Chemical Engineering Research & Design最新文献

Horizontal stratified and intermittent gas-liquid two-phase flows exhibit several sub-regimes. Identifying these correctly would enable the development of more robust predictive models. This study reports on experimental investigation, based on observations and the collection of time series of pressure drop in a 40 mm ID pipe. Nine different sub-regimes (SS, 2D wave, 3D wave, RW, ED+RW, PS+RW, plug, LAS, HAS) were revealed. An original flow pattern map for this diameter is proposed including transitory regions between the sub-regime. Comparison of experimental observations with existing flow maps has highlighted the effect of pipe diameter on transition of sub-regimes. As reported in literature the sub-regimes, could be identified by direct visualization of the pressure drop time series obtained from differential pressure sensor a swell as using Probability Density Function. Furthermore, statistical analysis of standard deviation as function of gas superficial velocity enabled detection of the transition of various sub-regimes. Finally, a space feature based on standard deviation and mixture Froude number is proposed as an identification tool between the different sub-regimes investigated.

Phase change materials (PCMs) are functional energy-storage materials that achieve reversible heat storage and release through phase transition processes. They have extensive applications in the thermal management and solar energy industries. However, their low electrical and thermal conductivities and poor stability often fail to meet application requirements. In this study, we utilised an abundant biomass-derived carbon source, sweet potatoes, to prepare a three-dimensional network of carbon aerogels. By simply vacuum-impregnating polyethylene glycol (PEG), the PCM was embedded in the carbon aerogel. The obtained PEG/carbon aerogel composite material exhibited high enthalpy (158.1 J/g) and good thermal and shape stability. They also demonstrated efficient photothermal (88.47 %) and electrothermal conversion (94.02 %). This research has significant potential for applications in solar energy storage and utilisation, building energy storage, space–ground thermal energy storage, and electronic device thermal management. This study provides a novel approach for the preparation and photothermal applications of bio-based PCMs.

Heavy crude oil upgrading in a supercritical water environment is a promising technology owing to diverse advantages such as heteroatom removal, high yields of low molecular weight fractions, and inhibition of coke production. In order to increase the performance of this process, some challenges need to be overcome by researching the reaction mechanisms and developing proper numerical models. Therefore, the kinetic studies reported in the literature for hydrothermal upgrading of heavy crude oil under supercritical water conditions and their results were systematically analyzed and discussed to achieve a better understanding of the diverse approaches considered to determine the distribution of reaction products and limitations. Additionally, fundamental aspects of the kinetic models, including experimental considerations and numerical methodologies applied for kinetic parameter estimation, are reviewed to obtain representative information about the reactant system that can be subsequently integrated into reactor design models or reservoir simulations.

Small-molecule compounds targeted for drug development have frequently exhibited poor solubility in water, leading to instances of liquid-liquid phase separation (LLPS) during cooling crystallization and anti-solvent crystallization processes. Addressing strategies for managing crystallization processes involving LLPS has become a significant concern. Predicting changes in the structure and concentration of each separated phase over time would contribute to setting conditions and guiding process design to prevent oiling-out and achieve particles with desired morphology. In this study, we assessed the potential of the phase-field method to predict LLPS through simulations in a typical LLPS system, especially a ternary water/ethanol/butylparaben system. Consequently, the phase states in each zone (stable, metastable, and unstable) were determined to be thermodynamically valid. Additionally, the size of the spherical dispersed phase was confirmed to change in proportion to one-third of the time according to the Ostwald ripening rule. Furthermore, the qualitative analysis of factors influencing phase structure, local composition, delay time for phase separation in spinodal decomposition, and the localized LLPS during anti-solvent addition is also feasible. These findings suggest that the phase-field method holds potential as a tool to aid in the design of crystallization processes.

Research has shown the correlation between porous membrane pore size and bubble formation including bubble size, frequency, and operating parameters. However, attempts to create a governing equation to establish this correlation have often suffered from low accuracy due to variable interactions. Therefore, it is necessary to identify the significant effects of membrane pore size on bubble formation to establish effective correlations. This study aimed to identify the significant effect of porous membrane pore size on bubble formation using analysis of variance (ANOVA) to establish a mathematical model that predicts porous membrane pore size using bubble formation. To achieve this, various porous membranes were fabricated by varying hydrophilic silica loadings. The resulting membranes were characterized regarding pore size and employed in an aeration device under variable air flow rates and inlet pressures to obtain bubble size and frequency data. JMP software developed a statistical model to characterize membrane pore sizes. The results show a significant effect of bubble formation information on pore size, with a p-value of 0.0089, R² of 0.96, and root mean squared error (RMSE) value of 0.02. Validation of the model using three membranes demonstrated minor deviations of 0–6.5 %, emphasizing the model's effectiveness in predicting membrane pore size.

Pandanus amaryllifolius leaves (PAL) are known for their aroma and are also a rich source of natural phytochemicals. The purity, yield, and stability of phytochemicals depend upon the efficiency and selectiveness of the extraction method and the solvent used. In this study, the phytochemical and antioxidant activity of PAL were evaluated by using non-thermal extraction techniques, i.e., ultrasound (US) and cold plasma (CP). The extraction was evaluated using two different solvents: petroleum ether and 30 % ethanol. Face-centered central composite design was used to design the experimental parameters. The process parameters used were amplitude (30, 45, and 60 %) and treatment time (15, 30, and 45 min) for US, and voltage (10, 20, and 30 kV) and time (10, 20, and 30 min) for CP. The extraction efficiency of both the treatment methods and solvents was evaluated based on the quantification of total phenolics, flavonoids, terpenoids, chlorophyll content, and antioxidant activity. The damaged cell structure as observed from SEM images, confirmed the extraction of phytochemicals. The presence of phenolic and flavonoid compounds in the extract of PAL was confirmed from the FTIR analysis, revealing its nutritional and medicinal properties. Antioxidant activity was higher in case of 30 % ethanol as compared to petroleum ether. In the case of phenolic compounds, CP along with ethanol, had higher extraction efficiency. The use of non-thermal technology along with a suitable solvent can extract phytochemicals and antioxidants from PAL that can be further utilized for value-added product development.

