Abstracts

Campbell, G.S., Huffaker, E.M., et al. 2004, 'Use of the Line Heat Source Method to Measure Thermal Conductivity of Insulation and Other Porous Materials', in Thermal Conductivity 27/Thermal Expansion 15, ed^eds H. Wang and W. Porter, DEStech, pp.

The line heat source method is now widely used to measure thermal properties of materials. Typically, in practise, a small needle containing a heater and a thermometer is inserted into the material under test and the needle temperature is monitored while current is applied to the heater. Thermal properties of the medium are determined by matching modeled temperature responses to the measured values. Errors in the measurement arise from 1) the finite size of the heat source and sensor, 2) temperature drift during the measurement and 3) imperfect contact between the sensor and the surroundings. We conducted experiments to evaluate effects of these sources of error on line heat source measurements in insulation and dry granular materials. Two probe sizes were tested in materials of known conductivity. Measurements were made with varying rates of change of ambient temperature, and various analysis techniques were tried for removing the effects of temperature drift. We also tried two types of thermal grease to decrease contact resistance between the probe and the surrounding medium.

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Cui, Y.J. and Tang, A.M. 2005, On the thermal conductivity of compacted MX80 clay, International Symposium on Engineered Barriers for High Level Radioactive Waste Disposal, Shanghai. 8-10 September pp. 121-131.

In the design of high-level radioactive waste disposals using engineered barriers, thermal conductivity of compacted bentonite in one of the most important properties. In this paper, a thermal probe based on the hot wire method was used to measure the thermal conductivity of compacted MX80 bentonite samples at unsaturated state. The experimental results evidenced the influence of dry density, water content, saturation degree, volumetric fraction of different constituents (air, water and solid) and microstructure of the soil. A linear relationship between pore air volumetric fraction and thermal conductivity was observed.

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Loudon, A.G. 1979, 'The thermal properties of lightweight concretes', International Journal of Lightweight Concrete, vol. 1, no. 2, pp. 71-85.

The thermal properties of lightweight concretes used for implementing UK Building Regulations are compared with those used in Europe and the USA. When corrected to the same moisture content, UK standard values for concretes are much the same as those used elsewhere, but thermal properties assigned to blockwork differ because other countries take account of mortar joints, and standard moisture contents vary. Some UK problems are discussed, including that of scrutinising claims for thermal conductivity values which are lower than would be expected, the difficulty of obtaining data for hollow blocks, and the difficulty of meeting UK Building Regulations with traditional double leaf masonry walls.

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