Asia-Pacific Journal of Chemical Engineering最新文献

Dividing-wall column (DWC) provides tremendous advantages in terms of energy savings and capital costs for three-component and even multi-component separations. With increasing industrial application of three-component DWCs, DWCs for separation of four-component have received considerable research attention. The aim of this work is to investigate the design of the two-staggered wall region and gas–liquid two-phase flow behavior on the tray in a double-partition DWC (DPDWC). The Aspen Plus was applied to simulate the steady state to obtain the gas–liquid-phase flow rate in each region to serve as the basis for the tray design. In different task regions, the gas- and liquid-phase flow varied in some ways. The drag models have variability for the study of fluid flow, and the Tomiyama model is more appropriate. Moreover, high-velocity gradients and recirculating phenomenon can be discovered owing to the existence of multiple partitions in DPDWC.

Ethylene plays a crucial role as an intermediate component in the cracking and combustion processes of large molecular alkane and olefins. In this article, the laminar flame speed of ethylene–air mixtures was measured using the heat flux method. The mechanism of ethylene was simplified by utilizing the error propagation directed relationship graph (DRGEP) and sensitivity analysis (SA), and the Arrhenius pre-exponential factors for 20 selected reactions in the skeletal mechanism were optimized using the particle swarm optimization (PSO) algorithm. Finally, an ethylene optimization mechanism including 39 species and 85 reactions was obtained. The prediction results for flame speed, ignition delay time, and species concentration were compared with experimental data and other mechanisms, covering a wide range of temperatures (298–1725 K), pressures (1–22.8 atm), and equivalence ratios (0.5–2.0). The findings demonstrate that the optimization mechanism not only improves the prediction results of laminar flame speed in the rich combustion zone and low oxygen environment but also enhances the prediction accuracy of the ignition delay time at high pressure and in the lean combustion zone, as well as the prediction accuracy of C₂H₄ and H₂O radicals. In conclusion, the optimized mechanism exhibits higher accuracy and broader applicability.

In this work, snowflake-like α-CaSO₄·0.5H₂O (α-CSH) hierarchical architectures were successfully synthesized by a facile one-pot method in an ethylene glycol-water system using Na₂EDTA as a crystal morphology modifier. Characterization techniques including X-ray diffraction (XRD), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) confirmed the progressive morphological evolution of α-CSH from rods to snowflake-like structures ultimately to hexagonal plates with increased Na₂EDTA concentrations. The results revealed that Na₂EDTA concentration played a critical role in directing the crystallization and self-assembly of α-CSH, and a mechanism is proposed where Na₂EDTA modulated crystal orientation through preferential adsorption and regulated the driving forces between ion-mediated crystallization and particle-mediated assembly. This work puts forward a simple yet effective strategy for facilely regulating the morphology of α-CSH microstructures, which could potentially expand their applications across diverse fields such as composites, construction, biomedicine, and drug delivery.

The large-scale accumulation of industrial by-product gypsum has led to land embezzlement and serious environmental pollution. Meanwhile, as a predominantly used nitrogen fertilizer, urea shows a disadvantage of high solubility in soil. Therefore, it can hydrolyze into large amounts of ammonium salts so rapidly that cannot be absorbed efficiently by crops. The sustainable method of using industrial by-product gypsum to synthesize urea gypsum cocrystals is a promising way to solve above challenges. The synthesized urea gypsum shows low aqueous solubility and hygroscopicity, which can be used as sustained release fertilizer. In this review, the present status regarding urea gypsum is systematically reviewed, including its development history, preparation methods, impact of different raw materials, evaluation of products performance, and large-scale trials. This review aims to reveal the current situation, identify current gaps, and provide suggestions for future investigations concerning urea gypsum.

The dividing-wall column (DWC) stands as an energy-efficient distillation technology designed to efficiently separate ternary systems into their pure components within a single column. Despite its efficiency, integrating two towers into a DWC poses challenges in controllability. Published studies have focused on developing controllers for disturbance rejection but have not addressed the issue of servo control. Addressing this, our study proposes a servo controller problem and a methodical approach to strategically select controlled variables that undergo consecutive set point step changes, aiming to track the purity of key products obtained from the DWC. To achieve this goal, we developed a dynamic model specifically tailored to the DWC. Determining the design parameters involved employing a genetic algorithm optimization technique, minimizing the total annual cost. Subsequently, we implemented three servo parallel proportional-integral (PI) feedback controllers for three distinct product streams. The fine-tuning of their controller gain and reset time is carried out by minimizing the integrated square error while adhering to valve opening constraints. Our investigation revealed a limitation: the introduction of simultaneous step changes in all three controlled variables proved unfeasible with the three active PI controllers. As an alternative, our findings recommend prioritizing two variables: the lightest (distillate) and heaviest (bottom) key components, alongside the middle component (side stream) and either the lightest or heaviest key component. This research underscores the complexities of implementing step changes in multiple controlled variables within a DWC, offering insights into optimal control strategies for enhancing the efficiency of this innovative distillation technology.

