Effect of Relative Humidity on Drying Kinetics of Agricultural Products

2014 ◽  
Vol 699 ◽  
pp. 257-262
Author(s):  
Sulastri Sabudin ◽  
Mohd Zairul Hakimi Remlee ◽  
Mohd Faizal Mohideen Batcha
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Energy Efficient ◽  
Human Population ◽  
Room Temperature ◽  
Food Preservation ◽  
Agricultural Products ◽  
Drying Behavior ◽  
Drying Rates ◽  
Kinetics Of

The demand for food has been ever increasing in proportion with the growing human population. This includes agricultural products including fruits. Hence, food preservation for extended usage through drying is gaining importance. This study reports the drying behavior of several agricultural products, namely sweet potato, carrot, ginger, turmeric, passion fruit and its rind. Focus has been given to the effect of relative humidity on drying for these products at room temperature. Experiments were carried out at 27°C by varying relative humidity at 40%, 60% and 80%. It was found that the relative humidity has a strong effect on drying, with lower relative humidity providing higher drying rates. In humid surrounding like Malaysia which has an average humidity more than 70%, controlling humidity of drying air may result in an energy efficient process in comparison to raising the drying air temperature

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 Drying kinetics of bananas by natural convection: Influence of temperature, shape, blanching and cultivar

2011 ◽  
Vol 35 (2) ◽  
pp. 368-376 ◽  
Author(s):  
Soraia Vilela Borges ◽  
Maurício C. Mancini ◽  
Jefferson Luiz Gomes Corrêa ◽  
Julia Benedito Leite
Keyword(s):  
Natural Convection ◽  
Exponential Model ◽  
Positive Influence ◽  
Drying Rate ◽  
Cylindrical Shape ◽  
Sample Shape ◽  
Drying Behavior ◽  
Drying Rates ◽  
Kinetics Of ◽  
Good Agreement

The influence of variables as temperature, solid shape, temperature, branching and cultivar on drying of bananas were studied. Bananas from cv. Prata and D'água, on disk and cylindrical shape, blanched or not, were dehydrated in a tray dryer in natural convection at 40 and 70ºC. Drying behavior was analyzed by using a mathematical model. The exponential model showed good agreement to experimental data (r² 0.93 - 0.99 and standard error: 0.01- 0.05). Temperature presented positive influence on drying rate in all the tested conditions. With respect to the sample shape, the disk shape carried out to significantly higher drying rates only for D'água cultivar without blanching. Blanching was significantly influent, with positive influence, on drying rate of banana cv. Prata at 40º C. The influence of the cultivar did not present a defined tendency.

scholarly journals An analysis of moist air energy potential during the process of paper band drying

2006 ◽  
Vol 60 (7-8) ◽  
pp. 188-194 ◽  
Author(s):  
Vladimir Valent ◽  
Milorad Krgovic ◽  
Srecko Nikolic
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Ventilation System ◽  
Specific Consumption ◽  
Moist Air ◽  
Energy Potential ◽  
Dry Air ◽  
Thermodynamic State ◽  
Flow Through ◽  
Kinetics Of

The energy potential of moist air venting from the dryer of the installation for drying paper bands was analyzed. The thermodynamic state of air is defined by the air temperature at the outlet of the dryer and the dew temperature of the air. For the temperature at the outlet of the dryer (55-85?C) and selected dew temperatures (45-65?C), the specific consumption of dry air was determined. For selected kinetics of paper band drying, 10-35 kgH2O/(m2h), the modification of energy potential of the air as a function of air temperature at the outlet of the dryer and the temperature of dew air was specified. The air flow through the dryer was also correlated with the operation of the ventilation system and recuperation of energy. An analysis of the thermodynamic state of moist air venting from the dryer and the calculation of its energy potential confirmed that increase of the dew temperature of the air decreases its energy potential. With the intensity of vaporization Ivm,isp = 10 kgH2O/(m2h), the decrease is 6%. With Ivm,isp = 35 kgH2O/(m2h), the decrease is much greater and amounts to 21.6%. With increasing dew temperature, the specific consumption of dry air decreases, as well as the relative humidity of the air.

Kinetical Investigations on Lamellar CalciumAluminateChromateHydrates with High Speed Detector

2004 ◽  
Vol 443-444 ◽  
pp. 299-302 ◽  
Author(s):  
J. Göske ◽  
U. König ◽  
Herbert Pöllmann
Keyword(s):  
Relative Humidity ◽  
High Speed ◽  
Room Temperature ◽  
Ordinary Portland Cement ◽  
Inorganic Ions ◽  
Hardening Process ◽  
Lamellar Phases ◽  
Interlayer Anion ◽  
Technical Features ◽  
Kinetics Of

Lamellar calciumaluminatehydrates are products of the hydration of ordinary Portland cement and play an important role in its hardening process. Due to the fixation ability of inorganic ions the technical features of this lamellar phases are important as reservoir minerals for pollutants (storage minerals). The lamellar calciumaluminatechromatehydrate Monochromate with the idealized formula C3A.Al2O3.CaCrO4.Ca(OH)2.nH2O has been investigated using a Philips Diffraction System X'Pert with the X'Celerator detector to measure the kinetics of the changes in interlayer dimensions in the lamellar calciumaluminatechromatehydrate at room temperature in air. A certain amount of water is weakly fixed in the interlayer depending on the interlayer anion, temperature and relative humidity of the atmosphere. Processes like ion exchange or water-loss in the interlayer cause a variation of the crystal dimension in c-direction. These "processes" can be very fast, therefore an ultra fast data collection and measurement times less than 2 minutes from 2° 2Θ to 70° 2Θ were essential.

