Abstract
This study presents the designing, constructing and validating processes of thermal conductivity apparatus using steady-state heat-transfer techniques with the capability of testing a material at high temperatures. This design is an improvement from ASTM D5470 standard where meter-bars with the equal cross-sectional area were used to extrapolate surface temperature and measure heat transfer across a sample. There were two meter-bars in apparatus where each was placed three thermocouples. This Apparatus using a heater with a power of 1,000 watts, and cooling water to stable condition. The pressure applied was 3.4 MPa at the cross-sectional area of 113.09 mm 2 meter-bar and thermal grease to minimized interfacial thermal contact resistance. To determine the performance, the validating process proceeded by comparing the results with thermal conductivity obtained by THB 500 made by LINSEIS. The tests showed the thermal conductivity of the stainless steel and bronze are 15.28 Wm-1K-1 and 38.01 Wm-1K-1 with a difference of test apparatus THB 500 are −2.55% and 2.49%. Furthermore, this apparatus has the capability to measure the thermal conductivity of the material to a temperature of 400°C where the results for the thermal conductivity of stainless steel is 19.21 Wm-1K-1 and the difference was 7.93%.
Highlights
Thermal conductivity is one of the important properties of the material and commonly is depend on the temperature especially in high-temperature condition [1]
For certain materials for thermoelectric material, the differences of thermal conductivity should not be ignored because thermoelectric operates at high temperature and the Seebeck number as the main parameter of its performance depends on thermal conductivity value [3]
Several methods for measuring thermal conductivity have already proposed such as steady state method using guarded hot plate (GHP) that it shows accuracy about 3% in deviation standard [4] and guarded cut-bar technique which measured thermal conductivity for the stainless steel 304 (SS304) was 19.17 Wm-1K-1 [5]
Summary
Thermal conductivity is one of the important properties of the material and commonly is depend on the temperature especially in high-temperature condition [1]. For certain materials for thermoelectric material, the differences of thermal conductivity should not be ignored because thermoelectric operates at high temperature and the Seebeck number as the main parameter of its performance depends on thermal conductivity value [3]. Based on these facts, measurements of thermal conductivity in high temperature need special apparatus in order to obtain an accurate result. Other efforts were proposed in collecting, monitoring, and processing data using acquisition Analog to Digital Converter (ADC) Advantech
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