scholarly journals Moisture Diffusivity and Activation Energy Estimation of White Yam (Dioscorea rotundata) Slices Using Drying Data from a Refractance WindowTM Dryer

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Akinjide A Akinola ◽  
Stanley N Ezeorah
Keyword(s):  
Activation Energy ◽  
Moisture Diffusivity ◽  
Effective Moisture Diffusivity ◽  
Process Conditions ◽  
Time Data ◽  
Energy Estimation ◽  
Effective Moisture ◽  
White Yam ◽  
Different Temperatures ◽  
Modelling And Optimization

The objective of this study was to estimate the moisture diffusivity of different sizes of white yam slices at different temperatures using a Refractance WindowTM dryer. To achieve this objective, dehydration of 1.5, 3.0 and 4.5 mm thick yam slices was performed with water temperatures of 65, 75, 85 and 95 oC in the flume of a Refractance WindowTM dryer. Variation of moisture content with dehydration time data were obtained during the dehydration operations. The activation energies of dehydration for different sizes of yam slices were estimated for the temperatures considered. For the process conditions studied, the effective moisture diffusivities varied from 5.35 x 10-08 to 1.45 x 10-07 m2/s. The effective moisture diffusivity, Deff, at a specified temperature was observed to increase with increasing yam slice size. The effective moisture diffusivity, Deff, at a specified yam slice size is observed to increase with increasing dehydrating temperature. The activation energy, Ea, for the yam slices, ranged from 23.21 to 28.30 (kJ/mol) and it was observed to increase with increasing thickness of the yam slices. The activation energy values estimated were within the range observed for other equipment. This study is important in that, the moisture diffusivities and activation energy parameters estimated will be useful in the design, modelling, and optimization of such dryers. Keywords: Yams; Moisture Diffusivity; Activation Energy; Refractance WindowTM Dryer

scholarly journals Some Thermodynamic Properties of White Yam (Dioscorea rotundata) Slices Dehydrated in a Refractance WindowTM Dryer

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Akinjide A Akinola ◽  
Stanley N Ezeorah
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Moisture Content ◽  
Gibbs Free Energy ◽  
Moisture Diffusivity ◽  
Process Conditions ◽  
Dioscorea Rotundata ◽  
History Data ◽  
White Yam ◽  
Different Temperatures

The objective of this study is to estimate the changes in Enthalpy, Entropy and Gibbs Free Energy of yam slices dehydrated at different temperatures using a Refractance WindowTM dryer. Dehydration of 1.5, 3.0 and 4.5 mm thick yam slices, was performed with water temperatures of 65, 75, 85 and 95oC in the flume of a Refractance WindowTM dryer. During the dehydration operations, the moisture-content history data were recorded. For the process conditions considered, the moisture content history data was used to calculate the moisture diffusivity and the activation energy of dehydration of the samples. Subsequently, changes in Enthalpy, , Entropy, , and Gibbs Free Energy, ), were calculated. For the process conditions studied, the changes in, , , and, varied from 20,381.33 to 25,217.05 J.mol-1., -140.69 to -122.29 J.mol-1.K-1.and 67,934.80 to 70,220.15 J.mol-1, respectively. This study is essential as knowledge of these thermodynamic parameters are useful for the optimal design and sizing of preservation dryers for argo-products. Keywords— Enthalpy; Entropy; Gibbs Free Energy; Refractance WindowTM Dryer; Yam 

Modelling Effective Moisture Diffusivity of Pumpkin (Cucurbita moschata) Slices under Convective Hot Air Drying Condition

2016 ◽  
Vol 12 (5) ◽  
pp. 481-489 ◽  
Author(s):  
Daniel I. Onwude ◽  
Norhashila Hashim ◽  
Rimfiel B. Janius ◽  
Nazmi Nawi ◽  
Khalina Abdan
Keyword(s):  
Activation Energy ◽  
Moisture Diffusivity ◽  
Effective Moisture Diffusivity ◽  
Slice Thickness ◽  
Cucurbita Moschata ◽  
Drying Time ◽  
Hot Air ◽  
Effective Moisture ◽  
Shrinkage Effect ◽  
Increasing Temperature

