Free-piston pulse tube refrigerator using all-carbon aerogel regenerative filler

Abstract

The invention discloses a free-piston pulse tube refrigerator using all-carbon aerogel regenerative filler. The free-piston pulse tube refrigerator comprises a plurality of pulse tube refrigerator units coupled through a thermal bridge. At least one of the pulse tube refrigerator tubes comprises a compressor, a regenerator, a cold-end heat exchanger, a pulse tube and a pulse tube hot-end heat exchanger, wherein the parts are connected in sequence, a free piston system comprising a spring and a free piston is disposed in the pulse tube, the free piston is connected with the pulse tube hot-end heat exchanger through the spring, and the free piston is made of an aerogel column which is in hermetic fit with the pulse tube. The low temperature end of the regenerator of the lowermost-temperature pulse tube refrigerator unit among the pulse tube refrigerator units is filled with an all-carbon aerogel layer. The all-carbon aerogel layers more than 95% in porosity and high in adsorptive capacity are filled in the regenerators of the pulse tube refrigerator, the free pistons of the pule tube refrigerator are made of aerogel material, and accordingly efficient cryogenic refrigeration is achieved.

Description

technical field [0001] The invention relates to a regenerative low-temperature refrigerator, in particular to a free-piston pulse tube refrigerator using all-carbon airgel regenerative filler. Background technique [0002] The liquid helium temperature zone plays an indispensable and important role in the fields of national defense, military, energy, medical, aerospace, low temperature physics and so on. Since the Dutch physicist Kamerlingh.Onnes first realized the liquefaction of helium in 1908, the liquid helium temperature zone (4K) has been the focus and difficulty of the research in the field of cryogenic engineering. At the same time, especially since the 1980s, human beings have higher technical and performance requirements for cryogenic refrigeration technology, and more and more stringent requirements have been put forward for the efficiency, reliability, volume, weight, and vibration of cryogenic refrigerators. Require. [0003] The pulse tube refrigerator was pr...

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Problems solved by technology

[0005] (1) The volumetric specific heat capacity of helium increases sharply in the temperature range below 15K, while the specific heat capacity of commonly used regenerative fillers (such as lead shot, stainless steel, etc.) decreases significantly, although magnetic regenerative fillers (Er3Ni, GOS, etc.) High volume specific heat capacity peak, but this peak only exists in its phase transition temperature region, which causes a sharp decrease in the efficiency of the deep-low temperature regenerator (such as Figure 4 As shown), the efficiency of the liquid helium temperature pulse tube refrigerator is extremely low, so finding a regenerative packing with a high specific heat capacity at a deep low temperature (<10K) is a key to solve the low efficiency of the current liquid helium temperature zone pulse tube refrigerator

[0006] (2) The intrinsic efficiency of the pulse tube refrigerator is lower than the Carnot efficiency due to the inability to recover the expansion work of the working medium in the pulse tube due to the use of passive phase modulation devices (such as inertial tubes / gas reservoirs, small hole valves, etc.) , so the recovery of sound work becomes another key to improve the efficiency of the pulse tube refrigerator

But as mentioned above, at deep low temperature (<10K), the specific heat capacity of the regenerator material will drop significantly, which will greatly affect the cooling efficiency of the regenerator and pulse tube refrigerator.

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