Effect of thermal dispersion and turbulent conduction on the heat transfer behavior of coaxial pulse tube cryocooler

Abstract

In this article, a numerical analysis is conducted for a miniature coaxial pulse tube cryocooler including the effect of an axial conduction enhanced term. This term is a representative of supplementary energy loss, which happens because of turbulent conduction, mixing, and thermal dispersion. The complex physical domain of cryocooler is modeled intelligently in one-dimensional model by splitting the total computational domain into two subsections. The individual subsections of the cryocooler have been discretized into a number of small control volumes. Both subsections are merged together to make a complete computational domain for the cryocooler. The conservative form of the nonlinear, coupled partial differential equations demonstrating its heat and fluid flow aspects have been discretized into algebraic equations by utilizing the finite volume technique. Final discretized algebraic equations have been solved iteratively to predict its heat and fluid flow behaviors. Suitable relaxation factors have been incorporated to accelerate the convergence of the simulation. Moreover, the variation of mean cyclic energy, enthalpy, and exergy flow have been visualized along its physical domain with and without fluid axial conduction enhancement loss processes. Influences of different length of inertance tube, outer to inner radius ratio of annular passage, and length to radius ratio of pulse tube on no-load temperature is studied for with and without fluid axial conduction heat loss.

Keywords:

• Coaxial configuration
• implicit scheme
• inertance phase shifter
• miniature cryocooler
• nonlinear equations
• numerical simulation
• relaxation factor
• thermal dispersion
• turbulent conduction
• upwind scheme