A protocol for accurately calibrating thermocouples at cryogenic temperatures

Abhishek Purandare, S. Vanapalli*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

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Abstract

To study the quenching characteristics of materials in a cryogenic liquid bath transient temperature measurements of high accuracy are necessary. Thermocouple is an ideal tool for this application because of its low self-heat capacity. However, they require calibration before usage that require multiple fixed-point temperatures. The common fixed-point temperatures are the water-ice melting temperature, the dry ice sublimation temperature, and the boiling temperature of liquid nitrogen. It is important to note that there are uncertainties associated with dry ice sublimation and liquid nitrogen boiling temperature inherent to the heat and mass transport phenomenon at their phase-changing interface or inside the bulk medium. The dry ice temperature is influenced by the mass transport phenomenon occurring at the interface between the dry ice and the ambient surrounding it. In a typical lab environment, dry ice temperature is significantly lower than the commonly quoted sublimation temperature of -78.5 °C at 1.013 bar. In the case of liquid nitrogen stored in a cryostat, temperature gradients develop in the liquid bath. This paper describes a protocol for calibrating thermocouples by accurately defining and using fixed-point temperatures of dry ice in a saturated environment and a liquid nitrogen slush.
Original languageEnglish
Title of host publicationCEC-ICMC-2023 - Cryogenic Engineering Conference and International Cryogenic Materials Conference
Number of pages8
Publication statusAccepted/In press - 20 Nov 2023
Event25th Cryogenic Engineering Conference and International Cryogenic Materials Conference, CEC/ICMC 2023 - Hawaii Convention Center, Honolulu, United States
Duration: 9 Jul 202313 Jul 2023
Conference number: 25

Conference

Conference25th Cryogenic Engineering Conference and International Cryogenic Materials Conference, CEC/ICMC 2023
Abbreviated titleCEC/ICMC
Country/TerritoryUnited States
CityHonolulu
Period9/07/2313/07/23

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