started by establishing a base case, with an insolation of 800 kW/m{dollar}sp2{dollar}, a feed gas temperature of 1000 K, a porosity of 0.85, and a feed rate of 0.25 kg/m{dollar}sp2{dollar}s. The surface temperature of the bed goes to about 1650 K and the gas products emerge from a 5 cm deep bed at about 1760 K at 0.95 atm. The gas achieved its equilibrium composition; the conversion of H{dollar}sb2{dollar}S to H{dollar}sb2{dollar} and S{dollar}sb2{dollar} was 0.71. The base case establishes a frame of reference for the parametric study, in which the effects of five independent parameters (feed gas temperature, solar energy flux, feed rate, sphere size, and thickness of the bed) and three dependent parameters (convective heat transfer coefficient, solid conductivity, and reaction rate constant) on the performance of the reactor were examined. The results suggest that the hydrogen production rate increases with the increase of feed gas temperature and solar energy flux. The production rate increases to its maximum value and decreases as the feed rate continues to increase. The production rate increases with decreasing sphere diameter and increasing thickness of the bed. The reaction rate constant deserves further chemical kinetics studies in a porous bed as its effect on the production rate is great. |
