Deff Values Research Articles

Effects of physical and chemical pretreatments on drying and quality properties of blackberry (Rubus spp.) in hot air dryer.

This research examines the impact of various pretreatments on effective moisture diffusivity coefficient (Deff), activation energy (Ea), specific energy consumption (SEC), color, and shrinkage of blackberry (Rubus spp.). Hot air drying experiments were conducted under three different temperatures (50, 60, and 70°C) and four pretreatments, including thermal pretreatment by hot water blanching at 70, 80, and 90°C, pulse pretreatment with microwave having power of 90, 180, and 360 W, chemical pretreatment using ascorbic acid (1% in distilled water), and mechanical pretreatment using ultrasonic vibration with working frequency of 28 ± 5% kHz for 15, 30, and 45 min. The results show that the highest Deff value, which was 1.00 × 10–8 m2/s, could be achieved by using a microwave pretreatment with power and drying temperature of 360 W and 70°C͘, respectively. Moreover, the lowest Deff value obtained from this similar pretreatment condition was 3.10 × 10–9 m2/s at a drying temperature of 50°C, while Ea ranged from 13.61 to 26.02 kJ/mol. The highest and lowest SECs were 269.91 kW hr/kg for the control sample and 75.63 kW hr/kg for the microwave pretreatment, respectively. Furthermore, the largest color change and shrinkage were detected in ascorbic acid pretreatment and control sample, respectively.

The Comparative Study of the Internal Tin Nb3Sn Wires with Different Layouts

The required combination of performance properties for internal tin Nb3Sn wires for high energy physics includes high critical current density (J c) and RRR values as well as low magnetization and effective diameters (Deff ) value. It is quite a challenge to achieve them all at once. A comprehensive study has been carried out on two internal tin Nb3Sn wires with essentially different layouts and 37 sub-elements each. The first type of wires has distributed diffusion barriers. The second one has common diffusion barrier with sub-elements internally divided by resistive separators. Two sets of data for two types of wires have been obtained, which include transport measurements of J c(B), magnetization loops M(B), superconducting transition temperature (Tc), RRR values, Sn-concentration by EDAX measurements and XRD analysis. XRD analysis of the superconducting layers has shown that the compressive macrostress is larger for the wire with overall barrier than for the wire with distributed diffusion barriers. This observation correlates with a shift of the stress-dependent curves of the superconducting transition. The difference in the volume fractions and the homogeneities of the Nb3Sn phase leads to a significant difference of the J c(B) dependences and the values of the Kramer critical field (BKr) for these types of wires. In summary, the high critical current density for the first type of wires and the low hysteresis losses for the second type of wires have achieved with high RRR values in both cases.

Modeling and mass transfer performance of Dioscorea alata L. slices drying in convection air dryer

AbstractThe drying experiments of Dioscorea alata L. slices were implemented in order to study the thin‐layer drying characteristics and kinetic in hot air forced convection tunnel dryer. The influences of temperatures, velocity, and slice thickness on the drying behavior were researched. Six commonly thin‐layer drying models were used to fit the experimental data to express the mass transfer characteristics. The fitting degree between models and experiment data was analyzed. The effective diffusion coefficients (Deff) and activation energy (Ea) were estimated. The air temperature, air velocity, and sample slice thickness had significant influence on drying time, dehydration rate, and Deff. The drying process had a momentary accelerating rate stage and a long falling rate stage; the Logarithmic model had good degree of fitting with all experiments data; and Arrhenius equation could be well expressed the relationship of Deff and drying temperature. The drying process of hot air thin layer of Dioscorea alata L. can be better described by the Logarithmic model. At the range of research conditions, the Deff value ranged from 4.77 × 10−10 m2/s to 8.90 × 10−10 m2/s; the Ea value was 20.74 kJ/mol.Practical ApplicationsPostharvest processing and storage of agricultural products is very important, and drying is a traditional and practical technology. The common drying method is heat drying. This research discussed the thin‐layer drying of Dioscorea alata L. with hot air and obtained the appropriate drying conditions, applicable drying model, and relevant parameters, which could provide reference to select the drying conditions and design the drying equipment for practical application.

