Foreword
This document is drafted in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and starting rules for standardization documents".
Please note that some of the contents of this document may involve patents. The issuer of this document does not assume responsibility for identifying patents.
This document is proposed by the State Forestry and Grassland Administration.
This document is attributed to the National Technical Committee for Wood Standardization (SAC/TC41).
1 Scope
This document describes the test apparatus, specimens, test procedures, calculation of results, and test reports for the determination of thermal conductivity of wood by the heat flow method.
This document applies to the determination of the radial, chordal and longitudinal thermal conductivity of wood.
2 Normative reference documents
The contents of the following documents constitute the essential provisions of this document through the normative references in the text. Among them, note the date of the reference document, only the date of the corresponding version applies to this document; do not note the date of the reference document, its latest version (including all the revision of the list) applies to this document.
GB/T 1927.2-2021 Test methods for physical and mechanical properties of small specimens of wood without defects Part 2: Sampling methods and general requirements
GB/T 1927.4-2021 Test methods for physical and mechanical properties of small specimens of wood without defects Part 4: Determination of moisture content
GB/T 1927.5-2021 Test methods for physical and mechanical properties of small specimens of wood without defects Part 5: Density determination
GB/T 4132 Insulation materials and related terms
LY/T 1788 Wood properties terminology
3 Terms and definitions
GB / T 4132, LY / T 1788 defined and the following terms and definitions apply to this document.
4 Principle
Heat flow method is in a steady state, one-way heat flow vertically through the plate specimen; hot end and cold end of the heat flow meter plate through its own known thermal conductivity, thermocouple distance, thermocouple and end distance and the measured temperature, cross-sectional area to calculate the heat flow through the two heat flow meter and the specimen hot end face and cold end face temperature, and then use its hot and cold end of the average value of heat flow as the heat flow through the wood specimen, calculate the thermal conductivity of the specimen coefficient.
5 Test apparatus
5.1 Schematic diagram of the test apparatus
The schematic diagram of the test apparatus is shown in Figure 1
6 Specimen
6.1 sawing 6.1.1 radial direction and chordal direction of the thermal conductivity measurement specimen sawing, the sampling direction in accordance with GB/T 1927.2-2021, Chapter 4, radial and chordal direction specimen sawing program.
6.1.2 The two faces of the longitudinal specimen should be perpendicular to the grain direction of the wood
6.2 Number
The number of specimens should comply with the requirements of GB/T 1927.2-2021 in 5.1
6.3 Size and flatness
Specimen width size should be not less than 50% of the hot flow surface measurement surface, thickness of not less than 10mm. two surface flatness of the specimen should be controlled within 0.50mm / m.
National standard out of the film
6.4 Moisture content
6.4.1 Specimens can be air-dry or dry material.
Note: The thermal conductivity of the specimen of other moisture content is affected by the moisture content, the results are only for reference.
6.4.2 air-dry material in the relative humidity of (65 Shi 5)% and temperature (202)C conditions before the determination of moisture content equilibrium treatment, until the mass is constant. Mass change of 8h interval does not exceed 0.2% can be considered constant quality
6.4.3 Adiabatic material specimens should be adiabatic treatment, drying should not appear after drying defects. Drying 8h interval weighing difference does not exceed 0.2%, that is, the specimen is considered to reach the absolute dry.
7 Test procedure
7.1 Measurement of specimen size and quality before testing
Measure the length, width and thickness more than 4 times with the instrument whose accuracy is not less than 0.05mm, and take the average value as the specimen size. The measurement of mass should be accurate to 0.01g.
Note: For the thermal conductivity measurement equipment with thickness measurement function, the measurement results shall be calibrated with the instrument whose accuracy is not less than 0.05mm, and the thickness measurement shall be carried out with the thermal conductivity measurement equipment after calibration.
7.2 Specimen installation
8 Calculation of results
8.1 General calculation
8.1.1 Heat flow density
Calculated according to the formula (4) ~ formula (6), taking two valid digits.
9 Test report
9.1 The number of the standard used for the determination, namely GB/T 42483-2023.
9.2 Specimen species, test direction, size.
9.3 test the temperature of the hot end and cold end, the average temperature of the specimen.
9.4 Calculated results and related statistical data according to Chapter 8.
9.5 Water content and density data of the specimen, mass and volume changes before and after the test (if any).
9.6 The time and place of measurement, the name of the measurement person or testing agency, the laboratory temperature, relative humidity.
Foreword
1 Scope
2 Normative reference documents
3 Terms and definitions
4 Principle
5 Test apparatus
6 Specimen
7 Test procedure
8 Calculation of results
9 Test report
