Drying Kinetics Research Articles

Impact of Air-Drying Temperatures on Drying Kinetics, Physicochemical Properties, and Bioactive Profile of Ginger.

Ginger (Zingiber officinale Roscoe) is a perishable commodity that requires proper processing to maintain its bioactivity. This study evaluated the effect of different air-drying temperatures (50 °C, 60 °C, and 70 °C) on ginger's drying kinetics and quality attributes. For an enhanced understanding of the drying kinetics, we employed a detailed approach by combining an existing drying model (namely, Midilli) with the Arrhenius model. This combined model facilitates a thorough analysis of how temperature and time concurrently affect the moisture ratio, offering more profound insights into the drying mechanism. A higher drying rate was achieved at 70 °C, yet elevated drying temperatures could compromise the quality attributes of ginger slices. Ginger slices dried at 50 °C displayed improved physicochemical properties and less color browning. The evaluation of the bioactivity profile of resultant ginger extracts also revealed higher total phenolic contents (1875.87 ± 31.40 mg GAE/100 g) and DPPH radical scavenging activity (18.2 ± 0.9 mg TE/kg) in 50 °C treated ginger samples. Meanwhile, the hydroethanolic mixture (70% ethanol) was also reorganized with better extraction efficiency than water and MWF (a ternary blend of methanol, water, and formic acid) solution. The promising outcomes of this study endorse the influence of drying temperature on the quality characteristics and bioactive profile of ginger and the selection of suitable extraction solvents to acquire phenolic-rich extract.

Effect of Drying on Insulin Plant Leaves for Its Sustainability and Modeling the Drying Kinetics by Mathematical Models and Artificial Neural Network

Effect of Drying on Insulin Plant Leaves for Its Sustainability and Modeling the Drying Kinetics by Mathematical Models and Artificial Neural Network

Kinetics of Oven Drying of Ocimum basilicum Leaves Harvested at Different Ages of Maturity

Kinetics of Oven Drying of Ocimum basilicum Leaves Harvested at Different Ages of Maturity

Kinetic Regularities of the Filtration Drying of Barley Brewer’s Spent Grain

The paper describes the study of the kinetics of filtration drying of barley brewer’s spent grain. The dependencies of the process at different parameters of the stationary layer and the heating agent are presented: different heights of the wet material H (40 mm, 80 mm, 120 mm, and 160 mm), different temperatures of the heating agent T (50 °C, 70 °C, 80 °C, and 90 °C), and the velocities of the heating agent through the stationary layer of material v0 (1.26 m/s, 1.55 m/s, 1.81 m/s, 2.31 m/s, and 2.82 m/s). The kinetic regularities of two drying periods were determined: the period of complete saturation of the heating agent with moisture and the period of partial saturation of the heating agent with moisture. The calculation dependencies describing the intensity of the filtration drying process in both periods are proposed. The equations for determining the drying time of barley brewer’s spent grain τI and τII during both periods are proposed. The absolute value of the maximum relative error of the experimental values of moisture content from the theoretically calculated ones is 19.83 %, and the average value of the relative error is 3.15 %, which is acceptable for practical design calculations of drying equipment.

Improving open sun and indirect solar drying kinetics with physicochemical quality of regal seedless grapes by novel pretreatment solution

This paper reports a study of the physicochemical quality and the drying behavior of regal seedless grapes (RSG), pretreated with a novel solution (Olive oil: 2%, calcium carbonate: 2% and distilled water: 96%), then open sun-dried and dried in an indirect solar dryer. To show the effect of soaking time and temperature of the solution, two soaking times are carried out (120 and 240 s) at two temperatures (333.15 and 353.15 K). Quality indicat or such as shrinkage, color, rehydration capacity, titratable acidity, power of hydrogen (pH) and polyphenol content are evaluated. The results show that the time required to dry treated RSG varies from 220 to 328h during indirect solar drying (ISD) (during 428 h for untreated samples), and from 164 to 180 h during open sun drying (OSD) (during 290 h for untreated samples). The effective moisture diffusivity of solar-dried RSG ranges from 0.316 to 3.030 mm2s−1and that of open sun-dried regal seedless grape ranges from 0.706 to 5.700 mm2 s−1. Pretreatment affects the pH values significantly, whereas the rehydration capacity showes a large difference between the treated and untreated RSG. The solar-dried RSG has more stable color and ISD retains more of their polyphenol content.

