Transient calorimetric technique for measuring total hemispherical emissivities of metals with rigorous evaluation of heat loss through thermocouple leads

Masuda, Hidetoshi; Higano, Mitsuo

doi:10.1364/josaa.2.001877

Cited by 21 publications

(8 citation statements)

References 9 publications

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“…Emissivity calculations are based on the transient calorimetric technique for measuring surface emissivity of metals [10][11][12]. In this technique, samples are heated up to a temperature in a vacuum chamber and then allowed to cool down while recording the temperature-time histories.…”

Section: Emissivity Calculationsmentioning

confidence: 99%

“…HT from the sample (eqn (5)) is due to convection, radiation and conduction along thermocouple wires. The cooling rate at any specific instant is obtained by expressing the temperaturetime history by an exponential function of the form of eqn (6) where the constants a and b are determined by using the least square method with a set of five adjacent experimental points as described in Masuda and Higano [10] and Tanda and Misale [12]. The convection HTC for the disc samples is defined from the empirical correlations eqns (7) and (8) derived by Krysa et al [13] with  having a value of 0º for the vertically suspended thin disc.…”

Section: Emissivity Calculationsmentioning

confidence: 99%

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Optimization of heat transfer in the finite element process modelling of inertia friction welding of SCMV and AerMet 100

Mohammed¹,

Bennett²,

Shipway³

et al. 2010

Advanced Computational Methods and Experiments in Heat Transfer XI

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Inertia friction welding is the process in which stored kinetic energy in a flywheel is converted to heat by relative sliding movement between the components' surfaces. The process is widely used in joining high strength aero-engine alloys. Heat transfer interactions play a fundamental role in determining weld quality as temperature has a significant impact on the mechanical, thermal and metallurgical behaviours of materials. Heating and cooling rates influence thermal stresses induced by variations in material properties due to variations in temperatures. Heat transfer modes involved in the IFW process, apart from conduction, were hardly mentioned in previous work while their significance has not been identified. In this paper the heat transfer modes and their significance in the modelling of the IFW process of the high strength steels SCMV and AerMet 100 has been identified and a methodology by which experimental, numerical and empirical approaches were collectively utilised to optimize the heat transfer analysis is presented. The methodology was validated for optimizing the heat transfer analysis of the IFW process of the high strength steels that are the subject of this study.

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Section: Emissivity Calculationsmentioning

confidence: 99%

Section: Emissivity Calculationsmentioning

confidence: 99%

Optimization of heat transfer in the finite element process modelling of inertia friction welding of SCMV and AerMet 100

Mohammed¹,

Bennett²,

Shipway³

et al. 2010

Advanced Computational Methods and Experiments in Heat Transfer XI

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“…The heat emitted by the shroud enclosure is of course black body radiation at the temperature of the shroud and some of this thermal energy is absorbed by the sample. Kirchoff s law5 is then employed to state that the hemispherical emittance of the sample at a given temperature is equal to its absorptance and consequently EI, is used in the second term of the equation (2) and solving for ch leads to equation (1). The misinterpretation of Kirchoff s law is where the theoretical problem lies.…”

Section: Theorymentioning

confidence: 99%

An Improved Formulation for Calorimetric Emittance Testing of Spacecraft Thermal Control Coatings

Kauder

2009

AIP Conference Proceedings

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Spacecraft often really heavily on passive thermal control to maintain operating temperature. An important parameter in the spacecraft heat balance equation is the emittance of thermal control coatings as a function of coating temperature. One method for determining the emittance of spacecraft thermal control from elevated temperature to cryogenic temperatures relies on a calorimetric technique. The fundamental equation governing this test method can be found in numerous places in the literature and although it generally provides reasonable results, its formulation is based on a conceptual flaw that only becomes apparent when the sample temperature approaches the wall temperature during testing. This paper investigates the cause for this error and develops the correct formulation for calorimetric emittance testing. Experimental data will also be presented that illustrates the difference between the two formulations and the resulting difference in the calculated emittance.

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“…The emittance or calorimetric methods [2] allow only global measurements of the various coefficient E, a or p. Some experiments measure the reflected radiation in the whole hemisphere with integrating sphere [3] but cannot measure the directional reflectance. To have more information about the reflection phenomena, it appears necessary to measure the directional distribution of the reflected radiation [4,5].…”

Section: Pea) = 1-a(a) And(a) = A(a)mentioning

confidence: 99%

An FT -IR based instrument for measuring infrared diffuse reflectance

Francou¹,

Hervé²

1998

Proceedings of the 1998 International Conference on Quantitative InfraRed Thermography

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The determination of the reflectance for directional irradiation of diffusely reflecting sample is important to improve the knowledge of thermal exchanges. It appears necessary to have some complete reflectivity measurements. Thus an infrared scattering instrument has been build and we have done measurements on several samples. The incidence angles range from 10· to 80·. The use of a Fourier Transform spectrometer permits measurements in the 650 cm-1 -8000 cm-1 wavenumber range (1.5 Ilm-15 11m) and the maximal spectral resolution is 0.125 cm-1. The instrument was tested on an alumina sample at room temperature. The wavenumber range is 1300 cm-1 -8000 cm-1.

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Transient calorimetric technique for measuring total hemispherical emissivities of metals with rigorous evaluation of heat loss through thermocouple leads

Cited by 21 publications

References 9 publications

Optimization of heat transfer in the finite element process modelling of inertia friction welding of SCMV and AerMet 100

Optimization of heat transfer in the finite element process modelling of inertia friction welding of SCMV and AerMet 100

An Improved Formulation for Calorimetric Emittance Testing of Spacecraft Thermal Control Coatings

An FT -IR based instrument for measuring infrared diffuse reflectance

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