scholarly journals DRYING OF ZUCCHINI AND CARROT SLICES: INFLUENCE OF TISSUE STRUCTURE ON MASS TRANSFER PARAMETERS

2022 ◽  
Vol 52 (1) ◽  
pp. 49-54
Author(s):  
Farhad Khoshnam
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Microwave Power ◽  
Moisture Diffusivity ◽  
Tissue Structure ◽  
Moisture Removal ◽  
Average Activation Energy ◽  
Rate Period ◽  
Transfer Parameters

The present work aimed mainly at investigating the influence of tissue structure on dehydration characteristics of zucchini and carrot. Microwave power levels of 100, 350, 550 and 750 W used to dehydrate the samples with thicknesses of 3, 5, 7 and 9 mm. The results showed that moisture removal from the slices occurred in a short accelerating period at the process beginning followed by a falling rate period. The moisture diffusivity increased with both increasing microwave power and the samples thickness where the average values for zucchini and carrot slices changed from 1.17×10-8 to 9.42×10-8 and from 0.73×10-8 to 5.51×10-8 m2 s-1, respectively. The average activation energy for zucchini and carrot slices varied in the range of 1.22–1.68 and 1.57–1.84 W g-1, respectively and decreased with increasing samples thickness.

scholarly journals INFRARED DEHYDRATION OF BLANCHED QUINCE SLICES: STUDY ON PROCESS AND MASS TRANSFER CHARACTERISTICS

2021 ◽  
Vol 51 (4) ◽  
pp. 241-247
Author(s):  
Mohsen Beigi
Keyword(s):  
Mass Transfer ◽  
Moisture Diffusion ◽  
Moisture Diffusivity ◽  
Moisture Removal ◽  
Convective Mass Transfer ◽  
External Resistance ◽  
Flow Rates ◽  
Surface Mass ◽  
Mass Evaporation ◽  
Biot Numbers

In the present work, moisture removal characteristics of quince slices in a convective tray dryer were studied. The blanched slices (with thicknesses of 3, 5 and 7 mm) were dried at drying temperatures of 50, 60 and 70 °C and air flow rates of 1, 1.5 and 2 m/s. The analytical model proposed by Dincer and Dost was used to determine the mass transfer parameters. The obtained Biot numbers (0.108‒0.293) revealed that both the internal and external resistance control the moisture diffusion within the samples. The moisture diffusivity and convective mass transfer coefficient were found to be in the ranges of 1.578×10-7‒7.331×10-7 m2/s and 2.040×10-5‒3.507×10-5 m/s, respectively. The activation energies for moisture diffusion and surface mass evaporation were determined to be in the ranges of 17.607 to 48.019 kJ/mol and 5.270 to 27.430 kJ/mol, respectively.

Mass Transfer Parameters and Modeling of Hot Air Drying Kinetics of Dill Leaves

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Hosain Darvishi ◽  
Zanyar Farhudi ◽  
Nasser Behroozi-Khazaei
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Moisture Content ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Transfer Model ◽  
Hot Air ◽  
Drying Behavior ◽  
Kinetics Of ◽  
Best Fit

Abstract Moisture diffusivity (Dem), mass transfer coefficient (hm), activation energy and drying kinetics of the dill leaves were studied and modeled as a function of temperature (40–70 °C) and moisture content (0.20–5.67 kg water/kg dry matter). Results showed that the Dem and hm significantly depend on the temperature and moisture content (p < 0.05). The average of Dem and hm varied between 4.02 × 10–9 to 9.65 × 10–9 m2/s, and 2.38 × 10–7 to 6.33 × 10–7 m/s, respectively. Activation energy showed a significant dependence on the moisture content and estimated as 16.84 kJ/mol for diffusion model and 28.70 kJ/mol for mass transfer model. Out of the six models considered, the logarithmic model showed the best fit to drying behavior of the dill leaves.

