Study on the Drying Mechanism and Dynamics of Palygorskite

2011 ◽  
Vol 422 ◽  
pp. 501-504
Author(s):  
Jiang Quan Ma ◽  
Qing Ling Lu ◽  
Jun Hao Xia ◽  
Xiao Bin Gan ◽  
Chao Yao
Keyword(s):  
Activation Energy ◽  
Environmental Protection ◽  
Drying Kinetics ◽  
Diffusion Activation Energy ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Curves ◽  
Kinetics Of ◽  
Diffusion Activation

Palygorskite had large applications in chemical, environmental protection, medicine processes and so on. However, since the mineral limitations of natural palygorskite, both improving its quality and meeting the need of industry, palygorskite usually needs to be activated before using it. The influences of activation during the drying process were studied, as well as the drying kinetics of the non-activated of palygorskite. The results showed that the drying rate of palygorskite increased at first, and then came to a constant value, and kept that value for some time. After that, drying rate decreased with time going. Compared with drying curves of the non activated palygorskite, the samples made some changes after activation. The drying process of non activated palygorskite could be described as the equation of MR=exp(-ktn). The diffusion activation energy (E) of non activated palygorskite was equal to 17.14kJ•mol-1, former factors of Arrhenius was equal to 4.19×10-5 m2•s-1.

Study on the Drying Mechanism and Dynamics of Palygorskite

2013 ◽  
Vol 706-708 ◽  
pp. 456-459
Author(s):  
Shi Long Wang ◽  
Li Na Wang
Keyword(s):  
Activation Energy ◽  
Environmental Protection ◽  
Drying Kinetics ◽  
Diffusion Activation Energy ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Curves ◽  
Kinetics Of ◽  
Diffusion Activation

Palygorskite had large applications in chemical, environmental protection, medicine processes and so on. However, since the mineral limitations of natural palygorskite, both improving its quality and meeting the need of industry, palygorskite usually needs to be activated before using it. The influences of activation during the drying process were studied, as well as the drying kinetics of the non-activated of palygorskite. The results showed that the drying rate of palygorskite increased at first，and then came to a constant value, and kept that value for some time. After that, drying rate decreased with time going. Compared with drying curves of the non activated palygorskite, the samples made some changes after activation. The drying process of non activated palygorskite could be described as the equation of MR=exp(-ktn).The diffusion activation energy (E) of non activated palygorskite was equal to 17.14kJ.mol-1, former factors of Arrhenius was equal to 4.19×10-5 m2.s-1.

Effect of Air Velocity and Temperature on the Drying Kinetics of Drumstick Leaves (Moringa Oleifera)

2012 ◽  
Vol 8 (4) ◽  
Author(s):  
Monica Premi ◽  
Harish Sharma ◽  
Ashutosh Upadhyay
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Moringa Oleifera ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Air Velocity ◽  
Drying Time ◽  
Effective Moisture ◽  
Kinetics Of

Abstract The present study examines the effect of air velocity on drying kinetics of the drumstick leaves in a forced convective dryer. The drumstick leaves were dried in the temperature range of 50–800 C, at different air velocity (Dv) of 0.5 and 1.3 m/s. The results indicated that drying temperature and air velocity are the factors in controlling the drying rate. Experimental data obtained for the samples for color, drying rate and drying time proved that air velocity of 1.3 m/s yielded the product superior in terms of both quality and energy efficiency as compared to the samples at 0.5 m/s. Activation energy for drumstick leaves dried with air velocity, 0.5 and 1.3 m/s was 12.50 and 32.74 kJ/mol respectively. The activation energy relates similarly with the effective moisture diffusivity which also increased with increase in air velocity and temperature.

scholarly journals Распад твердого раствора межузельного магния в кремнии

2019 ◽  
Vol 53 (3) ◽  
pp. 314
Author(s):  
В.Б. Шуман ◽  
А.Н. Лодыгин ◽  
Л.М. Порцель ◽  
А.А. Яковлева ◽  
Н.В. Абросимов ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Single Crystal ◽  
Diffusion Activation Energy ◽  
Practical Application ◽  
Float Zone ◽  
Sandwich Method ◽  
Kinetics Of ◽  
Diffusion Activation

AbstractThe decomposition of a solid solution of interstitial magnesium Mg_ i in silicon is studied. Float-Zone dislocation-free single-crystal n -Si with a resistivity of ~8 × 10^3 Ω cm and oxygen and carbon contents of ~5 × 10^14 cm^–3 and ~1 × 10^15 cm^–3 is used in the experiments. The samples are doped using the diffusion sandwich method at T =1100°C followed by quenching. Decomposition of the supersaturated Mg_ i solid solution is studied by observing the kinetics of increasing the resistivity of doped samples resulting from their annealing in the range T = 400–620°C. It is found that the decomposition is characterized by an activation energy of E _ a ≈ 1.6 eV, which is close to the previously determined diffusion activation energy of Mg_ i in silicon. It is also shown that Si:Mg exhibits stable properties at temperatures not exceeding 400°C, which is important for its possible practical application.

