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Abstract
This article studies the effect of operating frequency and fill pressure on the performance of a high frequency miniature scale pulse tube cryocooler. Pulse tube cryocoolers are robust, rough cryocoolers without a moving component at their cold ends. They are usually used in cryogenic cooling of high-performance electronics in space applications where reliability is vital. Miniaturizing cryocoolers is vital because their minimal size and weight facilitates many applications such as space operations. In spite of extensive studies, the extent of possible pulse tube cryocooler miniaturization is not clear. For miniature cryocoolers, computational fluid dynamics modeling is the best available method to accurately represent the processes that occur in the device as the scale is reduced. The present computational fluid dynamics simulation results indicate the significant influence of the operating frequency on the performance of the miniature pulse tube cryocooler and slight improvement of the performance as the fill pressure increases.
Nomenclature
| A | = | Piston displacement amplitude (m) |
| F | = | operating frequency (Hz) |
| t | = | time (s) |
| v | = | intrinsic velocity (m/s) |
| E | = | energy (J/kg) |
| p | = | pressure (Pa) |
| g | = | gravity (m/s2) |
| T | = | temperature (K) |
| k | = | thermal conductivity (W/mK) |
| C2 | = | inertial resistance factor (m−1) |
| Cp | = | specific heat (J/kgK) |
Greek letters
| ω | = | angular frequency |
| ϕ | = | porosity |
| ρ | = | density (kg/m3) |
| α | = | permeability |
| μ | = | viscosity (kg/ms) |
| = | stress tensors (N/m2) |
Subscripts
| f | = | fluid |
| s | = | solid |
| r | = | radial coordinate |
| x | = | axial coordinate |