Identification of the Moisture Distribution in the Intensively Heated Porous Sand Mould

2016 ◽  
Vol 367 ◽  
pp. 121-129
Author(s):  
Zenon Ignaszak ◽  
Paweł Popielarski
Keyword(s):  
Moisture Content ◽  
Moisture Transfer ◽  
Time Moment ◽  
Gravimetric Method ◽  
Moisture Distribution ◽  
Water Evaporation ◽  
Sand Sample ◽  
Molding Sand ◽  
Mould Material ◽  
Sand Mould

The problem presented in the paper concerns physical properties of porous multi-component mould material, into which a liquid metal is poured. The aim of the study was to determine the distribution of moisture in an intensively heated porous sand mould. In the past, several measuring methods have been developed, consisting in water evaporation out of a test sample (at a given time moment , the selected position coordinates of a sample), to determine the accumulated amount of water in the sample, which is a percentage of moisture content. The study described in the paper includes experiments of heating a green sand sample. Moisture distribution in a moisture transfer zone of the sample (temperature of the molding sand is approx. 100°C) was determined. In order to determine the moisture distribution, an original method was used. This method allows interfere in various layers of material of predetermined thickness, parallel to the surface of the mould in contact with a heat source. The classical measurement method (gravimetric method) was used for determining the moisture content of each layer.

scholarly journals Effect of Moisture Content on the Permeability of Tailing Sand Samples Gathered from Ex Tin Mines in Perak State Malaysia

2011 ◽  
Vol 66-68 ◽  
pp. 1384-1389
Author(s):  
A. Abdullah ◽  
Shamsuddin Sulaiman ◽  
B.T. Hang Tuah Baharudin ◽  
M.K.A.M. Arifin ◽  
T.R. Vijayaram
Keyword(s):  
Moisture Content ◽  
Research Work ◽  
Casting Process ◽  
Vital Role ◽  
Sand Casting ◽  
Sand Sample ◽  
Molding Sand ◽  
Sand Mixture ◽  
Testing Procedures ◽  
Work Samples

Tailing sand is one of the residue minerals obtained after tin extraction. It contains silica in between 94% and 99.5% and available in abundance at the Kinta Valley, Perak State, Malaysia. Permeability is one of the important molding sand properties and considered much in the sand casting mold preparation. This molding sand property plays a vital role in the sand casting process and helps to remove the gases during the casting processing. In this research work, samples of tailing sands were gathered from four identified ex tin mines located at the Perak State, Malaysia. They were investigated by the standard sand testing procedures prescribed by the American Foundrymen Society (AFS). Sand specimens of size Ø50 mm×50 mm in height from various sand–water ratios bonded with 4% and 8% clay were compacted on applying three ramming blows of 6666 g each by using a Ridsdale-Dietert metric standard rammer. The specimens were tested for permeability number with the aid of a Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured by using a moisture analyzer. The results were compared with the properties of the molding sand samples collected from RCS Manufacturing Sdn. Bhd., the company supplying sand to the Proton Casting unit car manufacturing company. The molding sand sample sample bonded with 8% clay was found to have maximum permeability with an optimum allowable moisture content range of 3.5-6.0% and for the sand mixture bonded with 4% clay at 3.0-3.5% moisture.

Mathematical modeling of drying of Masson pine lumber and its asymmetrical moisture content profile

Holzforschung ◽  
2014 ◽  
Vol 68 (3) ◽  
pp. 313-321 ◽  
Author(s):  
Jie Zhang ◽  
Ping Miao ◽  
Di Zhong ◽  
Lin Liu
Keyword(s):  
Moisture Content ◽  
Moisture Transfer ◽  
Free Water ◽  
Dirichlet Boundary Conditions ◽  
Moisture Distribution ◽  
Parabolic Partial Differential Equation ◽  
Vapor Permeability ◽  
Drying Process ◽  
Permeability Model ◽  
Masson Pine

