Theoretical And Experimental Study On A Single Stage Pulse Tube Cryocooler Operating At 120Hz

Military applications and aerospace applications, which have strict size and weight restrictions for cryocooler systems, are two main forces to promote the development of cryocooler. Stirling type pulse tube cryocooler (S-PTC) has been widely used in these applications due to its unique characteristic. Nowadays, with maintained cooling performance, the miniaturization of S-PTC naturally becomes the new development trend.If a high frequency pulse tube cryocooler operates over hundred hertz, with higher frequency, higher charging pressure, proper regenerator dimensions and finer matrix, the compressor and the cold head can be diminished in size remarkably while the cooling capacity and the efficiency can be remained. Then the weight of the cryocooler system can be reduced, the fast cooling down can be achieved as well. Those features make the high frequency PTC operating over hundred hertz quite appealing to military applications and space applications. But researches on PTC over hundred hertz are still in the start stage with many scientific and technical problems to be solved. Therefore, research work is carried out as following sections:1. Reports on single stage PTCs for military and space applications from 1989 to 2010 are collected and sorted; the datum of the cryocoolers'compactness have been compared with the early research datum.2. Energy flow analysis is discussed and summarized systematically; energy flows in an ideal PTC are analyzed, and losses in a real PTC are classified and analyzed as well; a linear compressor model based on phasor analysis is built, and used in this paper for analyzing the characteristic of the compressor operating at higher frequency and calculating the compressor efficiency respectively. 3. The behaviors of the linear compressor and the regenerator operating over hundred are analyzed by using the compressor model developed in this paper and REGEN3.2 respectively; stainless steel velvet is proposed as regenerator matrix for high frequency operation, and layer matrix is proposed for diminishing pressure loss in the regenerator.4. Optimized by using REGEN3.2, a single stage pulse tube cryocooler operating at 120 Hz, has been designed, fabricated and tested; an 8.0W of lift at 78.6K with 500W electrical input as well as a rapid cooling down from ambient temperature to 80K in 5.7 mins is achieved; experimental results show that the performance of the PTC is independent of the pulse tube orientation at a high frequency of 120Hz; the layer matrix performance is also tested.