scholarly journals Moisture Sorption and Thermodynamic Properties of Wood under Dynamic Condition

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Tiantian Yang ◽  
Erni Ma
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Molecular Level ◽  
Dynamic Condition ◽  
Moisture Sorption ◽  
Adsorbed Water ◽  
Specimen Thickness ◽  
Dynamic Sorption ◽  
Sorption Hysteresis ◽  
Two Temperatures

Thermodynamic approach is a useful method to study interactions between water and wood at molecular level. This work investigated the dynamic moisture sorption and thermodynamic properties for two thick poplar woods (Populus euramericanaCv.) subjected to sinusoidal relative humidity (RH) changes between 45% and 75% for cyclic period of 1, 6, and 24 h, at two temperatures of 25°C and 40°C. Moisture changes of the specimens were measured during the successive adsorption and desorption processes, giving the following results: (1) moisture content changed sinusoidally with the imposed RH and was inversely related to specimen thickness as well as temperature, but in a positive correlation with cyclic periods; (2) all ofQL,ΔG, andTΔSof the adsorbed water during dynamic sorption decreased with increasing moisture content or specimen thickness and decreasing cyclic period. However, temperature had opposite effects onΔGandTΔS. (3) Both moisture sorption hysteresis and thermodynamic sorption hysteresis could be found. The former became weak with rising temperature or thicker specimens, while the latter got clear when temperature or specimen thickness increased.

Moisture adsorption thermodynamics of wood from fractal-geometry approach

Holzforschung ◽  
2004 ◽  
Vol 58 (3) ◽  
pp. 274-279 ◽  
Author(s):  
J. Cao ◽  
D.P. Kamdem
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Adsorption Isotherms ◽  
Fractal Geometry ◽  
Moisture Sorption ◽  
Fractal Dimensions ◽  
Future Research ◽  
Differential Heat ◽  
Internal Surfaces ◽  
Differential Heat Of Adsorption

Abstract The fractal-geometry approach was used to calculate the thermodynamic properties of moisture sorption by wood from the adsorption isotherms in this study. The results were compared with those from an isosteric approach and a calorimetric approach. The adsorption isotherms of Southern yellow pine (Pinus spp.) were measured at 4, 15, 30, and 40°C to provide source data for the calculation of both fractal-geometry and isosteric approaches. The results show that the fractal dimensions of the internal surfaces of wood vary between 2.4 and 2.5. The curves of the differential heat of adsorption −∆H against moisture content from the fractal-geometry approach are similar to those from calorimetric measurements in previous research. The −∆H values from the isosteric approach increased with moisture content within a moisture content range up to 3%. And, at moisture contents higher than 3%, the −∆H values from this method are much higher than those from the fractal-geometry approach and calorimetric approach. As a result, the fractal-geometry approach is applicable to calculate the differential thermodynamic properties of moisture sorption by wood in future research.

Sorption isotherms and moisture sorption hysteresis of intermediate moisture content banana

2008 ◽  
Vol 86 (3) ◽  
pp. 342-348 ◽  
Author(s):  
Zhengyong Yan ◽  
Maria J. Sousa-Gallagher ◽  
Fernanda A.R. Oliveira
Keyword(s):  
Moisture Content ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Sorption Hysteresis

scholarly journals MATHEMATICAL MODELS AND THERMODYNAMIC PROPERTIES OF MOISTURE SORPTION ISOTHERMS OF FERMENTED CASSAVA FLOUR BY RED YEAST RICE

2017 ◽  
Vol 13 (1) ◽  
pp. 29 ◽  
Author(s):  
Mutiara Nur Alfiah ◽  
Sri Hartini ◽  
Margareta Novian Cahyanti
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Sorption Isotherm ◽  
Moisture Sorption ◽  
Red Yeast Rice ◽  
Cassava Flour ◽  
Red Yeast ◽  
Moisture Sorption Isotherm ◽  
Gab Model ◽  
Monolayer Moisture