Effects of power ultrasound enhancement on infrared drying of carrot slices: Moisture migration and quality characterizations

To investigate the intensive effect of contacting ultrasound applied in infrared (IR) drying, a self-designed ultrasound-assisted IR (US-IR) dryer was developed, the water diffusion kinetics of carrot slices during hybrid US-IR drying was studied and the quality properties of dried products were evaluated. Results showed that the drying rates and rehydration ratios were significantly enhanced when the ultrasound was applied. Compared to pure IR dying, the drying durations shortened by 21%, 17%, and 11% for US-IR drying at 900, 1200, and 1500 W, respectively. The intensive effect of ultrasound increased the water activity when the moisture content of carrot slices decreased from 4.23 to 0.11 g water/g dry solids. The Deff values of US-IR dried samples were in the range of 8.09–26.98 × 10−10 m2/s, which were higher than the IR dried samples (6.34–22.92 × 10−10 m2/s). The micrographs showed the applied ultrasound created more porous structures to allow water migration from the inside of carrot tissue to the outside. Besides, ultrasound could be helpful to mitigate the formed dense layer on the surface of carrot slices during drying at high IR power.

Compaction Dynamics during Progenitor Cell Self-Assembly Reveal Granular Mechanics

Summary We study the self-assembly dynamics of human progenitor cells in agarose microwells that are used for production of chondrogenic organoids. Using image analysis on time-lapse microscopy, we estimate the aggregate area in function of time for a large number of aggregates. In control conditions, the aggregate radius follows an exponential relaxation that is consistent with the dewetting dynamics of a liquid film. Upon introducing Y-27632 Rho kinase inhibitor, the compatibility with the liquid model is lost, and slowed-down relaxation dynamics are observed. We demonstrate that these aggregates behave as granular piles undergoing compaction, with density relaxation that follows a stretched exponential. Using simulations with an individual cell-based model, we construct a phase diagram of cell aggregates that suggests that the aggregate in presence of Rho kinase inhibitor approaches glass transition.

Effect of Drying on Lettuce Leaves Using Indirect Solar Dryer Assisted with Photovoltaic Cells and Thermal Energy Storage

The thin layer drying behavior of lettuce leaves was investigated using an indirect pilot solar dryer with thermal energy storage in water, equipped with solar collectors and photovoltaic cells. The drying procedure consisted of shredded lettuce leaves, temperature ≤ 52 °C, airspeed, 1.0 m∙s−1, and process time ~10.0 h. Fifteen drying models were adjusted to the experimental data obtained; three models with maximum values of coefficient of determination (R2)—Page, Midilli, and Kucuk, and Weibull Distribution, whose values of R2 ≥ 0.998, and other statistical parameters, χ2, SSE, and RMSE values closer to zero were chosen. The initial browning index BI = 120.5 ± 0.7 decreased compared to the dry sample BI = 78.99 ± 0.5, with chromatic coordinate degradations a* and b*; but not the luminosity L*; where ΔE = 8.26; whose meaning is that the dry sample is a “more opaque brownish color” due to the difference in the chroma ΔC = 6.65, and with a change from the yellow-green to yellow-red zone, and a difference in hue angle, Δh° = 14.27, between the fresh and the dried sample. Deff values for shredded lettuce leaves were 1.8 × 10−9 m2 s−1 for values ≤ 52 °C.

Analyzing the universality of the dimensionless vibrating number based on the effective moisture diffusivity and its impact on specific energy consumption