Abstract A mathematical model is discussed in terms of moisture transfer during the drying process of Masson pine (Pinus massoniana) lumber in industrial practice. The model was validated by comparing the simulated result of moisture distribution with experimental data. In the model, the wood drying process was divided into two phases. The first one dealt with processes above fiber saturation point (FSP), that was driven by capillary flux of free water and conductive flux of vapor, and the second one dealt with those of below FSP, which was driven by diffusive flux of bound water and vapor. Moisture content distribution (MCD) inside wood is simulated by solving a parabolic partial differential equation under Dirichlet boundary conditions. The moisture content profile (MCP) was asymmetrical in experiments, and the simulation result agreed well with the experiments. An easy empirical formulation was also proposed to calculate real wood permeability, as it showed general characteristics of liquid and vapor permeability. This permeability model is verified as the cause of asymmetrical MCP in this paper.

scholarly journals Moisture Transfer Finite Element Modeling with Soil-Water Characteristic Curve-Based Parameters and its Application to Nhan Co Red Mud Basin Slope

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Nguyen Van Hoang ◽  
Hoang Viet Hung ◽  
Pham Van Dung
Keyword(s):  
Finite Element ◽  
Soil Moisture ◽  
Moisture Content ◽  
Slope Stability ◽  
Moisture Transfer ◽  
Characteristic Curve ◽  
Moisture Distribution ◽  
Wetting Front ◽  
Strength Parameters ◽  
Rainwater Infiltration

Since the year of 2017 landslides at the red mud basins in Nhan Co alumina factory, Dak Nong province have been occurring during the rainy seasons. The change of the soil physical and mechanical parameters due to rainwater infiltration has been considered as the main factor of the slope instability. The soil cohesion and angle of internal friction depend very much on the soil moisture: soil with a lower moisture content has a higher shearing strength than that with higher moisture content. The finite element modeling of moisture transfer in unsaturated soils through the relationship between soil moisture, soil suction, unsaturated permeability and soil-moisture dispersivity is capable of accurately predicting the wetting front development. The element sizes and time steps have been selected based on detailed analysis of analytical error estimation and on the numerical simulations with different element sizes numerical simulation errors. Soil samples had been taken and the soil different suctions and corresponding soil moisture values have been determined in the laboratory. The soil water characteristic curve (SWCC) parameters (a, n and m) have been determined by the best fitting using the least squared error method. The hydraulic conductivity of the saturated soil, one of the key input parameters was also determined. The results of the application to the study area's slope has shown that the wetting front depth can be up to 8 meters for 90 days of moisture transfer due to the rainwater infiltration The wetting front depth and the length of the intermediate part of the moisture distribution curve have increased with the infiltration time. The soil moisture distribution with a depth is an essential information to have soil strength parameters for the slope stability analyses. The slope stability analysis with the soil shear strength parameters which are strictly corresponding with the moisture change would provide the most accurate and reliable slope stability results and provide more reliable slope stabilization solutions.

Influence of High Temperature Heat Sources on the Moisture and Temperature Distribution in a Real/Virtual Foundry Sand Mould

2016 ◽  
Vol 7 ◽  
pp. 69-83
Author(s):  
Paweł Popielarski ◽  
Zenon Ignaszak
Keyword(s):  
Cast Iron ◽  
Physical Properties ◽  
Rapid Heating ◽  
Temperature Fields ◽  
Coupled Modeling ◽  
Molding Sand ◽  
Mould Material ◽  
Sand Mould ◽  
Thermal Phenomena ◽  
Thermo Physical Properties

The problem described in the paper concerns the thermo-physical properties of the green mould material to which the cast iron is most often poured. The study includes the experiment of pouring the cast iron plate into green bentonite-sand mould. The temperature fields of casting and in different zones of the mould were recorded. The goal of the study was to determine the substitute thermo-physical properties of mould sand containing the over-moisture zone by means of simulation tests (inverse problem). An originality of the related research is an attempt to take into account the effects of the global thermal phenomena occurring in the quartz sand bonded by bentonite-water binder, by application of the substitute thermal coefficients without using the coupled modeling. In the simulation tests in order to achieve the effect of rapid heating of the mould (below temperatures 100 °C) by poured cast iron (T>1300 °C), the function of the latent heat source and the modified values of substitute thermal conductivity and substitute specific heat of the molding sand were used. In order to facilitate the solution, the mould was divided into zones, in which different starting humidity of molding sand was assumed.

