逆布雷顿制冷机空间应用进展

Development of reverse-Brayton cryocooler in space application

以逆布雷顿循环为基础的透平制冷机具有大冷量、长寿命、低震动、高可靠的优势,目前已在70 K温区NICMOS制冷机、20 K温区ZBO制冷机和MELFI多温区低温储箱等空间项目上得到了应用。透平-逆布雷顿循环制冷机采用永磁电机驱动的气浮无油离心压缩机,其最高转速达55.2万转/分,效率可达67%;透平膨胀机采用膨胀-发电一体技术,可有效回收膨胀功,最高效率77%;高效紧凑式间壁换热器则出现了微管壳式换热器、硅片微加工换热器等新技术,有效提升了比表面积,降低了传热温差,换热效率预计可超99.5%。逆布雷顿制冷机制冷温度最低已达液氦温区,可获得千瓦级大冷量,在空间多温区大冷量制冷领域具有巨大的应用潜力。

Mechanical cryocoolers based on reverse-Brayton cycle have some advantages including large cooling capacity, long life, low vibration and high reliability and have been adopted in several important space applications like NICMOS cryocooler @70 K, ZBO cryocooler @20 K and the multi-temperature storage tank MELFI. Turbo-Brayton cryocooler adopts oil-free centrifugal compressor driven by permanent magnet motor whose rotational speed reaches 552 000 r/min, and the performance of some compressors reaches 67%. Turbo-expander combines expanders and alternators to recycle the expansion work, and its highest efficiency reaches 77%. Micro bare-tube heat exchanger and silicon micro-machined recuperator have been invented as high-efficiency compact recuperators, which increase the specific surface area, decrease the temperature difference and enable a heat transfer efficiency to be beyond 99.5%. The lowest temperature that a Baryton cryocooler can achieve reaches liquid helium temperature and a cooling capacity on kW-scale can be obtained. Baryton cryocooler is quite promising in space applications requiring multi-temperature zone and high cooling capacity.