scholarly journals Influence of Air Temperature and Humidity on Dehydration Equilibria and Kinetics of Theophylline

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Amira Touil ◽  
Roman Peczalski ◽  
Souad Timoumi ◽  
Fethi Zagrouba
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Solid Phase ◽  
Gravimetric Analysis ◽  
Dehydration Rate ◽  
Processing Times ◽  
Theophylline Monohydrate ◽  
Temperature And Humidity ◽  
Polymorphic Forms ◽  
Kinetics Of

The effect of hygrothermal conditions (air temperature and relative humidity) on the dehydration of theophylline monohydrate was investigated. Firstly, the equilibrium states of theophylline were investigated. The data from gravimetric analysis at constant temperature and humidity were reported as desorption isotherms. The PXRD analysis was used to identify the different polymorphic forms of theophylline: the monohydrate, the metastable anhydrate, and the stable anhydrate. Solid-solid phase diagrams for two processing times were proposed. Secondly, the dehydration kinetics were studied. The water content evolutions with time were recorded at several temperatures from 20°C to 80°C and several relative humidities from 4% to 50%. Different mathematical models were used to fit the experimental data. The spatially averaged solution of 2D Fickian transient diffusion equation best represented the water mass loss versus time experimental relationship. The dehydration rate constant was found to increase exponentially with air temperature and to decrease exponentially with air relative humidity.

scholarly journals The evaporation kinetics of pure water droplets at varying drying rates and the use of evaporation rates to infer the gas phase relative humidity

2018 ◽  
Vol 20 (36) ◽  
pp. 23453-23466 ◽  
Author(s):  
Yong-yang Su ◽  
Rachael E. H. Miles ◽  
Zhi-ming Li ◽  
Jonathan P. Reid ◽  
Jiang Xu
Keyword(s):  
Relative Humidity ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Pure Water ◽  
Analytical Models ◽  
Volatile Components ◽  
Water Droplets ◽  
Drying Rates ◽  
Kinetics Of ◽  
Evaporation Kinetics

Numerous analytical models have been applied to describe the evaporation/condensation kinetics of volatile components from aerosol particles for use in many applications.

scholarly journals THE EFFECT OF MICROWAVE OUTPUT POWER ON DRYING KINETICS OF YOGHURT AND MATHEMATICAL MODELING OF DRYING CURVES

2021 ◽  
Vol 51 (2) ◽  
pp. 127-131
Author(s):  
Ayşe Nur Yüksel
Keyword(s):  
Effective Diffusivity ◽  
Microwave Oven ◽  
Drying Kinetics ◽  
Layer Model ◽  
Domestic Microwave Oven ◽  
Drying Behavior ◽  
Drying Rates ◽  
Drying Curves ◽  
Kinetics Of

The objectives of this study were investigation the effects of microwave output powers on drying kinetics of yoghurt, selecting the best fitted thin-layer model to characterize the drying behavior of yoghurt and determination of the activation energy and effective diffusivity. In order to achieve these objectives, low-fat yoghurt was dried by using domestic microwave oven at different microwave output powers (100, 180 and 300 W). Average drying rates were determined as 1.49, 4.43 and 7.90 g H2O m-2 s-1 for microwave output powers of 100, 180 and 300 W, respectively. The effective moisture diffusivities were determined as 3.30 x 10-9, 6.62 x 10-9 and 1.15 x 10-8 m2 s-1 for 100, 180 and 300 W, respectively. The Ea of yoghurt was found as 3.62 W g-1. Midilli and others model was selected as best fitted model due to highest values of R2 and low values of χ2, RMSE and RSS.

scholarly journals Drying kinetics and effective diffusion of watermelon seeds

2020 ◽  
Vol 9 (4) ◽  
pp. e16942887
Author(s):  
Valdiney Cambuy Siqueira ◽  
Geraldo Acacio Mabasso ◽  
Wellytton Darci Quequeto ◽  
Caroline Ramos Da Silva ◽  
Elton Aparecido Siqueira Martins ◽  
...  
Keyword(s):  
Activation Energy ◽  
Citrullus Lanatus ◽  
Linear Regression Analysis ◽  
Effective Diffusion ◽  
Drying Kinetics ◽  
Air Velocity ◽  
Different Temperatures ◽  
Drying Behavior ◽  
Drying Rates ◽  
Kinetics Of

Studying the drying kinetics allows describing the process by mathematical models and obtaining information that helps to understand the phenomenon in question. Considering that watermelon (Citrullus lanatus) seeds have high moisture content and need to be subjected to drying, the objective was to select the model that best represents the drying behavior of watermelon seeds and determine the diffusion coefficient, activation energy and drying rate of these seeds at different temperatures. The seeds were dried in an experimental dryer at temperatures of 40, 45, 50, 55 and 60 °C, with air velocity of 0.8 m s-1, in four replicates. The models were fitted with non-linear regression analysis using the Gauss-Newton method. It was concluded that the models that best represent the drying kinetics of watermelon seeds are Approximation of Diffusion for temperatures of 40, 50 and 55 °C and Page for 55 and 60 °C. The highest drying rates are observed at the highest temperatures. The diffusion coefficients presented magnitude of 7.69684×10-10 and 1.27585×10-9 for the range from 40 to 60 °C, and the activation energy was 12.2641 kJ mol-1.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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