Using vibro-fluidized bed dryers (VFB) is an alternative to perform drying with less specific energy consumption compared to fluidized bed dryers (FB). Finding an optimum combination of the dimensionless vibrating number (Γ) with the drying conditions is a key factor to analyze the viability of VFB towards energy efficiency. In the present study, the performance of a VFB was investigated by correlating the drying kinetics of porous particles with the specific energy consumption to obtain an optimum drying condition. Experiments were carried out under different operating conditions and three combinations of vibration amplitude (A) and frequency (F) chosen to yield a constant value of Γ. The impact of the operating parameters was analyzed by effective moisture diffusivity (Deff,G), estimated by fitting the diffusive model to the experimental data. It was found that vibration intensifies Deff,G and is the preponderant effect in the convective mass transfer. Different values of Deff,G were found for the same Γ obtained under the tested combinations of A and F, which indicates that this parameter cannot be used alone as a single descriptor of the vibration energy. Using a high temperature and a gas velocity exceeding the minimum fluidized velocity combined to a higher value of A and a lower value of F enhanced drying, as this combination yielded the highest Deff,G. This same combination of high A and low F associated to low values of temperature and gas velocity enhanced the energy performance. The results also showed that only Γ is not an adequate parameter to perform energy analysis of VFB.

Correlation between age and head diameters in the paediatric patients during CT examination of the head

Abstract An estimate of patient dose, patient size should be used to normalise the output dose of CT machine in the terms of volume CT dose index, CTDIvol. There are two metrics to characterise the patient size, i.e. the effective diameter (Deff) and the water-equivalent diameter (Dw). These two metrics could be estimated by patient age. However, to date, relationships between the age and head patient size (Deff and Dw) have not been established for the pediatric patients. The aim of this study was to establish the relationships between the age and head patient size (Deff and the Dw) as the basis for calculating the size-specific dose estimate (SSDE) for paediatric head CT examination. The data were retrospectively collected from serial images of the CT head in the DICOM file from one hundred and thirteen paediatric patients aged 0-17 years (63 male and 50 female patients) underwent head CT examinations. The patient’s sizes (Deff and Dw) were calculated from the patient’s images using the IndoseCT version 15a software. The Deff and Dw values were correlated with age of patients using regression analysis. It was found that patient size (Deff and Dw) correlated well with the age of the patient with R2 more than 0.8. The size of the Dw is bigger than the Deff. The Deff values for male patients are 12.38 to 16.21 cm, and Dw values are 11.96 to 18.16 cm, respectively. For female patients, the values of Deff are from 11.54 to 16.87 cm, and the values of Dw are from 11.60 to 17.86 cm, respectively.

INFRARED DRYING OF APRICOT POMACE

Effect of infrared powers (62, 74, 88, 104 and 125 W) on drying kinetics of apricot pomace was investigated. It is observed that drying characteristics of apricot pomace were greatly influenced by infrared power. Henderson and Pabis model was investigated for describing thin-layer drying of apricot pomace. The model because of the high coefficient of determination (R2) as well as the lowest reduced chi-square (c2) and root mean square error (RMSE) values adequately described the experimental data of apple pomace drying. Effective moisture diffusivity (Deff) values were increased by increasing infrared power and changed between 1.67×10-9 and 6.03×10-9 m2/s. Activation energy was estimated by a modified Arrhenius type equation and found to be 2.32 kW/kg. The colour results were affected by drying conditions.

The effect of microwave and convective dryer with ultrasound pre‐treatment on drying and quality properties of walnut kernel

In this study, the drying kinetics of walnuts was investigated including specific energy consumption (SEC), shrinkage, and walnut kernels' color in two dryers, namely ultrasonic-convection (US-CON) and ultrasonic-microwave (US-MIC). To carry out this study, walnut samples were dried at three MIC powers (270, 450, and 630 W), three input air temperatures (40, 55, and 70°C) and four duration of ultrasonic pre-treatment (0 min (control sample), 10, 20, and 40 min). Fifteen mathematical models were used to describe the walnuts' moisture ratio. The results showed that the Midilli et al. model was the best model for describing the process of drying walnuts in US-CON and US-MIC dryers. Effective moisture diffusivity (Deff) values were calculated to be between 2.77 × 10–9 and 5.56 × 10–9 m2/s for the US-CON dryer and 3.12 × 10–9 to 8.99 × 10–9 m2/s for the US-MIC dryer. The lowest rates of color change were observed in the US-MIC dryer at the lowest microwave power and the lowest duration of ultrasonic pre-treatment. The lowest SEC for the US-CON dryer was 19.52 kWh/kg, and it was 15.90 kWh/kg for the US-MIC dryer. The highest rate of shrinkage was 14.21%, which was seen in the US-CON dryer at the air temperature of 70°C and the duration of ultrasonic pre-treatment of 40 min. According to the results, the best quality of walnut with the lowest changes of color and shrinkage in the microwave dryer was calculated at microwave power 270 W and control sample. Practical applications Drying foods and agricultural products using microwave dryers is a relatively cheap method and has attracted the attention of many researchers today. Also, numerous studies have been conducted on drying agricultural products through microwave and convection dryers with ultrasound pre-treatment. The result of this study could be applied for gathering comprehensive information regarding the drying process (kinetic, Deff, Ea, and SEC) as well as the qualitative properties (color and shrinkage) of walnut kernels dried using the microwave and convective hot air dryers accompanied by ultrasound pre-treatment.

