New approach for the dimensionless analysis of a unidirectional flow solar reactor based on Damköhler's number profiles

Abstract

A methodology for the analysis of the behavior of complex reactors based on the construction of profiles of a dimensionless number (Damköhler) for each main chemical species (Dai) was proposed. A 4-chlorophenol mineralization reaction in a heterogeneous solar reactor with suspended TiO2 and addition of H2O2 with tubular geometry and radiation collectors, fluid flow and a recirculation system was selected as a complex model system in order to validate the approach. The dynamic behavior of the reactor in dimensionless variables was modeled as a function of Dai. Where Dai(z,t) is a local property and grouped the optical and surface's properties of the catalyst, catalyst load, radiation intensity, the photon absorption rate, rate of non-photochemical reactions, the H2O2 effect, the reaction rate of different stages like adsorption, attack of radicals, surface reactions, plus design and operation variables like reactor volume and volumetric flow.A coupling of orthogonal collocation and Runge-Kutta methods were used to solve the PDEs and carry out the simulations to the different experimental conditions, resulting in profiles of Dai, Ci, and conversion in function of time and space. The Dai profiles proposed in the new methodology are capable of describing the disturbances in solar reactors, to indicate consumption and generation rates, instantaneous changes of reaction rate, to describe competitive reactions and quenching effects and to determine equilibrium concentrations, all of the above at each time and space. Therefore, this approach is a analysis tool of reactors which complements the concentration profile. This methodology can be extended to other reactive systems, adapting the intrinsic reaction rates.