Computational Analysis, Three-Dimensional Simulation, and Optimization of Superfluid Stirling Cryocooler

The aim of this work is to analyze a superfluid Stirling cryocooler using superfluid helium as the working medium. The idea behind this kind of cryocooler is to utilize two conjoined Stirling coolers with a phase difference as to achieve heat transfer between them and thus negate the need for a regenerator. The two cycles exchange heat at an exchanger, referred to as a recuperator, placed where the regenerator would be typically. This apparatus is simulated through a 1D model where the full equations of state for the superfluid are being used, opposed to the common simplifications when modeling superfluids. This model provides the expected results for the initial case of 180 deg phase difference between the engines, and then finds the optimal phase difference for the best coefficient of performance. A 3D model is designed in the ansys fluent software, and the superfluid data are used in the computational fluid dynamics calculation. Running different cases, the optimal phase difference for the 3D case was found and compared to the 1D model. Additionally, the cryocooler was simulated to work in different frequencies for finding its optimal speed and deriving the cooling power to frequency plot.