scholarly journals Effect of blanching methods on drying kinetics of bell pepper

2011 ◽  
Vol 11 (48) ◽  
pp. 5457-5474
Author(s):  
Toyosi Tunde - Akintunde ◽  
◽  
BO Akintunde ◽  
A Fagbeja ◽  
◽  
...  
Keyword(s):  
Palm Oil ◽  
Water Movement ◽  
Drying Kinetics ◽  
Bell Pepper ◽  
Drying Rate ◽  
Drying Process ◽  
Oil Water ◽  
Drying Rates ◽  
Kinetics Of

Various blanching methods and drying temperatures were applied to bell pepper (Capiscum annum) to investigate the effect on its drying characteristics. Pepper (Capiscum annum) is an abundant and cheap source of vitamins, minerals and fibre. However, its high moisture content makes it susceptible to deterioration. The most common method of preservation is drying but the dried products obtained are of reduced nutritional qualities. Pretreatment of pepper before drying improves the quality of the dried pepper and increases its drying rate. Steam and water blanching as a form of pretreatment has been reported to increase drying rate and improve the quality of dried products but there is not much information on other types of oil/water blanching methods. The effect of blanching (steam, water, palm oil/water and groundnut oil/water) as a pretreatment on the drying kinetics of bell pepper dried at temperatures of 50, 60, 70, 80 and 90o C, was studied. Drying of raw untreated bell pepper was taken as a control. The results indicate that water removal at the initial stage of the drying process was highest and there was a rapid decrease as drying continued until equilibrium was reached at the end of process. The blanched samples generally had higher drying rates (at p<0.05) than the untreated samples. The values for the drying rate for steam and water blanched samples were higher (but not at p<0.05) than the drying rates for samples blanched in oil/water mixtures. The drying rate as well as effective moisture diffusivity, Deff, increased with increasing drying temperature. Values of Deff varied from 3.55 x 10-9 m 2/s to 2.34 x 10-9 m 2/s with the highest being SB (steam blanched) at 80oC and the lowest UB (unblanched) at 50oC. The drying process took place mainly in the falling rate period. The activation energies varied from 39.59 to 83.87 kJ/mol, with PB (palm oil/water blanched) samples having the lowest and UB having the highest Ea value. The lower values for pretreated samples imply that water movement from the internal regions is faster in pretreated samples. This suggests that blanching as a method of pretreatment generally increases water diffusion.

scholarly journals Drying kinetics and effective diffusion of buckwheat grains

2020 ◽  
Vol 44 ◽  
Author(s):  
Valdiney Cambuy Siqueira ◽  
Rafael Araújo Leite ◽  
Geraldo Acácio Mabasso ◽  
Elton Aparecido Siqueira Martins ◽  
Wellytton Darci Quequeto ◽  
...  
Keyword(s):  
Effective Diffusion ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Linear Regression Method ◽  
Drying Process ◽  
Food Sector ◽  
Drying Time ◽  
Air Speed ◽  
Kinetics Of

ABSTRACT Buckwheat has become important in the food sector as its flour does not contain gluten. Since buckwheat is a relatively new crop in the agricultural environment, there is little information available regarding its processing. Drying is one of the most important post-harvest stages of buckwheat. The aim of the present study was to describe the drying process of buckwheat grains. Buckwheat grains with a moisture content of 0.41 ± 0.01 (dry basis, d.b.) were harvested, followed by drying in an experimental dryer at the temperatures of 40, 50, 60, 70, and 80 °C, at an air speed of 0.8 m s-1. The drying rate was determined, and the mathematical models generally employed to describe the drying process of several agricultural products were fitted to the experimentally obtained data. Model selection was based on the Gauss-Newton non-linear regression method and was complemented by Akaike Information Criterion and Schwarz’s Bayesian Information Criterion. It was concluded that the drying rate increased with an increase in temperature and decreased with an increase in drying time. It is recommended to use the Midilli model to represent the drying kinetics of buckwheat grains at the temperatures of 40, 60, and 70 °C, while the Approximation of diffusion model is recommended for the temperatures of 50 and 80 °C. The magnitudes of effective diffusion coefficients ranged from 1.8990 × 10-11 m2 s-1 to 17.8831 × 10-11 m2 s-1. The activation energy required to initiate the drying process was determined to be 49.75 kJ mol-1.

