Heat Transfer and Fluid Flows in Gas Springs

Abstract

Thermodynamical processes and fluid mechanics phenomena occurring in an unlubricated piston-cylinder gas spring are investigated. Existing instantaneous heat transfer correlations are not applicable to the piston-cylinder compressed volumes. Accurate prediction of the transient thermal properties, heat transfer and fluid flows for the high performance, tight tolerance and lubricant-free gas compressors (e.g. cryo-cooling industry) is of high industrial importance. Research is here done with the use of ANSYS CFX finite-volume numerical package, modelling the closed fluid domain in a valveless non-lubricated one-piston-cylinder gas spring. Obtained numerically simulated values are compared to experimentally measured pressure and heat-flux data; very good agreement is observed. Broad discussion and conclusions with regard to thermodynamic and fluid-flow phenomena occurring are presented.