Academic literature on the topic 'Moisture Sorption Isotherms'
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Journal articles on the topic "Moisture Sorption Isotherms"
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Vitázek, I., and J. Havelka. "Sorption isotherms of agricultural products." Research in Agricultural Engineering 60, Special Issue (2014): S52—S56. http://dx.doi.org/10.17221/35/2013-rae.
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The aim of the paper is to expand the theory of sorption and equilibrium moisture contents as well as to present the methodology of developing two types of sorption isotherms – I and II. The attention is also paid to the importance of the isotherms in the thermodynamics of drying and in the process of storage of agricultural products. Presented methodology of obtaining the isotherms is based on selected equations of the theory of adsorption and on the results of experimental measurements of equilibrium moisture content. Definition of the new isotherm II is introduced as dependence of equilibrium moisture content dry basis on time at constant temperature, constant relative moisture of the ambient air and stable biological properties (e.g. germination). The results show following graphic dependences: isothermal distort plane; sorption isotherm I of maize grains at various temperatures; moisture loss rate in dependence on time and sorption isotherm II. These theoretical dependences supported by experimental measurements broaden the scope of the theory of sorption and may be successfully applied in long-term storage of maize grains.
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Menkov, N. D., and D. I. Gelyazkov. "Moisture sorption isotherms of millet seeds." Czech Journal of Food Sciences 18, No. 3 (2000): 86–90. http://dx.doi.org/10.17221/8316-cjfs.
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The equilibrium moisture contents were determined for millet seeds of two cultivars using the gravimetric static method at 10, 25 and 40°C over a range of relative humidities from 0.112 to 0.868. The sorption capacity of the seeds decreased with an increase in temperature at constant relative humidity. The hysteresis effect is not distinctly expressed but statistically significant. The differences between equilibrium moisture contents of the cultivars are small. Four models were applied for analyzing the experimental data using the following equations: modified Chung-Pfost, modified Halsey, modified Oswin, and modified Henderson. The modified Chung-Pfost model was found to be the most suitable for describing the relationship between equilibrium moisture content, relative humidity and temperature.
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Zhou, Z., and K. P. Zubarev. "The use of sorption and excess sorption isotherm in the mathematical modeling of the unsteady-state heat and humidity regime of the building envelope." Journal of Physics: Conference Series 2131, no. 5 (2021): 052072. http://dx.doi.org/10.1088/1742-6596/2131/5/052072.
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Abstract In the given article the development of the moisture transfer equation based on the theory of moisture potential is considered. The task of combined heat and moisture transfer is one of the most complicated tasks in the building thermal physics field. The classical equations of moisture transfer by K.F. Fokin representing the transfer of moisture under the action of partial transfer potentials - the gradient of the partial pressure of water vapor and the gradient of humidity F - are listed. The possibility of uniform accounting of the combined water vapor transfer on the basis of the moisture potential F is described. The sorption isotherm for aerated concrete is constructed in accordance with the experiment carried out in a desiccator with an aqueous solution of sulfuric acid. A new equation of moisture transfer which takes into account moistening with vaporous moisture in the sorption zone of moisture and liquid moisture in the excess sorption zone of moisture is derived. In order to simplify the work with the obtained equation a new value of the relative potential capacity is introduced. A graph construction of sorption and excess sorption isotherms which are obtained using an analytical expression for the relative potential capacity is proposed. In the sorption zone of humidification the sorption and excess sorption isotherms coincide with the classical sorption isotherm. Meanwhile, in the excess sorption zone of humidification the sorption and excess sorption isotherms depend on temperature.
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JOHN, BOSCO KAWONGOLO, I. MURANGA FLORENCE, and HENSEL OLIVER. "DETERMINATION OF THE SORPTION ISOTHERMS FOR Matooke (Musa sp., AAA-EAHB)." Journal of Advances in Food Science & Technology 4, no. 2 (2017): 52–61. https://doi.org/10.5281/zenodo.1411655.
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Banana, (<em>matooke</em>) <em>Musa </em>sp<em>.</em> triploid <em>acuminate </em>genome group (AAA-EAHB) is an important crop in Uganda. <em>Matooke</em> flour contains more than 80% starch (db) which is good for both food and nonfood industrial applications, however, there is no information on moisture sorption isotherm for<em> matooke</em>. The main objective of the study was to establish the moisture sorption isotherms for <em>matooke</em> flour in order to standardize the stability of raw <em>matooke</em> flour with respect to microbiology and shelf life. The static gravitation method recommended by COST 90 Project was used for determination of moisture sorption isotherms. <em>Matooke</em> isotherms exhibited type II curve behavior which is characteristic of foodstuffs. Among the six models fitted to describe the adsorption and desorption isotherms for <em>matooke,</em> the GAB model best described all the adsorption and desorption moisture isotherms. <em>Matooke</em> should be dried to moisture content below or equal to 10% (wb) in order to obtain a microbiologically shelf-stable dry product (<em>matooke</em> flour). The hysteresis phenomenon was exhibited by the moisture sorption isotherms for <em>matooke.</em> The isoteric heat of sorption for both adsorption and desorption isotherms increased with decreased moisture content. <em>Matooke’</em>s total isosteric heat of sorption for the adsorption and desorption isotherms ranged between 4,586 – 2,386 kJ/kg and 18,194– 2,391 kJ/kg respectively, for equilibrium moisture content from 0.3 – 0.01 (db). The minimum energy required for drying 1 kg of fresh <em>matooke</em> from 80 - 10% (wb) was 5,793 kJ.
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Mitrevski, Vangelce, and Cvetanka Mitrevska. "Mathematical modelling of moisture sorption isotherms of some fruits." INTERNATIONAL JOURNAL OF THERMAL-FLUID ENGINEERING AND MODERN ENERGETICS 1, no. 1 (2022): 74–82. http://dx.doi.org/10.51558/2831-0527.2022.1.1.74.
