Title: Temperature and enthalpy of fusion calibration of Calvet calorimeter from -150°C to 156°C

Authors: Daeho Kim; Suyong Kwon; Sungjun Lee

Addresses: Thermometry and Fluid Flow Metrology Group, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Yuseong-gu, Daejeon, 34113, South Korea ' Thermometry and Fluid Flow Metrology Group, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Yuseong-gu, Daejeon, 34113, South Korea; Department of Measurement Science University of Science and Technology (UST) 217 Gajeong-ro, Yuseong-gu, Daejeon, 34113, South Korea ' Thermometry and Fluid Flow Metrology Group Korea Research Institute of Standards and Science 267 Gajeong-ro, Yuseong-gu, Daejeon, 34113, South Korea

Abstract: To calibrate a commercial Calvet calorimeter and promote accurate measurement for an unknown sample, a calibration method using reference materials was studied within a wide temperature range of -150 ~ 156°C. We present the results of two experiments that we conducted to calibrate the calorimeter for temperature and enthalpy of fusion measurements. The calibration materials included cyclopentane and n-heptane in the low-temperature region, in addition to water, gallium, and indium, which are fixed-point realisation materials specified in ITS-90 at temperatures above 0°C. We determined the onset temperature and enthalpy of fusion at a heating rate of 0.1-0.4 K/min by analysing the heat flow signal and calculating the area under the corresponding curve. For each material, we obtained calibrated temperatures that showed a valid range with a maximum deviation of 0.17°C from the fitted line. We successfully calibrated enthalpies of fusion with relative uncertainties ranging from 0.38% for water to 3.56% for gallium. We found that the overall uncertainty of the Calvet calorimeter was within 5.3%. Future research efforts will aim to further reduce the uncertainty by using a heating cell with Joule heating to enable continuous data collection over the entire temperature range.

Keywords: Calvet calorimeter; temperature calibration; onset temperature; heat flow calibration; enthalpy of fusion.

DOI: 10.1504/IJNT.2024.137420

International Journal of Nanotechnology, 2024 Vol.21 No.3, pp.204 - 211

Published online: 18 Mar 2024 *

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