Modeling Thin Layer Drying Kinetics, Moisture Diffusivity and Activation Energy of Hazelnuts during Microwave-Convective Drying

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Narjes Malekjani ◽  
Zahra Emam-Djomeh ◽  
Seyed Hassan Hashemabadi ◽  
Gholam Reza Askari
Keyword(s):  
Activation Energy ◽  
Microwave Power ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Drying Method ◽  
Drying Process ◽  
Dominant Effect ◽  
Thin Layer Drying ◽  
Kinetics Of

AbstractThe effects of microwave-convective drying as an efficient drying method, on drying kinetics of hazelnuts were studied. Drying experiments were conducted at three temperature (40, 50 and 60°C) and microwave power (0, 450 and 900 W) levels. The moisture ratio and the temperature of the hazelnuts were recorded during the drying. The results showed that microwave power had a more dominant effect than drying air temperature. Mathematical modeling was performed in order to predict the moisture changes during drying process. It was concluded that two term and Midilli et al. models were the best models to predict the drying kinetics of hazelnut in different conditions. The effective moisture diffusivities varied from 3.80327×10‒8to 1.71233×10‒6m2/s and had an increasing polynomial relationship with temperature and microwave power. The activation energy was also between 15.61675 and 41.0053 kJ/mol with a second-order relationship with microwave power.

scholarly journals Effect of Temperature and Microwave Power Levels on Microwave Drying Kinetics of Zhaotong Lignite

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 74 ◽  
Author(s):  
Pengfei Zhao ◽  
Chenhui Liu ◽  
Wenwen Qu ◽  
Zhixiu He ◽  
Jiyun Gao ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thin Layer ◽  
Apparent Activation Energy ◽  
Microwave Power ◽  
Microwave Drying ◽  
Hot Air Drying ◽  
Air Drying ◽  
Hot Air ◽  
Thin Layer Drying ◽  
Rate Period

Microwave drying is a promising and effective way to drying and upgrading lignite. The influence of temperature (100–140 °C) and microwave power levels (500–800 W) on thin-layer drying characteristics of Zhaotong lignite under microwave irradiation were investigated. Fourteen thin-layer drying models were used to analyze the microwave drying process while six thin-layer drying models were used to analyze the hot-air drying process. The microwave drying processes at all temperature (100–140 °C) or low microwave power levels (500–700 W) exhibited four periods: a warm-up period, a short constant period, the first and second falling rate period, while one falling rate period was found during hot-air drying. The effective diffusion coefficient of lignite were calculated and it increases with increasing temperature and microwave power levels. During microwave drying, the two-term exponential model is the most suitable model for all applied conditions, while the Modified Page model is the most suitable model to describe the hot-air drying experiments. The apparent activation energy were determined from Arrhenius equation and the values for the first and second falling rate period are 3.349 and 20.808 kJ·mol−1 at different temperatures, while they are 13.455 and 19.580 W·g−1 at different microwave power levels. This implies the apparent activation energy is higher during the second falling rate period, which suggest that the dewatering of absorbed water is more difficult than capillary water. The value of apparent activation energy in hot-air drying is between the first and second falling rate period of microwave drying. Results indicate that microwave drying is more suitable to dewatering free water and capillary water of lignite.

scholarly journals Temperature, microwave power and pomace thickness impact on the drying kinetics and quality of carrot pomace

2019 ◽  
Vol 50 (1) ◽  
pp. 28-37
Author(s):  
Ernest Ekow Abano ◽  
Robert Sarpong Amoah ◽  
Eugene Kwabena Opoku
Keyword(s):  
Activation Energy ◽  
Ascorbic Acid ◽  
Air Temperature ◽  
Microwave Power ◽  
Moisture Diffusivity ◽  
Sample Thickness ◽  
Microwave Drying ◽  
Drying Time ◽  
Air Drying