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The moisture sorption isotherms of some fruits namely pear and quince were determined at 15, 30, 45 and 60oC over a range of water activity from 0.110 to 0.920 using the standard, static-gravimetric method. The experimental sorption data were fitted with generated three-parameter sorption isotherm models on Mitrevski et al., and the referent Anderson model known in the scientific and engineering literature as Guggenheim-Anderson-de Boer (GAB) model. In order to find which models give the best results, large number of numerical experiments was performed. After that, several statistical criteria for estimation and selection of the best sorption isotherm model was used. The performed statistical analysis shows that the generated three-parameter model from Mitrevski et al. gave the best fit to the sorption data of pear and quince than the referent three-parameter Anderson model. Keywords: Sorption isotherms Pear Quince Statistical criteria
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Setyawan, N., Clarissa, E. Y. Purwani, and A. Budiyanto. "Moisture Sorption Isotherm Characteristic of Composite Flour (Cassava, Rice, Sorghum, and Sago) at Various Fitting Models." IOP Conference Series: Earth and Environmental Science 1024, no. 1 (2022): 012053. http://dx.doi.org/10.1088/1755-1315/1024/1/012053.
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Abstract Cassava, rice, sorghum, and sago flour can be mixed into composite flour. The properties of composite flour easily absorb water, so it is necessary to know the isotherm sorption through various models, such as Brunauer-Emmet-Teller (BET), Oswin, Hasley, Henderson, Caurie, Chen-Clayton and Guggenheim, Anderson, and Boer (GAB). Information on the sorption properties of foods is of great importance in food dehydration, especially in the quantitative approach to predicting the shelf life of dried foods such as flour. This research aims to determine the sorption isotherms of composite flour experimentally and evaluate the suitability of various mathematical models for fitting the isotherms. Samples were stored at 28 ± 2 ° C with various water activity conditions (aw 0.05-0.97). The results showed that the moisture sorption isotherm of composite flour followed the sigmoid type II behavior frequently found in dry food products. The behavior of composite flour (Formula A and C) equilibrium moisture in the study was satisfactorily described by means of the moisture sorption isotherm of Oswin model with MRD value respectively is 5.64 and 4.93. While the behavior equilibrium moisture for other flour (Formula B and D) was precisely depicted by means of the moisture sorption isotherm of Chen Clayton model with MRD value respectively is 5.08 and 3.39.
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Rachtanapun, Pornchai, and R. Suriyatem. "Prediction Models for Moisture Sorption Isotherms of Soy Protein Isolate/Carboxymethyl Chitosan/Oleic Acid Blend Films." Advanced Materials Research 506 (April 2012): 595–98. http://dx.doi.org/10.4028/www.scientific.net/amr.506.595.
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Soy protein isolate/carboxymethyl chitosan/oleic acid (SPI/CMCH/O) blend films were prepared by solution casting. The effect of various oleic acid content (0, 2.5, 5.0, 10.0, 20.0 pph of SPI and CMCH) on water sorption isotherm of SPI/CMCH base film was investigated. The sorption isotherm of SPI/CMCH/O blend films was evaluated at serveral relative humidity (0, 16, 35, 55 and 76% RH), at 25±1°C. The isotherms showed equilibrium moisture content (%EMC) of SPI/CMCH/O blend films decreased when oleic acid content increased. Understanding of sorption isotherms is an importance for prediction of moisture sorption properties of films via moisture sorption empirical models. Guggenheim-Anderson-de Boer (GAB), BrunauerEmmettTeller (BET) and Oswin sorption models were tested to fit the experimental data. The root mean squares (RMS) of GAB, BET and Oswin were in the range of 68.60-87.02, 22.86-79.38 and 694.78-3797.23, respectively. BET model was found to be the better-fitted model for SPI/CMCH/O blend films at 25±1°C.
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Luthra, Kaushik, Soraya Shafiekhani, Sammy S. Sadaka, and Griffiths G. Atungulu. "Determination of Moisture Sorption Isotherms of Rice and Husk Flour Composites." Applied Engineering in Agriculture 36, no. 6 (2020): 859–67. http://dx.doi.org/10.13031/aea.13822.
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HighlightsMoisture sorption isotherms of rice and husk flour composites were determined.Adsorption isotherms were best modeled by the Chung-Pfost and Oswin equations.Desorption isotherms were best modeled by the Polynomial and Chung-Pfost equations.The Modified Oswin model was the best for both adsorption and desorption.Abstract. Empirical models describing isotherms specifically for adsorption and desorption have not been described for rough rice and husk flour composites. Such models are vital for process control and monitoring operations which use rice husk and rice flours or their mixtures for food or material processing. The current study was undertaken to determine the moisture sorption isotherms of rice husk flour, rough rice flour and their mixtures subjected to different temperature levels. Effects of rice husk flour to rough rice flour ratio of 0:1 (0.0%), 1:49 (2.0%), 1:16 (5.9%), and 1:0 g/g (100.0%) on rough rice moisture isotherms at temperature levels of 20°C, 40°C, and 60°C were investigated. The dynamic dewpoint isotherm technique (DDI) was used to generate accurate isotherms. Several empirical models were tested to fit the experimental EMC data. All the isotherms showed typical sigmoidal type 2 shapes. The equilibrium moisture content (EMC) over equilibrium relative humidity (water activity) ranging from 10% to 95% showed temperature dependence. Hysteresis was evident for all samples, with a decreasing level at a higher temperature. Rice husk flour to rough rice flour ratio, as a factor, showed a significant effect on the EMC of rough rice. The EMC decreased with an increase in rice husk flour levels. Chung-Pfost and Oswin were the two best models for describing adsorption isotherm, and Polynomial and Chung-Pfost were the best models for fitting the desorption isotherm. Modified Oswin model was the best model amongst the two-variable models for describing both adsorption and desorption isotherms. Keywords: Empirical models, Equilibrium moisture content, Rice husk flour, Rough rice flour, Sorption isotherms.
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Willems, Wim. "A critical review of the multilayer sorption models and comparison with the sorption site occupancy (SSO) model for wood moisture sorption isotherm analysis." Holzforschung 69, no. 1 (2015): 67–75. http://dx.doi.org/10.1515/hf-2014-0069.
