Heat and fluid flow in a free piston Stirling refrigerator

摘要

The present work aims to develop a mathematical model for numerical simulations of free piston Stirling coolers. Stirling refrigeration cycles are found on some applications such as low operating temperature coolers, medical diagnostic equipments and sophisticated electronics (superconductivity components and devices). In this work, it is explored a Stirling cooler machine for domestic refrigerators, as an alterative for conventional hermetic compressors and vapor compression cycles. The model explores the working gas thermodynamic behavior and evaluates the performance of the Stirling cooler components. To simulate the working fluid behavior inside the chambers, use was made of a global thermodynamic model. To model the heat exchanger and the regenerator a discretized approach was adopted using the finite volume methodology. Dynamic equations were used to simulate the system composed by the piston, displacer, and springs. An electric circuit represented the linear electric motor and its components. A computational code was generated to simulate the refrigerator and to help in the design process of new coolers and machines. Validations of the results obtained by comparisons with experiments indicated consistence of the physical and mathematical model. As explored, the Stirling cooler reached values of performance comparable to conventional hermetic compressors.