The creep of wood destabilized by change in moisture content. Part 1: The creep behaviors of wood during and immediately after drying

Holzforschung ◽  
2004 ◽  
Vol 58 (3) ◽  
pp. 261-267 ◽  
Author(s):  
C. Takahashi ◽  
Y. Ishimaru ◽  
I. Iida ◽  
Y. Furuta
Keyword(s):  
Elastic Modulus ◽  
Relative Humidity ◽  
Moisture Content ◽  
Stable State ◽  
Unstable State ◽  
Drying Process ◽  
Temperature Creep ◽  
Long Time ◽  
Content Part

Abstract To better understand mechano-sorptive creep, creep behaviors were compared in wood samples during the drying process, immediately after drying, and after a long conditioning under constant humidity and temperature. Creep was greater in the sample tested immediately after drying than in the sample conditioned for a long time under relative humidity equal to that after drying, despite the fact that these samples had almost the same moisture content (MC). While the wood that has been moisture-conditioned for a long time is in a stable state, the wood tested immediately after the drying is presumed to be in an unstable state. Moreover, creep of the sample tested during the drying process was greater than that of the sample tested immediately after the drying. It has also been found that the instability decreased with time, indicating that stabilization and destabilization occur simultaneously during the drying process. In recent studies, a decrease in the elastic modulus and an increase in the fluidity of wood immediately after a change in MC or temperature have been reported. These findings are attributed to the instability caused by changes in MC or temperature. Based on the results of the present study and recent studies, we consider the increase in the fluidity of wood as the MC changes to be attributable to instability.

scholarly journals Drying of Sisal Fiber: A Numerical Analysis by Finite-Volumes

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2514
Author(s):  
Jacqueline F. B. Diniz ◽  
João M. P. Q. Delgado ◽  
Anderson F. Vilela ◽  
Ricardo S. Gomez ◽  
Arianne D. Viana ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Sisal Fiber ◽  
Moisture Removal ◽  
Drying Process ◽  
Porous Bed ◽  
Bed Porosity ◽  
Long Time ◽  
Sisal Fibers ◽  
Drying Conditions

Vegetable fibers have inspired studies in academia and industry, because of their good characteristics appropriated for many technological applications. Sisal fibers (Agave sisalana variety), when extracted from the leaf, are wet and must be dried to reduce moisture content, minimizing deterioration and degradation for long time. The control of the drying process plays an important role to guarantee maximum quality of the fibers related to mechanical strength and color. In this sense, this research aims to evaluate the drying of sisal fibers in an oven with mechanical air circulation. For this purpose, a transient and 3D mathematical model has been developed to predict moisture removal and heating of a fiber porous bed, and drying experiments were carried out at different drying conditions. The advanced model considers bed porosity, fiber and bed moisture, simultaneous heat and mass transfer, and heat transport due to conduction, convection and evaporation. Simulated drying and heating curves and the hygroscopic equilibrium moisture content of the sisal fibers are presented and compared with the experimental data, and good concordance was obtained. Results of moisture content and temperature distribution within the fiber porous bed are presented and discussed in details. It was observed that the moisture removal and temperature kinetics of the sisal fibers were affected by the temperature and relative humidity of the drying air, being more accentuated at higher temperature and lower relative humidity, and the drying process occurred in a falling 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.

Drying technology of mesquite pods (Prosopis laevigata) and microstructural insights

2020 ◽  
Vol 122 (9) ◽  
pp. 2953-2963
Author(s):  
Sadoth Sandoval Torres ◽  
Daniel Lopez Cravioto ◽  
Juan Rodríguez Ramírez ◽  
Lilia L. Méndez Lagunas ◽  
Luis Gerardo Barriada Bernal ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Food Industry ◽  
Characteristic Curve ◽  
Drying Process ◽  
Sem Images ◽  
Content Type ◽  
Milling Operation ◽  
Drying Technology ◽  
First Time