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Abstract The wood moisture sorption (WMS) isotherm is generally considered to contain information on the water-cell wall interaction and the abundance of water sorption sites (SSs) in wood. The Hailwood-Horrobin (HH) model – as an example of the multilayer surface sorption models – is discussed for its suitability to analyze experimental WMS isotherms, to elaborate the fundamental sorption parameters. Based on multiple independent experimental and theoretical arguments, it was concluded that the basics of the surface multilayer-sorption models do not apply to wood. This is clearly illustrated by applying the analysis to the temperature-dependence of WMS isotherms, to the comparison of adsorption vs. desorption isotherms and to the quantification of SSs in wood. A sorption site occupancy (SSO) model is presented as an alternative for the HH model. It provides a comprehensive, thermodynamically consistent and quantitative basis for the analysis of WMS isotherms. The predicted SS densities are realistic and can be used to quantify sorption hysteresis and cell wall relaxation.
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TSAMI, E., G. K. VAGENAS, and D. MARINOS-KOURIS. "MOISTURE SORPTION ISOTHERMS of PECTINS." Journal of Food Processing and Preservation 16, no. 3 (1992): 151–61. http://dx.doi.org/10.1111/j.1745-4549.1992.tb00197.x.
Full textDissertations / Theses on the topic "Moisture Sorption Isotherms"
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Al-Muhtaseb, Ala'A. "Moisture sorption isotherms and drying characteristics of starch materials." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403272.
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Hashimoto, Yemia Turnage, and Yemia Turnage Hashimoto. "Sorption isotherms of trichloroethylene to sand at varying moisture contents." Thesis, The University of Arizona, 1998. http://hdl.handle.net/10150/626777.
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The sorption of trichloroethlyene (TCE) vapors to low foe silica sand wetted at five
moisture contents (approximately 5.3, 9.2, 13.2, 17.2 and 21.2%) in stainless steel
columns was studied using three techniques: complete breakthrough curves, step-wise
desorption, and adsorption pulses. Distribution coefficients ~) were determined and
there is no trend with moisture content. ~ varied for the different techniques, with
complete breakthrough curves giving the most consistent values. These results also
indicate that desorption experiment protocols need further evaluation and that rate-limited
aqueous diffusion can bias adsorption pulse experiments. The results are inconclusive as
to whether the sorption isotherm is linear. Further research on aqueous sorption
coefficients at different concentrations is necessary to accurately define the isotherm
shape.
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Peters, Richard Edward. "An experimental apparatus for the measurement of sorption isotherms of moisture in porous building materials." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040234/.
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Zhang, Zhidong. "Modelling of sorption hysteresis and its effect on moisture transport within cementitious materials." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1055/document.
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La durabilité des structures en béton armé ainsi que leur durée de vie sont étroitement liées à la mise en œuvre simultanée de nombreux phénomènes physiques et chimiques. Ceux-ci sont de diverses natures mais restent, en général, fonction des propriétés hydriques des matériaux étudiés. Ainsi, la prédiction des dégradations potentielles d'un matériau cimentaire requiert l'étude du transport de l'eau liquide et des phases gazeuses à travers ce dernier, considéré comme un milieu poreux. En milieu naturel, les structures subissent des variations périodiques de l'humidité relative extérieure (HR). Cependant, la plupart des modèles de transfert hydrique préexistants dans la littérature, s'intéresse uniquement au processus de séchage. Il existe peu de modèles décrivant à la fois l'humidification et le séchage du matériau (ces deux phénomènes se produisent dans le matériau en condition naturelle d'humidité relative (HR)). Tenir compte des phénomènes d'hystérésis dans les transferts hydriques réduit à nouveau le nombre de modèles à disposition. Ainsi, cette thèse s'attache à proposer une meilleure compréhension de l'état hydrique du béton en fonction des variations d'humidité relative extérieure, sur la base d'une nouvelle campagne expérimentale et de modélisations numériques. Un soin sera apporté afin de tenir compte dans les modèles numériques des effets d'hystérésis. Dans ce travail, nous détaillerons, tout d'abord, un modèle multi-phasiques complet. Un modèle simplifié est obtenu, sur la base de considérations théoriques et de vérifications expérimentales dans le cas où la perméabilité intrinsèque à l'eau liquide reste très inférieure à la perméabilité intrinsèque au gaz. Une étude comparative des modèles d'hystérésis couramment utilisés permet d'obtenir un jeu de modèles proposant les meilleures prédictions d'isothermes de sorption d'eau et de leurs hystérésis. Par la suite, le modèle de transport simplifié est couplé avec les modèles d'hystérésis sélectionnés afin de simuler les transferts hydriques dans des bétons soumis à des cycles d'humidification-séchage. La comparaison avec des données expérimentales révèle que la prise en compte de l'hystérésis de l'isotherme de sorption d'eau ne peut pas être négligé. De plus, il est montré que les prédictions obtenues avec des modèles d'hystérésis théoriques, sont les plus cohérentes avec les résultats expérimentaux, en particulier, pour des chemins secondaires d'hystérésis. Plusieurs scénarios (conditions environnementales, bétons différents) sont également simulés. Les résultats obtenus pointent à nouveau la nécessité de tenir compte de l'hystérésis lors de la modélisation des transferts hydriques à travers des matériaux cimentaires soumis à des variations d'humidité relative. La définition d'une profondeur pour laquelle le profil hydrique du béton est modifié par les variations périodiques d'humidité relative permet de mieux comprendre comment la modélisation de la pénétration des espèces ioniques est influencée par les cycles d'humidification-séchage. Par ailleurs, notre analyse révèle qu'il est pertinent de considérer l'effet de Knudsen pour la diffusion de la vapeur afin d'améliorer la prédiction de la diffusivité apparente<br>The durability of reinforced concrete structures and their service life are closely related to the simultaneous occurrence of many physical and chemical phenomena. These phenomena are diverse in nature, but in common they are dependent on the moisture properties of the material. Therefore, the prediction of the potential degradation of cementitious materials requires the study of the movement of liquid-water and gas-phase transport in the material which is considered as a porous medium. In natural environment, structures are always affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on the drying process. There are few researches considering both drying and wetting, although these conditions represent natural RH variations. Even few studies take into account hysteresis in moisture transport. Thus, this work is devoted to better understand how the moisture behaviour within cementitious materials responds to the ambient RH changes through both experimental investigations and numerical modelling. In particular, hysteretic effects will be included in numerical modelling. In this thesis, we first recalled a complicate multi-phase continuum model. By theoretical analysis and experimental verification, a simplified model can be obtained for the case of that the intrinsic permeability to liquid-water is smaller than the intrinsic permeability to gas-phase. The review of commonly-used hysteresis models enabled to conclude a set of best models for the prediction of water vapour sorption isotherms and their hysteresis. After that, the simplified model was coupled with selected hysteresis models to simulate moisture transport under drying and wetting cycles. Compared with experimental data, numerical simulations revealed that modelling with hysteretic effects can provide much better results than non-hysteresis modelling. Among different hysteresis models, results showed that the use of the conceptual hysteresis model, which presents closed form scanning loops, can provide more accuracy predictions. Further simulations for different scenarios were also performed. All comparisons and investigations enhanced the necessity of considering hysteresis to model moisture transport for varying relative humidity at the boundary. The investigation of moisture penetration depth could provide a better understanding of how deep moisture as well as ions can move into the material. Furthermore, the analysis revealed that the consideration of Knudsen effects for diffusion of vapour can improve the prediction of the apparent diffusivity
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Betiol, Lilian Fachin Leonardo [UNESP]. "Estudo das isotermas de adsorção do bagaço de mandioca proveniente da indústria de fécula." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/145009.
