An ultrasound tomography (UST) system was employed as a non-invasive and non-intrusive measurement tool to investigate the liquid phase precipitation of calcium carbonate and to detect the onset of the precipitation process. UST-based tomographic reconstructions also offered useful insights into the reagent feeding visualization in the stirred-tank reactor.

Abstract

The application of an ultrasound tomography (UST) system in a liquid-phase reactive crystallization process is reported. The measurement system was applied to precipitated calcium carbonate processing where liquid Na₂CO₃ was added to a CaCl₂ solution. Analysis of the measured sound velocity signals from the experiments demonstrated a clear change in the average time-of-flight (TOF) delay signals, indicating the detection of the onset of the precipitation and the formation of the microcrystalline stable phase of calcite. Moreover, spatial-centric TOF signals from the tomographic images were associated with an increase in the overall suspension density. These findings highlight the potential of the UST measurement system for studying the solidification phenomenon during CaCO₃ precipitation.

A nature-inspired evolutionary algorithm, black widow optimization (BWO), for parameter identification is proposed and applied to a 5-kW tubular solid oxide fuel cell system. A series of test runs on minimization of standard benchmark functions have been performed and compared with other metaheuristic algorithms. In terms of accuracy, robustness, convergence, and statistics, BWO is a competitive method.

Abstract

A new effective method for optimization of unknown parameters in solid oxide fuel cell (SOFC) stack models is suggested. The overall voltage of the SOFC stack depends on these predicted parameters. The goal is to reduce the mean square error (MSE) between the empirical and the predicted polarization curve obtained using the method. Black widow optimization (BWO), a metaheuristic method inspired by nature, describes the minimization process. This algorithm is made to alter the search space, avoid local optima, and deliver greater efficiency in the exploitation and exploration stages. Situations based on multidimensional benchmark functions and SOFC stack temperature variations are investigated to ascertain the system consistency.

Spherical agglomeration has the potential to improve the handling of unfavourably shaped crystals. A large number of process parameters must be adjusted to carry out spherical agglomeration, which is a challenging task, especially for complex organic molecules. The possibility of preparing spherical crystals in different solvent systems for two active pharmaceutical ingredients is examined.

Abstract

The possibility of spherical agglomeration was investigated for two active pharmaceutical ingredients from different classes of the Biopharmaceutics Classification System. The effects of different batch crystallization solvent systems on the granulometric properties and structures of dronedarone hydrochloride and ceritinib were investigated. Light and stereomicroscopy were used to determine the size and shape of the agglomerates, while X-ray powder diffraction was applied to assess the changes in polymorphic form. Since the change in the solvent system had no effect on the crystal structure but did alter the size and shape of the crystals, dissolution experiments were carried out to determine drug release profiles.

The dispersion of batch time considering stochastic nucleation in an L-arginine-water system was estimated by repetitive computer simulation in the case of internally seeded cooling crystallization with direct nucleation control. Mathematical models and conditions used in the simulation are explained and results of the simulation are described.

Abstract

The dispersion of batch time, i.e., the time for finalizing batch crystallization satisfying batch end conditions, in internally seeded cooling crystallization with direct nucleation control (DNC) was estimated by computer simulation. The batch time is considered to disperse at such crystallization due to stochastic nucleation. In this study, first, a population balance equation was digitized for numerical calculation, and the simulation was developed in MATLAB. Then, repetitive simulations of internally seeded cooling crystallization considering stochastic nucleation with DNC were performed. Finally, the batch time of each simulation was arranged. As a result, it was found that there is little batch time dispersion in crystallization controlled by DNC and without adding seed.

A membrane crystallization method using ultrafiltration was investigated to obtain high-quality protein crystals for structural analysis. Membrane surface concentrations, which could not be measured, can be estimated by simulation. The membrane surface concentration increased rapidly during initial pressurization at any pressure, which was found to be the initial stage of crystal formation.

Abstract

High-quality single crystals are necessary for structural analysis of proteins. However, it is difficult to obtain high-quality single crystals in a short time. Therefore, a membrane crystallization method was applied in which lysozyme is concentrated on the membrane surface using an ultrafiltration membrane. Membrane surface concentrations, which cannot be measured, were calculated based on the measurable permeation flux. At all operating pressures, the measured and simulated permeation fluxes were in close agreement, allowing the membrane surface concentration to be estimated. The membrane surface concentration increased rapidly at all pressures during the initial pressurization, indicating that crystals were formed at an early stage.

