Effect of temperature-dependent specific heat of the working fluid on the performance of cryogenic regenerators

Abstract

The governing differential equations of a regenerator operating with a fluid with temperature-dependent specific heat have been formulated in terms of characteristic reduced parameters. A numerical solution of these equations is presented for several combinations of fluid-flow parameters using normal and parahydrogen as working fluid. It is observed that a constant specific heat model with the harmonic mean reduced length is adequate except at large values of reduced length or period and when the specific heat variation exceeds a factor of two over the temperature range. The matrix and gas exit temperature profiles, however, show a significant difference between the two models, which may be critical in some applications.