BEHAVIOR EVALUATION OF THE FLUID DYNAMICS OF A DRYING PROCESS TO OBTAIN ROOF TILES

Currently, several researches have been developed on the drying of ceramic materials, most of which are carried out experimentally. This process requires high investments and energy consumption, resulting in high costs for companies in the sector. The drying process can be defined as a unit operation that consists of removing water from porous materials through heat transfer. So, aiming at a better cost benefit, it is common to use theoretical solutions that allow, with relative ease of replication and low cost, to change operational and geometric conditions of the dryer or drying object. In this sense, this work aims to predict the drying process of a ceramic tile in a kiln via computational fluid dynamics (CFD). To carry out the simulations, the commercial package Ansys CFX® 22.R1 was used. For a drying temperature of 82,7 °C, the results of drying and heating kinetics, product moisture content, oven air velocity and pressure are displayed and analyzed. A comparison between predicted and experimental data of the average moisture content of the tile throughout the process was performed and a good agreement was obtained.

Kinetic simulation of convection drying for its effect on nutritional, functional, and phytochemical profiling of Colocasia antiquorum and Nasturtium officinale leaves of the Himalayan region

AbstractColocasia antiquorum (Taro) and Nasturtium officinale (Watercress) leaves are highly potent indigenous crops with rich nutritional and phytochemical profiles. The leaves were mathematically modeled, using thin‐layer models, to study the process kinetics for convection drying and its cumulative effect on the physico‐chemical, nutritional, functional, phytochemical, and targeted metabolite profiles. The best‐fit model for C. antiquorum was the two‐term model, whereas for N. officinale, Page model showed the best adequacy with the determination of least Chi‐square and high co‐efficient along with root mean square error. The color and pigment degradation were the prominent changes observed in the quality characteristics of C. antiquorum and N. officinale leaves depicted by the color degradation study. The nutritional composition was significantly affected by the convective drying with reduced ash, protein, and phenolic contents. The extraction yields were however higher along with some elevated metabolite contents estimated for convection drying in comparison to freeze‐dried leaves.Practical applicationsThis study explores the drying kinetic behavior for the progression of moisture loss occurring over the drying time and moderation of drying to achieve a desired moisture content at certain drying rates. The quality characterization before and after selected drying conditions revealed the sensitivity of the chlorophyll/carotenoid pigments, nutrients, and phenolics retained significantly after the end point of drying. Also, the effect of convective drying on the physicochemical, nutritional, and phytochemical contents was significant, which edifies the extent of alterations occurring due to convective drying on the quality characteristics of Colocasia antiquorum (Taro) and Nasturtium officinale (Watercress) leaves. Consequently, these two leafy vegetables hold good potential as crops to be promoted for nutritional security and health and wellness due to their rich bioactive profiles.

Solar Greenhouse Drying Kinetics Efficiency of Hydroxide Sludge in Marrakesh, Morocco

This paper presents a case study of solar drying of hydroxide sludge in the region of Marrakesh, Morocco. The experiments of solar greenhouse drying processes of the hydroxide sludge were studied in summer and winter seasons. The representative samples were in three volumes. The greenhouse sludge dryer was designed and constructed as a horticultural plant. Results showed that the dry of the three samples was reached in only 13 hours in summer and 25 hours in winter. The time of solar greenhouse drying registered was significantly lower compared to several studies. The higher values of drying rate were obtained in early hours of experiments in summer. The maximum ranges obtained were 0.25 kg water/kgDS.h for the hot season and 0.020 kg water/kgDS.h for the cold season. The important influence of the temperature had a greater effect with wind speed on drying rate. The sludge water evaporation caused a large volume reduction with a shrinkage during the processes in both seasons.

Study on the Drying Kinetics of Zinc Smelting Iron Slag Assisted by Ultrasonic Waves.

This study investigates the impact of ultrasonic treatment on the drying kinetics of zinc smelting iron slag. Through the Arrhenius equation, it was found that the reaction order of zinc smelting iron slag remains constant at 1/2 before and after ultrasonic treatment, indicating a proportional relationship between the reaction rate and the square root of the reactant concentration. Despite the increased drying rate of the iron slag due to ultrasonic pretreatment, the reaction order remains at 1/2. Additionally, it was observed that the drying kinetics of untreated iron slag aligns with the Wang and Singh model, while the drying kinetics of ultrasonically pretreated iron slag fits the Page model. The Page model facilitates the prediction of drying rate and drying time for ultrasonically pretreated iron slag, enabling the optimization of the drying process, enhancing efficiency, and comparing drying performance under different conditions. Using ultrasonic pretreatment, the subsequent drying process of iron slag can significantly shorten the time and save energy. These findings provide essential theoretical foundations for optimizing the drying process of zinc smelting iron slag.

