Canadian Journal of Chemical Engineering最新文献

Electrospinning produces micro- and nanofibres by forcing a polymeric solution through a fine needle in an electric field that produces a filament that accumulates onto a collector plate. The fibre morphology depends on solution properties, distance between needle and plate, feed rate, and electric field intensity. Membranes, films, capsules, and multilayer fibres are possible by introducing multiple needles, changing the plate configuration, moving the plate, or intermittent feeding. Its versatility, simplicity, and low-cost has accelerated the adoption of this technology for adsorbents, catalysts, membranes, gas separation, electronic devices, electrodes in supercapacitors, drug delivery, and nanomedicine/tissue engineering. Since 1997, Web of Science Core Collection has indexed over 40,000 articles with electrospinning as a keyword in the ‘Topic’ search field. Multidisciplinary materials science, polymer science, nanoscience nanotechnology, and applied physics are the scientific disciplines that publish the most articles related to electrospinning, while chemical engineering is ranked 10th. The main clusters of research are: (1) membranes, fibres, polymer morphology, and medical type applications (scaffolds, drug delivery, antimicrobial); (2) nanoparticles/composites, photocatalysis, and graphene; (3) membranes, ultrafiltration, desalination, and carbon nanotubes; and, (4) waste water treatment, adsorption, and heavy metals. Here we highlight research conducted over the past decades and remaining challenges, including developing industrial scale-up guidance, replacing/reducing hazardous and costly solvents, and devising theoretical models to determine optimal operating parameters.

Component failures in integrated heating and cooling networks impact reliable energy supply. This work studies reliability of heating and cooling systems constrained either by the annualized capital cost (ACC) or by the annualized total cost (ATC). A novel approach for assessing the supply reliability, representing energy networks as stochastic graph networks, is introduced, thereby enabling imposition of operational uncertainties and constraints as well as budgetary limitations as the graph networks' features. The reliability index is defined as the average percentage of the demands that are met. Single or multiple component failures may occur anytime; the reliability evaluation method is not restricted to one failure at a time. Examples of two different energy supply networks, maximizing the reliability under ACC or ATC constraints, are presented to illustrate the methodology. It is shown that, under ATC or ACC constraints, the 100% reliability and maximum consecutive loss of load hours (MCLOLH) equal to zero can be attained via a wide range of equipment sizes provided the thermal storage is sized correctly. Maps representing relative costs of heating, cooling, and storage, for the given system structure, help decision makers to determine equipment sizes if scaling up/down the system, while maintaining a high level of reliability.

This study presents the first integrated evaluation of how particle size distribution (PSD) of weighting materials affects both the rheological behaviour of water-based drilling fluids and the predictive accuracy of advanced rheological models. The originality lies in using complete mud formulations with multiple weighting materials, baryte, haematite, ilmenite, and Micromax, in both raw and milled forms, which enables a broader assessment than previously reported. Practically, the findings offer a pathway to optimize drilling fluid design for better viscosity control, improved wellbore stability, and reduced formation damage. Experimentally, reducing the D50 of baryte from 17.78 to 3.13 μm and haematite from 12.49 to 3.60 μm led to an approximate 50% increase in plastic viscosity and over 70% increase in yield point at a density of 16 ppg. Rheological models including Newtonian, Bingham Plastic, Power Law, Herschel–Bulkley, and Cross were applied, with Herschel–Bulkley and Cross models yielding R² values near 1.0 and RMSE as low as 0.23. Notably, finer particle sizes were better captured by advanced models, with Herschel–Bulkley and Cross outperforming simpler models, particularly at higher mud densities. These results demonstrate the critical role of PSD not only in fluid behaviour but also in selecting accurate rheological models for better prediction and formulation strategies. These results demonstrate the critical role of PSD not only in fluid behaviour but also in the selection of accurate rheological models for better prediction and formulation strategies.

Electrochemical polarization and electrochemical impedance spectroscopy (EIS) tests were performed to evaluate corrosion resistance of 316 L weld metal in different nutrient solutions at the temperature of 20°C. Both hot-rolled 316 L plates with dimensions of 200 mm × 100 mm × 8 mm were welded together by manual metal arc welding with an E316L-16(A022) electrode. Welding was performed using direct current electrode negative (DCEN). A welding current of 88 ~ 115A, arc voltage of 22 ~ 23 V, and welding speed of 120 ~ 160 mm/min were used to manufacture specimens, while inter-pass temperatures were maintained below 60°C. Potentiodynamic polarization measurements were taken at a scan rate of 10 mV/s at a potential initiated at −600 to +1600 mV. EIS measurements were performed at corrosion potential value by employing a signal with amplitude of 10 mV in a frequency range of 100 mHz–100 kHz. Observation of the optical microstructure of parent material revealed the equiaxed austenite grain, delta ferrite stringers, and micro-carbides distributed along cold rolling in the inner region. Weld metal zones consisted of an austenite/skeletal and spherical delta ferrite structure. The polarization test showed that corrosion potentials of the weld metal (−0.377 V, −0.268 V, −0.350 V, respectively, in 45 wt.% KH₂PO₄, 45 wt.% KNO₃, and 45 wt.% Ca(NO₃)₂) were clearly lower than those of the parent material (−0.233, −0.199, and −0.015 V) due to the heterogeneity of the microstructure in the welds. EIS data indicate that the corrosion mechanism is under diffusion control in the 45 wt.% KNO₃ solution, and under charge transfer control in the 45 wt.% KH₂PO₄ and 45 wt.% Ca(NO₃)₂ solutions. The results showed that there was need for corrosion protection by inhibitors in the 45 wt.% KH₂PO₄ and 45 wt.% Ca(NO₃)₂ solutions.