Modeling and Optimization of Solar-Powered Pyrolysis Reactor for Plastic Waste Conversion into Valuable Products

Abstract

The conversion of plastic waste into useful fuels and chemicals can mitigate landfill accumulation while offsetting fossil-derived energy demand. This study develops a low-cost solar-thermal approach for providing the high process temperatures required for plastic pyrolysis by modelling, fabricating, and experimentally evaluating a parabolic dish concentrator integrated with solar tracking. A theoretical framework is presented for solar radiation capture, concentrator geometry, concentration ratio, and receiver heat-loss-based thermal performance, alongside efficiency metrics commonly used to assess plastic-to-oil conversion (waste-reduction efficiency, conversion efficiency, and oil recovery). A prototype parabolic dish (rim angle 45°) was designed with key geometric parameters, including a 0.61 m diameter, a 0.06 m focal point, and an estimated concentration ratio of 100, selected to accommodate low-cost reflector materials. Three reflector preferences, including a Polyethylene Terephthalate (PET) mirror, an emergency blanket, and a conventional mirror, were tested under comparable conditions using a dual-axis tracking structure. Experimental outcomes demonstrate that the dishes can achieve very high focal temperatures (up to ~ 817 °C for the emergency blanket and ~ 807 °C for the mirror configuration in the reported dataset), with maximum thermal power on the order of 361-389 W across configurations. When techno-economic indicators are included, the emergency blanket reflector exhibits the most favourable practicality, yielding the lowest mass-to-heat-power ratio (1.04 × 10^-3 kg·W^-1) and cost to-heat-power ratio (1.41 THB·W^-1). These results support the feasibility of lightweight, low-cost solar concentrators as a heat source for decentralised plastic waste pyrolysis. This study provides an experimental comparison of low-cost reflective materials and identifies key design considerations for lightweight solar parabolic dish concentrators.