کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
7059029 1458085 2013 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of aggregate size on soil thermal conductivity: Comparison of measured and model-predicted data
ترجمه فارسی عنوان
اثرات اندازه دانه بر هدایت حرارتی خاک: مقایسه داده های اندازه گیری شده و مدل پیش بینی شده
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
چکیده انگلیسی
Soil thermal conductivity is largely influenced by soil water content and state of aggregation. The aim of this study was to compare measured and model-predicted thermal conductivity as a function water content for both non-aggregated soil (<0.25 mm) and five aggregate fractions (0.25-0.5, 0.5-1, 1-3, 3-5 and 5-10 mm). The measured thermal conductivity (λ) was derived from the equation k × CV where k is the thermal diffusivity as determined from measurements of temperature change due to the temperature gradient and CV is the volumetric heat capacity as determined from measurements of the specific heat using calorimetric method and the dry bulk density of the soil and aggregate fractions. All the measurements were performed for 13 selected water contents in the range of 0.15-0.53 kg kg−1 obtained using standard Richards tension chambers and drying at room temperature. Measured thermal conductivities were then compared with those predicted using statistical-physical model. The model requires readily available soil characteristics such as soil texture, soil bulk density and water content. The results showed that λ were highest in non-aggregated soil and successively decreased in 0.25-3 mm and 3-10 mm aggregates due to likely reduced contact area between heat-conductive solids and water films. We found a satisfactory agreement between measured and model-predicted thermal conductivities for whole range of water contents with the highest accuracy for the non-aggregated soil. The root mean square error (RMSE) and maximum relative error (MRE) of the model (for all treatments) were 0.104 W m−1 K−1 and 64.2%, respectively. The model used showed a reasonable sensitivity of the thermal conductivity on the aggregate fraction size. The modelled values tended to underestimate the thermal conductivity in the range of low thermal conductivity values (mostly for the 3-10 mm aggregate beds) and to overestimate for medium conductivity values in the region of intermediate conductivities (mostly for the 0.25-3 mm aggregates). The results revealed that investigation of thermal conductivity of structural soils and other similar media must take into account the aggregate size and associated arrangement of solid, air and water.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 57, Issue 2, February 2013, Pages 536-541
نویسندگان
, , , ,