ChemEngineering

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11 pages, 3641 KiB

Open AccessArticle

Indirect Dryers for Biomass Drying—Comparison of Experimental Characteristics for Drum and Rotary Configurations

by Jan Havlík and Tomáš Dlouhý

ChemEngineering 2020, 4(1), 18; https://doi.org/10.3390/chemengineering4010018 - 10 Mar 2020

Cited by 17 | Viewed by 8743

This paper focuses on indirect biomass drying. It compares the operating characteristics of a laboratory-scale drum dryer and a pilot-scale rotary dryer. Before the design of an industrial dryer for a specific material, it is important to experimentally prove the process and to [...] Read more.

This paper focuses on indirect biomass drying. It compares the operating characteristics of a laboratory-scale drum dryer and a pilot-scale rotary dryer. Before the design of an industrial dryer for a specific material, it is important to experimentally prove the process and to determine the drying characteristics of the material. To verify the portability of experimental results for indirect dryers, a drum dryer with indirect electric heating in a laboratory scale was designed and built to test and study the process of indirect drying. Based on the results obtained on a small-scale device, a prototype of a pilot steam-heated rotary dryer was designed and manufactured. A broad range of experiments with green wood chips and wet bark from open-air storage with moisture contents of 50 to 65 wt % were carried out on both dryers. The drying curves indicating the process, the square and volumetric evaporation capacities, and the drying energy consumption were obtained and compared, and the feasibility of indirect drying for these tested types of biomass was confirmed. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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14 pages, 1029 KiB

Open AccessArticle

A Numerical Implementation of the Soret Effect in Drying Processes

by Bartolomeus Häussling Löwgren, Julius Bergmann and Odilio Alves-Filho

ChemEngineering 2020, 4(1), 13; https://doi.org/10.3390/chemengineering4010013 - 17 Feb 2020

Cited by 4 | Viewed by 3026

Abstract

Drying of porous media is strictly governed by heat and mass transfer. However, contrary to the definition that drying is simultaneous transport mechanisms of heat and mass, most past and current models either account for temperature or concentration gradient effects on drying. Even [...] Read more.

Drying of porous media is strictly governed by heat and mass transfer. However, contrary to the definition that drying is simultaneous transport mechanisms of heat and mass, most past and current models either account for temperature or concentration gradient effects on drying. Even though the complexity of computations of these processes varies with area of application, in most cases, the Dufour and Soret effects are neglected. This leads to deviations and uncertainties on the assumptions and interpretations of these and other relevant effects on drying. This paper covers the theoretical methods to derive the coupled transfer effects. In addition, this work proposes and formulates relevant heat and mass transfer equations, as well as the governing equations for drying processes with Dufour and Soret effects. The application of a numerical approach to solve the equations allows for studying of the influence of these effects on the design and operation of dryers. It is shown that the Soret effect can be highly relevant on drying operations with dynamic heating operation. While for drying processes where the steady state drying process predominates, the effect is deemed negligible. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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12 pages, 283 KiB

Open AccessArticle

The Influence of Maltodextrin and Inulin on the Physico-Chemical Properties of Cranberry Juice Powders

by Anna Michalska-Ciechanowska, Joanna Majerska, Jessica Brzezowska, Aneta Wojdyło and Adam Figiel

ChemEngineering 2020, 4(1), 12; https://doi.org/10.3390/chemengineering4010012 - 17 Feb 2020

Cited by 25 | Viewed by 4831

Abstract

Cranberry juice has a high content of polyphenols, which makes it a valuable raw material with health-promoting properties. On the other hand, the bitter and astringent taste of cranberry limits its consumption in fresh form (fruit, juice). For this reason, new formulations of [...] Read more.

Cranberry juice has a high content of polyphenols, which makes it a valuable raw material with health-promoting properties. On the other hand, the bitter and astringent taste of cranberry limits its consumption in fresh form (fruit, juice). For this reason, new formulations of cranberry products based on natural additives are sought, e.g., in the form of carriers, which not only allow the drying of liquids to form powders, but which can also affect the retention of bioactive compounds. This study aimed at the evaluation of the influence of different carriers and concentrations applied to cranberry juice and their influence on the physico-chemical properties of the powders obtained. Freeze-dried powders had approximately eight times higher moisture content than products gained after the spray-drying process. The bulk density of freeze-dried product was approximately 11% higher when compared to spray-drying. Freeze-drying and spray-drying had a similar influence on the total polyphenolic compound content and antioxidant capacity. When the concentration of carriers was concerned, it was indicated that a higher content of carrier resulted in a lower moisture content, water activity, CIE L*a*b* coordinates, total polyphenolic content, and antioxidant capacity of the powders obtained, pointing to a strong influence of the juice composition on the final properties of the powders. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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14 pages, 6337 KiB

