The electrode drying process is a crucial step in the manufacturing of lithium-ion batteries and can significantly affect the performance of an electrode once stacked in a cell. High drying rates may ...induce binder migration, which is largely governed by the temperature. Additionally, elevated drying rates will result in a heterogeneous distribution of the soluble and dispersed binder throughout the electrode, potentially accumulating at the surface. The optimized drying rate during the electrode manufacturing process will promote balanced homogeneous binder distribution throughout the electrode film; however, there is a need to develop more informative in situ metrologies to better understand the dynamics of the drying process. Here, ultrasound acoustic-based techniques were developed as an in situ tool to study the electrode drying process using NMC622-based cathodes and graphite-based anodes. The drying dynamic evolution for cathodes dried at 40 and 60 °C and anodes dried at 60 °C were investigated, with the attenuation of the reflective acoustic signals used to indicate the evolution of the physical properties of the electrode-coating film. The drying-induced acoustic signal shifts were discussed critically and correlated to the reported three-stage drying mechanism, offering a new mode for investigating the dynamic drying process. Ultrasound acoustic-based measurements have been successfully shown to be a novel in situ metrology to acquire dynamic drying profiles of lithium-ion battery electrodes. The findings would potentially fulfil the research gaps between acquiring dynamic data continuously for a drying mechanism study and the existing research metrology, as most of the published drying mechanism research studies are based on simulated drying processes. It shows great potential for further development and understanding of the drying process to achieve a more controllable electrode manufacturing process.
Hybrid perovskite photovoltaics combine high performance with the ease of solution processing. However, to date, a poor understanding of morphology formation in coated perovskite precursor thin films ...casts doubt on the feasibility of scaling-up laboratory-scale solution processes. Oblique slot jet drying is a widely used scalable method to induce fast crystallization in perovskite thin films, but deep knowledge and explicit guidance on how to control this dynamic method are missing. In response, we present a quantitative model of the drying dynamics under oblique slot jets. Using this model, we identify a simple criterion for successful scaling of perovskite solution printing and predict coating windows in terms of air velocity and web speed for reproducible fabrication of perovskite solar cells of ∼15% in power conversion efficiencyin direct correlation with the morphology of fabricated thin films. These findings are a corner stone toward scaling perovskite fabrication from simple principles instead of trial and error optimization.
The electrode drying process (DP) is a crucial step in the lithium-ion battery manufacturing chain and plays a fundamental role in governing the performance of the cells. The DP is extremely complex, ...with the dynamics and their implication in the production of electrodes generally being poorly understood. To date, there is limited discussion of these processes in the literature due to the limitation of the existing in situ metrology. Here, ultrasound acoustic measurements are demonstrated as a promising tool to monitor the physical evolution of the electrode coating in situ. These observations are validated by gravimetric analysis to show the feasibility of the technique to monitor the DP and identify the three different drying stages. A possible application of this technique is to adjust the drying rates based upon the ultrasound readings at different drying stages and to speed up the drying time. These findings prove that this measurement can be used as a cost-effective and simple tool to provide characteristic diagnostics of the electrode, which can be applied in large-scale coating manufacturing.
Purpose
Thermally stable, spray dried vaccines targeting respiratory diseases are promising candidates for pulmonary delivery, requiring careful excipient formulation to effectively encapsulate and ...protect labile biologics. This study investigates the impact of dextran mass ratio and molecular weight on activity retention, thermal stability and aerosol behaviour of a labile adenoviral vector (AdHu5) encapsulated within a spray dried mannitol-dextran blend.
Methods
Comparing formulations using 40 kDa or 500 kDa dextran at mass ratios of 1:3 and 3:1 mannitol to dextran,
in vitro
quantification of activity losses and powder flowability was used to assess suitability for inhalation.
Results
Incorporating mannitol in a 1:3 ratio with 500 kDa dextran reduced viral titre processing losses below 0.5 log and displayed strong thermal stability under accelerated aging conditions. Moisture absorption and agglomeration was higher in dextran-rich formulations, but under low humidity the 1:3 ratio with 500 kDa dextran powder had the lowest mass median aerodynamic diameter (4.4 µm) and 84% emitted dose from an intratracheal dosator, indicating strong aerosol performance.