Investigation of kinetics of thin layer drying of fruits using computational fluid dynamics

Investigation of kinetics of thin layer drying of fruits using computational fluid dynamics

Efficiency Investigation of Coffee Production Waste Drying by Filtration Method

This article presents the results of determining the technologically feasible parameters of filtration drying of coffee production waste based on experimental data on the kinetics of material drying and the hydrodynamics of thermal agent filtration. The lowest total energy costs were observed with the following process parameters: the material layer height of 120 mm, the thermal agent temperature of 90 °C, the velocity through the stationary layer of 1.76 m/s, and the specific energy consumption of 5857 kJ per 1 kg of water. Based on the determined technologically feasible process parameters, an evaluation of the filtration drying method for coffee production waste was performed at an industrial installation. According to the calculation, using the filtration method, 1164 kW h of energy was required to dry about 1000 kg of coffee production waste. A total energy of about 1.65 kW h/kg was required to remove 1 kg of moisture from the material in an industrial filtration drying installation. The results were compared with a drying material with similar initial parameters. It was calculated that to dry 1000 kg of coffee production waste in a rotary dryer, it is necessary to spend about 1625 kW h, and the total energy consumption for removing 1 kg moisture from the studied material is approximately 2.37 kW h/kg. Thus, for a similar output of about 1000 kg/h, filtration drying can reduce energy consumption by about 465 kW·h and reduce the required drying time by more than 20 times. The overall economic effect of using the filtration drying method in industry is expected to be higher, given the significant heat losses to the environment for a rotary dryer due to its large size, long drying time, design features, and the need for energy-intensive auxiliary equipment. After calculating the energy consumption per 1 kg of dry material, it is necessary to spend 12 950 kJ/kg of dry matter, about 41.5 % less than the higher calorific value for experimental samples of briquetted solid fuel made from this material. This result makes it economically feasible to further dry coffee production waste to produce alternative solid fuels.

Investigation of kinetics of thin layer drying of fruits using computational fluid dynamics

Investigation of kinetics of thin layer drying of fruits using computational fluid dynamics

CONVECTIVE DRYING KINETICS OF YACON (Smallanthus sonchifolius Poepp. Endl.) SLABS AND EVALUATION OF THE DRYER PID TEMPERATURE CONTROL SYSTEM

Yacon is a functional food that is rich in fructooligosaccharides (FOS) and highly perishable, which requires inexpensive methods for its preservation. The objectives of this research were to model the kinetics of convection drying of yacon slabs and to assess the effect of air velocity on the temperature record of the heating zone controlled by the Proportional-Integral-Derivative control system (PID). Different temperatures (60, 70, and 80 °C) at constant air velocity (0.87 m s-1) were evaluated in a convective tray drying system. To determine the effect of air velocity on the PID temperature controller, different air velocities (0.81-2.06 m s-1) at constant temperature (70 °C) were studied. The results showed that Page’s model was the best fitting of the data obtained, the effective diffusivity of convective drying of yacon ranged from 1.22x10-10 to 1.9x10-10 m2 s-1 and the activation energy was 21.76 kJ mol-1. With PID temperature control, it was observed that the best drying rate and lowest temperature signal error occurred at an air velocity of 1.46 m s-1, where the temperature signal was more stable and closer to the reference temperature. In conclusion, the kinetic modeling of the convective drying of yacon provides optimal drying parameters as well as behavior of mass and heat transfer phenomena, particularly considering that the effect of air velocity influences the drying kinetics and the PID temperature control of the dryer.

Hot-air drying and degradation kinetics of bioactive compounds of gilaburu (Viburnum opulus L.) fruit

This study aims to determine whether drying is a suitable preservation method for gilaburu fruit and the changes in the bioactive components of gilaburu fruit (Viburnum opulus L.) at the end of the drying process. In this study, gilaburu fruits were dried in a cabinet dryer at different temperatures (50?C, 60?C, and 70?C). The analyses of trans-resveratrol, water-soluble vitamins, organic acids, and phenolic compounds were made using the HPLC method, while total phenolic contents and antioxidant activity were spectrophotometric. As a result of drying of gilaburu fruit at 50?C, 6 ?C, and 70?C, the highest component loss was observed at 70?C. Losses of 73.64% and 84.08%, respectively, were detected in the total phenolic substance and antioxidant capacity content of gilaburu fruit after drying at 70?C. While the trans-resveratrol content was 1.26?0.05 (g/100 g dry weight (DW)) in fresh fruit, it reduced to 0.31?0.03, 0.30?0.01 and 0.21?0.01 after drying at 50?C, 60?C and 7 ?C, respectively. In terms of vitamins, the highest loss was seen in niacin. The contents of ascorbic acid, pyridoxine, niacin and thiamine contents of fresh gilaburu fruit decreased after drying at 50?C, 60?C and 70?C. In addition, drying kinetics of water-soluble vitamins, total phenolic contents, antioxidant activity, and trans-resveratrol were modeled. The Page model best described the drying behavior of fruits at 70?C, and the parabolic model at both 50?C and 60?C. Thermal degradation of water-soluble vitamins, total phenolic contents, antioxidant activity, and trans-resveratrol were fitted in the first-order kinetic model.