PurposeMesquite pods offer a high nutritional content; A flour can be produced from them; nevertheless, the moisture content makes the milling process difficult. Then, before the milling operation a drying process must be implemented, but drying technology must be studied in order to characterise the process and identify the effect of drying temperature on the magnitude of drying rate.Design/methodology/approachProsopis Laevigata pods were collected in Oaxaca (Southern of Mexico) and they were dried. Three stages of maturity were identified and pods in the stage three of maturity were dried by forced convection. The internal structure of the pods was analyzed by scanning electron microscopy (SEM). The pods were dried in a tunnel dryer at 40, 50, 60 and 70° C, 10% relative humidity and air velocity of 2.6 m/s. From experimental data, a lumped analysis was conducted for drying.FindingsWe found that the internal microstructure of this material is a limiting factor for moisture migration. In order to reduce the moisture content in the pods, a minimum air temperature of 60° C must be applied. The characteristic drying curve shows a good agreement with the experimental drying kinetics. The nutritional composition (carbohydrates, sugar and protein) of pods reveals important applications for the food industry.Practical implicationsThe mesquite pods are important ethnic foods. In order to obtain flour, the drying of pods is mandatory. Drying must be applied in stage three of maturity which can be identified based on color changes and moisture content. The moisture content affects the performance of milling operation, then a minimum drying temperature of 60° C and low relative humidity must be applied. SEM images show the complex microstructure of the pods which hinders the moisture diffusion. The drying characteristic curve was deduced for the first time; it helps to understand the drying behavior of pods. The chemical composition of mesquite pods reveals interesting applications for the food industry. The methodology for drying is useful for researchers and producers.Originality/valueMezquite pods is an interesting ethnic food for people with celiac disease. This is the first time a research paper describes the drying process at detail. The SEM images, the convective drying operation and the characteristic curve are presented for the first time. The information will be useful for the industry and academia.

scholarly journals Kajian Pengering Kopi Gayo Semi Basah Menggunakan Alat Pengering Tipe Hohenheim

2020 ◽  
Vol 4 (4) ◽  
pp. 362-371
Author(s):  
Antoni Hardi ◽  
Ichwana Ichwana ◽  
Rita Khathir
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Water Content ◽  
Drying Process ◽  
Arabica Coffee ◽  
Drying Temperature ◽  
Average Daily Temperature ◽  
Coffee Beans ◽  
Simple Technology

Abstrak. Sebagai produsen kopi Arabica, masyarakat Gayo terkendala pada suhu lokal di Aceh Tengah yang relatif dingin dan teknologi sederhana yang digunakan untuk proses pengeringan kopi. Suhu rata-rata harian adalah 23-29°C. Bahan yang digunakan pada penelitian ini yaitu biji kopi yang diolah dengan metode semi basah sebanyak 9kg. Parameter penelitian meliputi suhu pengeringan, kelembaban relatif, kadar air dan rendemen. Hasil penelitian menunjukkan bahwa suhu pengeringan menggunakan alat pengering Hohenheim jauh lebih tinggi sekitar 10-20°C dari suhu pengeringan secara penjemuran. Proses pengeringan kopi labu sampai bisa digiling membutuhkan waktu selama 12 jam yaitu 8 jam pada hari pertama dan 4 jam pada hari ke-2. Sedangkan proses pengeringan tahap 2 membutuhkan waktu selama 16 jam sampai menghasilkan kopi beras dengan kadar air 9,32%. Kualitas kopi beras yang dihasilkan sudah baik dengan kadar air  yang sudah memenuhi standar SNI, tidak berbau busuk, dan tidak terkontaminasi. Nilai rendemen kopi beras berbasis kopi labu adalah 35%.Study of Drying Semi Washed Gayo Coffee Use Dryer Type Hohenheim Abstrack. As an Arabica coffee producer, the Gayo community is constrained by the relatively cold local temperatures in Central Aceh and the simple technology used for the coffee drying process. The average daily temperature is 23-29 ° C. The material used in this study was coffee beans which were processed by the semi-wet method of 9kg. Research parameters include drying temperature, relative humidity, moisture content and yield. The results showed that the drying temperature using a Hohenheim dryer is much higher around 10-20 ° C than the drying temperature by drying. The process of drying pumpkin coffee until it can be ground needs 12 hours, which is 8 hours on the first day and 4 hours on the second day. While the process of drying stage 2 takes 16 hours to produce rice coffee with a moisture content of 9.32%. The quality of rice coffee produced is good with water content that meets SNI standards, does not smell bad, and is not contaminated. The yield of pumpkin coffee-based rice coffee is 35%.

