计算岩石的热扩散系数的标准实施规范

详细信息   

• 中文主题词：额定值 ; 建筑 ; 岩石 ; 热扩散系数 ; 天然石料 ; 砌块 ; 石 ; 数学计算 ; 施工材料
• 标准号：ASTM D4612-2003
• 发布日期：2003
• 英文题名：Standard Practice for Calculating Thermal Diffusivity of Rocks
• 英文主题词：density ; heating tests-specific heat ; enthalpy ; isotropic content ; porosity ; rock ; temperature tests ; thermal analysis-diffusivity
• 标准状态：现行
• 发布单位：US-ASTM
• 载体形态：4P.;A4
• 中国标准分类号：P13
• 国别：美国材料与试验协会

文摘

The thermal diffusivity is a parameter that arises in the solution of transient heat conduction problems. It generally characterizes the rate at which a heat pulse will diffuse through a solid material.

The number of parameters required for solution of a transient heat conduction problem depends on both the geometry and imposed boundary conditions. In a few special cases, only the thermal diffusivity of the material is required. In most cases, separate values of k, x03C1;, and c_p are required in addition to x03B1;. This practice provides a consistent set of parameters for numerical or analytical heat conduction calculations related to heat transport through rocks.

In order to use this practice for determination of the thermal diffusivity, all of the required parameters ( k, x03C1;, c_p) must be determined under as near identical specimen conditions as possible.

The diffusivity determined by this practice can only be used to analyze heat transport in rock under thermal conditions identical to those existing for the k, x03C1;, and c_p measurements.

Note 38212;Notwithstanding the statements on precision and bias contained in this test method; the precision of this test method is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D 3740 are generally considered capable of competent and objective testing. Users of this test method are cautioned that compliance with Practice D 3740 does not in itself assure reliable testing. Reliable testing depends on many factors; Practice D 3740 provides a means of evaluating some of these factors.

1.1 This practice involves calculation of the thermal diffusivity from measured values of the mass density, thermal conductivity, and specific heat at constant pressure. It is applicable for any materials where these data can be determined. The temperature range covered by this practice is 20 to 300176;C.

Note 18212;The diffusivity, as determined by this practice, is intended to be a volume average value, with the averaging volume being 8805; 2 x 10^-5 m³ (20 cm³). This requirement necessitates the use of specimens with volumes greater than the minimum averaging volume and precludes use of flash methods of measuring thermal diffusivity, such as the laser pulse technique.

Note 28212;This practice is closely linked to the overall test procedure used in obtaining the primary data on density, specific heat, and conductivity. It cannot be used as a "stand alone" practice because the thermal diffusivity values calculated by this practice are dependent on the nature of the primary data base. The practice furnishes general guidelines but cannot be considered to be all-inclusive.

1.2 The practice is intended to apply to isotropic samples; that is, samples in which the thermal transport properties do not depend on the direction of heat flow. If the thermal conductivity depends on the direction of heat flow, then the diffusivity derived by this practice must be associated with the same direction as that utilized in the conductivity measurement.

1.3 The thermal conductivity, specific heat, and mass density measurements must be made with specimens that are as near identical in composition and water content as possible.

1.4 The generally inho......