Application of Life Cycle Sustainability Assessment to Used Lubricant Oil Management in South Brazilian Region

Used Lubricant Oil (ULO) is a hazardous waste resulting from lubricant oil used in motorized equipment to reduce friction between moving surfaces that, over time, wear outs and becomes contaminated. The purpose of this study is to compare the sustainability of two ULO management systems in Brazil: one designated in this study by the TTR scenario (which includes transportation, trans-shipment, and re-refining phases), the other designated by the TsTR scenario (without the trans-shipment phase) to evaluate which scenario is socially, economically, and environmentally more efficient. The study uses the life cycle sustainability assessment (LCSA) methodology. As a combination of life cycle assessment (LCA), life cycle cost (LCC), and social life cycle assessment (s-LCA), it integrates the three sustainability dimensions (environmental, social, and economic). The sustainability index was calculated by aggregating data from eight environmental indicators, five economic indicators, and five social indicators. The results showed that the TsTR scenario presented the best values for the sustainability assessment than the TTR scenario. The TsTR scenario had the best social and economic performance, and the TTR scenario had the best environmental performance. The differences observed in those scenarios’ performances were noted by the absence or presence of the trans-shipment center. The absence of this center improved the social and economic performance of the scenario. The social dimension was improved by the elimination of the stage that causes problems related to social and economic dimensions by reducing several costs that can be associated with it. The presence of the trans-shipment center improves the environmental performance scenario by reducing the number of hazards that could impact the re-refining phase. The LCSA methodology enables a comparative life cycle assessment of two alternative system evaluations of ULO management by the sustainability index of each scenario. This index helps to analyze the contributions of each of the 18 categories and subcategories in the perspective of the sustainability dimensions and, consequently, to carry out their integrated evaluation, aiming to define the best sustainability scenario.

Sorption of oils by a commercial non-woven polypropylene sorbent

Non-woven polypropylene (PP) sorbents are materials that can be used in oil recovery following spills, which are interesting alternatives to remediate contaminated areas. This work aimed to characterize a non-woven sorbent made of PP. The physicochemical characteristics of the material, sorption capacity, kinetics, and adsorption isotherms were evaluated. The physicochemical study included the determination of thickness, density, thermal and chemical properties of the sorbent, and fiber morphology. Sorption tests were performed according to the standard method ASTM 726-12. The kinetic models of pseudo-first and pseudo-second order were tested. The fit of the experimental data to the adsorption isotherms of Langmuir, Freundlich, and Temkin was also carried out. The sorbates used in the tests were diesel, petroleum, and lubricant oil. The sorption capacity of the PP nonwoven blanket relative to diesel, petroleum, and lubricant oil in long-term tests was 5.3, 12.3, and 18.7 g∙g-¹, with increasing values when sorbates were more viscous. The results of the short and long-term tests did not show a statistical difference in the sorption capacity of the blanket. The kinetic study showed that the sorption of the three sorbates followed pseudo-second-order kinetics. The diesel oil presented a better fit to the Langmuir isotherm (R² = 0.998), whereas the petroleum presented an excellent fit to all three isotherms (R² = 0.996-0.999). Regarding sorbent reusability, the sorption capacity stabilized after the second cycle, and the samples whose sorbate removal was carried out by centrifugation have presented and maintained the highest sorption capacities.

Experimental Investigation of the Influence of Engine Operating and Lubricant Oil Parameters on Sliding Bearing and Friction Behavior in a Heavy-Duty Diesel Engine

