Influence of drive chamber discharging process on non-linear displacer dynamics and thermodynamic processes of a fluidic-driven Gifford-McMahon cryocooler

Abstract

Abstract Continuous effort is made on Gifford-McMahon cryocoolers (GMC) to amplify its refrigeration power, so they can be used to cool the cryopumps, high Tc magnets and development of efficient small-scale hydrogen liquefiers, etc. The fluidic-driven GMC is considered to be more reliable and prominent candidate than the mechanically-driven GMC due to its structural simplicity and reliability. Nonetheless, cooling mechanism of the fluidic-driven GMC is complicated, as the displacer motion inside the displacer cylinder is simultaneously controlled by the pressure difference between drive chamber and compression/expansion chamber. Different paths of displacer can be traced inside the displacer cylinder for different drive-chamber discharging process, hence, pressure–volume power of compression and expansion chambers, and refrigeration power changes. A theoretical study is conducted in present paper to visualize the influence of drive-chamber discharging process on the thermodynamic characteristics of fluidic-driven GMC for the first time. Thermodynamic cycles are drawn at the expansion chamber of the fluidic-driven GMC for different values of drive-chamber discharging process for two types of valve timing arrangements. Energy and work loss behaviors in different components of the GMC are also analysed. Adequate experimental investigations have also been carried out on a fluidic-driven displacer type GMC to verify the simulation results.