Effect of ultrasonic power on drying process and quality properties of far-infrared radiation drying on potato slices.

The experiments of contact ultrasound-assisted far-infrared radiation (FIR) drying on potato slices were conducted to investigate the effects of ultrasonic power on drying characteristics and quality properties. The results showed that contact ultrasound was helpful for accelerating mass transfer of the samples, and the improvement of ultrasonic power could significantly shorten drying time. The ultrasonic reinforcement effect on drying rate declined along with the decrease in moisture content. D eff values were within 1.15 × 10-10 and 1.96 × 10-10m2/s, and improved with an increase in ultrasound power. Compared with FIR dried ones, more and larger pore size of microcapillaries in the samples' tissue structure could be observed with contact ultrasound application, and higher ultrasonic power produced more microtunnels. Contact ultrasound in FIR drying could reduce the color difference of dried potato slices, and decrease the hardness and brittleness values. Higher TPC and TFC could be achieved as ultrasonic power increased.

DRYING CHARACTERISTICS OF RED BEET (BETA VULGARIS ESCULENTACRUENTA) PUREE IN A MICROWAVE OVEN

The aims of this study are to observe the effects of different microwave power and amount of samples on the drying characteristics of red beet puree, to determine the physical properties of the red beet powders and to calculate the energy efficiency of the drying process. The drying experiments were conducted at five different microwave power and thicknesses of the sample. Seven thin-layer drying models were fitted to the experimental data and Page model which had the highest R2 and lowest χ2 and RMSE for all drying experiments was found to satisfactorily describe the drying behavior of red beet puree. The total drying times increased depending on an increasing amount of sample and decreasing microwave power. The Deff and Ea values ranged between 1.095E-08 to 3.438E-06 m2.s-1 and 14.35 to 77.35W.g-1, respectively. The energy efficiency values of the drying processes are evaluated in terms of MER and SEC.

Method for avoiding cracks during drying of masonry units made of illite raw material

Drying is one of the most important steps in the production process of masonry units. In order to prevent the formation of cracks during drying information’s about the moisture migration rate variability as well as the material strength variability through drying are necessary. The main goal of this paper was to find a solution how to prevent the crack formation at the beginning (during the first hour) of the drying for the drying sensitive illite raw material. The first step was to record a series of isothermal Deff – MR curves at different drying air temperatures and constant drying air velocity and humidity. As it was already reported all moisture transport mechanisms during isothermal drying are visible on those curves. Characteristic spots registered on these curves were then transposed on the experimentally registered figure material strength us moisture content. It was found that the material strength for the cracked masonry units at the beginning of drying was around 0.09 MPa and that the time of cracking was near the characteristic spot B. Registered material strength and the crack time position (spot B) has additionally confirmed that the drying sensitivity of the raw material are obviously related with the present clay mineral constituents structure and the initial moisture content of the green heavy clay units. Using the Deff values registered for each experiment in the spot B we were able to calculate the maximal moisture transport rate and consequently the proper drying air parameters which are safe and which will not initialize the formation of the cracks at the beginning of the drying.

