Drying influence on the development of cracks in Eucalyptus logs

The aim of this study was to evaluate the effect of the moisture loss, diameter, and wood density on the appearance of surface cracks and end splits in Eucalyptus urophylla logs. The drying and emergence of defects were evaluated in 108 logs with diameters ranging from 60 mm to 150 mm from the initial moisture content to the equilibrium moisture content. The defects were measured during this time. Smaller diameter logs dried faster than larger diameter logs and took less time to reach the fiber saturation point. Surface cracks tended to develop during the loss of bound water. End splits developed during free water loss and continued to appear during bound water loss. Smaller diameters presented higher percentages of surface cracks compared with larger diameters, while larger diameters had a tendency for higher percentages of end splits compared with smaller diameters. The density did not influence the total emergence of end splits, but it did influence the total emergence of surface cracks, indicating a possibility for the selection of genetic material with lower tendency for cracking. Overall, the results reinforce the need to control drying at its beginning in order to decrease the risk of defects.

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Mode for hot air drying of alder blanks that retain the colour acquired during the steaming process

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0015.2379 ◽

2021 ◽

Vol 114 ◽

pp. 86-91

Author(s):

Ladislav Dzurenda

Keyword(s):

Moisture Content ◽

Initial Moisture Content ◽

Bound Water ◽

Free Water ◽

Hot Air Drying ◽

Air Drying ◽

Water Steam ◽

Color Changes ◽

Hot Air ◽

Relative Air Humidity

Mode for hot air drying of alder blanks that retain the colour acquired during the steaming process. The paper presents a hot-air mode for drying steamed alder in the form of blanks with dimensions: 38x100x800 mm from the initial moisture content W1 ≈ 50 % to the final moisture content W2 = 10%, while maintaining the colour of wood obtained in the process of steaming with saturated water steam. The drying process is divided into two parts: (I) evaporation of free water from wet wood at drying medium temperatures td = 35 - 40 °C and relative air humidity φ = 70 – 60%, when there are no chemical changes in the lignin-saccharide complex of alder wood manifested by a change in colour; (II) evaporation of bound water from alder wood below the hygroscopicity limit is performed at temperatures td = 60 - 80 °C. The color coordinates of steamed alder wood after drying by a given mode in the CIE L* a* b* colour space are: L* = 62.5 ± 1.7; a* = 13.1 ± 0.8; b* = 18.5 ± 0.9. Total colour difference ∆E = 1.6. According to the categorization of wood color changes in thermal processes of wood , this change belongs to small (insignificant) color changes.

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Moisture in softwoods: fiber saturation point, hydroxyl site content, and the amount of micropores as determined from NMR relaxation time distributions

Holzforschung ◽

10.1515/hf-2012-0057 ◽

2013 ◽

Vol 67 (3) ◽

pp. 291-300 ◽

Cited By ~ 46

Author(s):

Ville-Veikko Telkki ◽

Miikka Yliniemi ◽

Jukka Jokisaari

Keyword(s):

Melting Point ◽

Relaxation Times ◽

Bound Water ◽

Nmr Relaxation ◽

Free Water ◽

Bulk Water ◽

Fiber Saturation Point ◽

Saturation Point ◽

Fiber Saturation ◽

Nmr Relaxation Times

Abstract Distributions of nuclear magnetic resonance (NMR) relaxation times provide detailed information about the moisture absorbed in wood. In this work, T2*, T2, and T1 distributions were recorded from fresh sapwood and heartwood samples of pine (Pinus sylvestris) and spruce (Picea abies) at various temperatures. Below the melting point of bulk water, free water is frozen and its signal disappears from the distributions. Then, the low-temperature distributions of the unfrozen bound water contain more information about its components, because the large free water peaks hiding some smaller bound water peaks are absent and the exchange between free and bound water is prevented. Comparison of the total moisture signal integrals above and below the bulk melting point enables the determination of fiber saturation point (FSP), which, in this context, denotes the total water capacity of cell wall. T2*, T2, and T1 distributions offer different kinds of information about moisture components. All the peaks in the distributions were assigned, and it was demonstrated that the accessible hydroxyl site content and the amount of micropores can be estimated based on the peak integrals.

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Within-ring movement of free water in dehydrating Norway spruce sapwood visualized by neutron radiography

Holzforschung ◽

10.1515/hf-2011-0234 ◽

2012 ◽

Vol 66 (6) ◽

pp. 751-756 ◽

Cited By ~ 8

Author(s):

Sabine Rosner ◽

Martin Riegler ◽

Peter Vontobel ◽

David Mannes ◽

Eberhard H. Lehmann ◽

...

