Impact of operating parameters on 80 K pulse tube cryocoolers for space applications

Pulse tube cryocoolers (PTCs) represent a significant enabling technology for infrared detectors in space applications. A PTC can be efficiently operated by optimizing the structural parameters and impedance characteristics among different components. While the structures of the components are determined, the operating parameters are the most effective and simple methods to optimize the cooling performance of a PTC. The regenerator losses (regenerative losses, heat conduction losses and pressure drop losses) and the phase shifting ability (phase angle) are affected by the operating parameters. Based on theoretical and simulated analysis, the effects of operating parameters on the linear motor, regenerator and phase shifter are investigated. The pressure ratio, waveforms of the pressure and displacement, phase angle, motor efficiency, input power and cooling capacity are then presented by an experiment to clarify the influence mechanism. The pressure ratio and phase characteristics at the entrances of the regenerator and inertance tube are changed with different operating parameters. Corresponding with the piston displacement and motor efficiency, there is an optimal average pressure for the best cooling efficiency. The results show that a high compressor efficiency of 88% and a relative Carnot efficiency (rCOP) of 16.08% is achieved at 2.5 MPa and 51 Hz, while a relative Carnot efficiency of 16.0% is achieved at 3.5 MPa and 52 Hz by optimizing the frequency and pressure. (C) 2018 Published by Elsevier Ltd.