<p>This research aims to determine moisture sorption isotherm curves, moisture sorption isotherm models and thermodynamic properties of fermented cassava flour by red yeast rice. The moisture sorption isotherm model used are Guggenheim Anderson deBoer (GAB), Brunauer Emmet Teller (BET) and Caurie. Meanwhile, the test of modelling accuray by Mean Relative Deviation (MRD) and Root Mean Square Error (RMSE). The thermodynamic properties, i.e., enthalpy and entropy were calculated by Clausius - Clapeyron equation. The result shows that the moisture sorption isotherm curve on fermented cassava flour in a sigmoid form (type II). The GAB model is the best model for moisture sorption isotherm of fermented cassava flour by red yeast rice. The MRD and RMSE values at 30˚C, 35˚C and 40˚C are 3.12%, 2.71%, 3.81%, and 1.01, 0.35, 0.42, respectively. The monolayer moisture content at 30˚C, 35˚C and 40˚C are 6.61%, 6.27% and 6.91%, based on GAB model. Meanwhile, when the BET model was used, the monolayer moisture content are 4.92%, 4.86% and 5.19%, while by Caurie model are 6.37%, 6.18% and 5.30%, at 30˚C, 35˚C and 40˚C, respectively. The enthalpy and entropy of water sorption process were decreased when moisture content increased.</p>

scholarly journals MATHEMATICAL MODELS AND THERMODYNAMIC PROPERTIES OF MOISTURE SORPTION ISOTHERMS OF FERMENTED CASSAVA FLOUR BY RED YEAST RICE

2017 ◽  
Vol 13 (1) ◽  
pp. 29 ◽  
Author(s):  
Mutiara Nur Alfiah ◽  
Sri Hartini ◽  
Margareta Novian Cahyanti
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Sorption Isotherm ◽  
Moisture Sorption ◽  
Red Yeast Rice ◽  
Cassava Flour ◽  
Red Yeast ◽  
Moisture Sorption Isotherm ◽  
Gab Model ◽  
Monolayer Moisture

<p>This research aims to determine moisture sorption isotherm curves, moisture sorption isotherm models and thermodynamic properties of fermented cassava flour by red yeast rice. The moisture sorption isotherm model used are Guggenheim Anderson deBoer (GAB), Brunauer Emmet Teller (BET) and Caurie. Meanwhile, the test of modelling accuray by Mean Relative Deviation (MRD) and Root Mean Square Error (RMSE). The thermodynamic properties, i.e., enthalpy and entropy were calculated by Clausius - Clapeyron equation. The result shows that the moisture sorption isotherm curve on fermented cassava flour in a sigmoid form (type II). The GAB model is the best model for moisture sorption isotherm of fermented cassava flour by red yeast rice. The MRD and RMSE values at 30˚C, 35˚C and 40˚C are 3.12%, 2.71%, 3.81%, and 1.01, 0.35, 0.42, respectively. The monolayer moisture content at 30˚C, 35˚C and 40˚C are 6.61%, 6.27% and 6.91%, based on GAB model. Meanwhile, when the BET model was used, the monolayer moisture content are 4.92%, 4.86% and 5.19%, while by Caurie model are 6.37%, 6.18% and 5.30%, at 30˚C, 35˚C and 40˚C, respectively. The enthalpy and entropy of water sorption process were decreased when moisture content increased.</p>

Static and dynamic sorption of lignin removed Populus euramericana

TAPPI Journal ◽  
2018 ◽  
Vol 17 (02) ◽  
pp. 71-77 ◽  
Author(s):  
Haizhen Zhou ◽  
Jingyu Li ◽  
Erni Ma
Keyword(s):  
Relative Humidity ◽  
Dynamic Condition ◽  
Moisture Sorption ◽  
Adsorption And Desorption ◽  
Dynamic Conditions ◽  
Populus Euramericana ◽  
Dynamic Sorption ◽  
Initial Stage

To investigate the effect of lignin on moisture sorption behaviors of wood under static and dynamic conditions, Populus euramericana cultivars measuring 20 mm tangentially × 20 mm radially × 4 mm along the grain was divided into three groups: untreated, extractives removed, and lignin removed. All the samples were subjected to static sorption where relative humidity (RH) was controlled at 11%, 45%, and 75%, and dynamic sorption where RH changed sinusoidally between 45% and 75% for cyclic periods of 1 h and 24 h, both conditions kept at 25C°. Moisture changes were measured during the adsorption and desorption processes. Moisture of the samples varied rapidly at the initial stage during static sorption. The rate decreased gradually until equilibrium was reached. Moisture changes for dynamic condition were generally sinusoidal but lagged behind the imposed RH.

scholarly journals Possibilities of Decreasing Hygroscopicity of Resonance Wood Used in Piano Soundboards Using Thermal Treatment

