Numeric study on solar-driven pyrolysis of plastic waste

Pyrolysis is a technology that converts plastics into fuel or chemicals at high temperatures, offering significant advantages over other plastic waste disposal methods. Currently, the energy required for plastic pyrolysis usually comes directly or indirectly from fossil fuels, thus causing carbon emissions. This study investigates a plastic pyrolysis method using solar energy as the heat source, aiming to reduce carbon emissions and achieve carbon neutrality. A numerical model was developed to investigate temperature distribution, reaction rates, yields, and energy utilization in plastic pyrolysis. Simulation results indicated that under certain conditions, the plastic conversion exceeded 73%, with an energy efficiency above 17.3%. Heat flux, structural parameters of porous medium and inlet parameters of plastic are the key factors affecting the plastic pyrolysis. Heat flux had a significant impact on the system performance, plastic conversion remained below 30% when heat flux was below 0.3 MW/m2. Structural parameters of porous medium affected the reaction through both temperature and heat transfer process, which made their impact more complex. Reducing the plastic inlet speed and increasing the temperature can improve the plastic conversion and increase the proportion of oil and gas components in the product.