In order to rise to global challenges such as climate change, environmental pollution and conservation of resources, internal combustion engine manufacturers must meet the requirements of substantially reduced emissions of CO2 and other greenhouse gases, zero pollutant emissions and increased durability. This publication addresses approaches that can help improve engine efficiency and durability through the engine crankshaft bearing and lubricant system. An understanding of the operating behavior of key engine components such as crankshaft main bearings in fired engine operation allows the development of appropriate tools for bearing condition monitoring and condition-based maintenance so as to avoid critical engine operation and engine failure as well as unnecessary engine downtime. Such tools are especially important when newly developed low viscosity oils are employed. Though these oils have the potential to reduce friction and to increase engine efficiency, their use comes with a higher risk of accelerated bearing wear and ultimately bearing failure. The specific target of this paper is therefore to obtain detailed knowledge of the influence of engine operating parameters and oil parameters on crankshaft main bearing temperature behavior and engine friction behavior in fired operation as a starting point for condition monitoring and condition-based maintenance approaches and as a basis for improving the bearing and lubricant system as a whole. To achieve this target, experimental investigations were carried out on an engine test bed employing an in-line six-cylinder heavy-duty diesel engine with a displacement of approximately 12.4 dm3. Defined and accurately reproducible engine operating conditions were ensured by comprehensive external conditioning systems for the coolant, lubricating oil, fuel, charge air and ambient air. Since the focus was on investigating the bearing and friction behavior by means of the base engine, several auxiliary systems were removed; these included the lubricating oil and coolant pumps, the front-end accessory drive and the generator. Each crankshaft main bearing was instrumented with a thermocouple on the back of its bottom bearing shell to measure the bearing temperature. Piezoelectric pressure transducers were applied to all six cylinders in order to facilitate the accurate determination of the friction mean effective pressure (FMEP) based on indicated and brake mean effective pressures. The variations in engine operating parameters (engine speed and torque) mainly serve as a reference for the variations in oil parameters. They confirm the existing knowledge that engine speed has a significant impact on FMEP and bearing temperature while the impact of engine torque is comparatively low. The variations in oil parameters reveal that lowering the viscosity grade from SAE 10W-40 to 5W-20 leads to a decrease in both bearing temperature and FMEP, which can be explained by the lower fluid friction in the bearing system and the increased mass flow and convective heat transport with the lower viscosity oil. An increase in the lubricating oil temperature at the engine inlet leads to a significant increase in bearing temperature and a decrease in FMEP; the former is explained by the increased heat influx from the lubricant oil, and the latter is caused mainly by the temperature dependency of the lubricant oil viscosity and its impact on fluid friction. The impact of engine oil inlet pressure on bearing temperature and FMEP is generally found to be low. The results will serve as the basis for future research that includes approaches to condition monitoring and evaluating improved engine operating strategies with regard to oil parameters.

Optimization of the Rheological Properties and Tribological Performance of SAE 5w-30 Base Oil with Added MWCNTs

The augmentation of lubricant oil properties is key to protecting engines, bearings, and machine parts from damage due to friction and wear and minimizing energy lost in countering friction. The tribological and rheological properties of the lubricants are of utmost importance to prevent wear under unembellished conditions. The marginal addition of particulate and filamentous nanofillers enhances these properties, making the lubricant oil stable under severe operating conditions. This research explores the improvement in SAE 5w-30 base oil performance after the addition of multiwalled carbon nanotubes (MWCNTs) in six marginal compositions, namely, Base, 0.02, 0.04, 0.06, 0.08, and 0.10 weight percentage. The effect of the addition of MWCNTs on flash and pour points, thermal conductivity, kinematic viscosity, friction coefficients, and wear are investigated and reported. X-ray diffraction and transmission electron microscopy are used to characterize the MWCNTs. The purity, crystallinity, size, shape, and orientation of the MWCNTs are confirmed by XRD and TEM characterization. Pour points and flash points increase by adding MWCNTs but inconsistency is observed after the 0.06 wt.% composition. The thermal conductivity and kinematic viscosity increase significantly and consistently. The friction coefficient and wear scar diameter reduce to 0.06 wt.% MWCNTs and then the trend is reversed due to agglomeration and inhomogeneity. A composition of 0.06 wt.% is identified as the optimum considering all the investigated properties. This composition ensures the stability of the tribo-film and hydrodynamic lubrication.