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Previous issue date: 2016-11-21<br>As isotermas de sorção tornaram-se importantes para prever o comportamento da cinética de secagem e as condições de armazenamento de resíduos da indústria alimentícia. O conhecimento de tal propriedade é útil para projetar equipamentos ou operações para fins de armazenamento ou processamento. O bagaço quando é apenas descartado, representa um desperdício de matéria prima, de compostos orgânicos com categoria bioquímica definida (proteínas, açúcares, ceras, graxas, resinas), que poderia ser aproveitada. Dentro deste contexto, a presente pesquisa teve como objetivo caracterizar quimicamente o bagaço de mandioca e fazer a determinação experimental das isotermas de sorção destes resíduos da indústria de fécula, além de calcular a entalpia e entropia, temperatura media harmônica e calor isostérico de adsorção. Para isso, o teor de umidade de equilíbrio nas isotermas de sorção, de bagaço de mandioca, foi determinado utilizando o método gravimétrico estático nas temperaturas de 20 a 80 °C. Modelos teóricos e empíricos foram usados para representar os valores experimentais das isotermas de sorção, sendo que o modelo de GAB foi o que apresentou os melhores ajustes. Utilizando o modelo de GAB foi possível determinar o calor isostérico de adsorção como função do teor de umidade. A teoria da compensação foi confirmada pela relação linear entre entalpia e entropia. Maiores valores de temperatura isocinética do que a temperatura harmônica reforçam a teoria da compensação e sugeriram que a adsorção de água pelo bagaço de mandioca é considerado um processo conduzido pela entalpia.<br>The sorption isotherms become important to predict the drying kinetics behavior and waste storage conditions of the food industry. The knowledge of such property is useful for designing equipment or operations for storage or processing. The bagasse is only when discarded, is a waste of raw materials, organic compounds with defined biochemical category (proteins, sugars, waxes, greases, resins), which could be harnessed. Within this context, this study aimed to chemically characterize the Cassava Bagasse and make the experimental determination of the sorption isotherms of these starch industry waste and calculates the enthalpy and entropy, harmonic average temperature and isosteric heat of adsorption. For this, the equilibrium moisture content in the sorption isotherms of cassava bagasse was determined using the gravimetric static method in temperatures 20-80 ° C. Theoretical and empirical models were used to represent the experimental values of sorption isotherms, and the GAB model was the one that presented the best fit. Using the GAB model was possible to determine the isosteric heat of adsorption and moisture content of the function. The theory of compensation was confirmed by the linear relationship between enthalpy and entropy. Isokinetic higher temperature values than the harmonic temperature reinforce the theory of compensation and suggested that the adsorption of water by mancioca bagasse and considered one of enthalpy driven process.
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Funk, Max. "Hysteresis der Feuchtespeicherung in porösen Materialien." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-88943.
