scholarly journals Cumulative Effect of Pressing and Drying on Stress Generation within a Green Ceramic Compact

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
E. Vidal-Sallé ◽  
D. Falgon ◽  
R. Peczalski ◽  
J-C. Boyer
Keyword(s):  
Ceramic Powder ◽  
Cumulative Effect ◽  
Constitutive Law ◽  
Stress Generation ◽  
Convective Drying ◽  
Elastic Behavior ◽  
Drying Process ◽  
Material Density ◽  
External Edge ◽  
Internal Stress Field

The internal stress field induced by uniaxial pressing and subsequent convective drying of a green ceramic powder was simulated by the finite element method. A density dependent elastoplastic constitutive law was used for the mechanical modeling of the compaction. A diffusive water transfer equation and a purely elastic behavior with imposed hydrostrain involving shrinkage were applied for the modeling of the drying process. The key material properties (hydrodiffusivity, hydrocontraction coefficient, Young’s modulus, Poisson’s ratio, and yield surface parameters) had been experimentally measured and introduced as functions of material density and water content. If residual stresses due to the compaction operation were taken into account, the maximum value of the tensile stress at the top external edge of the wheel and at the beginning of the drying process was two times higher than for a stress free green ceramic compact. Beyond the residual stress onset, the compaction operation induced density heterogeneities which had important consequences on the mechanical behavior of the compact.

OPTIMIZATION OF CONVECTIVE DRYING PROCESS BASED ON ECONOMIC INDICATORS

1998 ◽  
Vol 16 (7) ◽  
pp. 1527-1528 ◽  
Author(s):  
Marko S. Blagojevic
Keyword(s):  
Economic Indicators ◽  
Convective Drying ◽  
Drying Process

Quality Assessment and Mathematical Modeling of Hot-Air Convective Drying of Persimmon (Diospyros kaki L.) Fruit

2017 ◽  
Vol 13 (7) ◽  
Author(s):  
Claudia Giovagnoli-Vicuña ◽  
Nelson O. Moraga ◽  
Vilbett Briones-Labarca ◽  
Pablo Pacheco-Pérez
Keyword(s):  
Quality Parameters ◽  
Time Function ◽  
Convective Drying ◽  
Diospyros Kaki ◽  
Drying Process ◽  
Temperature Function ◽  
Persimmon Fruit ◽  
Hot Air ◽  
Volume Method ◽  
Good Agreement

Abstract The influence of drying on the color, porosity, shrinkage and moisture of persimmon fruit during convective drying was determined by computer vision. The experiments were performed with persimmon fruit that were cut into slab 20 × 20 mm, which were arranged into a bigger slab, 60 × 60 mm. Drying process was carried out at 60 °C. Noticeable changes in quality parameters (color, porosity and shrinkage) could be observed during the drying process, where the central region of the sample evidenced less changes. Persimmon’s physical properties were experimentally obtained as the temperature function and heat and mass convective coefficients were adjusted as a time function. A numerical simulation using the Finite Volume Method allowed to describe the evolution of temperature and moisture content distributions during drying. The numerical and experimental results of temperature and moisture during persimmon drying were found to be in a good agreement.

scholarly journals Differential Sea-Ice Drift. II. Comparison of Mesoscale Strain Measurements to Linear Drift Theory Predictions

1974 ◽  
Vol 13 (69) ◽  
pp. 457-471 ◽  
Author(s):  
W. D. Hibler
Keyword(s):  
High Pressures ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Local Pressure ◽  
Strain Measurements ◽  
Linear Drift ◽  
Special Cases ◽  
Drift Theory ◽  
Sea Ice Drift ◽  
Frequency Behavior

A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicate that the ice divergence rate and vorticity follow the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds the divergence rate was found to be negative with the vorticity being counter-clockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior was shown to agree with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen (1970) for pack ice. The best least-squares values of the constitutive law parametersηandζwere found to be ≈ 1012kg/s. Using typical divergence rates these values yield compressive stresses of the magnitude of 105N/m which are similar to values suggested by the Parmerter and Coon (1972) ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low-pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer).Calculations were also carried out using a more general linear visco-elastic constitutive law that includes memory effects and which includes a generalized Hooke’s law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates overall a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated “viscosities” similar to the Glen law behavior at temporal frequencies less than ≈ 0.01 h−1.

