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The thermal conductivity of soil is a fundamental physical property related to heat conduction and also one of the widely applied parameters in geotechnical engineering. Thermal needle tests were performed to measure the thermal conductivity of transparent sand. The thermal conductivity of three particle sizes of transparent sand was measured at different porosities and temperatures. The result shows that the thermal conductivity of transparent sand decreases with the increase of porosity and temperature. A modified model is proposed to calculate the thermal conductivity of the tested sand. Compared with the literature models, which are only suitable for room temperature, the modified model in this paper is applicable to a wider temperature range, ranging from 5∘C to 45∘C. It will also be beneficial to future studies on thermal reponses of granular materials, i.e., energy pile model test using transparent sand. [ABSTRACT FROM AUTHOR]

Subcooled boiling of alcohol flowing through micro-cylinder-groups with different heights in aligned arrangement was investigated. Meanwhile, the outlet temperature and Nusselt number of the working fluid were obtained when the heating power was 80 W, 60 W and 40 W respectively. Subcooled boiling is divided into two parts: the partially developed stage and fully developed stage. The result showed that the outlet temperature of the fully developed stage in subcooled boiling changed rarely as the Reynolds number decreased. At the same heating power, the heights of the micro-cylinders had little effects on the outlet temperature of working fluid in the fully developed stage. However, for the same height of micro-cylinder, the fully developed stage of subcooled boiling came earlier as the heating power increased. And the Nusselt number in the fully developed stage was greater than that in the partially developed stage. Based on the regression analysis of experimental data, a correlation formula of Nusselt number for subcooled boiling in micro-cylinder-groups was established and made comparison with existing correlation. [ABSTRACT FROM AUTHOR]