Conversion of Alkoxide Solutions to Oxides: Evaporation of Products

1989 ◽  
Vol 155 ◽  
Author(s):  
R. A. Lipeles ◽  
D. J. Coleman
Keyword(s):  
High Flow ◽  
Drying Rate ◽  
Flow Rates ◽  
Long Time ◽  
Drying Rates ◽  
Drying Conditions ◽  
Kinetics Of ◽  
By Products ◽  
Evaporation Kinetics ◽  
Kinetics Monitoring

ABSTRACTThe evaporation of organic by-products released during drying of 1-mm thick silicon tetramethoxide gels was analyzed using gas chromatography. The evaporation kinetics of methanol depended on the drying rate achieved by flowing dry air over the gel. For drying at flow rates less than 50 cm 3/min, exponential kinetics were observed initially with a long time constant (about 100- to 400-min). For drying rates greater than 70 cm3/min, diffusional (t−1/2) kinetics were observed initially. Cracking of the gel during drying was used to indicate the degree of stress. At low drying rates, minor cracking was observed near the edges of the gel. At high flow rates, extensive cracking was observed in samples that exhibited early t−1/2 kinetics. Monitoring the kinetics of drying is essential to optimizing the drying conditions to minimize stress and cracking in gels.

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.

Effect of Drying on Degradation kinetics of carotenoids and color of tomato pulp

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Indu Parmar ◽  
Gurpreet Kaur Chandi ◽  
Kalika Gupta ◽  
Balmeet Singh Gill
Keyword(s):  
Rate Constant ◽  
Color Change ◽  
Degradation Kinetics ◽  
Drying Rate ◽  
Drying Temperature ◽  
Hot Air ◽  
Visual Color ◽  
Tomato Pulp ◽  
Drying Conditions ◽  
Kinetics Of

Abstract Tomato pulp was dried under various drying conditions using hot air oven (65-950C), and cabinet drier (65-950C). The drying rate constant increased with increase in drying temperature. Among different combinations of Hunter L, a and b parameters, L*a could be used to describe the visual color change in tomato pulp during dehudration process.

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 Influence of the temperature and ultrasound application in drying kinetics of apple skin

2018 ◽  
Author(s):  
Juan A. Cárcel ◽  
Matheus P. Martins ◽  
Edgar J. Cortés ◽  
Carmen Rosselló ◽  
Ramón Peña
Keyword(s):  
Physical Structure ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Drying Time ◽  
Different Temperatures ◽  
Ultrasound Application ◽  
Quality Of Products ◽  
Drying Conditions ◽  
Kinetics Of ◽  
By Products

The great amount of waste produced by food industry contains interesting bioactive compounds. The extraction of these compounds requires the by-products previous stabilization being the convective drying one of most used techniques to this end. Drying conditions can affect both drying kinetics and final quality of products. The apple skin, byproduct of apple juice or cider industries, is rich in functional compounds such as polyphenols or vitamin C. The main goal of this contribution was to quantify the influence of temperature and ultrasound application in drying kinetics of apple skin. For this purpose, drying experiments at different temperatures (-10, 30, 50 and 70 ºC) and with (20.5 kW/m3) and without application of ultrasound were carried out. Drying kinetics were modelled by using a diffusion based model. As can be expected, the higher the temperature the faster the drying. Ultrasound application accelerated the process at every temperature tested being the influence slightly lower than found from the literature for other products. This can be attributed at the physical structure of the apple skin, less porous than the pulp. In any case, the application of ultrasound significantly reduced the drying time. Keywords: by-products; dehydration;diffusivity; mass transfer

scholarly journals Kinetika Pengeringan Cabai dengan Perlakuan Blansing Suhu Rendah-Waktu Lama

2021 ◽  
Vol 10 (1) ◽  
pp. 24-35
Author(s):  
Andi Muhammad Irfan ◽  
Nunik Lestari ◽  
Arimansyah Arimansyah ◽  
A Ramli Rasyid
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Drying Rate ◽  
Suitable Model ◽  
Drying Time ◽  
Drying Characteristics ◽  
High Temperature Short Time ◽  
Long Time ◽  
Short Time ◽  
Kinetics Of