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In dieser Arbeit wird eine einheitliche physikalische Beschreibung des Feuchtespeicherverhaltens poröser Materialien gegeben, und ein anwendungsorientiertes Modell daraus abgeleitet. Insbesondere wird die Hysteresis der Feuchtespeicherung berücksichtigt. Die thermodynamischen Grundlagen der Feuchtespeicherung werden vollständig abgeleitet. Die Energie des kondensierten Wassers wird durch die Energie der freien Flüssigphase zuzüglich einer Porenwechselwirkungsenergie dargestellt. Um das Kondensationsverhalten zu beschreiben, wird ein thermodynamisches Kondensationspotential eingeführt; dabei werden ein Ungleichgewicht zwischen Kondensatphase und Wasserdampf sowie mehrere unabhängige Wassergehalte im Porensystem zur Darstellung der Hysteresis berücksichtigt. Für verschiedene in der Literatur beschriebene Sorptionsprozesse wird mit einheitlichen Zustandsgrössen das Kondensationspotential berechnet. Die Hysteresis wird als verzögerte Bewegung des Systemzustandes in der Berg- und Tallandschaft des Kondensationspotentials interpretiert. Es wurden an 11 Materialien Sorptionsmessungen im hygroskopischen Luftfeuchtebereich (0-92% RH) durchgeführt: Eine Adsorptionskurve und mehrere Desorptionskurven, sowie eine Langzeitmessung der Feuchteaufnahme bei 92% RH. Aus dem Adsorptions-Desorptionsverhältnis entnimmt man, dass der Hysteresis-Effekt typischerweise etwa 20% ausmacht. Mit den Messungen werden für alle Materialien das Modell der unabhängigen Domänen, das hysteretische thermodynamische Kondensationspotential und das Sorptionskurvensystem parametrisiert. Die Feuchteaufnahme bei dem Langzeitexperiment lässt sich durch eine bimodale Exponentialfunktion beschreiben. Die Kurven von hygroskopischer Adsorption und Desorption werden durch analytische Funktionen angenähert. Die Steigungen der Zwischenkurven werden aus den Steigungen der Hauptkurven berechnet. In gleicher Weise wird auch der überhygroskopische Bereich dargestellt, unter Zuhilfenahme externer Messdaten. Schliesslich ergeben sich zwei getrennt parametrisierte, aneinander angrenzende Sorptionsschleifen für den hygroskopischen und den überhygroskopischen Bereich. Alle Parameter werden so angepasst, dass eine grösstmögliche Übereinstimmung mit dem Domänenmodell erzielt wird<br>This work gives a unified physical description of moisture storage in very different porous materials and derives an application-oriented model, especially the hysteresis of moisture storage has been investigated extensively. A full derivation of the thermodynamics of moisture sorption is given. The energy of condensed water is described by the energy of the free liquid plus a pore interaction energy. To describe the condensation behaviour, a thermodynamic condensation potential is introduced. It takes into account a non-equilibrium between condensed water and water vapour as well as several independent moisture contents in the liquid phase to describe the hysteresis. For many different sorption processes described in literature the condensation potential is derived, using always the same state variables. Hysteresis is interpreted as a delayed movement of the system in the hill-and-valley-landscape of the condensation potential. Sorption measurements have been performed for 11 different materials in the hygroscopic region (0-92% RH). One adsorption curve and several desorption curves and also the time dependent moisture sorption at 92% RH in a long-time experiment have been measured. From the adsorption-desorption ratio it can be concluded that the influence of hygroscopic hysteresis is typically about 20%. From the measurement results, for all materials the model of independent domains, the hysteretic condensation potential and the sorption curve system are parameterised. The moisture uptake of the long-time experiment can be described by a bimodal exponential function. The curves of hygroscopic adsorption and desorption are approximated by analytical functions. The slopes of the intermediate curves are calculated from the slopes of the main curves. In the same way the overhygroscopic region is approximated, using external measurement results. Finally a model is presented with two neighbouring sorption loops, one for the hygroscopic, one for the overhygroscopic region. All parameters are fitted to the predictions of the domain model
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Wang, Jing-hung, and 王景弘. "Study on Sorption Isotherms and Moisture Migration of Composite Foods." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/87944445697621662134.
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碩士<br>大葉大學<br>生物產業科技學系<br>100<br>Preserved foods containing more than one component are called as composite foods, among which moisture transfer phenomenon often occurs. In the condition of long-term preservation, moisture transfer easily occurs among each heterogeneous component, results in a tremendous impact on food quality, and affects food safety. Previous studies of the moisture in composite foods focused on discussions of overall water activity, and seldom involved equilibrium moisture content of heterogeneous components and moisture transfer among them. Therefore, this study selected composite foods containing two types of different components, sold in markets, as samples. Then established their sorption isotherms by static method, and analyzed their moisture migration so as to further observe the transfer of moisture between heterogeneous components and its effects on equilibrium moisture content after separately or commonly storing. Samples including almonds & dried fishes and cereals & raisins were stored in 8 relatively different humidity environments. Besides, researches in sensory evaluation on two types of composite food were carried out in the shelf life in order to understand effects of moisture transfer between heterogeneous components on consumers’ sensory organs. Experimental results showed equilibrium moisture content of two types of composite foods, including almonds & dried fishes and cereal & raisins, increased with the rise in relative humidity of preserved environment. The reason was that food absorbed moisture in the environment gradually when food’s water activity was relatively low. Results of measurement of equilibrium moisture content in almonds and dried fishes showed that when they were preserved together, dried fishes water activity rises due to interactions with almonds while effects on almonds, were not obvious due to structural denseness and rich in fat. But moisture content of dried fishes rose immediately, which will affect food quality and cause food spoilage. Results of measurement of equilibrium moisture content of cereal and raisin showed cereal as stable component, which is beneficial to food quality, since effects from cereal absorbing condition water were not shown on water activity. Raisin’s sorption isotherms for common preserved had the trend to move towards left obviously when preserved with cereal. The effect of interactions between two heterogeneous components reduced the water activity of raisin. The above results showed moisture interaction occurred between heterogeneous components when composite foods were in preservation, and it indeed affected equilibrium moisture content and water activity of food.In terms of sensory evaluation, three control groups of almonds and dried fishes in dry condition, general condition and in the condition of just unpacked had no significant differences in scores. However, overall preference of control groups was well accepted. Sensory evaluation experiments for cereal and raisins showed foods stored in dry condition were the best loved by judges.
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Funk, Max. "Hysteresis der Feuchtespeicherung in porösen Materialien." Doctoral thesis, 2010. https://tud.qucosa.de/id/qucosa%3A26043.
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In dieser Arbeit wird eine einheitliche physikalische Beschreibung des Feuchtespeicherverhaltens poröser Materialien gegeben, und ein anwendungsorientiertes Modell daraus abgeleitet. Insbesondere wird die Hysteresis der Feuchtespeicherung berücksichtigt.
Die thermodynamischen Grundlagen der Feuchtespeicherung werden vollständig abgeleitet. Die Energie des kondensierten Wassers wird durch die Energie der freien Flüssigphase zuzüglich einer Porenwechselwirkungsenergie dargestellt. Um das Kondensationsverhalten zu beschreiben, wird ein thermodynamisches Kondensationspotential eingeführt; dabei werden ein Ungleichgewicht zwischen Kondensatphase und Wasserdampf sowie mehrere unabhängige Wassergehalte im Porensystem zur Darstellung der Hysteresis berücksichtigt. Für verschiedene in der Literatur beschriebene Sorptionsprozesse wird mit einheitlichen Zustandsgrössen das Kondensationspotential berechnet. Die Hysteresis wird als verzögerte Bewegung des Systemzustandes in der Berg- und Tallandschaft des Kondensationspotentials interpretiert.