Keyword(s):

Moisture Content ◽

Norway Spruce ◽

Neutron Radiography ◽

Free Water ◽

Neutron Imaging ◽

Moisture Distribution ◽

Moisture Loss ◽

Annual Rings ◽

Ambient Conditions ◽

Dimensional Changes

Abstract This study is a first approach to visualize moisture distribution and movement between annual rings during sapwood drying by neutron imaging (NI). While Norway spruce [Picea abies (L.) Karst.] sapwood beams were allowed to dehydrate on a balance at ambient conditions, NI was performed in 1–10 min time steps. From NI raw files, radial dimensional changes were calculated during dehydration and transmission profiles were drawn for different relative moisture content (MC) steps from full saturation until equilibrium moisture content. The NI technique proved to be a useful tool to visualize the movement of free water within, and between, annual rings. Removal of free water in the middle part of the wood beam did not proceed continuously from the surface to the central part, but was strongly influenced by wood anatomy. Water is removed from earlywood during early stages of dehydration and later, at higher moisture loss (<50% MC), from the main latewood parts. It is therefore concluded that the radial dimensional changes measured at moderate moisture loss are not only caused by cell wall shrinkage of the outer wood parts located beneath the wood surface, but a result of elastic deformation of earlywood tracheids under the influence of negative hydrostatic pressures.

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In Vivo Cutaneous and Perceived Comfort Response to Fabric: Part VI: The Effect of Moist Fabrics on Stratum Corneum Hydration

Textile Research Journal ◽

10.1177/004051759706701209 ◽

1997 ◽

Vol 67 (12) ◽

pp. 926-931 ◽

Cited By ~ 11

Author(s):

Kathryn L. Hatch ◽

Harriet H. Prato ◽

S. Haig Zeronian ◽

Howard I. Maibach

Keyword(s):

Moisture Content ◽

Stratum Corneum ◽

Water Loss ◽

Initial Moisture Content ◽

Polyester Fabric ◽

Evaporative Water Loss ◽

Evaporative Water ◽

Potential Health ◽

Stratum Corneum Hydration

Materials placed over human skin may change the stratum corneum (sc) hydration level, an important phenomenon because increases in normal levels of sc hydration pose potential health problems. This study examines the relationship between fabric moisture content and level of sc hydration so that the role of fabric moisture on sc hydration may be better understood. Three fabric/moisture treatments are placed on the sc—3.5-denier polyester fabric with an initial moisture content of 35% and cotton fabrics with either 44% or 75% initial moisture content—then covered with an occlusive dome. sc evaporative water loss (ewl) is measured before treatment placement and after 30 and 60 minutes of contact. The amount of moisture in the fabric at time of removal is calculated two different ways, and three analyses of variance are done using the evaporative water loss and two fabric final moisture content data sets. The rate of ewl is significantly higher after 30 minutes of treatment contact with sc than after 60 minutes of contact. The amount of moisture in the fabrics is significantly less at time 60 than at time 30, implying that the sc is more hydrated at 30 minutes than at 60 minutes. However, the fabrics contain less moisture when removed at 60 minutes than at 30 minutes. As fabric moisture content decreases, sc hydration decreases. The question we are not able to answer is “Where does the moisture go that is initially in the fabric?’

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Design, Fabrication and Characterization of a Solar Fish Dryer

NIGERIAN ANNALS OF PURE AND APPLIED SCIENCES ◽

10.46912/napas.183 ◽

2020 ◽

Vol 3 (3b) ◽

pp. 156-174

Author(s):

MD Tyona ◽

ED Ojiya

Keyword(s):

Moisture Content ◽

Initial Moisture Content ◽

Dry Season ◽

Moisture Loss ◽

United Nations Economic Commission ◽

Storage Unit ◽

Ambient Temperatures ◽

Economic Commission ◽

Sunshine Hours

Herein, a forced convection solar fish dryer is designed, constructed and characterized to yield a better main of drying fish. The designed dryer incorporated a heat storage unit which complimented the drying rate of the product during off sunshine hours. The device was characterized during raining and dry seasons and results clearly indicated the influence of seasonal variation on the performance of the device. Average hourly variation of the dryer and ambient temperatures measured on the selected days of the different months of measurement during the two seasons, clearly indicated that temperatures were significantly enhanced by the device. This was due to the high ability of the designed solar collector to trap large amount of long waves. Maximum dryer and ambient temperatures during raining season were measured to be (58.9±2) oC and (40±2) oC whereas, (73.5±1.3) oC and (45±1.8) oC respectively, were measured during the dry season. Average daily moisture loss from the drying fish was notably high, especially during dry season which was due to the high dryer temperatures and decrease in atmospheric humidity. The efficiency of the solar dryer was estimated to be 76 %. The fishes with initial moisture content of 87 % was dried to 13 %. This moisture content is in range with the United Nations Economic Commission for Europe (UNECE) Standard DDP-19 concerning the marketing and commercial quality control of dried fish.

