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Thermal Conductivity Testing Method
Category:
Adiabatic
There are various methods for measuring thermal conductivity, which can generally be divided into two categories: the steady-state method and the transient method.In the steady-state method, the test sample is heated by a heat source until a stable temperature distribution is established, and measurements are then performed. In contrast, the transient method measures thermal properties based on temperature changes within the sample over time, such as periodic temperature variations.
Thermal Conductivity Measurement Methods - Steady-State Method
The steady-state method uses Fourier’s law of heat conduction to measure thermal conductivity. It determines the heat transfer rate of the test sample based on the heat flow direction, heat flux conservation, and auxiliary layers with known thermal properties. Common measurement methods include:
1)Guarded Hot Plate Method (GHP)
2)Protected Hot Plate Method
3)Direct Heating Method
4)Pipeline Method
Detailed Introduction to Steady-State Testing Methods
The advantages of the steady-state method compared with other methods are as follows:
● Simple mathematical expressions
● An absolute and primary method for low-conductivity materials
● Acceptable testing time
● Partially applicable to powdered, granular, and solid materials
● For insulation materials near room temperature, the uncertainty is 1–2%
● Small specimen sizes are acceptable (except for concentric spheres)
The limitations of the steady-state method compared with other methods are as follows:
● Requires sophisticated instruments to achieve high precision
● Measurement uncertainty may reach 10% or higher under certain conditions
● Time-consuming
● Measurement errors caused by contact resistance
● Difficulties in measuring samples with complex geometries (such as concentric cylinders or spheres)
● Heat losses, especially in parallel-plate and concentric-cylinder methods
● Difficulty in measuring heat flux values of two specimens
● Measurement errors associated with moisture-containing samples
Thermal Conductivity Measurement Methods - Transient Method
The main advantage of the transient method is its short measurement time, allowing thermal properties to be determined efficiently. This method relies on signal measurement and acceptable temperature differences.Transient techniques measure thermal properties by analyzing the response generated when a signal is introduced into the sample and produces heat. Common transient methods include:
1)Hot Wire Method (THW)
2)Heated Needle Probe Method
3)Dynamic Thermal Stripe Method
4)Hot Plate Method
5)Laser Flash Analysis
6)Photothermal Method
7)Thermal Comparison Method
8)Temperature Swing Method
9)3 Omega Method
10)Fitch Method
Detailed Introduction to Dynamic Testing Methods
Summary of Standards for Thermal Conductivity Testing Methods
ASTM C177/C177-13 Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus
ASTM C518/C518-10/C518-15 Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus
ASTM C335/335-10e1 Standard Test Method for Steady-State Heat Transfer Properties of Pipe Insulation
ASTM C653-97(2012) Standard Guide for Determination of the Thermal Resistance of Low-Density Blanket-Type Mineral Fiber Insulation
ASTM C680-14 Standard Practice for Estimate of the Heat Gain or Loss and the Surface Temperatures of Insulated Flat, Cylindrical, and Spherical Systems by Use of Computer Programs
ASTM C687-12 Standard Practice for Determination of Thermal Resistance of Loose-Fill Building Insulation
ASTM C1303/C1303M-15 Standard Test Method for Predicting Long-Term Thermal Resistance of Closed-Cell Foam Insulation
ASTM C1114-06(2013) Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater Apparatus
ASTM C1363/C1363-05/ C1363-11 Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus
ASTM C1667-15 Standard Test Method for Using Heat Flow Meter Apparatus to Measure the Center-of-Panel Thermal Transmission Properties of Vacuum Insulation Panels
ASTM C1696-14ae1 Standard Guide for Industrial Thermal Insulation Systems
ASTM C1774-13 Standard Guide for Thermal Performance Testing of Cryogenic Insulation Systems
ASTM D5470-06 Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials
ASTM E1225-09/E1225-13 Standard Test Method for Thermal Conductivity of Solids by Means of the Guarded-Comparative-Longitudinal Heat Flow Technique
ASTM E1530-06/E1530-11 Standard Test Method for Evaluating the Resistance to Thermal Transmission of Materials by the Guarded Heat Flow Meter Technique
ASTM F433-02(2014) Standard Practice for Evaluating Thermal Conductivity of Gasket Materials
ASTM D5334-08 Standard Test Method for Determination of Thermal Conductivity of Soil and Soft Rock by Thermal Needle Probe Procedure
DIN EN 12667/12939 Thermal performance of building materials and products - Determination of thermal resistance by means of guarded hot plate and heat flow meter methods - Thick products of high and medium thermal resistance; German version EN 12939:2000
DIN EN 13163 Thermal insulation products for buildings - Factory made expanded polystyrene (EPS) products - Specification
ISO 8301/8302 Thermal insulation; determination of steady-state thermal resistance and related properties; guarded hot plate apparatus
ISO 8894-1 (EN 993-14) Refractory materials - Determination of thermal conductivity - Part 1: Hot-wire method (cross-array)
ISO 8894-2 (EN 993-15) Refractory materials - Determination of thermal conductivity - Part 2: Hot-wire method (parallel)
ASTM C1113/C1113M-09 (2013) Standard Test Method for Thermal Conductivity of Refractories by Hot Wire lpar;Platinum Resistance Thermometer Techniquerpar;
SATISFY offers one-stop thermal conductivity testing services, including preliminary assessment, preparation and submission of relevant documentation, full-process test monitoring, report interpretation, data analysis, and recommendations for corrective actions.
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