Modelling and Simulation Moisture Transfer in Wheat Stored in a Simulated Sealed Pit

2008 ◽  
Vol 4 (3) ◽  
Author(s):  
Mohamed A. Ismail ◽  
Michael P. Douglass ◽  
Brian C. Stenning
Keyword(s):  
Finite Difference ◽  
Moisture Content ◽  
Input Data ◽  
Moisture Transfer ◽  
Storage Period ◽  
Moisture Distribution ◽  
Wall Material ◽  
Moisture Contents ◽  
Grain Moisture ◽  
Grain Temperature

A mathematical model, coupled to another one which was used to calculate the conductive heat transfer, was developed to predict the change of moisture distribution with time in the radial and axial directions in a simulated sealed cylindrical pit storing wheat. The finite difference method was used in the model to calculate the diffusive moisture transfer. The model predicts the grain moisture contents in the pit during the storage period using input data of initial grain temperature, initial grain moisture content, storage time and number of spatial elements in both radial and axial directions. Other input data include the finite difference spatial increment in both directions, the finite time increment, temperatures of soil surrounding the pit and the physical properties of grain, pit wall material and surrounding soil. To validate the model, predicted moisture contents were compared with measured data for wheat of Apollo variety being stored in a simulated sealed pit for a period of 70 days. The wheat was stored in a cylindrical mild steel tank with 0.6 m in both diameter and height. The initial uniform grain temperature was 15 °C and the initial uniform grain moisture content was 12.45% (w.b.). Both measured and predicted moisture contents show that the major change in wheat moisture content took place during the first week of the storage and an establishment of steady state under the storage conditions of the pit is unattainable i.e. moisture diffusion is a very slow process. At the end of the storage period, the grain moisture contents were increased by an average of 1.62% (w.b.) and the grain temperatures were decreased by an average of 2.63°C at the top layer of the pit. For the bottom layer of the pit, the grain moisture contents were decreased by an average of 0.50% (w.b.) and the grain temperatures increased by an average of 7.04°C. The diffusive moisture transfer model predicted the grain moisture contents with a standard error of estimate between measured and predicted of 0.18 -0.75% and of 0.18-0.74% (w.b.) using Chung's equation and modified Henderson's equation, respectively. There was no difference between the two sorption equations (Chung's and modified Henderson's equations) used in predicting grain moisture contents.

scholarly journals Influence of Initial Moisture Content on Heat and Moisture Transfer in Firefighters’ Protective Clothing

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Dongmei Huang ◽  
Song He
Keyword(s):  
Moisture Content ◽  
Protective Clothing ◽  
Moisture Transfer ◽  
Burn Injury ◽  
Initial Moisture Content ◽  
Water Evaporation ◽  
Vapor Density ◽  
Degree Burn ◽  
Heat And Moisture ◽  
Second Degree

This paper presents a model for heat and moisture transfer through firefighters’ protective clothing (FPC) during radiation exposure. The model, which accounts for air gaps in the FPC as well as heat transfer through human skin, investigates the effect of different initial moisture contents on the thermal insulation performance of FPC. Temperature, water vapor density, and the volume fraction of liquid water profiles were monitored during the simulation, and the heat quantity absorbed by water evaporation was calculated. Then the maximum durations of heat before the wearer acquires first- and second-degree burns were calculated based on the bioheat transfer equation and the Henriques equation. The results show that both the moisture weight in each layer and the total moisture weight increase linearly within a given environmental humidity level. The initial moisture content in FPC samples significantly influenced the maximum water vapor density. The first- and second-degree burn injury time increase 16 sec and 18 sec when the RH increases from 0% to 90%. The total quantity of heat accounted for by water evaporation was about 10% when the relative humidity (RH) is 80%. Finally, a linear relationship was identified between initial moisture content and the human skin burn injury time before suffering first- and second-degree burn injuries.