Improvement of heat & mass transfer with added ozone into drying air on corn-soy

Corn and soy have wide-ranging uses in food and biofuel industries due to its nutritional and energetic properties. In the present work, artificial drying experiments with hot air convection in different temperatures (30, 40 and 50 °C) were carried out with the addition of ozone (5, 10 and 15 min) applying a central composite design (CCD). The effective diffusion coefficient Deff as thermodynamic properties was evaluated with and without the incorporation of ozone into drying air on corn and soy. The CCD showed different Deff values and a numeric model was fitted to moisture diffusion during the drying-ozonation process (DOP) on corn-soy. Activation energy decreased from 43.90 to 35.20 kJ mol−1 for corn and 38.23 to 34.29 kJ mol−1 for soy when ozone was added into the drying air; similar observation occurred to enthalpy and entropy. Thus, the drying-ozonation process can be useful for technological purposes for energy improvement during postharvest stages, as well as maintaining the quality of cereal products and design of new dryers.

Mathematical modelling of paddy drying using fluidized bed dryer

Several mathematical models have been developed to illustrate the drying process of crops, and one of them is thin-layer modelling. However, there are still limited information about mathematical modelling in paddy drying. In this paper, thin layer modelling of paddy drying curve on drying using fluidized bed dryer is presented. The drying paddy was done with drying temperature variations of 50, 60, 70, 80, and 90 °C. The initial paddy moisture content is 33 % dry basis. The drying process was done for 1,5 hours. Paddy moisture was measured every 10 minutes using grain moisture meter. The thin layer models used are Newton, Page, Modified Page, Henderson and Pabis, Logarithmic, Two-term, and Wang and Singh models. Model fittings were done using MATLAB 2015 software by sum square error minimization. Experimental results showed that Modified Page model gave the best results, evidenced by the highest average R2 value of 0.9949 and lowest average RMSE (Root Mean Square Error) value of 0.0631, followed by Page model and Henderson and Pabis model. The plotting of MR (Moisture Ratio) and time at five drying temperatures showed that effective diffusivity (Deff) value ranged from 1.0334 x 10−8 m2/s to 2.1983 x 10−8 m2/s and the value increases as drying temperature increases. The plotting results of ln Deff and 1/T (absolute temperature) showed that the value of diffusivity factor (Do) is 8.5293 x 10−6 m2/s and activation energy (Ea) is 18.11 kJ/mol.

Comparison of convective and infrared heating as means of drying pomegranate arils (Punica granatum L.)

The purpose of this study is to compare convective and infrared heating as means of drying pomegranate arils. The drying process was conducted at 50, 60 and 70 °C. The minimal times required to reach 9 ± 0.2% moisture (mass/mass) starting from 78 ± 0.2% were 510 and 94 min respectively for convective and infrared drying. Calculation of aril effective diffusivity (Deff) was based on Fick’s second law of diffusion. At all temperatures, Deff values ranged from 2.56·10–10 to 4.75·10–10 m2/s, and from 0.87·10–9 to 2.64·10–9 m2/s respectively for convective and infrared drying. Effective moisture diffusivity (Deff) values were found to increase as temperature to increase. Pomegranate is one of the major sources of polyphenolic phytochemicals. Polyphenol stability might be affected by heat treatments that are required during drying. Based on the maximal total polyphenol content (205 ± 0.89 mg/100 g) of the dried product, the optimal temperature for infrared drying was 50 °C. This product also had an intense garnet-red color and a satisfactory rehydration capacity. Various models of drying kinetics were tested for conformity with the results obtained in this study. The model that best fit the drying data was the modified logistic model of Midilli et al., than other models.

Effect of hot air drying on quality characteristics and physicochemical properties of bee pollen

Abstract The aim of this study was to investigate the effect of hot air drying on quality characteristics, physicochemical properties, morphological structure and organoleptic characteristics of bee pollen, and compute the effective moisture diffusivity and activation energy during hot air drying of bee pollen. Bee pollen samples were dried at 40, 45, 50, 55 and 60 °C. Effective moisture diffusivity (Deff) values ranged from 1.38 × 10 −10 to 4.00 × 10−10 m2/s, and the activation energy (Ea) was found to be 42.96 kJ/mol. Protein, fat, total carbohydrates and vitamin C of bee pollen were affected by the drying temperature. Dried bee pollen samples had high solubility index, and had lower L* and b* values as compared with those of the fresh bee pollen. Total color difference (Δ E) was the lowest for the bee pollen dried at 40 °C. Morphological changes on dried bee pollen surfaces increased with increasing the drying temperature. Bee pollen dried at 40 °C took the highest sensory scores and retained its quality attributes better than the bee pollen samples dried at 45, 50, 55 and 60 °C. Hot air drying at 40 °C is recommended for the drying of bee pollen.

