Investigation Of Cooling Extraction Method Of Single-Stage Pulse Tube Cryocooler

Pulse tube cryocoolers(PTCs)are different from conventional regenerative cryocoolers.The PTC has no moving parts at its cold end except the compressor which provides the input power.The compressor is connected to the cold finger through a connecting tube,this arrangement away from the compressor greatly reduces the vibration effect and make it widely used in various fields.Among them,space infrared detection is the most widely used platform for PTCs,and the development of space infrared detection technology is invariably promoting the development of cryogenic technology.In general,a scientific satellite usually carries two and more detectors to cover a wider range of detection wavelengths.The operating temperature required for different detection wavelengths varies greatly and needs to be cooled to a suitable temperature to ensure the detection work is carried out properly to obtain high-quality imaging,with a common operating temperature range of 40 K-90 K.The optical system on the satellite also needs to be cooled to 120 K-200 K by a cryogenic cooler due to parasitic heat leakage.This shows that there is a very strong need for simultaneous cooling in multiple temperature zones in the space exploration field,and therefore it is necessary to research multi-temperature cooling in PTCs.Existing solutions for this need include multi-stage structures and one-two structures,both of which suffer from a lack of compactness.In this paper,a systematic study from theory to simulation to experiment is carried out for the multi-stage cooling of a single-stage coaxial PTC,taking the compactness of the whole machine as the starting point,while also meeting the demand for simultaneous cooling in multiple temperature zones.Specific studies include,1)Based on the thermodynamic basis,the thermodynamic processes under closed and open refrigeration systems are given.The energy flow in the ideal case of a pulse tube refrigerator is analyzed in conjunction with the enthalpy-flow-phase regulation theory.The actual energy flow distribution is given by taking into account the losses that exist within the pulse-tube refrigerator in the real situation,in particular the main loss components such as the regenerator and the pulse tube.The effect of the addition of intermediate cooling on the actual losses is also analyzed.In addition,the phase distribution of inertance tube-type pulse tube refrigerators is analyzed based on thermoacoustic and phase characteristics.(2)Based on the basic parameters of the single-stage pulse tube cryocooler,a numerical model of the multi-stage cooling from the single-stage PTC is established with the numerical simulation software.Under the different intermediate cooling power,the changes in the main internal component losses,enthalpy flow,entropy flow,phase distribution,compressor impedance,and other parameters of the pulse tube cryocooler are investigated and analyzed.The simulation results show that the PV power is dissipated most in the regenerator,followed by the inertance tube and the pulse tube.An increase in the intermediate cooling capacity causes a slight increase in the regenerator losses and the inertance tube losses,while the pulse tube losses are almost unaffected.On this basis,the effect of the intermediate cooling capacity on the various types of losses within the three components,including flow resistance losses,incomplete heat transfer losses,and radial losses,is also discussed in detail.The trend of the enthalpy flow of the regenerator and the enthalpy flow of the pulse tube with the intermediate cooling is also analyzed.(3)Experimental research was carried out on single-stage coaxial pulse tube cryocooler with multi-stage cooling.The experimental study mainly includes the basic performance tests of PTC,the effects of cooling capacity on temperature of cold finger and power factor of compressor,and the relationship between input power and multi-stage cooling.The relationships presented in the experiments for the effect of inter-cooling on the PTC are consistent with the trends of the numerical simulation results,which also prove the simulation and theoretical analysis,and the relevant reasons are given for the existence of numerical errors.Charging pressure of 3.2 MPa,the operating frequency of 49 Hz,hot end temperature of 293 K operating conditions,when the input work is 150 W,70.7 K@4 W and 237.7 K@4 W of cooling power can be achieved simltaneously.This can prove the feasibility and reliability of the single-stage PTC with intermediate cooling and provides a new idea for the PTC with simultaneous cooling in two temperature zones.