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HIGH-TEMPERATURE MICRONIZATION OF FLAX SEEDS

Известия вузов. Пищевая технология ◽

10.26297/0579-3009.2018.2-3.21 ◽

2018 ◽

Author(s):

С.В. ЗВЕРЕВ ◽

В.А. ЗУБЦОВ

Keyword(s):

Heat Treatment ◽

Moisture Content ◽

Initial Moisture Content ◽

Raw Material ◽

Moisture Loss ◽

Oxidative Enzymes ◽

Heating Process ◽

Ir Radiation ◽

Temperature And Humidity ◽

Flax Seeds

Проведены исследования процесса термообработки семян льна для снижения их влажности. Эксперименты проводили на лабораторной установке путем нагрева сырья в потоке инфракрасного (ИК) излучения – микронизации. Получена зависимость текущего влагосодержания от температуры зерна и исходной влажности. Установлена ее инвариантность к режимам нагрева. Предложена математическая модель изменения влагосодержания от температуры семян и исходной влажности. Для разработки модели влагопотери использованы зависимости, описывающие изменение температуры и влажности от времени в процессе нагрева, полученные А.В. Лыковым и его учениками. Обоснованы рациональные технологические режимы получения стабилизированных семян льна с минимальной активностью окислительных ферментов, улучшенными органолептическими свойствами и повышенным объемом. Разработанный способ включает очистку семян льна от примесей, пропаривание водяным паром, термическую обработку методом ИК-облучения и охлаждение до комнатной температуры. Researches of process of heat treatment of seeds of flax for decrease in their humidity are carried out. Experiments were carried out at the laboratory facility by heating the raw material in the flow of infrared (IR) radiation – micronization. The experimental dependences of seed temperature and humidity on the heating time under different modes of infrared heat treatment are obtained. The dependence of the current moisture content on the grain temperature and initial humidity is obtained and its invariance to the heating regimes is established. The proposed mathematical model the change of moisture content from the temperature of the seeds and initial moisture content. To develop the model of moisture loss used dependences describing the change in temperature and humidity from time to time in the heating process, obtained A.V. Lykov and his students. Rational technological regimes of obtaining stabilized flax seeds with minimal activity of oxidative enzymes improved organoleptic properties and increased volume are explain. The developed method consists of cleaning flax seed from impurities, steaming by water vapor, heat treatment by IR irradiation, and cooling to room temperature.

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Development of a Device for Staged Determination of Water Activity and Moisture Content

Proceedings ◽

10.3390/proceedings2130881 ◽

2018 ◽

Vol 2 (13) ◽

pp. 881 ◽

Cited By ~ 1

Author(s):

Carlo Tiebe ◽

Marc Detjens ◽

Annika Fechner ◽

Stefanie Sielemann ◽

Andreas Lorek ◽

...

Keyword(s):

Moisture Content ◽

Water Activity ◽

Bound Water ◽

Free Water ◽

Characteristic Parameter ◽

Industrial Applications ◽

Wide Range ◽

Temperature Equilibrium

Moisture content and water activity are important parameters for quality characterizationof products like bulk materials, powders, granules. Thus, an exact determination is necessarilyrequired in a wide range of industrial applications. Moisture of materials is the content ofnon-chemically bound water in a solid or liquid. Water activity (aw) is a characteristic/parameter ofthe non-chemically bound (“free”) water in materials and is measured as humidity over asolid/liquid surface at constant temperature (equilibrium moisture content). It is an importantparameter to characterize the quality of e.g., pharmaceutical and food products. In ourcontribution, we present the developed MOISHUM device for staged determination of wateractivity and moisture content of liquid and solid materials.

