scholarly journals In Situ Determination of Thermal Resistivity of Soil: Case Study of Olorunsogo Power Plant, Southwestern Nigeria

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Michael Adeyinka Oladunjoye ◽  
Oluseun Adetola Sanuade
Keyword(s):  
Grain Size ◽  
Power Plant ◽  
Moisture Content ◽  
Size Distribution ◽  
Thermal Resistivity ◽  
Dry Density ◽  
Physical Parameters ◽  
Southwestern Nigeria

This study measured in situ the thermal resistivity of soils at Olorunsogo Gas Turbine Power Station (335 MW Phase 1) which is located in Ogun State, Southwestern Nigeria. Ten pits, each of about 1.5 m below the ground surface, were established in and around the power plant in order to measure the thermal resistivity of soils in situ. A KD 2-Pro was used for the in situ measurement of thermal properties. Samples were also collected from the ten pits for laboratory determination of the physical parameters that influence thermal resistivity. The samples were subjected to grain size distribution analysis, compaction, specific gravity and porosity tests, moisture content determination, and XRD analysis. Also, thermal resistivity values were calculated by an algorithm using grain size distribution, dry density, and moisture content for comparison with the in situ values. The results show that thermal resistivity values range from 34.07 to 71.88°C-cm/W with an average of 56.43°C-cm/W which falls below the permissible value of 90°C-cm/W for geomaterials. Also, the physical parameters such as moisture content, porosity, degree of saturation, and dry density vary from 13.00 to 16.20%, 39.74 to 45.64%, 40.72 to 63.52%, and 1725.05 to 1930.00 Kg/m3, respectively. The temperature ranges from 28.92 to 35.39°C with an average of 32.11°C in the study area. The calculated thermal resistivity from an algorithm was found to vary from 48.43 to 81.22°C-cm/W with an average of 65.56°C-cm/W which is close to the thermal resistivity values measured in situ. Good correlation exists between the in situ thermal resistivity and calculated thermal resistivity with suggesting that both methods are reliable.

scholarly journals Effect of Grain Size Distribution on Recrystallisation Kinetics in an Fe-30Ni Model Alloy

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 369 ◽  
Author(s):  
Mo Ji ◽  
Claire Davis ◽  
Martin Strangwood
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Cold Deformation ◽  
Avrami Exponent ◽  
Model Alloy ◽  
Avrami Parameter ◽  
In Situ Heating

This paper discusses the role of grain size distribution on the recrystallisation rates and Avrami values for a Fe-30 wt. % Ni steel, which was used as a model alloy retaining an austenitic structure to room temperature. Cold deformation was used to provide uniform macroscopic strain distributions (strains of 0.2 and 0.3), followed by recrystallisation during annealing at 850–950 °C. It was shown that the Avrami parameter was directly related to the grain size distribution, with a lower Avrami exponent being seen for a larger average and wider grain size distribution. A method to predict the Avrami exponent from the grain size distribution was proposed. In situ heating in an SEM with EBSD showed the recrystallisation kinetics to be affected by differences in stored energy and nucleation in the different grain sizes supporting the proposed relationship.

scholarly journals The effect of lime Ca(OH)2 to the constant of granulation rate (k) of Sidoarjo mud (LuSi) and its grain size distribution

2019 ◽  
Vol 276 ◽  
pp. 05010
Author(s):  
Dasyri Pasmar ◽  
Noor Endah Mochtar ◽  
Ali Altway
Keyword(s):  
Grain Size ◽  
Moisture Content ◽  
Water Temperature ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Inclination Angle ◽  
Rotation Rate ◽  
Water Resistance ◽  
Dry Weight ◽  
Granulation Process

Sidoarjo mud (LuSi) is very hot and sticky mud-like substance produced by eruption of Kujung, Kalibeng, and Pucangan formations caused by well exploration for gas in Porong, Sidoarjo, East Java, Indonesia. LuSi submerged villages, industrial areas, and rice fields in Porong. The eruption is still taking place so that it needs more area and higher dike surrounded to retain the mud. Therefore, it is very urgent to use LuSi in huge volumes such as for borrowed materials. LuSi grain size and its strength, however, do not meet the borrowed materials requirement. Therefore, the grain size was improved using granulator drum and lime Ca(OH)2 was used to increase its strength. The grain size produced by granulator was affected by length, diameter, and rotation rate of granulator drum, and also by constant of granulation rate ‘k’ that was function of other parameters, inclination angle of granulator drum (S), moisture content (W), and water temperature (T). The results show that lime needed for stabilization is 10% of LuSi dry weight. The “k” is affected by lime where parameters (S) and (W) become smaller and (T) is higher. Lime also produces dryer granular, higher water resistance, and shorter granulation process. Besides, higher water temperature during granulation process is needed to develop bigger grain size for granular stabilized-LuSi.

scholarly journals Revisiting Field Capacity (FC): variation of definition of FC and its estimation from pedotransfer functions

2014 ◽  
Vol 38 (6) ◽  
pp. 1750-1764 ◽  
Author(s):  
Theophilo Benedicto Ottoni Filho ◽  
Marta Vasconcelos Ottoni ◽  
Muriel Batista de Oliveira ◽  
José Ronaldo de Macedo ◽  
Klaus Reichardt
Keyword(s):  
Moisture Content ◽  
Soil Properties ◽  
Field Capacity ◽  
Pedotransfer Functions ◽  
Soil Morphology ◽  
Soil Water Retention ◽  
Input Variables ◽  
Definition Of

Taking into account the nature of the hydrological processes involved in in situ measurement of Field Capacity (FC), this study proposes a variation of the definition of FC aiming not only at minimizing the inadequacies of its determination, but also at maintaining its original, practical meaning. Analysis of FC data for 22 Brazilian soils and additional FC data from the literature, all measured according to the proposed definition, which is based on a 48-h drainage time after infiltration by shallow ponding, indicates a weak dependency on the amount of infiltrated water, antecedent moisture level, soil morphology, and the level of the groundwater table, but a strong dependency on basic soil properties. The dependence on basic soil properties allowed determination of FC of the 22 soil profiles by pedotransfer functions (PTFs) using the input variables usually adopted in prediction of soil water retention. Among the input variables, soil moisture content θ (6 kPa) had the greatest impact. Indeed, a linear PTF based only on it resulted in an FC with a root mean squared residue less than 0.04 m³ m-3 for most soils individually. Such a PTF proved to be a better FC predictor than the traditional method of using moisture content at an arbitrary suction. Our FC data were compatible with an equivalent and broader USA database found in the literature, mainly for medium-texture soil samples. One reason for differences between FCs of the two data sets of fine-textured soils is due to their different drainage times. Thus, a standardized procedure for in situ determination of FC is recommended.

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