A new fast response cryogenic evaporative calorimeter

Andrew K. Gillespie, Cuikun Lin, Robert P. Thorn, Heather Higgins, Robert Baca, Andrew A. Durso, Django Jones, Ruth Ogu, Jeremy Marquis, R. V. Duncan

Research output: Contribution to journalArticlepeer-review

Abstract

We present the principle and implementation of a new type of fast response evaporative calorimeter designed to work at cryogenic temperatures and above-ambient pressures. It is capable of measuring input energy from an electric pulse and the thermal output energy by measuring the evaporation of liquid nitrogen through a mass flow meter. This system may be used to measure either the steady heat output from the system submersed under the cryogen or the heat output that results from a fast square-wave profile electrical pulse of duration from 10 μs or longer. The energy output of metal capillary-wire composite systems has been measured calorimetrically. A four-wire measurement was used to monitor the input electric energy with an uncertainty less than 5% for a typical pulse. Mass flow meters and pressure regulation systems were used to monitor the rate of evaporation of liquid nitrogen with a typical precision of 2 std.-ml/min. For a typical pulse, the integrated mass flow of nitrogen could be determined with an uncertainty less than 3%. The pressure controllers and ballast compliance volumes allow the system to return to a steady state of mass flow in less than 2 min following an electric pulse. The system is capable of housing and measuring four separate wire-capillary systems in a single Dewar. On average, a calibration resulted in 3.9 std. ml evaporated per joule of input energy. This corresponds to a 97% efficiency for this calorimeter.

Original languageEnglish
Article number085103
JournalReview of Scientific Instruments
Volume91
Issue number8
DOIs
StatePublished - Aug 1 2020

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