-150℃逆布雷顿空气制冷机动态温降特性研究

Study on the Dynamic Cooling Performance of a-150 ℃ Reverse Brayton Cycle Air Cryocooler

为了研究空气制冷机的动态温降特性,对采用工作轮直径为24mm的小型透平膨胀机和板翅式换热器的逆布雷顿循环空气制冷机实验台进行了改进。采用高真空绝热冷箱对制冷机进行绝热,可使绝对压力低于10-3 Pa,得到的设计制冷温度为-150℃。对不同进口参数和采用不同直径风机轮的制冷机工况进行了实验研究,获得了透平膨胀机的实际温降曲线;以实验系统为基础建立了数学模型,得到了相应的理论温降曲线。研究结果表明:风机轮尺寸对空气制冷机动态温降过程的影响较大,实验的最低温度低于-150℃;所建理论模型能够较好地预测实际系统温降的过程。

A turboexpander having a working wheel with a diameter of 24 mm and a plate-fin heat exchanger were applied in a retrofitted --150 ℃ air cryocooler system. A vacuum cryogenic trap （absolute pressure 〈 10 -3 Pa） was used for insulation. The dynamic cooling performance of the whole system was studied under the conditions of different brake wheel configurations. A numerical model in respect of the dynamic system was established. The results show cooling performance of the cryocooler, and cooling performance of the --150 ℃ air cryocooler that the brake wheel size significantly affects the the lowest system temperature is under --150 ℃. Additionally, the numerical results agree well with the experimental data.