High-Precision and Reliable Thermal Conductivity Measurement for Graphene Films Based on an Improved Steady-State Electric Heating Method
Jiahao LuXin MingYingjun LiuYuanyuan HaoPeijuan ZhangSonghan ShiHan MaYue YuShengying CaiZhen XuChao Gao
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Thermal conductivity measurement
Electric heating
A laser flash method developed for the measurement of thermal conductivity of solids was applied to liquids of low thermal conductivity. The sample liquid was sandwiched in between a small thin metal disk and a sample holder. When the laser beam is absorbed in the front surface of the metal disk, the temperature of the disk quickly rises about 2 K and heat then flows downwards through the sample liquid as one-dimensional heat flow. The thermal conductivity of liquid can be obtained from the temperature fall of the disk without employing any reference materials and also without measuring the thickness of the sample liquid layer. Thermal conductivities of water and toluene near room temperature were measured by this method with a mean deviation of 2.6%. This laser flash method may be applied to the measurement of the thermal conductivity of liquids such as molten salts at elevated temperatures.
Laser flash analysis
Thermal conductivity measurement
Liquid metal
Liquid nitrogen
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The heated probe for measuring thermal conductivity of materials is designed and made based on the theory of line heat source.The effects of heating power and heat-up time on measurement of thermal conductivity are studied.Thermal conductivities of soil are measured with the self-made heated probe.The experimental results show that the heated probe method is effective for measuring the thermal conductivity of soil.This method has some advantages of quick measuring and convenient operating.
Thermal conductivity measurement
Thermal effusivity
Line source
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Thermal conductivity measurement
Measurement device
Thermal transmittance
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The market of LEDs increases exponentially over the years as well as their power. However, at the same time the mean time to failure should remain superior to 100,000 hours. The major difficulty comes from the mechanical stress in the LED structure, which is roughly proportional to the inverse of the thermal conductivity. Consequently, it is really important to determine thermal conductivity of the materials used in LEDs. In the same way, the thermal conductivity of films is lower than the thermal conductivity of the bulk material. Unfortunately, thermal conductivity measurement is difficult on two-dimensional structures. Then an appropriate had to be developed. The 3 omega thermal conductivity measurement has been used extensively to measure the thermal properties of bulk and thin film dielectric materials. Tests on different materials will allow to find materials with a higher thermal conductivity. The thermal conductivity measurement will be elaborated by two different methods defined the isotropic and anisotropic properties, the slope method and the 2D heat conduction.
Thermal conductivity measurement
Thermal effusivity
Thermal transmittance
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A micro thin-film thermal conductivity probe is developed to measure thermal conductivity of biological tissues based on the principle of traditional hot-wire method. The design of this new micro probe consists of a resistive line heating element on a substrate and a RTD based temperature sensor. The transient time response of the heating element depends on the thermal conductivity of the surrounding medium and the substrate. A theoretical analysis of the transient conduction for this configuration where the heater source is sandwiched between two materials (the substrate and the surrounding medium) shows that the composite thermal conductivity calculated from the temperature versus time response is simply the average of the thermal conductivity of the two materials. The experiments conducted to measure thermal conductivity of Crisco and agar gel show a good match with the theoretical and numerical analyses. The technique demonstrates the potential of the microprobe for in vivo measurements of thermal conductivity of biological tissues.
Thermal conductivity measurement
Resistive touchscreen
Transient (computer programming)
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Estimation of thermo-physical characteristics of the exterior stratified walls is based on thermal conductivity measurements on samples of the materials that make up these walls. The methods used for these experimental measurements require the use of dry samples, a different condition that the wall material is in office. Measurement of thermal conductivity of the material composition of an external wall layers can be made in situ using a new type of thermo probe. This type of probe is based on linear heat source method for measuring thermal conductivity and measures simultaneously the thermal conductivity in two different points.
Thermal conductivity measurement
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Purpose: The purpose of the present study was to demonstrate the procedure for determining the thermal conductivity of a solid material with relatively high thermal conductivity, using an original self-designed apparatus. Design/methodology/approach: The thermal conductivity measurements have been performed according to the ASTM D5470 standard. The thermal conductivity was calculated from the recorded temperature values in steady-state heat transfer conditions and determined heat flux. Findings: It has been found from the obtained experimental results that the applied standard test method, which was initially introduced for thermal conductivity measurements of thermal interface materials (TIMs), is also suitable for materials with high thermal conductivity, giving reliable results. Research limitations/implications: The ASTM D5470 standard test method for measurement of thermal conductivity usually gives poor results for high conductive materials having thermal conductivity above 100 W/mK, due to problems with measuring heat flux and temperature drop across the investigated sample with reasonably high accuracy. Practical implications: The results obtained for the tested material show that the presented standard test method can also be used for materials with high thermal conductivity, which is of importance either for the industrial or laboratory applications. Originality/value: The thermal conductivity measurements have been carried out using an original self-designed apparatus, which was developed for testing broad range of engineering materials with high accuracy.
Thermal conductivity measurement
Thermal transmittance
Thermal grease
Thermal effusivity
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As an application of the usual hot wire method, a method of determining the thermal conductivity of the specimen is discussed theoretically, in which the hot wire is sandwiched between a plate-type specimen and a reference material of the known thermal conductivity. It is found that when the thermal conductivity of the reference material is known the thermal conductivity of the specimen can be determined theoretically just as in the case of applying the usual hot wire method to a homogeneous material. The error and the reproducibility of the experimental values by this method are within ±4 % and ±1.5 % of the thermal conductivities of standard materials respectively and this method is found very good.
Thermal conductivity measurement
Hot plate
Transient (computer programming)
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Thermal conductivity measurement
Titanium alloy
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