Microwave-Assisted Hot Air Drying of Orange Snacks: Drying Kinetics, Thin Layer Modeling, Quality Attributes, and Phenolic Profiles

Citrus fruits, regarded as a prominent fruit crop, are cultivated extensively around the globe and orange (Citrus sinensis L.) is a widely cultivated popular member of the citrus family. Dried oranges have gained recognition as a healthy snack option among consumers and worldwide markets due to the absence of additional ingredients such as sugar and chemicals, whilst yet containing significant natural beneficial components. The drying method is very intriguing due to its ability to facilitate the efficient production, packaging, storage, and transportation of dried oranges at a cost-effective price. In this study, the effects of microwave pretreatment (Mpt) (90 W, 30 min) on hot air drying (HTAD-MW) (60, 70, and 80°C) were investigated, along with the effects on the drying kinetics, rehydration capacity, and quality properties of the orange snack including phenolic compounds (vanillic acid, gallic acid, epicatechin, hesperidin, naringenin, chlorogenic acid, sinapic acid, and o-coumaric acid), antioxidant capacities (with DPPH, FRAP, and CUPRAC methods), and ascorbic acid contents. For modeling the kinetics of orange snack drying in all tests, logarithmic, Wang and Singh’s, diffusion approach, two term, and Wang and Sing’s models performed best. Hot air drying (HTAD) at 70°C applied orange snacks showed the lowest △E ∗ ab value, and the color values were close to those of fresh orange slices. The levels of total and individual phenolics, antioxidant capacity (AC), and ascorbic acid (AA) in dried orange snacks were found to be significantly lower ( p < 0.05) than in the fresh orange slices. Results also showed that HTAD-MW-applied orange snacks contained more total phenolic (TP) content, individual phenolic content, and AC but lower AA than HTAD-applied samples. The highest amount of phenolic compound was hesperidin for fresh and dried orange snacks. The method that best preserves the TP content and AC of dried orange snacks was found at the drying condition of HTAD-MW at 60°C. As a conclusion, it was suggested that the use of microwave and hot air combination is a promising method to introduce a new functional healthy snack to the dried product market with high quality.

Experimental Study of Polish Sausage Drying Kinetics and Contraction by Image Data Analysis

Abstract The goal of this paper has been to add an experimental data set for drying a meat product and provide a comparison with well-established thin-layer drying models. This article presented experimental investigations on the convective drying of Polish sausage slices at a temperature of 40°C. Slices have been in the thickness of 3 to 8mm. Measurements of mass loss and size change were performed. The data have been presented in the form of standard drying kinetics. Additionally, the estimation of the diffusion coefficient according to the simplified graphical approach is made. Based on the best-fit approach the coefficients for typical semiempirical correlations for MR (moisture ratio) estimation have been calculated and presented.

Oil Extraction and Natural Drying Kinetics of the Pulp and Seeds of Commercially Important Oleaginous Fruit from the Rainforests of Guyana

Ambient sun drying is the method most used by Indigenous communities for preserving fruits and seeds harvested from the forest. It is an effective method to increase the shelf-life of highly perishable foods and prevent spoilage until important bioactive compounds can be extracted at distant locations. The ambient sun drying kinetics and oil extraction of the pulp and seeds of commercially important oleaginous fruit directly obtained from the rainforests and swamps of Guyana, namely Astrocaryum vulgare (Awara), Astrocaryum aculeatum (Kuru), Oenocarpus bacaba (Turu), Mauritia flexuosa (Ite), Euterpe oleracea (Acai), Caryocar nuciferum (Souari), Attalea maripa (Kukrit), and Carapa guianensis (Crabwood), were studied. The fruits were dried under ambient conditions from initial moisture contents ranging from 24–71% to a final moisture content of 5%. Three models, the Lewis model, the modified Page model, and the standard logistic function (SLF) model, were utilized to model the drying kinetics and to estimate the parameters governing the drying process. These models were demonstrated to fit the experimental data with excellent goodness of fit (>0.98). The SLF, never used before to model drying kinetics, was observed to be the best-suited model overall, with the highest correlation coefficient and the least Chi-square (χ2). Depending on the fruit type, the estimated point where the maximum drying rate occurs varies from 35 min to 350 min for sun-dried fruit pulp and up to 4000 min for sun-dried kernels. The steepness of the drying curves varied from −0.5 to −3.5 g/min. The results of this work will aid in the design, development, optimization, and control of the ambient drying processes of economically and functionally important oleaginous forest fruits. This knowledge will assist in addressing the key challenge of spoilage faced by Indigenous communities in the preservation of tropical oleaginous fruits and seeds, possibly aiding in the preservation of functional characteristics of the extracted oils and adducing to the sustainable economic utilization of such fruit.

