An analytical model for internal moisture content during the decreasing drying rate period

AIChE Journal ◽  
2008 ◽  
Vol 54 (2) ◽  
pp. 475-486 ◽  
Author(s):  
L. Derdour ◽  
H. Desmorieux
Keyword(s):  
Moisture Content ◽  
Analytical Model ◽  
Drying Rate ◽  
Rate Period

Forced Convective Drying of a Porous Cube: Non-Intrusive Temperature and Mass Transfer Measurements

2014 ◽  
Author(s):  
Eoin Fanning ◽  
Tim Persoons ◽  
Darina B. Murray
Keyword(s):  
Mass Transfer ◽  
Temperature Distribution ◽  
Moisture Content ◽  
Surface Temperature ◽  
Convective Drying ◽  
Drying Rate ◽  
Local Surface ◽  
Number Range ◽  
Rate Period ◽  
Local Surface Temperature

The evolution of the mass transfer rate and temperature of a porous body in a convective drying process shows two main stages: A constant-drying rate period and a falling-drying rate period. This study investigates the simultaneous time evolution of moisture content and local surface temperature of a porous cube inside a rectangular flow channel for a range of air flow temperatures and Reynolds numbers. The moisture content is measured using a precision mass balance. Local surface temperature distribution is measured using a thermal imaging camera. In the constant-drying rate period, an average Nusselt number in the range 7.1 ≤ Nu ≤ 13.3 and an average Sherwood number of 4.7 ≤ Sh ≤ 6.0 are calculated for a Reynolds number range of 180 ≤ Re ≤ 595. Infrared thermography shows that the falling-drying rate period begins, the temperature distribution becomes non-uniform and approaches the temperature of the surroundings. This transition occurs first near the edges of the cube and, in particular, near the leading edge of the cube, as witnessed in previous studies.

scholarly journals Performance Analysis of Solar Assisted Fluidized Bed Dryer Integrated Biomass Furnace with and without Heat Pump for Drying of Paddy

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
M. Yahya
Keyword(s):  
Moisture Content ◽  
Fluidized Bed ◽  
Heat Pump ◽  
Specific Energy Consumption ◽  
Drying Rate ◽  
Fluidized Bed Dryer ◽  
Moisture Extraction ◽  
Rate Period ◽  
Drying Behaviour ◽  
Kinetics Of

The performances of a solar assisted fluidized bed dryer integrated biomass furnace (SA-FBDIBF) and a solar assisted heat pump fluidized bed dryer integrated biomass furnace (SAHP-FBDIBF) for drying of paddy have been evaluated, and also drying kinetics of paddy were determined. The SA-FBDIBF and the SAHP-FBDIBF were used to dry paddy from 11 kg with moisture content of 32.85% db to moisture content of 16.29% db (14% wb) under an air mass flow rate of 0.1037 kg/s within 29.73 minutes and 22.95 minutes, with average temperatures and relative humidities of 80.3°C and 80.9°C and 12.28% and 8.14%, respectively. The average drying rate, specific energy consumption, and specific moisture extraction rate were 0.043 kg/minute and 0.050 kg/minute, 5.454 kWh/kg and 4.763 kWh/kg, and 0.204 kg/kWh and 0.241 kg/kWh for SA-FBDIBF and SAHP-FBDIBF, respectively. In SA-FBDIBF and SAHP-FBDIBF, the dryer thermal efficiencies were average values of 12.28% and 15.44%; in addition, the pickup efficiencies were 33.55% and 43.84% on average, whereas the average solar and biomass fractions were 10.9% and 10.6% and 36.6% and 30.4% for SA-FBDIBF and SAHP-FBDIBF, respectively. The drying of paddy occurred in the falling rate period. The experimental dimensionless moisture content data were fitted to three mathematical models. Page’s model was found best to describe the drying behaviour of paddy.

Study on drying characteristics of chemical treated slit green chillies under hot air oven

2019 ◽  
Vol 4 (02) ◽  
pp. 229-232
Author(s):  
Ravi Kumar ◽  
Vivak Kumar ◽  
G. R. Singh ◽  
B. R. Singh ◽  
Samsher . ◽  
...  
Keyword(s):  
Moisture Content ◽  
Potassium Carbonate ◽  
Initial Moisture Content ◽  
Drying Rate ◽  
Humid Climate ◽  
Drying Characteristics ◽  
Hot Air ◽  
Rate Period ◽  
Different Temperatures ◽  
Potassium Carbonate Solution

Chilli (Capsicum annuum L.) is one of the important commercial crops of India. It is a crop of tropical and subtropical regions and requires a warm humid climate. Chilli is a highly perishable vegetable with a short shelf-life and commonly encounter postharvest problems; to deal such problems, drying was done using hot air oven. Three different temperatures (50, 60 and 70 °C) use in hot air oven. Before drying chillis were slitted and treated with Butylated Hydroxy Anisole and Potassium Carbonate solution. Overall drying rate increased with temperature in hot air oven. Drying of dipsol green chilli took place in falling rate period. Initial moisture content of the green chilli was an average of 84.20±1 % w. b.

Heat and Mass Transfer and Volume Variations during Drying of Industrial Ceramic Bricks: An Experimental Investigation

2012 ◽  
Vol 326-328 ◽  
pp. 267-272 ◽  
Author(s):  
J. Barbosa da Silva ◽  
G. Silva Almeida ◽  
Gelmires Araújo Neves ◽  
W.C.P. Barbosa de Lima ◽  
Severino Rodrigues de Farias Neto ◽  
...  
Keyword(s):  
Experimental Study ◽  
Moisture Content ◽  
Air Temperature ◽  
Atmospheric Pressure ◽  
Drying Rate ◽  
Drying Process ◽  
Air Velocity ◽  
Brick Clay ◽  
Constant Weight ◽  
Rate Period

The purpose of this paper is to present an experimental study of brick drying. For the drying experiments, industrial brick (clay) was dried in an oven under controlled conditions of air velocity, air temperature and air relative humidity. The continuous drying experiments ended when the mass reached constant weight. In order, to obtain the balanced moisture content, each sample was kept under the same drying air temperature for 48 hours inside the oven. The tests were performed under atmospheric pressure. Results of the drying and heating kinetics and volume variations during the process are shown and analyzed. It was verified that air temperature has big influence in the drying rate during process. It was verified that the largest temperature, moisture content and stress gradients are located in the vertexes of the brick. The drying process happens in the falling drying rate period.

