scholarly journals Effects of air temperature and relative humidity on equilibrium moisture content and time-lag of forest land surface dead fine fuels

2016 ◽  
Vol 40 (3) ◽  
pp. 221-235
Author(s):  
HU Hai-Qing ◽  
◽  
LU Xin ◽  
SUN Long ◽  
QU Zhi-Lin ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Air Temperature ◽  
Land Surface ◽  
Time Lag ◽  
Forest Land ◽  
Fine Fuels

Equilibrium moisture content of dead fine fuels of selected central European tree species

2013 ◽  
Vol 22 (6) ◽  
pp. 797 ◽  
Author(s):  
Christian Schunk ◽  
Clemens Leutner ◽  
Michael Leuchner ◽  
Clemens Wastl ◽  
Annette Menzel
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Input Parameter ◽  
Fire Danger ◽  
Pedunculate Oak ◽  
Salt Solutions ◽  
Test Procedures ◽  
Climate Chamber ◽  
Central European ◽  
Fine Fuels

Fine fuel moisture content is a key parameter in fire danger and behaviour applications. For modelling purposes, equilibrium moisture content (EMC) curves are an important input parameter. This paper provides EMC data for central European fuels and adds methodological considerations that can be used to improve existing test procedures. Litter samples of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) were subjected to three different experiments using conditioning in a climate chamber and above saturated salt solutions. Climate chamber conditioning yielded the best results and can generally be recommended, however saturated salt solutions are able to produce lower relative humidities, which are relevant to forest fire applications as they represent the highest fire danger. Results were within the range of published sorption isotherms for forest fine fuels. A fairly clear gradation was present with higher EMC values in leaf litters than in needle litters. These differences are in accord with values from the literature and suggest general differences in the sorption properties of leaves and needles, which may be caused by differing chemical and physical properties. The influence of temperature on EMC described in the literature could be confirmed.

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 Numerical Simulations of Effects of Soil Moisture and Modification by Mountains over New Zealand in Summer

2011 ◽  
Vol 139 (2) ◽  
pp. 494-510 ◽  
Author(s):  
Yang Yang ◽  
Michael Uddstrom ◽  
Mike Revell ◽  
Phil Andrews ◽  
Hilary Oliver ◽  
...  
Keyword(s):  
Soil Moisture ◽  
New Zealand ◽  
Moisture Content ◽  
Air Temperature ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Surface Air Temperature ◽  
Shortwave Radiation ◽  
Lower Sensitivity ◽  
The South

Abstract Historically most soil moisture–land surface impact studies have focused on continents because of the important forecasting and climate implications involved. For a relatively small isolated mountainous landmass in the ocean such as New Zealand, these impacts have received less attention. This paper addresses some of these issues for New Zealand through numerical experiments with a regional configuration of the Met Office Unified Model atmospheric model. Two pairs of idealized simulations with only contrasting dry or wet initial soil moisture over a 6-day period in January 2004 were conducted, with one pair using realistic terrain and the other pair flat terrain. For the mean of the 6 days, the differences in the simulated surface air temperature between the dry and moist cases were 3–5 K on the leeside slopes and 1–2 K on the windward slopes and the central leeside coastal region of the South Island in the afternoon. This quite nonuniform response in surface air temperature to a uniformly distributed soil moisture content and soil type is mainly attributed to modification of the effects of soil moisture by mountains through two different processes: 1) spatial variation in cloud coverage across the mountains ranges leading to more shortwave radiation at ground surface on the leeside slope than the windward slope, and 2) the presence of a dynamically and thermally induced onshore flow on the leeside coast bringing in air with a lower sensitivity to soil moisture. The response of local winds to soil moisture content is through direct or indirect effects. The direct effect is due to the thermal contrast between land and sea/land shown for the leeside solenoidal circulations, and the indirect effect is through the weakening of the upstream blocking of the South Island for dryer soils shown by the weakening and onshore shift of the upstream deceleration and forced ascent of incoming airflow.