This study investigated the effect of air temperature, microwave power, and pomace thickness on the drying kinetics and quality of dried carrot pomace. The study established that the drying of carrot pomace occurs in the falling rate period, suggesting that drying was driven by molecular diffusion. The microwave-drying moisture diffusivity increased with microwave power and ranged between 1.57×10–8 and 2.61×10–8 m2/s. As regards convective air-drying, the moisture diffusivity values were between 3.38×10–10 and 8.27×10–10 m2/s. The microwave powerto-mass activation energy was 15.079 W/g for 5 mm, 7.599 W/g for 10 mm and 9.542 W/g for 15 mm dried samples. Meanwhile, the temperature-dependent activation energy for carrot pomace was found to be 27.637 kJ/mol for 5 mm, 17.92 kJ/mol for 10 mm and 38.76 kJ/mol for 15 mm thickness pomace. Generally, drying time decreased with increasing microwave power or air temperature. The ascorbic acid content of the fresh carrot pomace reduced after both microwave and convective air-drying. However, microwave power, and sample thickness had significant effect on the β-carotene content of dried products but air temperature did not have a significant effect. The effect of temperature and sample thickness on brown pigment formation was substantial with air temperature compared to microwave. The study has demonstrated that microwave drying, compared to conventional drying, enhances moisture removal, drying time, and preservation of carotenoids and ascorbic acid. Therefore, microwave drying can be considered as an alternative method for obtaining quality dried carrot pomace.

Thin Layer Modelling of Microwave-Convective Drying of Tomato Slices

2013 ◽  
Vol 9 (1) ◽  
pp. 75-90 ◽  
Author(s):  
Tilahun S. Workneh ◽  
Moruf O. Oke
Keyword(s):  
Activation Energy ◽  
Thin Layer ◽  
Microwave Power ◽  
Hot Air Drying ◽  
Air Drying ◽  
Hot Air ◽  
Thin Layer Drying ◽  
Rate Period ◽  
Air Ventilation ◽  
Best Fit

AbstractThe thin layer drying behaviour of tomato slices dried using microwave power densities of 1.13, 2.08 and 3.11 W/g combined with air ventilation (50°C) and hot air drying at 40, 50, 70 and 80°C was investigated. The tomato slice dried faster when subjected to microwave heating coupled with hot air ventilation. Drying time decreased considerably with increase in microwave power density and with increase in hot air temperature. Drying took place in a constant rate period followed by the falling rate period after a short heating period. The drying data were fitted to Newton (Lewis), Page, Henderson and Pabis, Logarithmic, Wang and Singh and Parabolic equations. The Parabolic model (R2 = 0.9999; χ2 = 0.0085; MBE = 0.0182 and RMSE = 0.0691) gave the best fit to predict the hot air ventilation drying of tomato slices while the Logarithmic model (R2 = 0.9951; χ2 = 0.0024; MBE = −0.0319 and RMSE = 0.0477) gave the best fit for microwave-assisted hot air drying of tomato slices. The values of the effective diffusivity coefficients of the tomato slices varied between 1.68 × 10–9 and 5.22 × 10–8 m2/s while the activation energy was 27.09 kJ/mol. The lower activation energy indicates that drying of tomato slices requires less energy and is hence a cost and energy-saving method. Microwave drying at 1.13 and 2.08 W/g maintained superior colour quality of the tomato slices.

scholarly journals Determining of moisture diffusivity and activation energy in drying of apricots

2009 ◽  
Vol 55 (No. 3) ◽  
pp. 114-120 ◽  
Author(s):  
E. Mirzaee ◽  
S. Rafiee ◽  
A. Keyhani ◽  
Z. Emam-Djomeh
Keyword(s):  
Activation Energy ◽  
Moisture Diffusivity ◽  
Second Law ◽  
Drying Rate ◽  
Air Velocity ◽  
Air Temperatures ◽  
Rate Period ◽  
Drying Curves

