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•Time-Scale Analysis (TSA) is a novel engineering analysis & design approach.•Characteristic Times are the fundamental elements of the TSA.•TSA enables analysis of microscale-based ...reactors and unit operations.•TSA facilitates analysis of microscale-based solid-catalyzed reaction process.
Time-Scale Analysis and Characteristic Times are suggested as a novel and useful tool in the analysis of the performance of microscale-based reactors, unit operations, and plant flow-sheet diagrams embodying microscale-based chemical processes. Transport phenomena, reaction kinetics, and phase contacting in microstructured architecture can be easily represented by unique time constants, τis. These Characteristic Times are estimated from first principles and are controlled by a user to support a meaningful chemical process analysis and provide insight or suggestions for successful design choices.
While the origin of Characteristic Times in microscale-based processes is rooted in fundamentals of molecular transport and reaction kinetics, the evolution of Characteristic Time definitions could be easily found in detailed mathematical models of microscale-based reaction processes and operations. The user-defined scaling parameters contribute to the flexibility of Time Scale Analysis implementation. This work uses a microscale-based solid catalyzed reaction process to demonstrate the concept of Time Scale Analysis and systematically define Characteristic Times and their origin. Lastly, varying forms of Time Scale Analysis have been implemented to evaluate specific phenomena or aspects of processes but have yet to encompass the full unit operation or process within the analysis. Part I and Part II of this work develop a comprehensive Time Scale Analysis for unit operations and a (bio)chemical process flowsheet (Part II only).
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•Time-Scale Analysis (TSA) is a novel design approach in Process Intensification.•Characteristic Times are the fundamental elements of the TSA.•TSA enables analysis of ...microscale-based bioreactors with immobilized cells.•TSA facilitates the analysis of process flowsheet diagrams.
Time-Scale Analysis and Characteristics Times are suggested as a novel and useful tool for analyzing the performance of microscale-based bioreactors with immobilized bioactive material (e.g. enzymes or microbial species), and plant flow-sheet diagrams of chemical processes. Transport rates, reaction kinetics, and phase contacting can be easily represented by unique time constants, which facilitate understanding and representation of these processes via the ‘heat-map tableau’ of Characteristic Times. Details related to the development and the origin of Characteristic Times are presented in Part I of this paper; Jovanovic et al. (2020). Time Scale Analysis & Characteristic Times is a technical approach germane to process improvement, where it facilitates the discovery of areas in need of process intensification. The feasibility and usefulness of this novel tool is demonstrated by considering a microbial biochemical reaction process performed in a traditional bioreactor vs. performance in a microscale-based bioreactor design and evaluating the balance of characteristic times associated with each technology. We believe that this technical approach will confidently find its place in the toolbox of practicing chemical reaction engineers.
The benefits of continuous processing and the challenges related to the integration with efficient downstream units for end-to-end manufacturing have spurred the development of efficient miniaturized ...continuously-operated separators. Membrane-free microseparators with specifically positioned internal structures subjecting fluids to a capillary pressure gradient have been previously shown to enable efficient gas-liquid separation. Here we present initial studies on the model-based design of a liquid-liquid microseparator with pillars of various diameters between two plates. For the optimization of in silico separator performance, mesoscopic lattice-Boltzmann modeling was used. Simulation results at various conditions revealed the possibility to improve the separation of two liquids by changing the geometrical characteristics of the microseparator.
This article evaluates a hip joint socket design by finite element method (FEM). The study was based on the needs and characteristics of a patient with an oncological amputation; however, the ...solution and the presented method may be generalized for patients with similar conditions. The research aimed to solve a generalized problem, taking a typical case from the study area as a reference. Data were collected on the use of the current improving prosthesis-specifically in interaction with its socket-to obtain information on the new approach design: this step constituted the work's starting point, where the problems to be solved in conventional designs were revealed. Currently, the development of this type of support does not consider the functionality and comfort of the patient. Research has reported that 58% of patients with sockets have rejected their use, because they do not fit comfortably and functionally; therefore, patients' low acceptance or rejection of the use of the prosthesis socket has been documented. In this study, different designs were evaluated, based on the FEM as scientific support for the results obtained, for the development of a new ergonomic fit with a 60% increase in patient compliance, that had correct gait performance when correcting postures, improved fit-user interaction, and that presented an esthetic fit that met the usability factor. The validation of the results was carried out through the physical construction of the prototype. The research showed how the finite element method improved the design, analyzing the structural behavioral, and that it could reduce cost and time instead of generating several prototypes.
Modern computer-aided design and dynamics simulation tools allow design and testing to be performed in a virtual-reality environment. The integration of controller synthesis programs also makes it ...possible to perform servo tuning without actually having to build a prototype. However, most servo controllers are based on integer processors for machine tools, and the integer numbers entering into a servo tuning interface often do not directly reflect the magnitudes of the actual controller parameters, impairing the virtual tuning. This study addressed this problem by employing a gain parameter to each control parameter, and developing an identification algorithm for these parameter gains. The identification results were used to tune the servo, which was first carried out within the solid-modeling simulation environment. This procedure makes it easy to implement the controller parameters in the actual machine. The actual implementation of the resultant controller verified that the proposed method improved the servo performance, including eliminating the overshoot in both position and velocity responses of the grinding machine.
The flourishing hi-tech industry development has prompted the need to carry out high performance servo design and testing without actually having to construct a prototype system. However, the ...complicated mechanical structure and the nonlinear effects in many of the high performance systems have made it very difficult to carry out the design without a suitable model. In recent years, the software advances has achieved very accurate dynamic simulation result. It is also possible to integrate the control synthesis with the dynamic simulation. This study examines the possibility of performing the servo design within the system design environment and then applies the result to a realistic platform model. The robust sliding mode controller is employed to deal with the nonlinear characteristics in the grinding machine. The dynamic model included the multi-degree of freedom behavior and the friction effects. The simulation results also show that the sliding mode controller is able to suppress the structure resonances and achieve high accuracy control under plant uncertainties.
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