Comparative rheological study on hybrid nanofluids with the same structure of MWCNT (50%)-ZnO(50%)/SAE XWX to select the best performance of nano-lubricants using response surface modeling

Influences of plasma treatment parameters on the hydrophobicity of cathode and anode materials from spent lithium-ion batteries

The recycling of spent lithium-ion batteries (LIBs) can not only reduce the potential harm caused by solid waste piles to the local environment but also provide raw materials for manufacturing new batteries. Flotation is an alternative approach to achieve the selective separation of cathode and anode active materials from spent LIBs. However, the presence of organic binder on the surface of hydrophilic lithium transition-metal oxides results in losses of cathode materials in the froth phase. In this study, plasma treatment was utilized to remove organic layers from cathode and anode active materials. Firstly, the correlations between plasma treatment parameters (e.g., input power, air flowrate, and treatment time) were explored and the contact angles of cathode and anode active materials were investigated by the response surface methodology. Secondly, differences in the flotation recoveries of cathode and anode active materials were enhanced with plasma modification prior to flotation, which is consistent with the contact angle measurement. Finally, the plasma-modification mechanisms of hydrophobicity of cathode and anode active materials were discussed according to Fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The proposed method could be a promising tool to enhance the flotation separation efficiency of cathode and anode active materials for the recycling of spent LIBs.

Copper Quantum Dot/Polyacrylamide Composite Nanospheres: Spreading on Quartz Flake Surfaces and Displacing Crude Oil in Microchannel Chips

Polyacrylamide, silica, and other nanoparticles have all been realized in the field of enhanced oil recovery. Researchers often explore the mechanisms of spreading behavior and simulated displacement to develop more efficient types of nanoparticles. In this study, copper quantum dots were introduced into a acrylamide copolymerization system to obtain composite nanospheres and its structure, topographic, and application performance were characterized. The results show that the composite nanospheres have a particle size of around 25 nm, are uniformly loaded with copper particles, and have good temperature resistance. The spreading ability on the quartz flake surfaces and displacement effect in microchannels of composite nanospheres, acrylamide copolymer nanospheres, and copper quantum dots were compared by nanofluid spreading experiments and microchannel chip oil displacement experiments. The results indicate that the composite nanospheres can effectively reduce the water contact angle, promote the spreading of aqueous phase, and accelerate the oil droplet removal process; the accelerating effect is stronger than other samples. Its oil displacement effect is also the strongest, and it is minimized by the influence of channel size, temperature, and dispersing medium, with better stratigraphic adaptability. This work supports the practical application of copper quantum dot/polyacrylamide composite nanospheres in the oilfield.

Performance enhancement and optimization of residential air conditioning system in response to the novel FAl2O3-POE nanolubricant adoption

This paper aims to evaluate residential air conditioning systems' performance enhancement and optimization by adopting a novel functionalized Al2O3 (FAl2O3)-Polyolester (POE) nanolubricant. Comprehensive discussions were conducted on key performance parameters, including heat absorption, compressor work, cooling capacity, coefficient of performance (COP), and power consumption. Novel FAl2O3 nanoparticles were dispersed into the POE lubricant using a two-step method. The findings reveal that FAl2O3-POE nanolubricant exhibits superior heat absorption compared to pure POE. Heat absorption decreases with an increased initial refrigerant charge, while cooling capacity performance improves with an increased initial refrigerant charge. The COP shows an increasing trend at all concentrations of FAl2O3-POE nanolubricant when operating with R32. FAl2O3-POE/R32 demonstrates an enhanced range of 3.12%-32.26% for COP. The results suggest that applying novel FAl2O3-POE nanolubricant with R32 can reduce electrical power consumption by 13.79%-19.35%. The central composite design (CCD) offers an optimal condition for FAl2O3-POE nanolubricant with a concentration of 0.11 vol%, an initial refrigerant charge of 0.442 kg, resulting in a COP of 3.982, a standard error of 0.019, and a desirability of 1.0.

Examining rheological behavior of CeO2-GO-SA/10W40 ternary hybrid nanofluid based on experiments and COMBI/ANN/RSM modeling

In this study, the rheological behavior and dynamic viscosity of 10W40 engine oil in the presence of ternary-hybrid nanomaterials of cerium oxide (CeO₂), graphene oxide (GO), and silica aerogel (SA) were investigated experimentally. Nanofluid viscosity was measured over a volume fraction range of VF = 0.25-1.5%, a temperature range of T = 5-55 °C, and a shear rate range of SR = 40-1000 rpm. The preparation of ternary-hybrid nanofluids involved a two-step process, and the nanomaterials were dispersed in SAE 10W40 using a magnetic stirrer and ultrasonic device. In addition, CeO₂, GO, and SA nanoadditives underwent X-ray diffraction-based structural analysis. The non-Newtonian (pseudoplastic) behavior of ternary-hybrid nanofluid at all temperatures and volume fractions is revealed by analyzing shear stress, dynamic viscosity, and power-law model coefficients. However, the nanofluids tend to Newtonian behavior at low temperatures. For instance, dynamic viscosity declines with increasing shear rate between 4.51% (at 5 °C) and 41.59% (at 55 °C) for the 1.5 vol% nanofluid. The experimental results demonstrated that the viscosity of ternary-hybrid nanofluid declines with increasing temperature and decreasing volume fraction. For instance, assuming a constant SR of 100 rpm and a temperature increase from 5 to 55 °C, the dynamic viscosity increases by at least 95.05% (base fluid) and no more than 95.82% (1.5 vol% nanofluid). Furthermore, by increasing the volume fraction from 0 to 1.5%, the dynamic viscosity increases by a minimum of 14.74% (at 5 °C) and a maximum of 35.94% (at 55 °C). Moreover, different methods (COMBI algorithm, GMDH-type ANN, and RSM) were used to develop models for the nanofluid's dynamic viscosity, and their accuracy and complexity were compared. The COMBI algorithm with R² = 0.9995 had the highest accuracy among the developed models. Additionally, RSM and COMBI were able to generate predictive models with the least complexity.