Distribution of soil moisture content and its effect on the potential growth of the over-story species in North-East Chalkidiki

2001 ◽  
Vol 66 ◽  
Author(s):  
M. Aslanidou ◽  
P. Smiris
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Soil Depth ◽  
Moisture Distribution ◽  
Taxus Baccata ◽  
Mixed Stands ◽  
Potential Growth ◽  
North East ◽  
Soil Moisture Distribution

This  study deals with the soil moisture distribution and its effect on the  potential growth and    adaptation of the over-story species in north-east Chalkidiki. These  species are: Quercus    dalechampii Ten, Quercus  conferta Kit, Quercus  pubescens Willd, Castanea  sativa Mill, Fagus    moesiaca Maly-Domin and also Taxus baccata L. in mixed stands  with Fagus moesiaca.    Samples of soil, 1-2 kg per 20cm depth, were taken and the moisture content  of each sample    was measured in order to determine soil moisture distribution and its  contribution to the growth    of the forest species. The most important results are: i) available water  is influenced by the soil    depth. During the summer, at a soil depth of 10 cm a significant  restriction was observed. ii) the    large duration of the dry period in the deep soil layers has less adverse  effect on stands growth than in the case of the soil surface layers, due to the fact that the root system mainly spreads out    at a soil depth of 40 cm iii) in the beginning of the growing season, the  soil moisture content is    greater than 30 % at a soil depth of 60 cm, in beech and mixed beech-yew  stands, is 10-15 % in    the Q. pubescens  stands and it's more than 30 % at a soil depth of 60 cm in Q. dalechampii    stands.

scholarly journals Effect of Radial Moisture Distribution on Frequency Domain Dielectric Response of Oil-Polymer Insulation Bushing

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1219 ◽  
Author(s):  
Daning Zhang ◽  
Guanwei Long ◽  
Yang Li ◽  
Haibao Mu ◽  
Guanjun Zhang
Keyword(s):  
Moisture Content ◽  
Space Charge ◽  
Frequency Domain ◽  
Water Distribution ◽  
Space Charge Polarization ◽  
Moisture Distribution ◽  
Mechanism Analysis ◽  
Loss Peak ◽  
Charge Polarization ◽  
Peak Value

In order to realize the diagnosis of water distribution, this paper analyzes the interface polarization and macroscopic space charge polarization mechanism when the water distribution is non-uniform. The experimental results of this paper and bushing show that when the moisture distribution is non-uniform, there is a significant loss peak in the tanδ-f curve. The loss peak shifts to higher frequencies as the non-uniformity coefficient increases. There are common intersection points between multiple tanδ-f curves. Further, this paper realizes the diagnosis of the location of moisture distribution through Frequency Domain Spectroscopy (FDS) testing of different voltages and different wiring methods based on the macroscopic space charge polarization. In the single-cycle FDS test, when the positive electrode is first added to the area with higher moisture content, the amplitude of the tanδ-f curve is smaller. The tanδ-f curves under different wiring methods constitute a “ring-shaped” loss peak. As the voltage increases, the peak value of the loss peak shifts to the lower frequency band. As the temperature increases, the peak value of the loss peak shifts to higher frequencies. Based on the above rules and mechanism analysis, this research provides a new solution for the evaluation of moisture content of oil-immersed polymers equipment.

scholarly journals Identification of heat and mass transfer processes in bread during baking

2005 ◽  
Vol 9 (2) ◽  
pp. 73-86 ◽  
Author(s):  
Ivanka Zheleva ◽  
Vesselka Kambourova
Keyword(s):  
Partial Differential Equations ◽  
Moisture Content ◽  
Differential Equations ◽  
Moisture Transfer ◽  
Partial Differential ◽  
Linear Partial Differential Equations ◽  
Mass Transfer Processes ◽  
Model Equations ◽  
Heat And Moisture ◽  
Simultaneous Heat

A mathematical model representing temperature and moisture content in bread during baking is developed. The model employs the coupled partial differential equations proposed by Luikov. Dependences of mass and thermal properties of dough on temperature and moisture content are included in the model. Resulting system of non-linear partial differential equations in time and one space dimension is reduced to algebraic system by applying a finite difference numerical method. A numerical solution of the model equations is obtained and simultaneous heat and moisture transfer in dough during baking is predicted. The changes of temperature and moisture content during the time of the process are graphically presented and commented.

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