A simulation model of the torrefaction process utilizing shredded empty fruit bunches as biomass is established, optimizing it for mass yield and energy consumption. The optimized torrefaction process is integrated into an existing biomass power plant. Torrefaction technology represents an improvement of biomass utilization technology, ultimately allowing for the maximum application of biomass energy.

Abstract

Torrefaction is a thermal procedure used to convert biomass into a substance resembling coal that possesses superior fuel properties compared to the original biomass. Torrefied biomass is hydrophobic and has a greater energy density, making it more advantageous for handling and storage. The purpose of this investigation is to establish a simulation model of the torrefaction process utilizing Malaysian biomass and optimize it for mass yield and energy consumption. Additionally, the objective is to integrate the optimized torrefaction process into an existing biomass power plant. By retrofitting a biomass-based power generation facility with torrefaction technology, the existing feedstock can be upgraded before sending it to the power plant. Essentially, torrefaction technology represents an enhancement of biomass utilization technology, ultimately allowing for the maximum application of biomass energy.

Sufficient renewable energy supplies and carbon neutrality by 2030 are carried forward with the current global economic and political endeavors. Green hydrogen has the potential to provide power networks with the necessary flexibility and to act as a buffer for the intermittent renewable power output, both promoting the future of renewable energy grids.

Abstract

Renewable energy and carbon neutrality by 2030 are gaining momentum with the current global economic and political endeavors. Green hydrogen has the potential to give power networks the much-needed flexibility and acts as a buffer for intermittent renewable power output, both of which might be beneficial for the future of renewable energy grids. If hydrogen proves effective, it might drastically reduce emissions of greenhouse gases. In this context, knowing the potential advantages of hydrogen is crucial. Between 2016 and 2019, technological progress occupied just 42.86 % of the total time. Innovation in this field is considered disruptive because of its high uniqueness rate (81 %). This article analyzes the most up-to-date information on the hydrogen economy (including its key benefits and drawbacks) and the potential implications of hydrogen for several businesses.

The effect of catalyst morphology on the dry reforming of methane (DRM) was studied by comparing electrospun nanofibrous and impregnated Co-based supported catalysts. The former shows higher DRM activity, and its distinctive morphology plays a crucial role in stabilizing the Co particles through strong metal-support interaction, which significantly impedes catalyst deactivation by carbon deposition.

Abstract

The prime cause for catalyst deactivation during dry reforming of methane (DRM) has been attributed to the deposition of carbon. Nanofibrous (NF) catalysts are attractive candidates that offer high catalytic activity and stability in DRM. A comparative study between electrospun and impregnated Co/CeO₂–La₂O₃ catalysts in the DRM reaction was carried out to evaluate the merits of the NF catalyst. Application of the electrospun catalyst yielded the highest activity in DRM and showed a substantial improvement in resistance to carbon formation. The unique structure of the NF electrospun catalyst, the robust metal-support interaction, and the increased surface area could more effectively suppress deactivation of the catalyst during an 8-h DRM reaction than the impregnated catalyst.

The effect of optimization of reaction parameters such as substrate concentration, temperature, and agitation rate of immobilized cells on β-cyclodextrin (β-CD) production and β-cyclodextrin glucanotransferase (β-CGTase) excretion was investigated. Both β-CD yield and CGTase excretion could be significantly improved, making the process more attractive for industrial applications.

Abstract

Cyclodextrin (CD) is an important substance for chemical, pharmaceutical, and food industries. Conventionally, free Escherichia coli (E. coli) cells expressing recombinant cyclodextrin glucanotransferase (CGTase) are used as the biocatalyst for CD production, but the process struggles with low CGTase excretion and CD yield. In this study, E. coli cells were immobilized on hollow-fiber membranes for β-CD production, and the process and reaction parameters were optimized via response surface methodology. The reusability of the immobilized cells was also evaluated. The parameter optimization significantly improved β-CD yield and CGTase excretion, making the process more attractive for industrial applications. The immobilized cells also revealed to be reusable multiple times.

Abstract

The application of mobile production units enables the production close to the customers or the raw materials source. The choice of location depends on the demand and requirements of the customers and their geographical distribution. Therefore, economic and qualitative evaluation criteria have to be considered. A method to develop a modular production network, validated in a case study, is presented in this paper.