Chemical Engineering & Technology最新文献

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The turbulent characteristics of bubble plumes in power-law fluids are studied by experiments and numerical simulations. The effects of liquid phase rheological properties and superficial gas velocity on liquid phase velocity, shear stress, turbulent kinetic energy, turbulent scale, and gas holdup of the bubble plume are investigated. The velocity, shear stress, and turbulent kinetic energy of the liquid phase are distributed in a circular pattern during the generation stage, forming stage, and free-surface interaction stage of the bubble plume. The average shear stress and average turbulence kinetic energy that decomposed turbulent scales in CMC aqueous solution are 31–50 times and 1.4–2 times than that in tap water environment. The gas holdup in the flow field decreases with the increase of concentration of liquid phase and increases with the increase of superficial gas velocity. The flow pattern of the bubble plume is significantly affected by the superficial gas velocity and the rheological properties of the liquid phase that affect the transfer of mass and momentum between phases.

This study involves the development of a self-pressurized water electrolyzer for H₂ production, highlighting the effects of electrolyzer configuration, operation temperature, flow rate, and pressure on the electrolyzer's performance. The compression of H₂ takes up a large proportion of the cost for H₂ production through water electrolysis in a polymer electrolyte membrane (PEM) electrolyzer. However, creating a high-pressure PEM electrolyzer comes with challenges, such as managing diffusion and ohmic losses that impact cell voltage and efficiency. To address these issues, a novel cell configuration was designed. This configuration aims to minimize the gap among various components, including electrodes, gas diffusion layers, and current collectors. The configuration also leads to reduced cost as well as the difficulty of processing and assembling. Additionally, the gas diffusion layers and current collectors were coated with Pt to enhance their conductivity, effectively reducing the ohmic losses within the cell. Further optimization efforts focused on investigating the effects of temperature, pressure, and water flow on concentration voltage to achieve peak performance. As a result, a cell voltage of 1.868 V was achieved at 1 A/cm² under 10 MPa operating conditions.

Displacement washing of filter cakes is a critical process in various filtration applications and the presence of a top layer of fine particles from preceding cake filtration may influence washing efficiency. To investigate the effect of such a top layer on the displacement washing process, filter cakes with solid volume fractions ranging from 15 % to 33 % are formed from crushed, irregularly shaped limestone particles of about 10 to 250 µm to minimize or induce segregation effects due to sedimentation superimposed on cake filtration. The structural properties of the filter cakes are measured using X-ray microscopy and dynamic image analysis. To predict the influence of cake structure on displacement washing, an advection–dispersion model is employed. Comparison between prediction and experimental data shows good agreement, highlighting the impact of cake structure on washing efficiency and providing valuable insights for optimizing displacement washing processes in industrial applications.

Conversion of carbon dioxide (CO₂) to other chemicals has attracted much attention due to the wide applications of products and its importance. Robust catalysts are critical for efficient conversion due to the inertness of CO₂. Immobilized ionic liquid (IL) is one of the most important catalysts with numerous advantages. Various immobilized ILs have been developed with different ILs and supporters. However, rare studies have been carried out to compare the influence of different supporters on the catalytic performance with the fixed IL, especially for the supporter with or without pores. Imidazolium-based IL, imidazolium hydrogen bromide (IMHBr), is immobilized on three different supporters, polystyrene (PS), Santa Barbara Amorphous-15 (SBA-15), and Materials of Institute Lavoisier-101 Chromium (MIL-101(Cr)), to form three immobilized ILs with the central aim to uncover the influence of supporter on the catalytic performance. The MIL-101-IMHBr exhibits better catalytic activity than PS-IMHBr although the immobilized amount of IMHBr on the former is less. The porous structure plays a critical role in enhancing the catalytic activity. In the future, we still need to commit ourselves to the development of catalysts with superior performance.

This study investigates the simultaneous separation process using a batch reactor coupled to a cellulose acetate membrane for the enzymatic hydrolysis of residual soybean oil. The membrane was manufactured with 30 s pre-evaporation time and 1-mm thickness. Their morphologies and wettability were analyzed. Pichia pastoris lipase was characterized based on temperature and pH and was applied to the hydrolysis of residual soybean oil at 45 °C and pH 7 in batches, with and without simultaneous separation. The results show that the process efficiency with the cellulose acetate membrane resulted in 55.58 % ± 2.78 % free fatty acids in enzymatic hydrolysis, compared with 39.72 % ± 1.99 % without the membrane. The membrane also achieved 100 % oil rejection.

Gas dewatering of filter cakes with non-uniform cake height is investigated. Two-phase fluid flow is described in a continuum approach by conservation of mass and momentum of both phases. A priori measurements of capillary pressure and relative permeability allow to predict the impact of different cake geometries on the dewatering kinetics. Transient saturation and flow velocity fields within the filter cakes are calculated and discussed. No measurable effect on the mean saturation is observed in the investigated cases. However, the total flux, which needs to be handled by the vacuum pump to prevent a drop of the pressure difference during gas dewatering, is affected significantly by cake geometry. Model predictions are compared to experimental data from preceding publications and show reasonable agreement within the margin of error.

This research investigates the development of a digital twin (DT) for ground heat exchangers (GHEs) and its potential to enhance the efficiency and sustainability of shallow geothermal energy systems. It introduces an innovative approach for building a GHE-DT that connects the physical and digital systems to monitor key parameters, predict issues, and optimize energy efficiency. The process involves several phases including implicit knowledge codification, data-driven analysis, model construction, and system design. The study emphasizes real-time monitoring of the effective parameters: ground temperature and fluid conditions (flow rate, temperature, and pressure). The GHE-DT's digital system mainly comprises three sections, namely, data storage, mathematical modeling, and data-driven modeling. The role of the presented mathematical model is to simulate the GHE's behavior and assess its performance characteristics, such as the heat exchanger's effectiveness and efficiency. Additionally, the data-driven model used in the proposed DT utilizes formal concept analysis and relation concept analysis to identify connections and associations among parameters for a better understanding of the GHE functioning. The GHE-DT provides useful services including trend analysis, problem prediction, and correlation analysis. These services provide engineers and operators with the opportunity to increase dependability, save maintenance costs, and optimize GHE performance.