Es wurden an 11 Materialien Sorptionsmessungen im hygroskopischen Luftfeuchtebereich (0-92% RH) durchgeführt: Eine Adsorptionskurve und mehrere Desorptionskurven, sowie eine Langzeitmessung der Feuchteaufnahme bei 92% RH. Aus dem Adsorptions-Desorptionsverhältnis entnimmt man, dass der Hysteresis-Effekt typischerweise etwa 20% ausmacht.
Mit den Messungen werden für alle Materialien das Modell der unabhängigen Domänen, das hysteretische thermodynamische Kondensationspotential und das Sorptionskurvensystem parametrisiert. Die Feuchteaufnahme bei dem Langzeitexperiment lässt sich durch eine bimodale Exponentialfunktion beschreiben.
Die Kurven von hygroskopischer Adsorption und Desorption werden durch analytische Funktionen angenähert. Die Steigungen der Zwischenkurven werden aus den Steigungen der Hauptkurven berechnet. In gleicher Weise wird auch der überhygroskopische Bereich dargestellt, unter Zuhilfenahme externer Messdaten. Schliesslich ergeben sich zwei getrennt parametrisierte, aneinander angrenzende Sorptionsschleifen für den hygroskopischen und den überhygroskopischen Bereich. Alle Parameter werden so angepasst, dass eine grösstmögliche Übereinstimmung mit dem Domänenmodell erzielt wird.:1. Einleitung
2. Allgemeine Thermodynamik der Feuchtesorption
3. Sorptionsmodelle in einheitlicher Beschreibung
4. Experimentell untersuchte Materialien
5. Parametrisierung von Modell und Sorptionskurven
6. Zusammenfassung
A.1. Details zur Theorie
A.2. Details zum Experiment
A.3. Details zur Parametrisierung<br>This work gives a unified physical description of moisture storage in very different porous materials and derives an application-oriented model, especially the hysteresis of moisture storage has been investigated extensively.
A full derivation of the thermodynamics of moisture sorption is given. The energy of condensed water is described by the energy of the free liquid plus a pore interaction energy. To describe the condensation behaviour, a thermodynamic condensation potential is introduced. It takes into account a non-equilibrium between condensed water and water vapour as well as several independent moisture contents in the liquid phase to describe the hysteresis. For many different sorption processes described in literature the condensation potential is derived, using always the same state variables. Hysteresis is interpreted as a delayed movement of the system in the hill-and-valley-landscape of the condensation potential.
Sorption measurements have been performed for 11 different materials in the hygroscopic region (0-92% RH). One adsorption curve and several desorption curves and also the time dependent moisture sorption at 92% RH in a long-time experiment have been measured. From the adsorption-desorption ratio it can be concluded that the influence of hygroscopic hysteresis is typically about 20%.
From the measurement results, for all materials the model of independent domains, the hysteretic condensation potential and the sorption curve system are parameterised. The moisture uptake of the long-time experiment can be described by a bimodal exponential function.
The curves of hygroscopic adsorption and desorption are approximated by analytical functions. The slopes of the intermediate curves are calculated from the slopes of the main curves. In the same way the overhygroscopic region is approximated, using external measurement results. Finally a model is presented with two neighbouring sorption loops, one for the hygroscopic, one for the overhygroscopic region. All parameters are fitted to the predictions of the domain model.:1. Einleitung
2. Allgemeine Thermodynamik der Feuchtesorption
3. Sorptionsmodelle in einheitlicher Beschreibung
4. Experimentell untersuchte Materialien
5. Parametrisierung von Modell und Sorptionskurven
6. Zusammenfassung
A.1. Details zur Theorie
A.2. Details zum Experiment
A.3. Details zur Parametrisierung
Books on the topic "Moisture Sorption Isotherms"
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Universitas Sam Ratulangi. Fakultas Perikanan., ed. Moisture sorption isotherm dari beberapa produk olahan traditional hasil perikanan di Sulawesi Utara: Laporan penelitian. Universitas Sam Ratulangi, Fakultas Perikanan, 1992.
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Labuza, Theodore P. Moisture Sorption: Practical Aspects of Isotherm Measurement and Use. 2nd ed. American Association of Cereal Chemists, 2000.
Find full textBook chapters on the topic "Moisture Sorption Isotherms"
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Weisser, Horst, and Franz Liebenspacher. "Determination of Water Content and Moisture Sorption Isotherms of Cellulose Packaging Material." In Food Properties and Computer-Aided Engineering of Food Processing Systems. Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2370-6_15.
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Caballero-Cerón, C., J. A. Guerrero-Beltrán, H. Mújica-Paz, J. A. Torres, and J. Welti-Chanes. "Moisture Sorption Isotherms of Foods: Experimental Methodology, Mathematical Analysis, and Practical Applications." In Food Engineering Series. Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2578-0_15.
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Sharma, A. K., N. R. Panjagari, and A. K. Singh. "Intelligent Modelling of Moisture Sorption Isotherms in Milk Protein-Rich Extruded Snacks Prepared from Composite Flour." In Communications in Computer and Information Science. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0755-3_10.
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Kumar Das, Susanta, and Madhusweta Das. "Water Activity and Moisture Sorption Isotherm." In Fundamentals and Operations in Food Process Engineering. CRC Press, 2019. http://dx.doi.org/10.1201/9780429058769-12.
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Saha, Nabanita, Madhusweta Das, Dipali S. Shinde, Antonin Minařík, and Petr Saha. "Moisture Sorption Isotherm and Isosteric Heat of Sorption Characteristics of PVP-CMC Hydrogel Film: A Useful Food Packaging Material." In Polymers and Polymeric Composites: A Reference Series. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-76573-0_36-1.
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Saha, Nabanita, Madhusweta Das, Dipali S. Shinde, Antonin Minařík, and Petr Saha. "Moisture Sorption Isotherm and Isosteric Heat of Sorption Characteristics of PVP-CMC Hydrogel Film: A Useful Food Packaging Material." In Polymers and Polymeric Composites: A Reference Series. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-77830-3_36.