Thermodynamic Theory of Convective Drying Process of Porous Media

2002 ◽  
Author(s):  
You-Rong Li ◽  
Dan-Ling Zeng
Keyword(s):  
Mass Transfer ◽  
Heat Source ◽  
Heat And Mass Transfer ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Thermodynamic Theory ◽  
Convective Drying ◽  
Internal Mass ◽  
Drying Process ◽  
Mass Source

Based on non-equilibrium thermodynamic theory and combined with the conservation laws, a comprehensive theoretical model was established to describe heat and mass transfer during convective drying process, and numerical calculation was performed. The results show that: (a) the external convective heat and mass transfer may be treated as the conductive heat transfer with internal heat source and the molecular mass diffusion with internal mass source, respectively, and the ability of heat and mass transfer mainly depends on the strength of the heat source and mass source; the higher the temperature of the drying media, the lower the strength of the internal heat source, but the higher that of the internal mass sources; (b) the evaporation of internal water takes place inside the whole material, and the molecular mass diffusion of the internal vapor is in the direction of decreasing mass transfer potential, not along the decreasing partial pressure of vapor.

scholarly journals 3D simulation on convective drying process for cylindrical tea particle using CFD software to analyze the heat and mass transfer phenomena

2020 ◽  
Author(s):  
Eflita Yohana ◽  
Nazaruddin Sinaga ◽  
Haryo Pachusadewo ◽  
M. Irfan Nugraha ◽  
M. Endy Yulianto ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
3D Simulation ◽  
Convective Drying ◽  
Drying Process

scholarly journals BIOFUELS DRYING PROCESS EFFICIENCY RESEARCH / BIOKURO DŽIOVINIMO PROCESO EFEKTYVUMO TYRIMAI

2013 ◽  
Vol 5 (6) ◽  
pp. 609-614
Author(s):  
Osvaldas Šlepikas ◽  
Audrius Čereška
Keyword(s):  
Positive Impact ◽  
Ultrasonic Transducer ◽  
Process Efficiency ◽  
Convective Drying ◽  
Drying Process ◽  
Wood Pellets ◽  
Drying Time ◽  
Hot Air ◽  
Special Stand ◽  
Experimental Rig

The paper deals with biofuel drying process efficiency opportunities.Research was carried out with a special stand and performingexperiments. Experimental rig consists of an ultrasonic generator,ultrasonic transducer, a drying chamber and the humidity,temperature gauge. Tests were used for wood pellets. During theexperiment, they were irrigated with water, dried with hot air andadditionally exposed to different frequency ultrasonic vibrations.The tests results have showed that the convective drying processis combined with the ultrasonic vibrations, the drying time isreduced, which means a positive impact on the ultrasonic process.Studies have confirmed that the effectiveness of convectivedrying method combined with operating ultrasonic vibrationsincreases. Santrauka Straipsnyje nagrinėjamos biokuro džiovinimo proceso efektyvumo didinimo galimybės. Tyrimams atlikti sukurtas specialus stendas ir sudaryta eksperimento atlikimo metodika. Eksperimentinį stendą sudaro ultragarsinis generatorius, ultragarsinis keitiklis, džiovinimo kamera ir drėgmės, temperatūros matuokliai. Buvo tiriamos medžio granulės. Eksperimento metu jos buvo drėkinamos vandeniu, džiovinamos karštu oru ir papildomai veikiamos skirtingo dažnio ultragarsiniais virpesiais. Atlikus bandymus, rezultatai parodė, kad, veikiant konvekcinio džiovinimo procesą ultragarsiniais virpesiais, džiovinimo laikas sutrumpėja. Tai reiškia teigiamą ultragarso poveikį procesui. Tyrimais patvirtintas konvekcinio džiovinimo metodo efektyvumo, papildomai veikiant ultragarsiniais virpesiais, padidėjimas.

Hydro-Thermo-Mechanical Model for Highly Deformable Product during Convective Drying

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Lamine Hassini ◽  
Roman Peczalski ◽  
Soufien Azzouz ◽  
Ali Belghith
Keyword(s):  
Mechanical Model ◽  
Thermal Model ◽  
Moisture Transfer ◽  
Solid Phase ◽  
Plane Deformation ◽  
Convective Drying ◽  
Elastic Behavior ◽  
Advection Equation ◽  
Convective Boundary ◽  
Spatio Temporal

The aim of this work was to simulate in 1D, the spatio-temporal evolution of the moisture content, the temperature and the mechanical stress within a highly deformable and saturated product during convective drying. The hydro-thermal model, written in a fixed coordinate system, consisted of solid mass balance equation, moisture transfer diffusion/advection equation and heat transfer conduction/advection equation. These equations were coupled by the solid phase velocity terms due to hydric shrinkage. Convective boundary conditions completed this set of equations. The hydro-thermal model had been merged with a static mechanical model which was based on the hypothesis of an elastic behavior, of a plane deformation and of an ideal shrinkage. The hydro-thermo-mechanical model had been applied to a parallelepipedical potato sample. Its thickness was small compared to the other dimensions, in order to observe an unidirectional drying and a negligible shear stress case. The transport and equilibrium properties of the product required for the modelling were determined from previous experiments which were independent of the drying trials.

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