Abstract This study seeks to investigate the effects of temperature (50, 60, 70 and 80 °C) and material thickness (3, 5 and 7 mm), on the drying characteristics of pumpkin (Cucurbita moschata). Experimental data were used to estimate the effective moisture diffusivities and activation energy of pumpkin by using solutions of Fick’s second law of diffusion or its simplified form. The calculated value of moisture diffusivity with and without shrinkage effect varied from a minimum of 1.942 × 10–8 m2/s to a maximum of 9.196 × 10–8 m2/s, while that of activation energy varied from 5.02158 to 32.14542 kJ/mol with temperature ranging from 50 to 80 °C and slice thickness of 3 to 7 mm at constant air velocity of 1.16 m/s, respectively. The results indicated that with increasing temperature, and reduction of slice thickness, the drying time was reduced by more than 30 %. The effective moisture diffusivity increased with an increase in drying temperature with or without shrinkage effect. An increase in the activation energy was observed due to an increase in the slice thickness of the pumpkin samples.

Effects of Blanching Methods on Drying Kinetics of Oyster Mushroom

2009 ◽  
Vol 5 (4) ◽  
Author(s):  
Brijesh Srivastava ◽  
K. Padmeshore Singh ◽  
Wungshim Zimik
Keyword(s):  
Moisture Diffusivity ◽  
Exponential Model ◽  
Hot Water ◽  
Effective Moisture Diffusivity ◽  
Oyster Mushroom ◽  
Model Parameters ◽  
Drying Rate ◽  
Drying Time ◽  
Effective Moisture ◽  
Different Temperatures

Oyster mushroom was treated with hot water and steam blanching prior to drying in cabinet dryer. A hot air cabinet dryer was used for drying mushroom at 40, 50, 60, 70 and 80°C temperatures. Solid loss was observed to be 25.46% and 3.32% (wb) during hot water and steam blanching, respectively. Highest drying rate was observed for hot water blanched mushroom followed by unblanched and steam blanched mushroom. This leads to more drying time for the steam blanched mushroom followed by the unblanched and hot water blanched mushroom for the same level of drying. The drying data was modeled for exponential and Page's drying model. Page's model was found to be better than the exponential model for the prediction of drying rate. The value of the model parameters of the exponential model was found to be higher than that of Page's model. The effective moisture diffusivity (De) was determined at different temperatures and found to be maximum for the hot water blanched mushroom and minimum for the steam blanched mushroom. The effective moisture diffusivity (De) increased with increase in temperature. The activation energy of hot water blanched, unblanched and steam blanched mushroom was estimated to be 25.324, 17.113 and 21.165 kJ/mol, respectively.

scholarly journals Determination of moisture diffusivity and activation energy on fixed bed drying of red pepper (Capsicum annum) on convective solar drying

2021 ◽  
Vol 4 (2) ◽  
pp. 110-116
Author(s):  
Siti Asmaniyah Mardiyani ◽  
Sumardi Hadi Sumarlan ◽  
Bambang Dwi Argo ◽  
Amin Setyo Leksono
Keyword(s):  
Activation Energy ◽  
Fixed Bed ◽  
Moisture Diffusivity ◽  
Effective Moisture Diffusivity ◽  
Red Pepper ◽  
Convective Drying ◽  
Energy Calculation ◽  
Solar Drying ◽  
Effective Moisture ◽  
Drying Behavior

Moisture diffusivity and activation energy are two important variables in a drying process to understand a certain product's drying behavior. This study aimed to determine the value of effective moisture diffusivity and the activation energy of red pepper in a conventional forced convective drying based on electricity (conventional convective drying/CCD) and forced convective drying based on solar energy (convective solar drying/CSD). The value of effective moisture diffusivity was determined using the equation, which refers to Fick’s second law. The Arrhenius equation determines the activation energy value as a model of the relationship of inverse temperature and the normal logarithmic value of effective moisture diffusivity. The results showed that the values of effective moisture diffusivity of CCD 70 °C were the highest. The regression analysis between the drying layers (X), and effective moisture diffusivity (Y) showed a polynomial pattern with a coefficient determination R2 value of 0.85 (CCD 70 °C), 0.81 (CCD 60 °C), 0.88 (CCD 50 °C), and 0.48 (CSD). (R2) The higher moisture diffusivity values in CCD indicated that the drying systems are more stable than CSD. The drying activation energy calculation showed that the value of CCD's activation energy was 36.36 kJ/mol.K, while the value of CSD's activation energy was 31.28 kJ/mol.K. Those results were consistent with the results of the previous studies.

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