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Aguilera, José Miguel. "Moisture Sorption Isotherms." In Encyclopedia of Agricultural, Food, and Biological Engineering, Second Edition. CRC Press, 2010. http://dx.doi.org/10.1081/e-eafe2-120007224.
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Mtori, Samia, Amira Touil, and Fethi Zagrouba. "Desorption Isotherms and Thermodynamic Properties of Prickly Pear Seeds." In Advances in the Modelling of Thermodynamic Systems. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-8801-7.ch004.
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Sorption isotherms of prickly pear seeds were determined by static gravimetric method at temperatures 45º, 60º, and 70ºC, over a relative moisture range of 5-95%. Sorption isotherms are important to define dehydration limits of the product, estimate moisture content alterations under environment conditions, and to acquire moisture content values for safe storage. Four mathematical models were applied to analyze the experimental data. Equilibrium moisture contents of prickly pear seeds decreased with temperature increment at a constant value of relative humidity. The GAB model showed the best fitting to the experimental data. Isosteric heat and differential entropy, determined by applying the Clausius-Clapeyron and Gibbs-Helmholtz equations respectively, decreased strongly as the moisture content increased and could be well adjusted by an empirical exponential relationship. Enthalpy-entropy compensation theory is valid for the sorption of prickly pear seeds, in which the water sorption mechanism in seeds can be considered to be enthalpy controlled.
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Seaidpour M. and Wadsö L. "Comparison of moisture equilibrium of cement-based materials in presence of slag and silica fume in different wetting and drying cycles." In Construction Materials and Structures. IOS Press, 2014. https://doi.org/10.3233/978-1-61499-466-4-813.
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Water vapor sorption isotherms are essential data in models to predict the service life of the cement based structures. The knowledge about sorption isotherms in the presence of supplementary cementitous materials (SCMs) is limited. This study investigates the influence of water to cement ratio (0.4, 0.5 and 0.6), and the presence of two SCMs (70% slag and 10% silica fume) on sorption isotherm in hygroscopic and above hygroscope RH ranges for paste and mortars. Dynamic vapor balance in hygroscopic rang and pressure plates above hygroscopic range are used to generate sorption isotherms. Based on Jennings model (CM-II) for C-S-H structure, desorption isotherms are divided to different parts in which different pores are emptied. The samples with silica fume and slag have higher moisture content than OPC, but, with higher amount of gel pores and lower amount of capillary pores. At low RH intervals all samples have very similar desorption curves and introduction of SCMs induce slightly increase on BET surface area. Above 30% RH, samples have different desorption curves and the initial desorption is higher than following desorption for all samples.
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A. Aviara, Ndubisi. "Moisture Sorption Isotherms and Isotherm Model Performance Evaluation for Food and Agricultural Products." In Sorption in 2020s. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.87996.
Full textConference papers on the topic "Moisture Sorption Isotherms"
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Zammouri, Amel, M. Ben Zid, N. Kechaou, and N. Boudhrioua Mihoubi. "Thermodynamic properties and moisture sorption isotherms of two pharmaceutical compounds." In 21st International Drying Symposium. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7702.
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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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Luna-Flores, Mario, Mariana Gisela Peña-Juarez, Angélica Mara Bello-Ramirez, Javier Telis-Romero, and Guadalupe Luna-Solano. "Moisture sorption isotherms and isosteric heat sorption of habanero pepper (Capsicum chínense) dehydrated powder." In 21st International Drying Symposium. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7637.
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Moisture sorption isotherms of the habanero pepper powder were determined using the Dynamic Vapor Sorption (DVS) method at 20, 25, 35, 45 and 55 °C in a range of water activity from 0.10 to 0.90 at which the processes of drying, packing and storage of habanero pepper are developed. The sorption capacity decreased with increasing temperature at a given water activity and the sorption isotherms showed a sigmoid form (Type II). The hysteresis phenomenon was observed in the sorption isotherms at all temperatures studied and it was more pronounced at temperatures high. The experimental sorption curves were fitting to the GAB, BET and Oswin models. It was concluded that the models that best describe the adsorption and desorption data for habanero pepper dehydrated powder were the GAB and Oswin models. The isosteric heat of water sorption was calculated with the moisture content data in equilibrium. The desorption isotherms present a higher isosteric heat in relation to the adsorption isotherms. In both, the isosteric heat decreased as the moisture content increased. Keywords: Habanero pepper dehydrated powder; Convective drying; Moisture sorption isotherms; Mathematic models
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Collazos-Escobar, Gentil Andres, Nelson Gutiérrez-Guzmán, Henry Alexander Vaquiro-Herrera, and Erika Tatiana Cortes-Macias. "Modeling sorption isotherms and isosteric heat of sorption of roasted coffee beans." In 21st International Drying Symposium. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7668.
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The aim of this work was determine the sorption isotherms in roasted beans of specialty coffee at temperatures of 25, 30 and 40 °C and water activities between 0.1 and 0.8 using the dynamic dew point method. The experimental sorption data were modeled using 12 different equations to represent the dependence of equilibrium moisture content with aw and temperature. The net isosteric heat of sorption was determined from the experimental sorption data using the Clausius-Clapeyron equation. The Weibull model satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in roasted coffee beans (R2adj =0.902 and RMSE = 0.00550 kg·kg-1d.b.). The net isosteric heat of sorption increase with increased moisture content. Keywords: water activity; sorption properties; equilibrium moisture content; hygroscopicity
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Razak, N. A., I. A. Jazlan, A. R. Shaari, and L. Y. Leng. "Modelling moisture sorption isotherms for Orthosiphon stamineus spray-dried powder." In GREEN DESIGN AND MANUFACTURE: ADVANCED AND EMERGING APPLICATIONS: Proceedings of the 4th International Conference on Green Design and Manufacture 2018. Author(s), 2018. http://dx.doi.org/10.1063/1.5066652.
