Investigation of multi-dimensional transfer effects in applied smouldering systems: A 2D numerical modelling approach

Abstract

Applied smouldering systems are gaining popularity for a variety of energy conversion applications. Radial heat loss plays a crucial role in these systems, as they cause multi-dimensional effects (e.g., in temperature, airflow, and chemical activity). These effects can control system operation limits and performance; therefore, a robust understanding of these multi-dimensional effects is crucial for design engineers. A multi-dimensional applied smouldering numerical model was developed that couples key physics and chemistry. The model was validated against highly instrumented smouldering experiments. The model was then used to qualitatively investigate the multi-dimensional effects and quantitatively analyze the energy balance that dictates the limits of the self-sustaining process. Moreover, a sensitivity analysis of the system energy efficiency, air flow, fuel concentration, and porous medium permeability was completed. The results provide insight into the interconnected nature of key physical (e.g., temperature, air flow, permeability) and chemical (e.g., oxygen concentration, reaction intensity) qualities. Altogether, this work provides a novel tool for investigating, designing, and optimizing smouldering reactors for a range of applications such as soil remediation, waste-to-energy, and improving sanitation in the developing world.