This work assesses the influence of transport phenomena on the growth of Yarrowia lipolytica 2.2ab (Yl2.2ab) and protease production during Solid-State Fermentation (SSF) in a bench-scale wall-cooled tubular bioreactor packed with substrate-based pellets derived from agro-industrial residues. Our engineering methodology, in a novel manner, includes: (i) developing a new pseudo-heterogeneous model, (ii) identifying and quantifying the impact of all transport phenomena on microbial kinetics, (iii) elucidating how fluid dynamics enhances heat and mass transfer processes, and hence microbial kinetics, and (iv) determining the operational and geometric parameters for optimal bioreactor performance. As main results: (i) all transport phenomena occurring within the bench-scale bioreactor are fundamental for its reliable simulation and will be essential for its scale-up, and (ii) the maximum production of proteases, 420 U kg_DS^‐1−1, is achieved under the following operational conditions: a tube to particle diameter ratio of 5.6, a bath temperature of 45°C, an inlet airflow rate of 1 L min⁻¹, and inlet fluid temperature of 43 °C. Finally, the pseudo-heterogeneous model is assessed by describing SSF-based observations from the literature, appropriately predicting the performance of Yl2.2ab in a bench-scale bioreactor. These results pave the way for future exploration of Yl2.2ab in SSF within larger-scale packed-bed bioreactors.

Successful production of 1:1 sulfamethazine-acetylsalicylic acid (SMZ-ASA) cocrystal was achieved through slow solvent evaporation, liquid-assisted grinding, and slurry conversion method. SCXRD, PXRD, DSC, FTIR, and Raman spectroscopy were employed to characterize the cocrystal. Ternary phase diagrams (TPD) for SMZ and ASA in acetonitrile (ACN) and deionized water (DIW) has been constructed at 25 ℃. Using TPD of the incongruent system, slurry compositions for stable production of cocrystal was determined in both the solvents. The cocrystal conversion process in slurry was monitored using in-situ Raman spectroscopy. Intermittent sampling was also carried out to determine the purity of the solid phase from the slurry using offline PXRD. In-situ Raman and offline PXRD measurements confirmed fast conversion of the pure coformer crystals to the cocrystal in ACN, within a span of 5 minutes. However, the conversion in DIW was much slower and the in-situ Raman measurements significantly underpredicted the transformation time in comparison to offline PXRD analysis. The study highlights the utilization of TPD for developing the cocrystallization process and the need for multiple characterization techniques for monitoring cocrystallization.

This study aims to develop a novel and efficient magnetic nanocatalyst for producing biodiesel from waste coconut scum oil (WCSO). In this regard, a retrievable and robust nanocatalyst, SnFe₂O₄/biochar derived from cigarette butts, was synthesized and applied in the transesterification of WCSO under ultrasonication. The aforementioned nanocatalyst was synthesized by sol-gel technique. Various analyses were conducted to characterize the prepared nanocatalyst. These analyses confirmed the successful decoration of biochar on SnFe₂O₄. The Surface area and pore diameter were 128.47 m²/g and 15.62 nm, respectively. Central composite design (CCD) was applied to optimize the parameters influencing biodiesel synthesis. Moreover, the highest biodiesel yield employing SnFe₂O₄/cigarette butt-derived biochar nanocatalysts was attained at 98.67 % under optimal conditions, which include a methanol/WCSO ratio of 11.81:1 mol/mol, ultrasonic time of 34.25 min, temperature of 64.05 °C, and a catalyst amount of 2.73 wt%. Besides, SnFe₂O₄/cigarette butt-derived biochar demonstrated a notable biodiesel yield (90.48 %) even after seven reuse steps, highlighting its exceptional reusability. The thermodynamic and kinetic analyses of transesterification indicate that the synthesis of biodiesel is an endothermic reaction. The SnFe₂O₄/cigarette butt-derived biochar nanocatalyst stands out as a highly promising candidate for future research due to biodiesel performance, quick reaction time, and remarkable catalyst reusability.

The severe consequences of thermal runaways, make process optimization of paramount importance for free radical polymerization reactors, in order to maximize in an integrated way their safety and productivity. Generally, this optimization is performed by simulation, for the sake of safety and cost. Today, the literature contains several models of free radical polymerization reactors in general; and methyl methacrylate (MMA) polymerization reactors, in particular. Although, MMA polymerization is commonly performed in semi-batch reactors at industrial level, most of the available models focus on batch reactors; while, the semi-batch reactor models are much scarcer. In this work, a model of a MMA solution polymerization batch reactor was modified in order to generalize it to semi-batch operation. The developed semi-batch model was used here for studying the effect of different operation conditions (feeding flow rate, initiator load, monomer initial load, and reactor temperature) on the quality characteristics of the produced polymer and on the safety and productivity of the polymerization reactor. The developed model can be used to optimize the operation conditions of a semi-batch reactor so that the final product quality meets the application requirements, while maintaining the reactor within its safe-operation envelope, and maximizing its productivity.