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Sharma, Adesh Kumar, Avnish Kumar Bhatia, Anurag Kulshrestha, and Ish Kumar Sawhney. "Neurogenetic Modeling of Moisture Sorption Isotherms in Dried Acid Casein." In 2020 Indo-Taiwan 2nd International Conference on Computing, Analytics and Networks (Indo-Taiwan ICAN). IEEE, 2020. http://dx.doi.org/10.1109/indo-taiwanican48429.2020.9181318.
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P.V.K.Jagannadha Rao, Susanta Kumar Das, and Madhusweta Das. "Moisture Sorption Isotherms of Sugarcane, Palmyra and Date-Palm Jaggery." In 2006 Portland, Oregon, July 9-12, 2006. American Society of Agricultural and Biological Engineers, 2006. http://dx.doi.org/10.13031/2013.20851.
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Tasara, Jutarut, Supawan Tirawanichakul, and Yutthana Tirawanichakul. "Thermodynamic properties and moisture sorption isotherms four types of natural rubber." In 2011 IEEE Colloquium on Humanities, Science and Engineering (CHUSER). IEEE, 2011. http://dx.doi.org/10.1109/chuser.2011.6163781.
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Amel, Fedol, and A. Cheriti. "Modelling the Water Sorption Isotherms of Warionia Saharae and determination of sorption heats and drying kinetics." In 21st International Drying Symposium. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7669.
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The hygroscopic equilibrium of Warionia saharae was studied, which allowed getting an idea of the equilibrium water content relative to a given humidity. The results of this study made it possible to have the sorption curves. The results of this study made it possible to obtain the sorption curves necessary for know the storage conditions of the plant and the study of its drying kinetics. The static gravimetric method was used to determine sorption isotherms of Warionia saharae leaves at 30and 40 ◦C and in the range of water activity varying from 0.063 to 0.898. The Gab, Peleg models was found to be the most suitable for describing the sorption curves. The isosteric heat calculated by applying the Clausius–Clapeyron equation .The desorption isosteric heat was higher than the isosteric heat of adsorption and both decreased continuously with increasing of the equilibrium moisture content. The experimental results obtained allowed us to determine the temporal evolution of the drying kinetics as a function of the moisture content. The curve of the evolution of the water content as a function of time shows the absence of the phases product temperature and constant drying rate Keywords: Sorption isotherm, isosteric heats, modelling, kinetics, Warionia saharae.
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Abdenouri, Naji, Hicham El Ferouali, Ahmed Zoukit, and Said Doubabi. "Solar convective drying kinetics and sorption isotherms of Citrus aurantium flowers." In 21st International Drying Symposium. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7656.
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Citrus aurantium flowers are high value aromatic and medicinal plants. The storage conditions and quality of dried Citrus aurantium flowers depends on their hygroscopic stability. The equilibrium moisture content was determined at temperatures (from 30 to 60 °C), and the sorption phenomenon is well described by Peleg model. The optimal water activity for the storage of the product was estimated at awop=0.373. Afterwards, the net isosteric heat was evaluated in the range of 88 kJ.mol−1 for small values of the moisture content (Xeq=0.14kg water/kg d.b), and it decreased along with the increase of Xeq. The experimental drying curves showed only a falling rate period. Finally, Midilli-Kucuk model was found to be the more suitable to describe the drying kinetic of Citrus aurantium flowers. Keywords: Drying kinetics; Solar energy; Modeling; Citrus aurantium; Sorption isotherms; Conservation process
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Tolstorebrov, Ignat, Trygve Magne Eikevik, Inna Petrova, Yulia Shokina, and Michael Bantle. "Investigation of influence of pre-treatment and low-temperature on drying kinetics, sorption properties, shrinkage and color of brown seaweeds (Saccharina Latissima)." In 21st International Drying Symposium. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7694.
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Drying kinetics of Saccharina latissima (raw and blanched) at low temperatures (10.0, 25.0 and 38.0 °C) was studied. The effective moisture diffusivity coefficient varied due to temperature alterations in the range between 1.4 and 4.5 10-10 m2/s for raw and 0.91 and 2.56 10-10 m2/s for blanched seaweeds. Significant changes in structural properties and chemical composition resulted in a much longer drying time of blanched seaweeds, when compared with raw. Drying temperature of 38.0 °C resulted in more brown color, when compared with other samples. Sorption characteristics of dried raw seaweeds depended on salt content and showed high accumulation of moisture at relative humidity of air of 80.0 %. The blanched seaweeds showed linear accumulation of moisture within increasing of relative humidity of drying air from 20.0 to 80.0 %, but high level of hysteresis was determined between sorption and desorption isotherms. The shrinkage development within dewatering of blanched and raw samples was also studied. Keywords: brown seaweeds, drying kinetics, sorption isotherms, color
Reports on the topic "Moisture Sorption Isotherms"
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Glass, Samuel V., Samuel L. Zelinka, Charles R. Boardman, and Emil Engelund Thybring. Promoting advances in understanding water vapor sorption in wood: relegating popular models and misconceptions. Department of the Built Environment, 2023. http://dx.doi.org/10.54337/aau541615744.
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Water vapor sorption is a fundamental characteristic of wood as a building material. Apart from empirical prediction, models are often used to interpret the time-dependent process of water vapor uptake (sorption kinetics) and equilibrium states of water in wood (sorption isotherms). This paper summarizes our recent investigations into measurement methods and popular models that are widely used for interpreting these physical phenomena. Commonly used criteria for determining equilibrium moisture content with the dynamic vapor sorption technique yield much larger errors than previously thought. A more rigorous equilibrium criterion and a method to reduce data acquisition time are proposed. Evaluation of the parallel exponential kinetics model with improved data and multi-exponential decay analysis indicates that this model is unable to characterize the full sorption kinetic response following a step change in relative humidity. Fitting of common sorption isotherm models to high-quality equilibrium data for wood gives model predicted physical quantities such as monolayer capacity and enthalpy of sorption that are far from agreement with independently measured data. Thus, these models are not valid for water vapor sorption in wood. New theoretical models are needed that correctly describe the physical phenomena.