RESUMO
The COVID-19 pandemic generated a new dynamic around waste management. Personal protective equipment such as masks, gloves, and face shields were essential to prevent the spread of the disease. However, despite the increase in waste, no technical alternatives were foreseen for the recovery of these wastes, which are made up of materials that can be valued for energy recovery. It is essential to design processes such as waste to energy to promote the circular economy. Therefore, techniques such as pyrolysis and thermal oxidative decomposition of waste materials need to be studied and scaled up, for which kinetic models and thermodynamic parameters are required to allow the design of this reaction equipment. This work develops kinetic models of the thermal degradation process by pyrolysis as an alternative for energy recovery of used masks generated by the COVID-19 pandemic. The wasted masks were isolated for 72 h for virus inactivation and characterized by FTIR-ATR spectroscopy, elemental analysis, and determinate the higher calorific value (HCV). The composition of the wasted masks included polypropylene, polyethylene terephthalate, nylon, and spandex, with higher calorific values than traditional fuels. For this reason, they are susceptible to value as an energetic material. Thermal degradation was performed by thermogravimetric analysis at different heating rates in N2 atmosphere. The gases produced were characterized by gas chromatography and mass spectrometry. The kinetic model was based on the mass loss of the masks on the thermal degradation, then calculated activation energies, reaction orders, pre-exponential factors, and thermodynamic parameters. Kinetics models such as Coats and Redfern, Horowitz and Metzger, Kissinger-Akahira-Sunose were studied to find the best-fit models between the experimental and calculated data. The kinetic and thermodynamic parameters of the thermal degradation processes demonstrated the feasibility and high potential of recovery of these residues with conversions higher than 89.26% and obtaining long-chain branched hydrocarbons, cyclic hydrocarbons, and CO2 as products.
RESUMO
Globally, the greenhouses' farming area comprises 500 000 ha, and they efficiently produce more than half of the vegetables consumed around the world. Nevertheless, high-yield crops tend to be incredibly energy-intensive. This study proposes designing and building a coupled geothermal heat pump for a 470 m2 greenhouse in the Andean zone conditions addressing a requirement of 15 °C at night and 30 °C during the day. Firstly, the study determined the energy potential of the solar and geothermal sources employing actual measurements and contrasting the results with theoretical models. Then, it developed an energy balance in the greenhouse to size the geothermal heat pump using the vapor compression cycle. Finally, the comprehensive system was built and evaluated through the Leveled Cost of Heat (LCOH). The operation requires a potential of 29.56 and 65.76 kW for heating and cooling; this is technically feasible when running the system with a heating flow driven by an optimized temperature ramp of 1.64 °C h-1. Also, the capacity factor (CF) shows that a lifespan between 12 to 14 years is required to reach acceptable LCOH when CF is as low as 0.45. Financially, it is necessary to foster customs exemptions to make it competitive versus more traditional sources such as electricity and LPG since the main components of the heat pump and the geothermal exchanger are not produced locally and represent nearly 70 % of the upfront costs.