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Study on the Moisture Distribution within the Wood Treated with Microwave

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.327.105 ◽

2011 ◽

Vol 327 ◽

pp. 105-108 ◽

Cited By ~ 1

Author(s):

Jian Fang Yu ◽

Ji Long Guo ◽

Jing Ya Nan ◽

Bing Hu Sun

Keyword(s):

Relaxation Time ◽

Bound Water ◽

Free Water ◽

Microwave Treatment ◽

Moisture Distribution ◽

Microwave Drying ◽

Water Molecules ◽

Saturation Point ◽

Initial Stage ◽

Before And After

In this paper, Siberian elm (Ulmus pumila L) which was regarded as our research object was measured with the technology of Nuclear Magnetic Resonance (NMR) before and after being treated with microwave at different periods of time. By comparing the spin - spin relaxation time of hydrogen nuclear (T2) which can reflect the mobility of water molecules, the states and changes of the moisture distribution within the wood in the process of microwave treatment have been analyzed. The results indicate that in the initial stage of drying, the degree of the decline in bound water is greater than that in free water, for there may be a process of the transformation from bound water to free water; With the drying going on, the movement and expulsion mainly happen to free water above the fiber saturation point (FSP); In the later stage of drying, when the moisture content decreases near the FSP, bound water has also begun moving significantly on the expulsion of plenty of free water. In the final stage of drying, the decrease of hydrogen bonds in water molecules resulting from a plentiful reduction in free water, as well as the increased permeability within the wood caused by the microwave drying makes the relaxation time of free water to rise up.

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Drying Rate of Grain Maize

Acta Technologica Agriculturae ◽

10.2478/ata-2013-0008 ◽

2013 ◽

Vol 16 (2) ◽

pp. 31-34

Author(s):

Ivan Vitázek ◽

Peter Vereš

Keyword(s):

Energy Consumption ◽

Moisture Content ◽

Initial Moisture Content ◽

Preventive Measure ◽

Moisture Loss ◽

Graphical Form ◽

Drying Rate ◽

Atmospheric Conditions ◽

Drying Time ◽

Thermal Drying

Abstract Maize is harvested after reaching maturity when its moisture content generally ranges from 30 % to 34 %, while the optimum moisture for storage is around 14-15 %. This moisture is usually achieved by thermal drying. Apart from initial moisture, the total drying time is affected by the temperature of the drying environment, atmospheric conditions and properties of the dried material. The present paper provides a description of the process of moisture loss and subsequent drying rate of grain maize from various growers. Obtained results are processed in a tabular and graphical form. After 30 minutes of drying, all the maize samples (10 samples two times in total) reached a moisture of 14 % and less, whereas 6 samples already after 20 minutes of drying. The rate of moisture loss was proportional to the initial moisture content. The drying of grain maize is considered one stage of the technological procedure in post-harvest treatment. Moreover, it is an essential preventive measure for wet harvest. Contemporary technologies of maize drying in modern dryers favourably influence the energy consumption in the process while maintaining the qualitative parameters of the dried material.

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Modelling drying processes of fuelbeds of Scots pine needles with initial moisture content above the fibre saturation point by two-phase models

International Journal of Wildland Fire ◽

10.1071/wf10119 ◽

2012 ◽

Vol 21 (4) ◽

pp. 418 ◽

Cited By ~ 4

Author(s):

Sen Jin ◽

Pengyu Chen

Keyword(s):

Moisture Content ◽

Scots Pine ◽

Initial Moisture Content ◽

Fibre Saturation Point ◽

Phase Model ◽

Fuel Moisture ◽

Drying Process ◽

Rating Systems ◽

Saturation Point ◽

Two Phase

Modelling the drying process of fuel moisture with initial moisture content above the fibre saturation point can be used to determine when fuel will become sufficiently dry (after precipitation) to burn and provide a more accurate prediction of fire potential. Based on analysis of the mechanism by which the drying process occurs, we propose a model comprising two phases distinguished by a moisture threshold of 0.35 g g–1, the fibre saturation point; one phase is controlled by evaporation and the other by diffusion. Each phase has a distinct equation with a different timelag. We compared our two-phase model with a one-phase model (one-timelag model) and another two-phase model by estimating drying of 15 Scots pine (Pinus sylvestris var. mongolica) needle fuelbeds. The results indicate that the two-timelag model improves moisture modelling, thereby reducing mean absolute error by more than 30%, i.e. from 0.0047 g g–1 (one-phase model) to 0.0030 g g–1. The model yields consistent results, further suggesting its potential for improving fuel moisture prediction of fire danger rating systems. The first timelag of the model is affected by fuelbed properties. Equations based on variables that represent fuelbed properties were established, thus saving time when estimating parameters for stand-specific fuel moisture models.

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