In Situ Measurement of Thermal Diffusivity in Anisotropic Media

Kruczek, T.; Adamczyk, Wojciech; Białecki, Ryszard A.

doi:10.1007/s10765-013-1413-3

Cited by 27 publications

(19 citation statements)

References 9 publications

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“…An element that converts part of an infra-red radiation sent by the body into an electrical signal is microbolometer array with a resolution of 640 x 480 pixels. To get the proper temperature recorded by THV-camera, calibration studies were conducted to determine the emissivity, which allows the exact temperature setting [18].…”

Section: Test Facilitymentioning

confidence: 99%

Free convection on a refrigerator’s condenser

Orzechowski

Stokowiec

2014

EPJ Web of Conferences

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Abstract. The paper presents the measurement of heat transfer coefficient for the refrigerator's condenser in free convection regime. The water was pumped through the steel coils of heat exchanger with a constant flow rate and its temperature was kept at a demanded value by means of ultrathermostat. The research was conducted in stationary conditions which were controlled by a continuous measurement of the water temperature at inflow and outflow to the heat exchanger. The temperature distribution at the external condenser surface was registered by means of an infrared camera. Single elements used to the analysis were selected using the thermogram registered. In free convection regime and in case of small temperature change the heat transfer coefficient value can be calculated by comparing the measured temperature area with analytical solution describing one-dimensional temperature distribution along the rib. The accuracy of the proposed method for measuring the heat transfer coefficient was examined by comparing the heat transferred to the air and the heat lost by water flowing through the spiral of heat exchanger. An error between these two parameters is about 6%.

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Section: Test Facilitymentioning

confidence: 99%

Free convection on a refrigerator’s condenser

Orzechowski

Stokowiec

2014

EPJ Web of Conferences

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“…Priori to testing, calibration studies of THV-camera were conducted to determine to emissivity of the surface where the thermal field should have been measured. With this the exact temperature could be set [13].…”

Section: Figurementioning

confidence: 99%

Boiling heat transfer on fins – experimental and numerical procedure

Orzechowski

Tyburczyk

2014

EPJ Web of Conferences

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Abstract. The paper presents the research methodology, the test facility and the results of investigations into non-isothermal surfaces in water boiling at atmospheric pressure, together with a discussion of errors. The investigations were conducted for two aluminium samples with technically smooth surfaces and thickness of 4 mm and 10 mm, respectively. For the sample of lower thickness, on the basis of the surface temperature distribution measured with an infrared camera, the local heat flux and the heat transfer coefficient were determined and shown in the form of a boiling curve. For the thicker sample, for which 1-D model cannot be used, numerical calculations were conducted. They resulted in obtaining the values of the local heat flux on the surface the invisible to the infrared, camera i.e. on the side on which the boiling of the medium proceeds.

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“…Of the references previously listed, [9] is the closest to the work discussed here. Some of the differences include the fact that convection is modeled in the present work, which is important in high-temperature applications, and the samples can be tested in standard flash diffusivity measurement systems, which are fairly ubiquitous.…”

Section: Introductionmentioning

confidence: 99%

“…All cases addressed in [8] involve isotropic materials. However, Kruczek et al [9] address anisotropic cases for measurements in samples that are large enough to be considered semi-infinite with one planar face. A pulse is applied to one point on the face and isotherms are fitted to a mathematical model.…”

Section: Introductionmentioning

confidence: 99%

“…The results discussed in this work allow data from a typical single-point-measurement flash diffusivity system to be analyzed to determine orthotropic properties, simplifying both the experimental setup and the analysis phase of the work. One advantage of the method used in [9] is that directional diffusivity can be measured in two directions in the plane parallel to the surface of the material, whereas the present method assumes the in-plane diffusivity to be uniform.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic Thermal Diffusivity Measurement Using the Flash Method

McMasters

Dinwiddie

2014

Journal of Thermophysics and Heat Transfer

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A well-established method for determining the thermal diffusivity of materials is the laser flash method. The work presented here compares two analysis methods for flash heating tests on anisotropic carbon bonded carbon fiber. This material exhibits a higher conductivity in the direction in which the fibers are oriented than in the direction perpendicular to the fiber orientation. Of the two analysis methods used, one method uses the temperature data from the entire surface of the sample by examining 201 temperature histories simultaneously, with each temperature history originating from an individual pixel within a line across the middle of the sample. The other analysis method uses only the temperature history from a single pixel in the center of the sample, similar to the data that is traditionally generated using the classical flash diffusivity method. Both analysis methods include accommodations for modeling the penetration of the laser flash into the porous surface of the carbon bonded carbon fiber material. The robustness of the method using the single-pixel temperature history shows that anisotropic thermal diffusivity can be measured using standard flash diffusivity instruments, if modeled properly, avoiding the additional complexity associated with the use of a thermal imaging camera. Nomenclature a = mean free path of photon in porous material, m Bi = Biot number (dimensionless) c = specific heat, J∕kg − K h = convection coefficient, W∕m 2 K i = counting integer k a = axial thermal conductivity, W∕m K k r = radial thermal conductivity, W∕m K L = thickness of sample, m m = counting integer for infinite series solution n = number of temperature measurements p = number of parameters q o = magnitude of flash, J∕m 2 q o ∕ρcL = heat pulse magnitude r = radial dimension variable, m r h = heated radius of sample, m r o = outer radius of sample, m T = calculated temperature in sample, K t = time variable, s x = spatial variable in the axial direction, m Y = measured temperature in sample above ambient, KGreek α = thermal diffusivity, m 2 ∕s α a = axial thermal diffusivity, m 2 ∕s α r = radial thermal diffusivity, m 2 ∕s Δr = radial finite difference length, m Δx = axial finite difference length, m ρ = density, kg∕m 3 σ = standard deviation of residuals, K

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In Situ Measurement of Thermal Diffusivity in Anisotropic Media

Cited by 27 publications

References 9 publications

Free convection on a refrigerator’s condenser

Free convection on a refrigerator’s condenser

Boiling heat transfer on fins – experimental and numerical procedure

Anisotropic Thermal Diffusivity Measurement Using the Flash Method

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