Open AccessArticle

Drying-Induced Strain-Stress and Deformation of Thin Ceramic Plate

by Yoshinori Itaya, Hiroya Hanai, Nobusuke Kobayashi and Tsuguhiko Nakagawa

ChemEngineering 2020, 4(1), 9; https://doi.org/10.3390/chemengineering4010009 - 1 Feb 2020

Cited by 7 | Viewed by 2644

Abstract

Ceramic thin plates are applied to several industrial purposes including electronic materials and sensors. Drying-induced shrinkage and strain-stress formation of a ceramic thin plate were studied experimentally and theoretically. A kaolin thin plate molded into 10 mm × 30 mm × 1 mm [...] Read more.

Ceramic thin plates are applied to several industrial purposes including electronic materials and sensors. Drying-induced shrinkage and strain-stress formation of a ceramic thin plate were studied experimentally and theoretically. A kaolin thin plate molded into 10 mm × 30 mm × 1 mm was dried in a hot air stream, and the drying characteristics and deformation were examined. Modeling was also performed to predict the behavior. Heat and moisture transfer conservation equations and constitution equations based on viscoelastic strain-stress were simultaneously solved by a finite element method. A test piece of the thin plate was warped when only one side of the plate was dried, while it was almost flat when both sides were dried. The behaviors of drying and deformation were predicted with a reasonable agreement by the modeling. Parametric analyses by the modeling revealed that the drying conditions with faster drying rate in the beginning period resulted in formation of greater maximum principal stress, and drying on only one side of the plate induced stronger tensile stress in falling rate period than that with both sides drying. The larger thickness of the plate influenced the formation of significantly greater tensile stress but affected maximum compressive stress only a little. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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13 pages, 2472 KiB

Open AccessArticle

High End Quality Measuring in Mango Drying through Multi-Spectral Imaging Systems

by Katrin Jödicke, Robin Zirkler, Timo Eckhard, Werner Hofacker and Bernd Jödicke

ChemEngineering 2020, 4(1), 8; https://doi.org/10.3390/chemengineering4010008 - 1 Feb 2020

Cited by 6 | Viewed by 2751

Abstract

In modern fruit processing technology, non-destructive quality measuring techniques are sought for determining and controlling changes in the optical, structural, and chemical properties of the products. In this context, changes inside the product can be measured during processing. Especially for industrial use, fast, [...] Read more.

In modern fruit processing technology, non-destructive quality measuring techniques are sought for determining and controlling changes in the optical, structural, and chemical properties of the products. In this context, changes inside the product can be measured during processing. Especially for industrial use, fast, precise, but robust methods are particularly important to obtain high-quality products. In this work, a newly developed multi-spectral imaging system was implemented and adapted for drying processes. Further it was investigated if the system could be used to link changes in the surface spectral reflectance during mango drying with changes in moisture content and contents of chemical components. This was achieved by recovering the spectral reflectance from multi-spectral image data and comparing the spectral changes with changes of the total soluble solids (TSS), pH-value and the relative moisture content x_wb of the products. In a first step, the camera was modified to be used in drying, then the changes in the spectra and quality criteria during mango drying were measured. For this, mango slices were dried at air temperatures of 40–80 °C and relative air humidities of 5%–30%. Samples were analyzed and pictures were taken with the multi-spectral imaging system. The quality criteria were then predicted from spectral data. It could be shown that the newly developed multi-spectral imaging system can be used for quality control in fruit drying. There are strong indications as well, that it can be employed for the prediction of chemical quality criteria of mangoes during drying. This way, quality changes can be monitored inline during the process using only one single measuring device. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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17 pages, 2844 KiB

Open AccessArticle

Economic Evaluation of Drying of Soot Sludge and Sawdust Mixture at Low Temperatures Using the Characteristic Drying Curve Method

by Tiina Myllymaa, Henrik Holmberg and Pekka Ahtila

ChemEngineering 2020, 4(1), 6; https://doi.org/10.3390/chemengineering4010006 - 12 Jan 2020

Cited by 3 | Viewed by 2789

Abstract

Soot sludge is a waste stream formed in the fuel oil gasification of formic acid and hydrogen peroxide production. The soot sludge has a high moisture content (95%) and is presently combusted with heavy fuel oil in order to dispose of the sludge. [...] Read more.

