نوع مقاله : پژوهشی
تازه های تحقیق
عنوان مقاله English
نویسنده English
The management of used oils in the lubricant industry requires integrated decision-making due to environmental hazards, reverse logistics costs, quality heterogeneity of returned flows, and the need to reduce carbon emissions. This study aims to develop a mixed-integer linear programming model for a low-carbon closed-loop supply chain, with a particular focus on the characteristics of the lubricant industry. In the proposed model, final products are differentiated into three quality grades, namely A, B, and C, while the annual demand of each buyer group is treated as exogenous. The novelty of the model lies in the simultaneous integration of multi-grade products, buyer-group-specific acceptance-level selection, quality-based allocation of returned flows, disposition of unused flows, and cost-intensive emission reduction decisions alongside a cap-and-trade emissions mechanism. To evaluate the behavior of the model, a calibrated numerical instance comprising five buyer groups was considered, and the resulting optimization problem was solved directly using the HiGHS solver in a Python environment. The baseline results indicated an annual supply chain profit of USD 114.05 million and total sales of 725 thousand tons. Approximately 269.97 thousand tons of products were supplied through reprocessing, accounting for 37.24% of total sales. The model also selected an emission reduction level of 90 thousand tons, resulting in net emissions of 308.75 thousand tons of CO₂ and consequently requiring the purchase of 8,750 tons of emission allowances. Scenario analysis showed that profit varied from USD 98.56 million to USD 129.80 million, while the share of reprocessed products ranged from 32.02% to 42.36%. Sensitivity analysis identified the cost of producing products from virgin raw materials, collection transportation costs, the base return rate, and reprocessing costs as the most influential factors affecting profit. The results of this numerical instance highlight the importance of reducing dependence on virgin raw materials, improving reverse logistics, and coordinating emission-reduction costs with carbon allowance prices within the structure under consideration.
کلیدواژهها English
Copyright © Fatemeh Mojibian
License
This article is released under the Creative Commons Attribution (CC BY 4.0) license. Anyone is free to copy, share, translate, and adapt this article for any purpose, whether commercial or non-commercial, as long as proper citation is given to the authors and original publication.
