Study on the stroke amplitude of the linear compressor

Abstract

Linear compressor is widely used to drive Stirling type cryocooler due to its advantages of low vibration, long life and compactness. In practice, it is often expected to operate at or near the resonant state under which it can reduce more mechanical loss and Joule heat loss, and transfer more electric energy into thermal acoustic energy of the gas. It is significant to explore the working characteristics of the linear compressor for realizing its high-efficient operation in the cryocooler system. In this study, considering the effects of both acoustic and mechanical impedances, a mass-gas-spring model is built to investigate the piston stroke amplitude of the linear compressor. Different with previous models that contain some uncertain parameters, an expression of the stroke amplitude that only based on easily obtainable parameters has been deduced for the first time. The calculated curve of the stroke amplitude at different operating frequencies provides a direct indication of whether the compressor is working at its resonant state or not. An existing high power linear compressor has been used to test and verify the equations. The theoretical stroke amplitude curve matches the experimental data quite well with a deviation of less than 10%. Further analyses about the influences of the operating parameters and intrinsic parameters of a compressor on its resonant characteristics have been given, which can be used as guidance of how to well utilize and design a linear compressor for a cryocooler system.