Comparative Analysis of Sorption Isotherms for Wood Pellets and Solid Wood

2019 ◽  
Vol 35 (4) ◽  
pp. 475-479 ◽  
Author(s):  
Jun Sian Lee ◽  
Shahab Sokhansanj ◽  
C. Jim Lim ◽  
Anthony Lau ◽  
Tony Bi
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Solid Wood ◽  
Wood Chips ◽  
Published Data ◽  
Wood Pellets ◽  
Wood Pellet ◽  
Equilibrium Relative Humidity

Abstract.The published data on equilibrium moisture content vs. equilibrium relative humidity (EMC-ERH) for wood pellet do not cover the range of temperature and relative humidity to which a pellet is exposed to during its storage and handling. A few published EMC-ERH relations covering a wider range of temperatures and relative humidity are available for solid wood (lumber) and wood chips. The question is whether the data for solid wood is applicable to wood pellets. For this research, we examined the sorption isotherms of wood pellets and solid wood. The analysis shows that EMC for solid wood is higher than the EMC for wood pellet for a relative humidity larger than 30%. The slope of EMC-ERH isotherm for solid wood in the range of 30%-70% is slightly steeper than the slope of isotherm for wood pellet, indicating the pellet’s EMC is less sensitive to ERH when compared to EMC-ERH for solid wood. Keywords: EMC, ERH, Densified biomass, Equilibrium moisture content, Equilibrium relative humidity, Solid wood, Wood pellets.

Sorption Isotherms and Isosteric Heat of Peanut Pods, Kernels and Hulls

2007 ◽  
Vol 13 (3) ◽  
pp. 231-238 ◽  
Author(s):  
P.C. Corrêa ◽  
A.L.D. Goneli ◽  
C. Jaren ◽  
D.M. Ribeiro ◽  
O. Resende
Keyword(s):  
Experimental Data ◽  
Relative Humidity ◽  
Moisture Content ◽  
Mathematical Models ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Statistical Parameters ◽  
Peanut Hulls ◽  
Pass Through

This study was carried out to evaluate the sorption isotherms of peanut pods, kernels and hulls for several temperature and humidity conditions and to fit different mathematical models to the experimental data, selecting the one best fitting the phenomenon. The dynamic method was applied to obtain the hygroscopic equilibrium moisture content. The environmental conditions were provided by means of an atmospheric conditioning unit, in which removable perforated trays were placed to allow air to pass through peanut mass, each one containing 50 g of the product. The mathematical models frequently used for the representation of hygroscopicity of agricultural products were fit to the experimental data. Based on those results, it was concluded that peanut pods, kernels and hulls presented differentiated hygroscopicity. The equilibrium moisture content for peanut pods, kernels and hulls increased with an increase in the relative humidity at any particular temperature and decreased with increase in temperature at constant relative humidity. At a constant water activity, peanut hulls samples had higher equilibrium moisture content than the pods and kernels samples. Based on statistical parameters, the modified Henderson and Chung-Pfost models were found to adequately describe the sorption characteristics of peanut pods, kernels and hulls. Isosteric heat of desorption were evaluated by applying the Clausius—Clapeyron equation to experimental isotherms and decreased with increasing moisture content. The peanut hulls had higher isosteric heat of sorption than that peanut pods and kernels.

Equilibrium moisture content and timelag of dead Pinus pinaster needles

2014 ◽  
Vol 23 (5) ◽  
pp. 721 ◽  
Author(s):  
Sérgio Lopes ◽  
Domingos Xavier Viegas ◽  
Luís Teixeira de Lemos ◽  
Maria Teresa Viegas
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Pinus Pinaster ◽  
Predictive Ability ◽  
Food Products ◽  
Forest Fuels ◽  
Best Fitting ◽  
Fine Fuels ◽  
Almost All ◽  
Moisture Content Determination

Modelling adsorption and desorption processes and equilibrium moisture content of dead fine fuels below fibre saturation is required to provide an accurate prediction of their drying and wetting processes within the range where flammability increases rapidly with decreasing moisture content. Data from laboratory tests on sorption processes and equilibrium moisture content isotherms of dead Pinus pinaster (Ait.) needles were used to evaluate several models applicable to fine forest fuels and agricultural and food products. Laboratory and field data were used to assess model accuracy in predicting drying and wetting curves and equilibrium moisture content isotherms showing a medium to high predictive ability for almost all cases. The best fitting combinations were obtained with the application of agricultural and food products models for drying and wetting phases and fine forest fuel models for equilibrium moisture content determination.

scholarly journals Moisture content changes of beech and ash elements during two years in room conditions

2021 ◽  
pp. 97-110
Author(s):  
Goran Milic
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Air Conditioning ◽  
Cold Winter ◽  
The Past ◽  
Average Relative Humidity ◽  
The Subject ◽  
Sawn Timber

The subject of this paper is the analysis of moisture content (MC) changes of beech and ash wood during two years in room conditions (heating during winter; no air conditioning during summer). The registered MC changes are primarily the result of changes in relative humidity of the air (measured by capacitive probes). The average relative humidity of the air in the interior is lower today than in the past, as also shown in this experiment (the average relative humidity of air during two years was 44%). The lowest wood MC was reached on very cold winter days when the heating was on even during the night - between 5% and 6%, and the highest one at the beginning of June: 10.4-10.9%. As expected, the wood did not reach equilibrium moisture content - during winter, MC is by about 1% higher, and in summer it is lower by up to 2.5% than the equilibrium. The recommendation that the sawn timber from which the interior products will be made should be dried at 7-8% MC was confirmed.