This study was aimed to determine the drying kinetics of chilies that have been pretreated with low temperature long time (LTLT) blanching. Drying chilies with LTLT blanching pretreatment at 60, 70, and 80 oC for 20 minutes was assigned as treatment in this research. Drying chillies with high temperature short time (HTST) blanching pretreatment, without blanching pretreatment in the dryer, and without blanching pretreatment in direct sunlight were also studied as the comparison. The results showed that chilies treated with blanching pretreatment, both LTLT and HTST, have a faster drying rate and achieve the target moisture content faster than chilies that were not blanched. The color of dried chilies that were dried in a dryer was also better than dried chilies that were dried in the sun. Of all the blanching treatments, chilies with LTLT blanching pretreatment at 80 oC for 20 minutes had the fastest drying rate, a drying time of 34 hours, and the attractive dried chilli color. The evaluation results also showed that the Page model was the most suitable model to describe the drying characteristics of chilies with LTLT pretreatment blanching, with R2 ranging from 0.9913-0.9935, X2 ranging from 0.0005-0.0009, and RSME ranging from 0.0221-0.0293. Keywords: Chili; blanching; color; drying; mathematical model   ABSTRAK Penelitian ini bertujuan untuk mengetahui kinetika pengeringan cabai yang diberi perlakuan awal low temperature long time (LTLT) blanching atau blansing pada suhu rendah dalam waktu yang relatif lama. Perlakuan pada penelitian ini yaitu pengeringan cabai dengan blansing metode LTLT pada suhu 60o, 70o, dan 80oC selama 20 menit. Sebagai pembanding, dilakukan juga pengeringan dengan perlakuan awal metode high temperature short time (HTST) blanching, pengeringan cabai tanpa perlakuan awal blansing di dalam alat pengering, serta pengeringan cabai tanpa perlakuan awal blansing di bawah sinar matahari secara langsung. Hasil penelitian menunjukkan bahwa cabai dengan perlakuan awal blansing, baik blansing metode LTLT maupun HTST, memiliki laju pengeringan yang lebih tinggi sehingga lebih cepat mencapai kadar air target dibandingkan dengan cabai tanpa perlakuan blansing. Warna cabai kering yang dihasilkan pada alat pengering juga lebih baik dari cabai kering yang dikeringkan langsung di bawah sinar matahari. Dari seluruh perlakuan yang melibatkan proses blansing, cabai dengan blansing metode LTLT pada suhu 80oC selama 20 menit merupakan perlakuan dengan laju pengeringan tercepat, dengan waktu pengeringan selama 34 jam, dan warna produk cabai kering yang menarik. Hasil evaluasi juga menunjukkan bahwa model Page adalah model yang paling sesuai untuk menggambarkan karakteristik pengeringan cabai dengan perlakuan awal blansing metode LTLT, dengan R2 berkisar antara 0.9913-0.9935, X2 berkisar antara 0.0005-0.0009, dan RSME berkisar antara 0.0221-0.0293. Kata kunci: Blansing; cabai; model matematika; pengeringan; warna

scholarly journals A Mathematical Model for Dehydration by Successive Pressure Drops: Simulation of Discarded Potatoes Dehydration

2021 ◽  
Vol 8 (2) ◽  
pp. 26-39
Author(s):  
Sebastian Gutierrez-Pacheco ◽  
Joahnn H Palacios ◽  
Alfonso Parra-Coronado ◽  
Stéphane Godbout
Keyword(s):  
Pressure Drop ◽  
Drying Kinetics ◽  
Operating Conditions ◽  
Thin Layers ◽  
Drying Rate ◽  
Pressure Drops ◽  
Mathematical Simulations ◽  
Kinetics Of ◽  
By Products ◽  
Selection Of

Dehydration by Successive Pressure Drops (SPD) is a process with high potential for treating heat-sensitive materials; this includes agro-industry by-products. However, the response of drying kinetics to operating conditions of SPD is not fully understood. The present manuscript refers to mathematical simulations to describe drying kinetics of discarded potatoes using SPD. While there are numerous theoretical, semi-theorical and empirical mathematical models, the selection of the appropriate model is a rigorous process. In this paper, the Thompson thin-layer semi-theoretical model was chosen since the assumptions for this model (e.g., product is arranged in thin layers) are fulfilled for the SPD. As a result of mathematical simulation, it was possible to describe the drying kinetics in terms of the major parameters of SPD namely pressurizing level (Pa) and the Frequency of Pressure Drop (FPD). The dehydration by SPD allows the removal of water from the material, mainly at the pressure drop. If this stage occurs more frequently, the drying rate increases. The model developed describes at less 91% of the variability of the experimental data. It is recommended to use high FPD and Pa equals to 0.50 MPa.

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.

Kinetics of Platelet Adhesion to Protein-Coated Surface in Whole Blood Samples at High Flow Rates

2020 ◽  
Vol 169 (2) ◽  
pp. 229-232
Author(s):  
Yu. N. Avtaeva ◽  
I. S. Mel’nikov ◽  
S. D. Okhota ◽  
N. I. Zozulya ◽  
Z. A. Gabbasov
Keyword(s):  
Whole Blood ◽  
Platelet Adhesion ◽  
High Flow ◽  
Flow Rates ◽  
Blood Samples ◽  
Coated Surface ◽  
Whole Blood Samples ◽  
Kinetics Of

scholarly journals DESIGN OF KEMPLANG CRACKERS DRYER USING TRAY DRYER BY UTILIZING BIOMASS ENERGY

2021 ◽  
Vol 14 (1) ◽  
pp. 26-34
Author(s):  
Della Yusfita Sari ◽  
Mustain Zamhari ◽  
Robert Junaidi
Keyword(s):  
Heat Energy ◽  
Biomass Energy ◽  
Drying Rate ◽  
Drying Process ◽  
Air Velocity ◽  
Long Time ◽  
Conventional Drying ◽  
Coconut Shells ◽  
Drying Conditions

The drying process on kemplang crackers is one of the factors that determine the quality of the resulting product. Conventional drying has many disadvantages, namely fluctuating heat and poor hygiene that will affect product quality. So that kemplang crackers can be stored for a long time, it is necessary to reduce the water content of kemplang crackers. Drying kemplang crackers can use a drying rack with a biomass energy source from coconut shells. This study aims to design a tray dryer with biomass energy to obtain dryer performance based on the drying rate and to obtain a product that meets SNI No. 8272-2016. The treatments that were varied were set point temperatures of 55oC, 60oC, 65oC, and 70oC with mass variations of 50 gr, 100 gr, and 150 gr. The results showed that the optimum drying conditions at 70oC for 4 hours with an air velocity of 5.2 m/s2 obtained 9,84% moisture content in 50 gr kemplang crackers, 15.39% in 100 gr crackers and 19,2 in kemplang crackers 150 gr and a drying rate of 0,035028 kg/hour m2. The drying process requires 5,24 kg of dried coconut shell to produce heat energy of 95.358,81024 KJ with a by-product in the form of liquid smoke.

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.

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