Stirling-type pulse tube refrigerator (PTR) driven by cold linear compressor.

This research paper focuses on the study of the Stirling-type pulse tube refrigerator (PTR) system in conjunction with introducing cold compression concept. When the working fluid (helium) is compressed at cryogenic temperature, the mechanical power (PV power) can be directly transmitted through the regenerator to the pulsating tube without under-going unnecessary precooling process. The required PV power generated by a linear compressor, furthermore, can be significantly diminished due to the relatively small specific volume of the working fluid at low temperature. The PTR can reach lower temperature efficiently with higher heat lift at the corresponding temperature than other typical single-stage Stirling-type PTRs. Utilizing a cryogenic reservoir as a warm end and regulating the entire operating temperature range of the PTR will enable a PTR to operate efficiently under space environment. This research paper proposes the design methodology with numerical computation (1D, axisymmetric) which considers the dynamic characteristics of the cold linear compressor with thermo-hydraulic governing equations for each sub component of the PTR. All the mass flow rates and pressures, as output parameters, are assumed to be sinusoidal, and then the thermal performance of the PTR is estimated in cooperation with the REGEN code. The experimental validation as a proof of concept is carried out to demonstrate the capability of PTR operating between 80 K and 20 K. The linear compressor is submerged in a liquid nitrogen (LN2) bath. No-load temperature of 23.2 K is recorded at the cold expansion volume.