Estimating Surface Temperature of a Calibration Apparatus for Contact Surface Thermometers from Its Internal Temperature Profile

Estimation of environmental effects on performance of contact surface thermometers using a calibration apparatus

“…Seven PRTs were inserted horizontally and aligned along the center axis of the copper cube, as shown in figure 1, for measurement of the temperature profile in the copper cube of the calibration apparatus. All the PRTs were calibrated at the National Metrology Institute of Japan/National Institute of Advanced Industrial Science and Technology in order to be traceable to the ITS-90 , following the same method reported in our previous work [12]. Specifically, five 1 mm diameter PRTs were inserted at depths of 5 mm, 10 mm, 15 mm, 20 mm and 30 mm, respectively, from the upper surface.…”

“…Specifically, five 1 mm diameter PRTs were inserted at depths of 5 mm, 10 mm, 15 mm, 20 mm and 30 mm, respectively, from the upper surface. Along with a sixth PRT at a depth of 67 mm, these PRTs provided the detailed temperature profile needed to make a highly accurate estimation of upper surface temperature [12].…”

“…As reported previously, our team developed an apparatus for calibrating contact surface thermometers [12]. In this apparatus, the temperature of the upper surface of a copper cube, determined by extrapolation of the temperature profile inside the cube, was used as the reference surface temperature.…”

“…Specifically, using five small PRTs, the temperature profile from 3 mm to the vicinity of the surface was precisely observed and the estimation of the reference surface temperature became more accurate. In the previous report [12], the surface temperature and its uncertainty of the calibration apparatus were estimated at temperatures around 50 • C, 100 • C, and 150 • C. Time dependencies of the surface temperature after applying a contact surface thermometer were also observed at each temperature [12].…”

“…Although the ambient temperature and air flow around the apparatus the laboratory were stabilized as much as possible in the previous work [12], the estimation of uncertainty components due to the stability of the environmental conditions was not sufficient. This can be an important factor because surface temperature and surface thermometers are easily affected by heat flow changes due to fluctuations in the environmental conditions.…”