Convection Calibration of Schmidt–Boelter Heat Flux Gauges in Stagnation and Shear Air Flow

Gifford, Andrew R.; Hoffie, Andreas; Diller, Thomas E.; Huxtable, Scott T.

doi:10.1115/1.3211866

Cited by 20 publications

(7 citation statements)

References 6 publications

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“…The voltage output of the Gardon gauge is approximately linearly proportional to the incident heat flux when measuring thermal radiation and the standard radiation sources are the optimal choice for calibrating the heat flux gauge. However, the heat flux gauges should be calibrated in an environment close to the actual environment and heat flux gauges calibrated using radiation sources may not be appropriate for measuring heat flux for convection [39][40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

A method to measure heat flux in convection using Gardon gauge

Fu¹,

Zong²,

Zhang³

et al. 2016

Applied Thermal Engineering

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Heat flux measurements are widely used in thermal environment analyses. The Gardon gauge is an excellent heat flux sensor with a wide measurement range and long lifespan in harsh environments. However, the Gardon gauge is usually calibrated for radiation heat transfer and is not good for convective heat transfer. This paper introduces a method to measure heat flux for convective heat transfer using the Gardon gauge by relating the measurement sensitivity for convection to that for radiation. The heat flux and convective heat-transfer coefficient can then be simultaneously determined by the standard thermo-electromotive voltage output of the Gardon gauge. The method was demonstrated for convective heat-transfer coefficient ranging from 200 to 3000 W/(m 2 K). The analysis illustrates that the measurement sensitivity for convection decreases with increasing convective heat-transfer coefficient. A correction is necessary especially for higher convective heat-transfer coefficient. The corrected convective heat-transfer coefficients and heat fluxes agree well with the actual values. The relative uncertainty in heat flux is within 0.64%. The method not only greatly improves the measurement accuracy of the Gardon gauge for convection applications, but also provides a reference for evaluating convective heat transfer coefficients in convection environments.

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Section: Introductionmentioning

confidence: 99%

A method to measure heat flux in convection using Gardon gauge

Fu¹,

Zong²,

Zhang³

et al. 2016

Applied Thermal Engineering

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“…In the mid-nineteenth century, James Prescott Joule carefully investigated the heat generated by an electric current. From this study, he found a law that relates the generated heat rate, q, as a function of the electric current, I, flowing through a conductor with electrical resistance, R. This law is also known as the Joule effect and given by Electrical Joule effect power measurement [42] Conditions that require heating 2-8 Peltier effect [43] Conditions that require cooling 3 Thermal Temperature difference [44][45][46][47][48][49][50][51][52] Conditions that a temperature difference over space caused by the heat flux can be measured 1-7…”

Section: Joule Effectmentioning

confidence: 99%

Heat transfer coefficient: a review of measurement techniques

Moreira

Colmanetti

Tibiriçá

2019

J Braz. Soc. Mech. Sci. Eng.

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Heat transfer coefficient is a basic parameter used in the calculation of convective heat transfer problems. Due to the importance of the experimental measurements for the development of convective heat transfer, this review identifies, classifies and describes the experimental methods used for the measurement of heat transfer coefficient. The methods were classified into five major groups: (1) direct method, (2) transient method, (3) Wilson method, (4) heat/momentum/mass transfer analogy method and (5) boundary layer thickness method. Their applications, limitations and the reported accuracy were evaluated in the context of new developments in temperature and heat flux measurement techniques. Finally, this review provides criteria for the selection of the most suitable technique for measurements of heat transfer coefficient according to the aspects of spatial resolution, geometric scale, intrusiveness, fluid type, response time and accuracy. Keywords Heat transfer coefficient • Temperature • Heat flux • Convection • Experimental measurements List of symbols 1D One-dimensional 2D Two-dimensional A Surface area (m 2) A e Outer tube surface area (m 2) A i Inner tube surface area (m 2) A s Surface area (m 2) C e Thermal resistances outside the tube and the tube wall (K/W) (constant) C i Constant C f Fanning friction factor (-), C f = s V 2 ∕2 c Constant (-) c p Specific heat capacity (J/kg K) c p,i Specific heat capacity at constant pressure (J/ kg K) d Diameter (m) d e Outer tube diameter (m) d i Inner tube diameter (m) D m Mass diffusivity (m 2 /s) f Darcy friction factor (-), f = 4 ⋅ C f * Cristiano Bigonha Tibiriçá