A Proposed Method for Quantifying Thermal Exposure Incurred during Rough-Rice Drying

2021 ◽  
Vol 64 (2) ◽  
pp. 475-484
Author(s):  
Seth Graham-Acquaah ◽  
Terry J. Siebenmorgen
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Thermal Desorption ◽  
Thermal Exposure ◽  
Drying Process ◽  
Rough Rice ◽  
Thermal Sterilization ◽  
End Use ◽  
Rice Drying ◽  
Drying Conditions

HighlightsDrying conditions affect rice end-use functionality.Thermal exposure incurred by rough rice may differ depending on drying conditions.A framework is proposed for deriving an index that can show how much heat exposure rough rice incurs during drying.Abstract. Heated air is used to dry most rice in the U.S. Thus, commercial rice drying can be considered a thermal process that aims to remove moisture from rough rice until a desired moisture content is reached. Parallels can be drawn between rice drying and thermal sterilization that is targeted at reducing microbial load because moisture content reduction during drying follows similar decay rate kinetics as the reduction in microbial load during thermal sterilization. Given the different combinations of drying air conditions (air temperature and relative humidity), as well as drying and tempering durations, employed in various dryer designs for rice drying and the impact that these conditions have on rice end-use functionality, this study sought to derive a thermal treatment index (drying process values) that is similar to the F0 value concept used in thermal sterilization for quantifying and comparing the thermal exposure incurred by rice during drying under various scenarios. Using data collected from rough-rice drying experiments, a decimal desorption value (Dmv) that represents the duration required to cause a 90% reduction in moisture ratio during drying at a specified temperature was determined, from which a thermal desorption constant (Zmv) that represents the increase in temperature necessary to cause a 90% reduction in Dmv during drying was established. Subsequently, a thermal desorption value (Fmv) was derived to express the duration that a rice lot would have been heat treated at a reference temperature during drying to produce an equivalent effect on moisture content as that produced by the actual drying process. Keywords: End use, Moisture content, Peak viscosity, Postharvest, Relative humidity, Rice, Temperature.

scholarly journals Hygroscopicity of Longitudinally Compressed Wood

2017 ◽  
Vol 13 (2) ◽  
pp. 135-144 ◽  
Author(s):  
Mátyás Báder ◽  
Róbert Németh
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Beech Wood ◽  
Research Work ◽  
Modification Method ◽  
Vapour Adsorption ◽  
Long Time ◽  
The Difference ◽  
Compressed Wood ◽  
Control Samples

AbstractKnowledge of hygroscopicity is extremely important both in the use of native wood and modified wood. In this study, the modification method was steaming at 100 °C, then longitudinal compression at a rate of 20%. The moisture content (MC) of treated and untreated green beech wood (Fagus sylvaticaL.) was reduced in a climate chamber with gradual reduction of air humidity at 20 °C. The difference of calculated fibre saturation points between control samples and samples compressed for a long time was 6% (MC%). In the course of desorption, this difference decreased, and finally disappeared at 10% moisture content (40% relative humidity). In the second step of the research work, the speed of vapour adsorption was checked. The absolute dry samples were placed in air with 95% relative humidity. The highest deviation in the moisture content was 1% (MC%) between the control and the compressed samples. The compressed wood dries faster than the control samples under the same conditions. Furthermore, during adsorption, the moisture content of the compressed samples at room conditions is lower.

scholarly journals “TEKO BERSAYAP” MODEL SOLAR DRYER FOR FISH DRYING

2016 ◽  
Vol 6 (2) ◽  
pp. 51-56 ◽  
Author(s):  
Yuwana Yuwana ◽  
Bosman Sidebang ◽  
Evanila Silvia
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Ambient Temperature ◽  
The Sun ◽  
Drying Process ◽  
Drying Time ◽  
Sun Drying ◽  
Ambient Relative Humidity ◽  
Chamber Temperature ◽  
Drying Chamber

This objective of this research was to design a dryer called “Teko Bersayap” model and then to test its performance in drying fish in order to solve problems arising from open air sun drying. The dryer consisted of drying chamber with trays inside, heat collectors equipped with air inlets at their lower ends, chimney with an exhaust fan inside and humid air outlet at its upper end, was constructed to dry fish, “Bleberan (Pepetak Leiognatus spp)” species. The results of the experiment indicated that the dryer produced the drying chamber temperature 8.83oC higher than the ambient temperature and the relative humidity 13.91% lower than the ambient relative humidity. The fish moisture content decreased exponentially with drying time and the dryer completed the fish drying process in 18.9 hours compared to 27.6 hours of drying time needed to complete the sun drying for the fish, suggesting that the dryer was ready for utilization

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