Conclusions
Overall, dextran-rich formulations increased viscosity during drying which slowed self-diffusion and favorably hindered viral partitioning at the particle surface. Reducing mannitol content also minimized AdHu5 exclusion from crystalline regions that can force the vector to air–solid interfaces where deactivation occurs. Although increased dextran molecular weight improved activity retention at the 1:3 ratio, it was less influential than the ratio parameter. Improving encapsulation ultimately allows inhalable vaccines to be prepared at higher potency, requiring less powder mass per inhaled dose and higher delivery efficiency.
The objective of the present study was to investigate the interaction between Cu-containing preservatives and birch (Betula spp.) and pine (Pinus sylvestris L.) wood, modified at a relatively mild ...temperatures (150 – 180ºC). The disposition of wood to absorb water was evaluated by capillary absorption (CA) tests through the specimens’ tangential and radial surface. Changes in wood drying characteristics due to thermal modification (TM) were evaluated by monitoring wood moisture dynamics after impregnation. In order to assess the capacity of wood to absorb preservatives, a vacuum/pressure process was used to impregnate small specimens for which uniform saturation into the entire volume can easily be reached. Quantitative determination of copper Cu content in the specimens was performed by using atomic absorption spectroscopy (AAS). The fixation of the absorbed Cu was evaluated by subjecting the specimens to leaching procedures according to EN 84 and assessing the ratio of retained Cu in the specimens. The CA test showed deceleration of capillary absorption in TM birch wood through both surfaces, with similar absorption rates regardless of treatment temperatures. A significant increase in the absorption rate through the tangential surface was recorded for TM pine wood and the increase was greater for specimens treated at higher temperatures. The results of moisture content monitoring showed a similar reduction in the drying rate due to thermal modification regardless of species. Comparing wood of one species with similar densities, less preservative was absorbed by TM wood. However, the results of AAS showed that, in comparison with unmodified wood, 10% (birch) and 25% (pine) more Cu per one gram of wood was introduced during impregnation. Nevertheless, TM also resulted in higher Cu leaching rates for both species.
Hybrid perovskite photovoltaics could play a vital role in future’s renewable energy production. However, there are still severe challenges when scaling the technology. In this work, perovskite ...solution films drying in laminar and slot-jet air flows are investigated extensively by optical in situ characterization. The main results are a quantitative model of perovskite drying dynamics and a novel in situ imaging technique – yielding valuable predictions for large-scale perovskite fabrication.
The dynamics of drying processes from porous media are critically influenced by the intensity of an adjacent free flow and by processes at the interface between free flow and the porous medium. In ...this paper, the influence of hydraulic properties of a porous medium and of the interaction between fluids and porous medium on the drying dynamics during the capillary‐flow dominated stage‐1 and transition to the diffusion‐dominated stage‐2 are studied using a coupled free‐flow—porous‐medium flow model on the REV scale. We present a detailed model concept that considers mass balance equations, an energy balance equation, and the coupling to the adjacent free flow. Key microscale processes are identified and incorporated in the macroscale description of the evaporation process. Own experimental results are used to illustrate main features of the modeling framework. We demonstrate that the use of a homogeneous distribution of soil parameters without consideration of pore‐scale induced nonlinearities in the numerical simulations results in a rather constant drying rate in stage‐1, which was not observed for the high evaporative demand in the experiments. To account for the dependency of the drying rate on the surface moisture content, special conditions based on the work of Haghighi et al. (2013) and Schlünder (1988) are analyzed for their applicability on the REV scale. Typical features of a drying process, such as different stages of the drying rate, could be reproduced.
