The offset and the performance of a valved linear compressor with anti-offset piston

Abstract

As a critical driving component of the Joule-Thomson (JT) throttling cryocooler for space applications, the output characteristics of the valved linear compressor (VLC) determine the overall efficiency of the cryocooler. Piston offset is an inherent characteristic of the VLCs. To improve the output capacity and efficiency of VLCs, valved linear compressor integrated with an anti-offset piston was developed in this study. The anti-offset piston can effectively suppress the piston offset, enhance VLC performance, and ensure the stable and efficient operation of the throttling cryocooler. Experimental verification was conducted to measure piston offset and the output characteristics of the VLC with anti-offset piston under various operating parameters. The results indicate that with the increase of the piston stroke, the offset establishment time is prolonged, the offset suppression effect is more obvious, and the effective stroke of the compressor is increased by nearly 40 %. Meanwhile, the suction pressure decreases, the discharge pressure increases, and the maximum pressure ratio is enhanced by 54.2 %. Under the same operating parameters, compared with the compressor without offset suppression, the anti-offset piston structure improves the efficiency of converting electric energy into mechanical energy and optimizes of compression thermodynamic cycle. The experimental results can provide important references for the development of piston offset suppression strategies.