In this study, Fick’s second law was used as a major equation to calculate the moisture diffusivity for apricot fruit with some simplification. Drying experiments were carried out at the air temperatures of 40, 50, 60, 70, and 80°C and the drying air velocity of 1, 1.5 and 2 m/s. The experimental drying curves showed only a falling drying rate period. The calculated value of the moisture diffusivity varied from 1.7 × 10<sup>–10</sup> to 1.15 × 10<sup>–9</sup> m<sup>2</sup>/s for apricot fruit, and the value of activation energy ranged from 29.35 to 33.78 kJ/mol at different velocities of air.

scholarly journals Vitis Labrusca L. Tipi Üzümün Mikrodalga Metodu ile Kurutma Kinetiğinin İncelenmesi

2019 ◽  
Vol 7 (4) ◽  
pp. 631
Author(s):  
Azmi Seyhun Kipcak ◽  
Berrin Saygi Yalcin
Keyword(s):  
Activation Energy ◽  
Microwave Power ◽  
Diffusion Coefficients ◽  
Moisture Diffusion ◽  
Vitis Labrusca ◽  
Drying Characteristics ◽  
Consumption Values ◽  
Effective Moisture ◽  
Rate Period ◽  
Drying Models

Vitis labrusca L. grape (Isabella Grape) is among the grape types that are consumed frequently in the world. Dry fruits are used frequently as snacks for people who work hard and in diet especially during the recent years compared to wet fruits. In this study, the drying characteristics of Vitis labrusca L. are investigated with using different microwave power levels. Mathematical modeling of drying is studied by using the drying models frequently used in the literature. By using spherical coordinates effective moisture diffusion coefficients and activation energy are calculated. Vitis labrusca L. are dried at 20, 6 and 2 minutes with 90, 180 and 360 W power levels, respectively. The best drying model was determined as Alibas and R2, , and root mean square error (RMSE) values were calculated between 0.999398 - 0.999715, 0.000182 - 0.000169, 0.010589 - 0.008675 respectively. Vitis labrusca L. are generally dried in a falling- rate period. Effective moisture diffusion coefficients were calculated between 2.11×10-7 - 6.61×10-8 m2/s and the activation energy were calculated as 75.464 kW/kg. Energy consumption values were determined as 108, 64.8 ve 43.2 kJ at the microwave power levels of 90, 180 and 360 W, respectively.

scholarly journals Impact of Binary Chemical Reaction and Activation Energy on Heat and Mass Transfer of Marangoni Driven Boundary Layer Flow of a Non-Newtonian Nanofluid

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 702
Author(s):  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Anigere Marikempaiah Jyothi ◽  
Ballajja Chandrappa Prasannakumara ◽  
Ioannis E. Sarris
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Boundary Layer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Velocity Gradient ◽  
Boundary Layer Flow ◽  
Biological Fluids ◽  
Porosity Parameter ◽  
Layer Flow

The flow and heat transfer of non-Newtonian nanofluids has an extensive range of applications in oceanography, the cooling of metallic plates, melt-spinning, the movement of biological fluids, heat exchangers technology, coating and suspensions. In view of these applications, we studied the steady Marangoni driven boundary layer flow, heat and mass transfer characteristics of a nanofluid. A non-Newtonian second-grade liquid model is used to deliberate the effect of activation energy on the chemically reactive non-Newtonian nanofluid. By applying suitable similarity transformations, the system of governing equations is transformed into a set of ordinary differential equations. These reduced equations are tackled numerically using the Runge–Kutta–Fehlberg fourth-fifth order (RKF-45) method. The velocity, concentration, thermal fields and rate of heat transfer are explored for the embedded non-dimensional parameters graphically. Our results revealed that the escalating values of the Marangoni number improve the velocity gradient and reduce the heat transfer. As the values of the porosity parameter increase, the velocity gradient is reduced and the heat transfer is improved. Finally, the Nusselt number is found to decline as the porosity parameter increases.

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