Key Points
Coupled REV‐scale modeling of drying processes
Concept for the saturation‐dependency of the drying rate
Analysis of the influence of porous‐medium properties on the drying dynamics
Grape growing in India is mainly confined to tropical peninsular regions of Maharashtra, Karnataka and Tamil Nadu. It is estimated that approximately 95% of total grapes are produced in Maharashtra ...and Karnataka alone. About 71 per cent of total grape production of the country is consumed as fresh and 27 per cent is processed into raisins. Grape drying is mainly concentrated in Sangli, Solapur and Nashik districts of Maharashtra and Vijayapura and Bagalkot districts of Karnataka. Generally, after dipping of grape bunches in solution of ethyl oleate and potassium carbonate (also known as Australian dip) the grape bunches are spread on nylon mesh inside grape drying shed and within 10-15 days drying process completed. There are several commercial products/substitutes for dip treatment available in the market. However, it has been reported that effectiveness of these products is variable. Therefore, present investigation was carried out to study effectiveness of a new commercial product for raisin production from Thompson Seedless grape variety in comparison to ethyl oleate. Grape bunches of Thompson Seedless were dipped in these solutions prior to drying inside raisin drying shed. Besides, the drying bunches were also sprayed with different concentrations of these products on 3rd and 5th days of drying. Observations were recorded on drying dynamics, browning index, colour intensity, content of phenols and tannins, sensory properties and quality parameters after storage for 4 months. It was observed that the dip treatment of Thompson Seedless grapes with a solution of 18 ml commercial product and 24 g potassium carbonate per litre of water for 2 minutes and sprays of 12 ml commercial product +16 g potassium carbonate per liter water on 3rd day and 6 ml commercial product + 8 g potassium carbonate per liter water on 5th day was found better than ethyl oleate for production of good quality raisins.
► Time-scale analysis is used to obtain a simplified first-principle-based model for freeze–drying processes. ► The matrix-scale model is the core of the proposed optimal control problem. ► The ...optimal conditions for minimizing freeze-drying cycle time while preserving quality of the final product are defined. ► Reductions of up to an 17.71% (one control variable case –TL) and up to 25.5% (two control variable case –TL, Pc) are achieved.
Freeze–drying is considered to be an attractive dehydration method of preserving the quality of high value foods products. Unfortunately, it is an expensive operation, which calls for efficient tools capable of minimizing time and/or energy while preserving product quality.
In this work, time-scale analysis has been applied to a detailed first-principle-based model. From such analysis a simplified model, capable of describing freeze–drying at the time scales relevant to quality, has been proposed. The model has been solved by the Finite Element method, showing good agreement with the results in literature. Likewise, the efforts associated with the computation of optimal operation policies have been reduced.
In this regard, different operational scenarios that take into account shelf temperature (TL) and chamber pressure (Pc) have been considered on a simulation basis. In all cases the resulting optimal control profiles obtained led to significant reductions of cycle time while ensuring product quality.
Abundant information resides in the pressure signal of a fluidized bed, especially when the pressure signal of that bed is mixed with steady flow, and the pulsed flow is more prevalent. In this ...paper, the authors established a stable and pulsed flow fluidized bed experiment platform. They also collected pressure signals with different times, different frequencies and different gas flow rates in the drying process. The pressure signals were analyzed by two approaches. One is based on the use of the multi-scale complexity entropy causality plane, and the other relies on a recurrence plot. With the drying characteristics of wet particles in the bed and flow pattern, the focus was on influence factors such as time lapse, air intake ratio and pulse frequency on both drying efficiency and the characteristics of complex nonlinear dynamics were analyzed. A study of the micro and macro mechanism of flow characteristics is also presented. The results show that the two approaches (i.e., methods) have a higher accuracy in judging the change of the interaction force between moist particles and the change of flow characteristics. The drying efficiency can be deduced by analysis of the dynamic characteristics of the fluidized bed; thus, the multi-scale complexity entropy causality plane and the structure of the recurrence plot corresponding to the best drying efficiency are obtained. A recommended reference range of the three parameters of a recurrence plot that are good for drying will be presented, which corresponds to the ratio of the stable flow and the pulsed flow.
Display omitted
•The drying dynamics of mixed pulsed fluidized bed was carried out.•MCECP and RP were applied to the analysis of the mixed pulsed fluidized bed.•A drying efficiency analysis model based on MCECP and RP was established.•A recommended range of RP parameters that are good for drying was presented.
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