An Overview of the Non-Energetic Valorization Possibilities of Plastic Waste via Thermochemical Processes.

The recovery and recycling/upcycling of plastics and polymer-based materials is needed in order to reduce plastic waste accumulated over decades. Mechanical recycling processes have made a great contribution to the circularity of plastic materials, contributing to 99% of recycled thermoplastics. Challenges facing this family of processes limit its outreach to 30% of plastic waste. Complementary pathways are needed to increase recycling rates. Chemical processes have the advantage of decomposing plastics into a variety of hydrocarbons that can cover a wide range of applications, such as monomers, lubricants, phase change materials, solvents, BTX (benzene, toluene, xylene), etc. The aim of the present work is to shed light on different chemical recycling pathways, with a special focus on thermochemicals. The study will cover the effects of feedstock, operating conditions, and processes used on the final products. Then, it will attempt to correlate these final products to some petrochemical feedstock being used today on a large scale.

New Concept of Power Generation Using TEGs: Thermal Modeling, Parametric Analysis, and Case Study.

In this manuscript, an innovative concept of producing power from a thermoelectric generator (TEG) is evaluated. This concept takes advantage of using the exhaust airflow of all-air heating, ventilating, and air-conditioning (HVAC) systems, and sun irradiation. For the first step, a parametric analysis of power generation from TEGs for different practical configurations is performed. Based on the results of the parametric analysis, recommendations associated with practical applications are presented. Therefore, a one-dimensional steady-state solution for the heat diffusion equation is considered with various boundary conditions (representing applied configurations). It is revealed that the most promising configuration corresponds to the TEG module exposed to a hot fluid at one face and a cold fluid at the other face. Then, based on the parametric analysis, the innovative concept is recognized and analyzed using appropriate thermal modeling. It is shown that for solar radiation of 2000 W/m2 and a space cooling load of 20 kW, a 40 × 40 cm2 flat plate is capable of generating 3.8 W of electrical power. Finally, an economic study shows that this system saves about $6 monthly with a 3-year payback period at 2000 W/m2 solar radiation. Environmentally, the system is also capable of reducing about 1 ton of CO2 emissions yearly.