The Horizontal Flame-Propagation Rate of Undyed Cotton Fabrics

1976 ◽  
Vol 46 (4) ◽  
pp. 238-246 ◽  
Author(s):  
Leon Segal ◽  
G. L. Drake
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Flame Propagation ◽  
Propagation Rate ◽  
Cotton Fabrics ◽  
Horizontal Position ◽  
Test Procedures ◽  
Oven Drying ◽  
Usual Test

Differentiation of the flammabilities of nonflame-retardant, all-cotton fabrics cannot be accomplished by the usual test procedures, as these merely provide the means for determining when a fabric exceeds a certain set standard. The desired differentiation, however, can be obtained by measurement of the flame-propagation rate using the Ahiba Flammability Tester with the sample in the horizontal position. Eight nonflame-retardant, undyed cotton fabrics of different constructions were studied. The weights of the fabrics fell into four groups: 3.1, 3.6–3.8, 4.1–4.4, and 7.5 oz/yd2. Specimens were cut from the warp and filling directions of the fabrics; one set of specimens was oven-dried prior to testing, while another set was conditioned to equilibrium moisture content at 65% relative humidity and 70°F. Burning was different in the warp and filling directions. Differences in flame-propagation rates were found that were not weight dependent. In general, flame-propagation rate was not constant over the length of the specimen; in the warp direction the rates increased with distance from point of ignition, while in the filling direction constant and decreasing rates were also found. Flame-propagation rate was not effected to the extent expected by changing from oven drying to conditioning to equilibrium moisture content; only four of the eight fabrics showed significant changes. Burning in the filling directions of two fabrics was markedly changed; smaller differences were found in the warp direction only of a third fabric and in both the warp and filling directions of a fourth fabric.

Effects of Post-Harvest Conditions on Sorption Isotherms of Soybeans

2021 ◽  
Vol 64 (3) ◽  
pp. 1027-1037
Author(s):  
Lina M Diaz-Contreras ◽  
Rani Puthukulangara Ramachandran ◽  
Stefan Cenkowski ◽  
Jitendra Paliwal
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Freezing And Thawing ◽  
Post Harvest ◽  
Drying And Wetting Cycles ◽  
Equilibrium Relative Humidity ◽  
Freezing And Thawing Cycles ◽  
Storage Temperatures

Abstract. This study focuses on the modeling of sorption characteristics of three varieties of soybeans (Akras R2, Lono R2, and Podaga R2). Three pretreatments related to post-harvest conditions were tested on the soybean varieties: (1) freshly harvested soybeans, (2) soybeans subjected to three drying and wetting cycles, and (3) soybeans subjected to three freezing and thawing cycles. The adsorption and desorption experiments were conducted at 5°C, 10°C, 15°C, 20°C, 25°C, and 30°C using a dynamic equilibrium relative humidity (ERH) apparatus. Equilibrium moisture content (EMC) and the corresponding ERH were measured. The parameters calculated for the modified Halsey equation are applicable for storage temperatures above 10°C in the relative humidity (RH) ranges of 10% to 80% for desorption and 30% to 80% for adsorption. No significant differences were found in sorption isotherms among the soybean varieties. However, the soybean varieties responded differently to the different pretreatments (i.e., drying/wetting and freezing/thawing cycles). The adsorption isotherms of Akras and Lono soybeans showed significant differences at 10°C to 30°C when subjected to drying and wetting cycles, while Akras and Podaga soybeans showed significant differences in the same temperature range when subjected to freezing and thawing cycles. The effect of drying and wetting cycles on the desorption isotherms was found only for Akras soybeans at 10°C and 15°C below 63% and 71% RH, respectively, and for Lono soybeans at 25°C and 30°C above 69% RH for both temperatures. In general, the effect of both pretreatments on the sorption isotherms of soybeans was a reduction in EMC of up to 20%, when compared to fresh samples at selected storage temperatures. The findings of this study serve as a primary tool for developing a lookup table for safe storage guidelines for soybeans. Keywords: Equilibrium moisture content, Equilibrium relative humidity, Halsey equation, Oswin equation, Soybeans.

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