2021 ◽  
Vol 11 (2) ◽  
pp. 475
Author(s):  
Petr Zatloukal ◽  
Pavlína Suchomelová ◽  
Jakub Dömény ◽  
Tadeáš Doskočil ◽  
Ginevra Manzo ◽  
...  
Keyword(s):  
Moisture Content ◽  
Conversion Efficiency ◽  
Dynamic Modulus ◽  
Moisture Sorption ◽  
Acoustical Properties ◽  
Longitudinal Dynamic ◽  
Moisture Content Level ◽  
Longitudinal Sound Velocity ◽  
Tan Δ ◽  
Resonance Wood

This article presents the possibilities of decreasing moisture sorption properties via thermal modification of Norway spruce wood in musical instruments. The 202 resonance wood specimens that were used to produce piano soundboards have been conditioned and divided into three density groups. The first specimen group had natural untreated properties, the second was thermally treated at 180 °C, and the third group was treated at 200 °C. All specimens were isothermally conditioned at 20 °C with relative humidity values of 40, 60, and 80%. The equilibrium moisture content (EMC), swelling, and acoustical properties, such as the longitudinal dynamic modulus (E’L), bending dynamic modulus (Eb), damping coefficient (tan δ), acoustic conversion efficiency (ACEL), and relative acoustic conversion efficiency (RACEL) were evaluated on every moisture content level. Treatment at 180 °C caused the EMC to decrease by 36% and the volume swelling to decrease by 9.9%. Treatment at 200 °C decreased the EMC by 42% and the swelling by 39.6%. The 180 °C treatment decreased the value of the longitudinal sound velocity by 1.6%, whereas the treatment at 200 °C increased the velocity by 2.1%. The acoustical properties EL′, Eb, ACEL, and RACEL were lower due to the higher moisture content of the samples, and only the tanδ increased. Although both treatments significantly affected the swelling and EMC, the treatment at 180 °C did not significantly affect the acoustical properties.

Research on Temperature Characteristic of Porous Cement Concrete

2011 ◽  
Vol 374-377 ◽  
pp. 2105-2109
Author(s):  
Li Qun Hu ◽  
Wei Si Ma ◽  
Hong Qing Hou
Keyword(s):  
Wind Speed ◽  
Moisture Content ◽  
Thermal Conduction ◽  
Temperature Characteristic ◽  
Specimen Thickness ◽  
Cement Concrete ◽  
Molding Process ◽  
Pressing Method ◽  
Island Effect ◽  
Conduction Properties

This research aims to study the temperature characteristic of porous cement concrete as an alternative pavement that can help to mitigate urban heat island effect, and all the benefits it can provide, along with several offspring. Three experiments conducted in this research focus on the effect of specimen thickness,moisture content and wind speed on the thermal conduction properties of porous cement concrete. Isostatic pressing method is adopted in the molding process of specimens and reserved holes method is utilized to measure the internal temperature of the specimens.The data presented in this paper explains the tend of thermal conduction properties accompanying the increase of specimen thickness,moisture content and wind speed.

scholarly journals Thermodynamic properties and moisture sorption isotherms of two pharmaceutical compounds

2018 ◽  
Author(s):  
Amel Zammouri ◽  
M. Ben Zid ◽  
N. Kechaou ◽  
N. Boudhrioua Mihoubi
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Water Sorption ◽  
Pharmaceutical Preparations ◽  
Sorption Isotherms ◽  
Integral Enthalpy ◽  
Isotherm Models ◽  
Water Sorption Isotherms

This investigation examines and compares the water sorption isotherms and the thermodynamic properties of two pharmaceutical preparations (Hypril and Azix) intended to be manufactured with the same process plant and equipment. The moisture equilibrium isotherms were determined at 50, 60 and 70 °C using a gravimetric technique. Five isotherm models were explored for their fitting to the experimental data. Azix showed sigmoid type II isotherms while Hypril showed type III isotherms according to the BET classification. All investigated models fitted well the water sorption isotherms of Hypril. By contrast, only GAB and Adam and Shove equations gave appropriate fit to the experimental data of Azix. For both formulations, the isosteric heat and the differential entropy decreased sharply with the increase of equilibrium moisture content to minimum values and thereafter remain constant. In the case of Azix, the integral enthalpy decreased with equilibrium moisture content while the integral entropy increased until reaching a constant value. Contrariwise, Hypril showed decreasing of the integral enthalpy and entropy with the equilibrium moisture content. Keywords: sorption isotherm, enthalpy, entropy, spreading pressure, pharmaceutical formulations  

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