Thermodynamic and Mechanical Design of the FNAL Central Helium Liquefier

Role of heat exchangers in helium liquefaction cycles: Simulation studies using Collins cycle

“…The rate of mass flow through the high temperature expander (ṁ EXP1 ) is 0.45 of the total compressor flow and that of the low temperature expander (ṁ EXP2 ) is 0.33 of the total compressor flow [10]. When varying the effectiveness or UA of a heat exchanger, the effectiveness of other heat exchangers is kept constant at 0.97 at their base values [17,18]. At very low temperatures where there is significant change in specific heat of helium it has been ensured that there is no internally crosses-over in heat exchanger operating at that temperatures and the Second Law is not violated.…”

“…Daus et al [7] have shown the power consumption, heat transfer surface and the relative plant costs as functions of the temperature difference of heat exchanger. Toscano et al [8] have evaluated the thermodynamic performance of the central helium liquefier of Fermi National Accelerator Laboratory (FNAL) for different sets of temperature approach of heat exchangers. Khalil et al [9] have given the practical temperature approaches of heat exchangers for different multi-expander Claude based helium refrigeration cycles having up to five expanders.…”

A cryogenic test stand for large superconducting solenoid magnets

“…Ultimately, the Fermilab Central Liquefier (CHL) [6] was selected as the site for the Solenoid Test Facility, where both space for the large test cryostat and a sufficient source of liquid helium are available. The CHL plant, which had been out of service since the end of Fermilab's Tevatron operation in 2011, was brought back into service to support this test stand.…”