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 Study on drying kinetics of summer onion

2015 ◽  
Vol 39 (4) ◽  
pp. 661-673 ◽  
Author(s):  
Md Masud Alam ◽  
Md Nurul Islam ◽  
Md Nazrul Islam
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Rate Constant ◽  
Variable Temperature ◽  
Air Flow ◽  
Drying Kinetics ◽  
Effect Of Temperature ◽  
Drying Rate ◽  
External Resistance ◽  
Kinetics Of

The present study was concerned with the kinetics of drying of summer onion. Drying was done in a mechanical dryer at constant air flow using blanched and unblanched onion with variable temperature (52, 60 and 680C) and thickness (3, 5 and 7 mm). Drying rate was increased with increase of temperature and decreased with the increase in thickness in blanched and unblanched onion. Blanched onion showed higher drying rate than unblanched onion. Drying rate constant and thickness can be expressed as power low equations. The value of index “n” were found to be 1.277 and 0.845 for onion indicating that the external resistance to mass transfer was highly significant. The effect of temperature on diffusion co-efficient follows an Arrhenius type relationship. The activation energy (Ea) for diffusion of water was found 5.781 Kcal/g-mole for unblanched and 2.46 Kcal/g-mole for blanched onion when onions were dried in mechanical dryer. DOI: http://dx.doi.org/10.3329/bjar.v39i4.22545 Bangladesh J. Agril. Res. 39(4): 661-673, December 2014

scholarly journals Drying kinetics of mango fruit using tray and oven dryer

2020 ◽  
Vol 3 (2) ◽  
pp. 51
Author(s):  
Nurhasmanina Norhadi ◽  
Ammar Mohd Akhir ◽  
Nor Roslina Rosli ◽  
Farid Mulana
Keyword(s):  
Moisture Content ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Airflow Rate ◽  
Drying Process ◽  
Air Velocity ◽  
Mango Fruit ◽  
Drying Time ◽  
Different Temperatures ◽  
Kinetics Of

Drying is generally used to increase the shelf life of food products. In this context, mango fruit is used as a sample for the drying process because of its high commercial value and particularly high moisture content. The mango was sliced into few batches of sample with a size of 20 mm × 30 mm × 5 mm each. The experiments were conducted using tray and oven dryer at different temperatures of 40, 50 and 60 °C with a steady airflow rate of 1.3 m/s. The objectives are to study the effect of drying time, temperature and air velocity towards drying of mango fruit, to compare the physical characteristics of mango sample after drying and to determine the best drying kinetics model fitted to each tray and oven dryer. The results showed that the increase in drying time, temperature and air velocity would reduce the moisture content while at the same time, drying rate increased significantly. Tray dryer was found to be more effective than oven dryer because of higher drying rate with better product quality and appearance at the end. Furthermore, the gathered data were fitted into few widely used drying mathematical models and it was found that Henderson and Pabis model at 60°C is best suited for tray dryer whereas Page model at 40 °C is the best for oven dryer.

scholarly journals Experimental and statistical analysis research of the triticale grain drying process when countercurrent-direct-flow blowing of the grain layer

2021 ◽  
Vol 82 (4) ◽  
pp. 38-46
Author(s):  
T. N. Tertychnaya ◽  
A. A. Shevtsov ◽  
S. S. Kulikov
Keyword(s):  
Experimental Studies ◽  
Moisture Diffusion ◽  
Drying Rate ◽  
Drying Process ◽  
Grain Drying ◽  
Flow Through ◽  
Agent Flow ◽  
Drying Curves ◽  
Counter Current ◽  
Kinetics Of

Experimental studies of the kinetics of the process of drying triticale grain during counter-current-direct blowing of the grain layer were carried out. In the experimental installation, a programmed change in the direction of the drying agent flow through the grain layer was carried out and the actual conditions of the drying agent supply through the supply and discharge boxes of the shaft grain dryer were emitted. Analysis of drying curves and drying rate of triticale grain showed the presence of only a period of decreasing drying rate, in which the intensity of moisture diffusion is significantly less than the intensity of moisture exchange. The organization of the experiment made it possible to fully adapt it to industrial mine grain dryers, in which the drying process is carried out in a continuous mode. Based on the results of the study, an empirical model of the drying process is proposed in the form of an exponential function, which establishes a unique functional relationship between the current moisture of the grain and the main parameters of the process: temperature, speed, moisture content of the drying agent and the thickness of the blown layer. Taking into ac-count the requirements to the process modes of grain drying, the triticale analyzes the ratio between the grain temperature and its humidity at various values of the mode parameters, which is proposed to be used as a restriction on the drying temperature mode.

Drying Kinetics of Malaysian Paddy (Group D Particles) in Spouted Bed Dryer

2006 ◽  
Vol 2 (3) ◽  
Author(s):  
Pin Pin Ng ◽  
Chung Lim Law ◽  
Siti Masrinda Tasirin
Keyword(s):  
Draft Tube ◽  
Air Flow ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Spouted Bed ◽  
Bed Height ◽  
Internal Structures ◽  
Drying Curves ◽  
Group D ◽  
Kinetics Of

Spouted bed is suitable for drying of coarse particles which are Group D of Geldart’s particle classification. Malaysian grown paddy was used as a Group D sample in a lab-scale spouted bed dryer. Drying was carried out in two different internal structures of the dryer, namely with or without the installation of a draft tube, and at several drying temperatures, air flow rates as well as bed heights. Spouted bed drying kinetics of paddy presented in drying curves showed only induction and falling rate periods, without constant drying rate period. The highest drying rate was achieved when paddy was dried without draft tube at low bed height, high drying temperature and air flow rate.

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