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Leveraging Real Fluid Effects as a Tool for Power Flow Measurements in 4 K Cryocooler Regenerators



Ryan Snodgrass, Vincent Y. Kotsubo, Joel Ullom, Scott Backhaus


The real fluid properties of helium have a major impact on the thermodynamics of pulse tube and Gifford-McMahon cryocoolers operating below about 30 K. For example, real fluid properties cause the temperature profile in low-temperature regenerator to be nearly constant at the cold end and allow heat to be applied at warmer, intermediate points along the regenerator axis without affecting cooling power at the cold heat exchanger. We leverage these unique properties and the injection of intermediate heat as a tool for probing and validating the total power equation. As an initial demonstration of this technique, we show how it can be used to measure steady mass flow through the regenerator. We also discuss and demonstrate more advanced measurement protocols that may be used to isolate other terms responsible for power flow in low-temperature regenerators.
Proceedings Title
Cryocoolers 21
Conference Dates
December 7-10, 2020
Conference Location
N/A (virtual), CO, US
Conference Title
21st International Cryocooler Conference


Cryocoolers, pulse tube refrigerator, thermodynamics


Snodgrass, R. , Kotsubo, V. , Ullom, J. and Backhaus, S. (2021), Leveraging Real Fluid Effects as a Tool for Power Flow Measurements in 4 K Cryocooler Regenerators, Cryocoolers 21, N/A (virtual), CO, US, [online], (Accessed May 23, 2024)


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Created April 1, 2021, Updated March 31, 2022