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

Abstract

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/m 3 , 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 R = +0.85 suggesting that both methods are reliable.

Thermal geological model of the city of Guayaquil, Ecuador

“…This temperature is significant when compared to the 22 • C found in the southern part of US, 21 • C in Dubai or 17.5 • C in Algeria (Lund et al, 2004). The values surveyed are similar to those found at more tropical locations such as Saudi Arabia (32 • C) and Nigeria (32.5 • C) (Sharqawy et al, 2009;Oladunjoye and Sanuade, 2012), complicating the heat transfer to the soil and reducing the efficiency of GSHPs. With respect to thermal conductivity values are between 0.782 and 1.668 W/m K, which is within the range of previous values of 1.3 W/m K in Algeria (Sharqawy et al, 2009) and 1.7 W/m K in Chile (Roth et al, 2004), suitable for thermal dissipation in the soil with the best location at the Cayo Formation.…”

Using artificial neural network to predict dry density of soil from thermal conductivity

“…An air-dried soil sample weighing 3 kg was mixed thoroughly with 3 kg of water. The soil was compacted into a pre-weighed mould in five layers, with each layer subjected to 27 blows in West African standards and 55 blows in modified American Association of State Highway and Transportation Officials (AASHTO) levels [10,16]. The compaction mould and the soil were reweighed when the collar and the mould were removed.…”

“…Dry density refers to the mass of soil particles per unit volume. An increase in dry density of a soil results in an increase in its thermal conductivity [6,9,10]. Other factors that have a secondary effect upon soil thermal conductivity include mineral composition, temperature, texture and time.…”

Data on the thermal properties of soil and its moisture content

“… The dataset could also be used for academic purposes to understand the applications of thermal properties of soil(s). Several similar Researches to this data article can be found in [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] . …”