Surface Temperature Measurement Errors

Keltner, N.R.; Beck, James V.

doi:10.1115/1.3245580

Cited by 35 publications

(11 citation statements)

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“…A detailed CALORE model is being developed to assess the errors of 63-mil ungrounded junction, sheathed TCs mounted on a flat shroud. 5 However, results of those simulations are not available at this time.…”

Section: Determining the "True" Shroud Temperature Using Two Methodsmentioning

confidence: 99%

Section: Interpretation Of Intrinsic Tc Datamentioning

confidence: 99%

“…A large body of published data (References [5] - [8]) on the response of intrinsic TCs on solid surfaces exists. Keltner and Beck [5] model a stylized intrinsic TC as a right circular cylinder welded perpendicular to the shroud surface. Though our geometry is different (the cylinder is welded parallel to the surface) the behavior shown in [5] is consistent with data from the experiments described here for TCs with "displaced junctions," i.e., where the location of the junction is above the surface being measured.…”

Section: Interpretation Of Intrinsic Tc Datamentioning

confidence: 99%

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Shroud boundary condition characterization experiments at the Radiant Heat Facility.

Suo-Anttila¹,

Nakos²,

Gill³

2004

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A series of experiments was performed to better characterize the boundary conditions from an inconel heat source ("shroud") painted with Pyromark® black paint. Quantifying uncertainties in this type of experimental setup is crucial to providing information for comparisons with code predictions. The characterization of this boundary condition has applications in many scenarios related to fire simulation experiments performed at Sandia National Laboratories' Radiant Heat Facility (RHF). Four phases of experiments were performed. Phase 1 results showed that a nominal 1000°C shroud temperature is repeatable to about 2°C. Repeatability of temperatures at individual points on the shroud show that temperatures do not vary more than 10 o C from experiment to experiment. This variation results in a 6% difference in heat flux to a target 4 inches away. IR camera images showed the shroud was not at a uniform temperature, although the control temperature was constant to about ±2°C during a test. These images showed that a circular shaped, flat shroud with its edges supported by an insulated plate has a temperature distribution with higher temperatures at the edges and lower temperatures in the center. Differences between the center and edge temperatures were up to 75°C. Phase 3 results showed that thermocouple (TC) bias errors are affected by coupling with the surrounding environment. The magnitude of TC error depends on the environment facing the TC. Phase 4 results were used to estimate correction factors for specific applications (40 and 63-mil diameter, ungrounded junction, mineralinsulated, metal-sheathed TCs facing a cold surface). Correction factors of about 3.0-4.5% are recommended for 40 mil diameter TCs and 5.5-7.0% for 63 mil diameter TCs. When mounted on the cold side of the shroud, TCs read lower than the "true" shroud temperature, and the TC reads high when on the hot side. An alternate method uses the average of a cold side and hot side TC of the same size to estimate the true shroud temperature. Phase 2 results compared IR camera measurements with TC measurements and measured values of Pyromark emissivity. Agreement was within measured uncertainties of the Pyromark paint emissivity and IR camera temperatures.

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Section: Determining the "True" Shroud Temperature Using Two Methodsmentioning

confidence: 99%

Section: Interpretation Of Intrinsic Tc Datamentioning

confidence: 99%

Section: Interpretation Of Intrinsic Tc Datamentioning

confidence: 99%

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Shroud boundary condition characterization experiments at the Radiant Heat Facility.

Suo-Anttila¹,

Nakos²,

Gill³

2004

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“…Errors due to heat loss along a thermocouple have been most closely studied when the thermocouple is just contacting the surface and otherwise exposed to an external environment [27]. Of the parameters that are subject to some range of control, errors are found to increase with increasing wire radius or increasing thermal resistance between the wire and the die surface.…”

Section: Perturbations Due To the Sensor Locationmentioning

confidence: 99%

Recommendations and guidelines for the performance of accurate heat transfer measurements in rapid forming processes

Dour

Dargusch

Davidson

2006

International Journal of Heat and Mass Transfer

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“…Besides, the uncertainty associated with the undisturbed temperature depends on the uncertainty of the measurement method; it is related to the pyrometer uncertainty in a direct radiometric measurement of surface temperature, while it is due to the uncertainty of the sensors embedded in the reference body when the surface-temperature extrapolation method is adopted [6]. In order to improve the sensor design to obtain better thermal contact with the surface, several simplified models have been proposed [7][8][9][10]. Nevertheless, a more systematic approach and a detailed model are desirable in order to better estimate the errors in temperature measurements during the calibration procedure.…”

Section: Introductionmentioning

confidence: 99%

A CFD Study on a Calibration System for Contact Temperature Probes

et al. 2008

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Surface-temperature measurements by means of contact probes require a detailed investigation of the probe-surface interaction. For an accurate calibration of such probes, the heat transfer processes involved in contact measurements must be well known and the impact of any influence parameters must be taken into account. At present, contact probes are generally calibrated by means of a temperature-controlled hot plate. A calibration system for contact surface-temperature probes, based on such a hot plate, was developed at INRIM. It covers the temperature range from ambient to 350 °C. The reference temperature is available on the upper surface of a metal block and is determined by linear extrapolation of the readings of three calibrated thermometers embedded into the block at different depths. However, the actual temperature of the reference surface largely depends on the sensor-to-surface interaction. The contact thermal resistance, the thermal conductivity of the block, the geometry of the probe, and the temperature of the surrounding fluid are just some of the parameters that affect a calibration and that may cause measurement errors if they are not properly taken into account and corrected for. Better insight into the interaction between the surface and the probe is therefore required. Since the experimental evaluation of measurement errors is not straightforward, mathematical modeling could represent a crucial tool to better understand the interactions between the probe and the calibration system. In this paper, a finite-element numerical model of the INRIM calibration system was developed in order to investigate the temperature field across the reference block as well as on its surface during a calibration. The thermal load introduced by a commercial contact probe during a calibration was also included in the simulation and its effect on the temperature field was studied. In order to obtain a detailed mathematical model, the surrounding air was also included in the simulation, avoiding the imposition of boundary conditions at the interface between solid parts and fluid. The proposed model was validated by comparing the results obtained with the available experimental data

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Surface Temperature Measurement Errors

Cited by 35 publications

References 0 publications

Shroud boundary condition characterization experiments at the Radiant Heat Facility.

Shroud boundary condition characterization experiments at the Radiant Heat Facility.

Recommendations and guidelines for the performance of accurate heat transfer measurements in rapid forming processes

A CFD Study on a Calibration System for Contact Temperature Probes

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