A new fast response cryogenic evaporative calorimeter.

Area of Science:

• Cryogenics
• Calorimetry
• Materials Science

Background:

• Accurate measurement of energy transfer is critical for understanding material properties under extreme conditions.
• Existing calorimeters may lack the speed or sensitivity required for dynamic measurements at cryogenic temperatures and elevated pressures.

Purpose of the Study:

• To introduce a novel fast-response evaporative calorimeter for cryogenic applications.
• To enable precise measurement of both electrical input and thermal output energy.
• To characterize the performance of metal capillary-wire composite systems.

Main Methods:

• Developed a calorimeter utilizing liquid nitrogen evaporation measured by a mass flow meter.
• Implemented a four-wire measurement system for precise electrical input energy monitoring (uncertainty < 5%).
• Employed pressure controllers and ballast volumes for rapid system stabilization (< 2 min).

Main Results:

• The calorimeter accurately measures steady-state heat output and pulsed electrical inputs (≥ 10 µs).
• Liquid nitrogen evaporation rate measured with a precision of 2 std.-ml/min.
• Integrated mass flow determination achieved with < 3% uncertainty.
• Calorimeter calibration yielded 3.9 std. ml evaporated per joule, indicating 97% efficiency.

Conclusions:

• The developed evaporative calorimeter offers high efficiency and fast response for cryogenic measurements.
• The system is suitable for characterizing energy output from various systems, including wire-capillary composites.
• This technology advances the capability for precise thermal analysis under demanding conditions.