Calibration of thermopile heat flux gauges using a physically-based equation

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Abstract

A thermopile, in which a number of thermocouple junctions are arranged on either side of a thin layer of insulation, is commonly used to determine the heat flux for steady-state measurements. Gauges using this method are available commercially and a new, generic calibration method is described here. For this purpose, an equation based on physical properties has been derived to determine the theoretical relationship between the measured voltage output of the gauge and the heat flux through it. An experimental rig has been built and used to calibrate gauges under steady-state conditions for heat fluxes between 0.5 and 8 kW/m 2. The gauge temperature was controlled between 30 and 110 °C, and voltage-flux correlation – based on the theoretical relationship – was determined using maximum likelihood estimation (MLE). For tests with constant gauge temperature, there was a linear relationship between the voltage and heat flux; owing to the temperature dependency of the Seebeck constants of the thermoelectric materials, the voltage increased with increasing gauge temperature. In all cases, there was very good agreement between the measured and correlated values, and the overall uncertainty of the correlation was estimated to be less than 5% of the measured heat flux.

Original languageEnglish
Pages (from-to)1806-1816
Number of pages11
JournalProceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy
Volume235
Issue number7
Early online date17 Jan 2021
DOIs
Publication statusPublished - 1 Nov 2021

Keywords

  • Flux gauge calibration
  • conduction calibration
  • heat flux measurement
  • maximum likelihood estimation

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Mechanical Engineering

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