CATFISH DRYING (Clarias Batraclus) USING ‘TEKO BERSAYAP’ SOLAR DRYER

2012 ◽  
Vol 2 (1) ◽  
pp. 14-20
Author(s):  
Yuwana Yuwana
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Ambient Temperature ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Time ◽  
Ambient Relative Humidity ◽  
Solar Dryer

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.

Effect of Pre-Treatment on the Drying Characteristics and Kinetics of Okra (Abelmoschus esculetus (L.) Moench) Slices

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Olajide Sobukola
Keyword(s):  
Air Temperature ◽  
Sample Thickness ◽  
Hot Water ◽  
Drying Rate ◽  
Diffusivity Coefficient ◽  
Drying Characteristics ◽  
Rate Period ◽  
Pretreatment Conditions ◽  
Air Dryer ◽  
Kinetics Of

The effects of air temperature (50, 60 and 70°C), sample thickness (2, 4 and 6mm) and pretreatment conditions (hot water blanching, 1 and 3% sodium metabisulphite solutions) on the drying characteristics and kinetics of okra were investigated using a convective hot air dryer at a flow rate of 1.5m/s. It was observed that pretreatment conditions, sample thickness and drying air temperature significantly (P<0.05) affected drying rate. Drying rate increases as temperature of drying air increases from 50 to 70°C. The drying curve for all experiments occurred in the falling rate period with no constant rate period. Three thin layer drying models (Page, modified Page I and Wang and Singh) were evaluated using coefficient of determination (R2), root mean square error (RMSE) and the reduced chi square (?2). The three models can appropriately describe the drying kinetics of okra slices considering the different experimental conditions. The effective diffusivity was determined using the Fick’s model and was observed to vary between 1.125x10-8 – 9.93x10-9m2/s and 1.165x10-8 – 7.131x10-9 m2/s for treated and untreated samples. The Arrhenius-type relationship describes the temperature dependence of diffusivity coefficient and was determined to be 16.749kJ/mol and 22.437kJ/mol for treated and untreated samples respectively.

Drying of Rough Rice in Oven: An Experimental Study

2015 ◽  
Vol 365 ◽  
pp. 77-81 ◽  
Author(s):  
J.V. Silva ◽  
E.M.A. Pereira ◽  
T.H.F. Andrade ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Experimental Study ◽  
Relative Humidity ◽  
Moisture Content ◽  
Product Quality ◽  
Air Temperature ◽  
Drying Rate ◽  
Rough Rice ◽  
Drying Conditions ◽  
Kinetics Of ◽  
Mechanical Movement

This paper aims to present an experimental study of rough rice (BRSMG CONAI cultivar) drying by using a stationary method. The grain was dried in an oven with air mechanical movement under controlled conditions of velocity, temperature and relative humidity. In order to obtain balanced moisture content, the samples studied were kept at 40 and 70°C. Results of the drying and heating kinetics of the grain during the process are shown and analyzed. It was found that higher drying rate and lower time for drying as higher air temperature (70°C) is used. It can be concluded that the reduction of the moisture content of the grain, is considered very complex and, depending on the method and drying conditions, can substantially provokes breaking and cracks, which reduces final product quality.

scholarly journals Effect of Supercritical CO2 Drying on Moisture Transfer and Wood Property of Eucalyptus urophydis

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1115
Author(s):  
Lin Yang ◽  
Honghai Liu
Keyword(s):  
Moisture Content ◽  
Supercritical Co2 ◽  
Moisture Transfer ◽  
Content Distribution ◽  
Wood Property ◽  
Drying Rate ◽  
Extractive Content ◽  
Moisture Content Distribution ◽  
Bordered Pits ◽  
Supercritical Co2 Drying

Wood dried using supercritical CO2 has unique properties because water is removed directly from the cell lumens through the cycling between supercritical and gas phases. Eucalyptus urophydis green wood was dried by supercritical CO2 at 50 °C and pressure of 10, 20, and 30 MPa; the effect of supercritical CO2 drying on moisture content distribution and transfer, as well as the permeability and extractive content of the wood, was investigated. The results showed that the supercritical CO2 drying rate was high, showing the highest drying rate at 20 MPa and the lowest at 10 MPa. Drying rate increased with pressure below 20 MPa in this study; drying rate represented no positive relation to pressure over 20 Mpa. Moisture content distribution was more uneven in the low-pressure drying conditions and in the middle transverse section of the specimens. The moisture content gradient in tangential was greater than that in longitudinal, especially for the drying of 10 MPa, indicating that water was removed mainly in the former direction of wood. More extractives were removed from wood at higher pressure during supercritical CO2 drying. Bordered pits were broken up more at higher pressure conditions. The decreased extract yields and increased amount of opened bordered pits increased the permeability of the wood after supercritical CO2 drying.

Impact of Wood Variability on the Drying Rate at Different Moisture Content Levels

2011 ◽  
Vol 61 (6) ◽  
pp. 435-442 ◽  
Author(s):  
Adin Berberović ◽  
Michael R. Milota
Keyword(s):  
Moisture Content ◽  
Drying Rate
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