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“…Recent measurements on a Schmidt-Boelter gage showed that the convective sensitivity (i.e., kW/m 2 /mV) coefficient was about 12% lower for convection (ref. [8]). Past, similar studies on Gardon gauges have shown the same behavior (ref.…”

Section: Literature Reviewmentioning

confidence: 99%

“…However, as indicated above, recent evidence shows that S-B type gauges also have different gage sensitivities to radiative and convective heat transfer (ref. [8]). …”

Section: Literature Reviewmentioning

confidence: 99%

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Description of heat flux measurement methods used in hydrocarbon and propellant fuel fires at Sandia.

Nakos¹

2010

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The purpose of this report is to describe the methods commonly used to measure heat flux in fire applications at Sandia National Laboratories in both hydrocarbon (JP-8 jet fuel, diesel fuel, etc.) and propellant fires. Because these environments are very severe, many commercially available heat flux gauges do not survive the test, so alternative methods had to be developed. Specially built sensors include "calorimeters" that use a temperature measurement to infer heat flux by use of a model (heat balance on the sensing surface) or by using an inverse heat conduction method. These specialty-built sensors are made rugged so they will survive the environment, so are not optimally designed for ease of use or accuracy. Other methods include radiometers, co-axial thermocouples, directional flame thermometers (DFTs), Sandia "heat flux gauges", transpiration radiometers, and transverse Seebeck coefficient heat flux gauges. Typical applications are described and pros and cons of each method are listed. Heat Flux Measurement Methods in Fires of 62 AcknowledgementsThe author would like to acknowledge the support of numerous colleagues who have developed these heat flux measurement methods and their use over the years. Some of these colleagues are (in alphabetical order) Bennie Blackwell, Tom Blanchat, Tom Diller, Victor Figueroa, Walt Gill, Chuck Hanks, and Ned Keltner. Thanks to Allen Ricks and Ben Blackwell for their peer review. Heat Flux Measurement Methods in Fires5 of 62 Heat Flux Measurement Methods in Fires7 of 62 List of Tables IntroductionHeat flux measurements are important because, in heat transfer applications, providing only a temperature measurement is sometimes not sufficient to fully specify the environment. Using the electrical analogy (Ohm's Law), one needs two of the three variables (current, potential difference, or resistance) to fully specify an electrical circuit. Similarly, in a heat transfer application, one needs two of the three variables (heat flux, temperature difference, and thermal resistance) to fully specify the problem of interest. The temperature difference is similar to a potential difference, heat flux is similar to current, and thermal resistance is similar to electrical resistance.Most often the metric of interest is the response of an item in a fire. This metric is more related to the heat flux than just to the temperature because the thermal resistances to radiation and convection are not captured when only the temperature is specified.The measurement of heat flux in hydrocarbon fuel fires (e.g., diesel, JP-8, etc.) is difficult due to the high temperatures (e.g., 1000qC or higher), the sooty and chemically reactive environment, and due to large temperature gradients which produce thermal stresses. Many commercially available sensors do not work well in fires because they are water-cooled. Soot builds up on the sensing surface due to thermophoresis and this layer of soot changes the gage sensitivity. Post-test soot deposit thicknesses of ¼" have been measured after fir...

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Convection Calibration of Schmidt–Boelter Heat Flux Gauges in Stagnation and Shear Air Flow

Cited by 20 publications

References 6 publications

A method to measure heat flux in convection using Gardon gauge

A method to measure heat flux in convection using Gardon gauge

Heat transfer coefficient: a review of measurement techniques

Description of heat flux measurement methods used in hydrocarbon and propellant fuel fires at Sandia.

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