Effect of Temperature on Drying Kinetics and Quality of Partially Deoiled Chia Flour Wheat Pasta

After chia oil extraction, a by-product, partially-deoiled chia flour (PDCF) with a high nutritional value (high content of fiber, protein, and antioxidant properties) remains. The effect of drying temperature on the quality and drying kinetics of wheat pasta enriched with PDCF was evaluated. Wheat pasta was prepared with different proportions of PDCF (0, 5 and 10%, wheat based) and dried at 45, 55 and 65 °C for 24 hours. Experimental data were fitted to different empirical models. Drying kinetics, drying rate (DR), effective moisture diffusivity (Deff), pasta cooking parameters, microstructure, textural and color were analyzed. The Midilli model had the most suitable performance to describe pasta drying kinetics behaviour. Pasta enriched with PDCF required higher energy input for drying. High drying temperatures had a great impact on enriched pasta quality. Pasta was darker, opaque, irregular, and porous. Cooking time and cooking losses decreased. Hardness was not affected. The strength and microstructure properties of enriched pasta improved at 65 °C, while the non-enriched pasta properties improved at 55 °C.

Drying behavior of solid digestate and reaction kinetics of ammonium degradation during laboratory-scale drying

Fundamental knowledge of the drying behavior and ammonia emission from digestate is required in order to properly design efficient drying processes. In this study, laboratory-scale drying experiments with two different digestates (D1 and D2) were conducted at four different drying temperatures (50, 60, 70, and 80 °C). The solid digestate D1 mainly consisted of plant silage (88.7%), while D2 comprised primarily of manure (55.9%). The drying experiments were performed in a controlled drying chamber using relatively small-sized samples of digestate (30 g for D1, 37 g for D2). These samples were characterized by an initial moisture content of about 74% wb (D1) and 78% wb (D2). This sample size mass was deliberately chosen to ensure homogeneous drying conditions within a thin layer and to facilitate precise laboratory quality measurements of parameters including water content, nitrogen contents (N-total, NH4-N), and pH values before and after the drying process. Both types of digestate exhibited a similar kinetics of drying and ammonium degradation. The first period of constant drying rate was followed by two periods with decreasing rates. Similarly, the ammonium degradation was characterized by three periods with decreasing reaction rates. Considering only the first reaction period herein, ammonium degradation was determined as a first-order reaction. The activation energy for this reaction period was obtained to be 20.00 kJ mol−1 for digestate D1 and 18.44 kJ mol−1 for digestate D2. The results of this study may serve as a basis for the conceptualization and design of optimized, continuous drying processes tailored to digestate materials.

Modeling and Analysis of the Drying Process of Lithium-Ion Battery Electrodes Based on Non-Steady-State Drying Kinetics

The drying process of lithium-ion battery electrodes is one of the key processes for manufacturing electrodes with high surface homogeneity and is one of the most energy-consuming stages. The choice of the drying parameters has a significant impact on the electrode properties and the production efficiency. In response to these issues, this study establishes the non-steady-state drying kinetic equation for the electrodes, revealing the comprehensive effects of various dominant factors on the drying process. The drying rate is closely related to the electrode surface temperature, thickness, and other factors. Furthermore, this study proposes a coupled model of hot air drying field and capillary porous electrode solvent evaporation. The results showed that approximately 90% of the solvent was removed in less than half of the drying time. Then, the mechanism and control factors of electrode solvent evaporation are analyzed. During the preheating phase, the drying rate is controlled by electrode heating and temperature rise. In the constant velocity phase, it is regulated by the heat transfer from the surface airflow, while in the deceleration phase, it is affected by the mass transfer from the electrodes. Additionally, the effects of different thicknesses, temperatures, and airflow speeds on the drying process were investigated. Finally, experimental verification demonstrated the optimal parameters within the scope of the study: a temperature of 363.15 K and airflow speeds of 2.3 m/s result in a higher drying rate, as well as favorable mechanical performance.