Experimental evaluation of beef drying kinetics in a solar tunnel dryer

This study focused on the experimental analysis on drying kinetics of beef in a solar tunnel dryer. During the drying process the parameters of drying air were monitored. Experimental drying curves were then determined. The drying data were fitted to five drying models and their constants evaluated by non-linear regression analysis. Validity of the models was assessed using the coefficient of determination (R2), the reduced chi-square (χ2), mean relative percent error (P) and root mean square error (ERMS). Effective moisture diffusivity (Deff) of beef was also determined. During the drying period, the ambient temperature, ambient relative humidity, inlet air velocity and solar radiation intensity varied from 21.3 to 38.9 °C, 48–69.5%, 0.02–0.18 m/s and 476.3–1000 W/m2 respectively. Temperature profile along the tunnel dryer increased with increased solar radiation and decreased continuously at high moisture content of beef. Whereas drying occurred predominantly in the falling rate period for both drying methods, samples dried in the solar drier had a higher drying rate compared to sun dried beef. The most suitable model for representing the drying characteristics of beef was the Page model. The Deff values for solar tunnel dried beef varied from 2.282 10−10 to 2.536 × 10−10 m/s2.

Determination of the drying kinetics and energy efficiency of purple basil (Ocimum basilicum L.) leaves using different drying methods

In this work, the effects of different drying methods, namely sun, freeze, convective and microwave oven drying on the drying time, rate and kinetics were investigated in purple basil leaves. Additionally, the energy efficiencies of the driers were determined. All the drying processes took place mainly in the falling-rate period. Comparatively, higher drying rates were obtained from microwave oven drying of the samples. Eleven thin-layer drying models, (Lewis, Page, Modified Page I, Henderson and Pabis, Modified Henderson and Pabis, Logarithmic, Midilli, Modified Midilli, Two-Term, Two-Term Exponential, and Wang and Singh) were fitted to the experimental moisture ratio data. Handerson and Pabis for freeze drying, logarithmic for sun drying and Page for convective and microwave oven drying were found to be the best models for explaining the drying behavior of the purple basil leaves with the highest R2 and lowest RMSE values. The effective moisture diffusivity (Deff) values of the dried purple basil leaves were calculated with Fick’s diffusion model and ranged from 1.62 × 10−9 to 7.09 × 10−8 m2/s. The energy efficiency of microwave oven drying was higher than the other methods.

Using PSO and GWO techniques for prediction some drying properties of tarragon (Artemisia dracunculus L.)

AbstractIn this article, the effects of air temperature and velocity on drying characteristics of tarragon (Artemisia dracunculus L.) were investigated. The experiments were done at four temperatures of 40, 50, 60, and 70 °C and three air velocities of 1, 1.5, and 2 m/s. According to the results, the drying term of tarragon reduced significantly with increasing drying air temperature. The values of effective moisture diffusivity (Deff) were ranged between 1.34 × 10−10 and 2.74 × 10−10 m2/s. Also, by increasing drying air temperature the values of specific energy consumption (SEC) were decreased. The values of SEC were between 20.50 and 66.90 MJ/kg. Also Deff and SEC values were modeled by particle swarm optimizer (PSO) and gray wolf optimizer (GWO) algorithms. Drying air velocity and air temperature were considered as input parameters for the models. Based on three statistical parameters includes R2, MSE, and MAE for predicting Deff and SEC, GWO performance was better than the PSO.Practical applicationsThe purpose of drying crops is decreasing of moisture content for providing secure storage and significant influence on the quality of dried crops. In this research, the effective moisture diffusivity (Deff) and specific energy consumption (SEC) values were modeled by PSO and GWO algorithms. The procedure can be applied in postharvest processing of medicinal plants.