Soot sludge is a waste stream formed in the fuel oil gasification of formic acid and hydrogen peroxide production. The soot sludge has a high moisture content (95%) and is presently combusted with heavy fuel oil in order to dispose of the sludge. Experimental tests earlier conducted by the authors have shown that the sludge can be convectively dried with sawdust in a fixed bed. By upgrading the sludge from waste to fuel, the utilization of oil can be decreased. In this study, characteristic drying curves (CDC) are determined for the sludge and sawdust mixture. The CDCs are further used to evaluate the economy of the mixture drying in a belt dryer by using the payback period method. Results show that the linear CDCs of the mixture can be used to extrapolate drying data from specific drying conditions to another when the bed height is 200 or 300 mm, and the inlet air temperature 40–100 °C. The economic analysis shows that drying is economical for all inlet air temperatures if the oil price is ≥350 €/t-oil. Sensitivity analyses reveal that the heat, sawdust and emission prices have no remarkable influence on the economy of drying if the oil price does not fall below c. 300 €/t-oil. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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8 pages, 3421 KiB

Open AccessEditor’s ChoiceArticle

Flavor Release from Spray-Dried Powders with Various Wall Materials

by Shisei Takashige, Hermawan Dwi Ariyanto, Shuji Adachi and Hidefumi Yoshii

ChemEngineering 2020, 4(1), 1; https://doi.org/10.3390/chemengineering4010001 - 28 Dec 2019

Cited by 6 | Viewed by 3698

Abstract

By using the ramping method for humidity at a constant temperature, the release rates of d-limonene were investigated from spray-dried powders with various wall materials, such as maltodextrin (MD) (dextrose equivalent (DE) = 25 and 19), lactose (Lac), and sucrose (Suc). Spray-dried [...] Read more.

By using the ramping method for humidity at a constant temperature, the release rates of d-limonene were investigated from spray-dried powders with various wall materials, such as maltodextrin (MD) (dextrose equivalent (DE) = 25 and 19), lactose (Lac), and sucrose (Suc). Spray-dried powders, which were sieved to the average powder size of 107–140 µm, contained d-limonene at about 90–97 mg/g-dry powder. d-limonene release profile was measured using a dynamic vapor sorption (DVS) system coupled gas chromatography at 30, 40, and 50 °C from 10% to 90% relative humidity (RH). The linear correlation was found between the release start humidity, sRH, of d-limonene release from the powder and the glass transition temperature of wall materials. The release rates for Suc and Lac increased rapidly at certain humidities and became the maximum rates. Then, these rates decreased gradually with increasing RH. This might have been due to the powder aggregation for Suc and to crystallization for Lac. The release behaviors significantly depended on the wall materials. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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12 pages, 4142 KiB

Open AccessArticle

Drying Technology Assisted by Nonthermal Pulsed Filamentary Microplasma Treatment: Theory and Practice

by Ivan Shorstkii and Evgeny Koshevoi

ChemEngineering 2019, 3(4), 91; https://doi.org/10.3390/chemengineering3040091 - 2 Dec 2019

Cited by 10 | Viewed by 2894

Abstract

Nonthermal pulsed filamentary microplasma treatment for drying is a nonthermal technology with promising perspectives to dehydrate plant agricultural materials. The modified set of Luikov’s equations for heat, mass and pressure transfer, has been used to analyze nonthermal pulsed filamentary microplasma treatment effects. The [...] Read more.

Nonthermal pulsed filamentary microplasma treatment for drying is a nonthermal technology with promising perspectives to dehydrate plant agricultural materials. The modified set of Luikov’s equations for heat, mass and pressure transfer, has been used to analyze nonthermal pulsed filamentary microplasma treatment effects. The finite element method in combination with the step-by-step finite-difference method for a coupled system of differential equations in partial derivatives was used for numerical simulation of heat, humidity and pressure potentials transfer. The drying time of samples treated by nonthermal pulsed filamentary microplasma treatment assisted by thermionic emission was reduced up to 20.6% (5 kV/cm; 1200 discharges) in comparison to intact tissue. The effect of the obtained approach is very useful for studying process mechanisms and for explaining nonthermal pulsed filamentary microplasma treatment effects. Refined transfer kinetic coefficients from a set of equations based on experimental drying curve can be used for the quantitative determination of thermodynamic coefficients. The agreement of the simulation data with the analytical equation and experimental results is satisfactory (discrepancy less than 3%). Obtained results showed that the proposed model with the refined transfer kinetic coefficients adequately describe the experimental data. Full article

(This article belongs to the Special Issue Selected papers from the Third Nordic Baltic Drying Conference (NBDC 2019))

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