Understanding the mechanisms of shale–water interaction by water vapour adsorption is crucial for predicting shale gas productivity. In this study, equilibrium adsorption data of water vapour on four different shales of the Sichuan Basin at three temperatures (298, 308, and 318 K) were measured using static gravity techniques. The water vapour adsorption isotherms were simulated by three statistical physics models. Steric parameters, including the number of water vapour molecules adsorbed per site (n), monolayer adsorption amount (q₀), and adsorption energy (ΔE^a), and thermodynamic parameters such as configuration entropy (S_a), internal energy (E_int), and free energy (G_a) derived from the selected model were used to explain the adsorption mechanism. The model analyses suggest that the adsorbed water vapour molecules are attached to the shale surface in a multi-anchorage manner. The adsorption of the first layer shows a Type I characteristics, while the adsorption of the subsequent layer is of Type III. The calculated adsorption energies indicate that the physical adsorption takes place on the water vapour molecules on the shale, and the main interaction forces are hydrophilic bonding forces and van der Waals forces. Negative E_int and G_a values indicate that the spontaneous properties are for water vapour adsorption and that the system requires the release of energy to capture the water vapour molecules.

To solve the high heat dissipation problem of lithium ion battery, the air-cooled heat dissipation with fins is adopted for the thermal management. Heat dissipation characteristics of two types of air inlets and outlets (single air inlet and outlet, and double air inlet and outlet) and two types of surfaces (smooth and fin structure) were simulated and compared. When the air inlet and outlet are single inlet and single outlet, compared with smooth battery packs, finned construction packs can increase the Nusselt number by 24.9%. When the air inlet and outlet are double inlet and double outlet, compared with smooth battery packs, finned construction packs can increase the Nusselt number by 13.3%. The double-air inlet and outlet battery pack can significantly reduce the average temperature of the battery pack compared with the single-air inlet and outlet battery pack. Compared with the single-inlet and single-outlet solar smooth battery pack, it can increase the Nu by 131.6%, and the comprehensive performance index can reach 1.66.

Direct air capture (DAC) of CO₂ is an important technology to mitigate mobile carbon emissions, reduce atmospheric CO₂ concentration, and cope with climate change. Moisture-swing adsorption is regarded as one of the most promising technologies in DAC due to its low energy consumption and ease of operation. In this work, a cheap and easily available moisture-swing adsorbent of potassium carbonate loaded on porous supports (i.e., activated carbon, magnesium oxide, and zeolite) was prepared for CO₂ capture from ambient air. The composite adsorbent of potassium carbonate on activated carbon showed the best performance with a DAC capacity of 0.562 mmol/g at 25°C and 5% relative humidity. The effects of temperature, relative humidity, and CO₂ concentration on the adsorption performance were investigated systematically, as well as the cyclic DAC performance. In 50 adsorption–desorption cycles, the adsorption capacity of the composite adsorbent decreased by ~40% due to potassium carbonate leaching loss during water evaporation but can be fully recovered simply by re-impregnating with potassium carbonate again.

Kinetics of antimony production via carbothermal reduction of Sb₂O₃–carbon powder–NaCl mixture using microwave and conventional heating was investigated to identify the dominant controlling mechanism. Results of conventional heating revealed the temperature range of conventional carbothermal reduction reaction is 500°C to 800°C, with the average activation energy of each stage being 81.97 kJ/mol (α = 0.1–0.5), 65.17 kJ/mol (α = 0.5–0.75), and 69.86 kJ/mol (α = 0.75–1.0), respectively. In the microwave field, the carbothermal reduction reaction of raw materials can be completed at 600°C to obtain antimony, and the weight loss data of the carbothermal reduction process were recorded for the first time. The above results show that the microwave field enhanced the interfacial chemical effect, accelerated the interfacial diffusion from the metal phase to the oxide phase, and reduced the activation energy of the carbon thermal reduction process to 6.85 kJ/mol. The growth index of antimony grain growth process is estimated to be 4.33, controlled by the surface diffusion. These data provide a reliable theoretical basis for studying the reduction reactions of minerals in microwave fields.

The purpose of this investigation was to determine whether pyriproxyfen (PPF), a synthetic juvenile hormone analog (JHA), could be encapsulated in supercritical carbon dioxide (scCO₂) using the process particles from the gas-saturated solutions (PGSS) for a controlled-release system. The PGSS process represents a promising two-step production system especially suited for the encapsulation and controlled-release system (CRS). In contrast to traditional encapsulation methods that often involve the use of harsh organic solvents or high temperatures, the PGSS process offers a gentler approach employing scCO₂ as an alternative. The solubility of scCO₂ in polymer (poly-ϵ-caprolactone [PCL]) allowed for the formation of PPF microparticles, and the particle size distribution could be controlled by adjustment of operating pressure and temperature. The obtained particles had a mean particle size of 73.6 ± 2 μm and encapsulation efficiency of 78.8 ± 9% at 60°C and 10 MPa. Furthermore, the in vitro dissolution profiles of PPF–PCL particles showed a low-level release pattern (42.5 ± 5 ppb/d) in water, followed by zero-order kinetics indicating a high-performance CRS. Finally, the in vivo bioassay using microparticles treated water exhibited 95%–100% emergence inhibition of mosquitoes, suggesting the effectiveness of PPF–PCL particles as a mosquito control agent.