活性炭吸附氦气式回热器低温比热与流阻特性的研究

摘要

An ideal regenerator material is characterized by a high specific heat capacity and a low flow resistance,and the specific heat capacity of the working gas must be low.However,the specific heat capacity of a helium working gas is much higher than that of the general regenerator materials in the temperature range 4-30 K,which severely limits the improvement of the refrigerator performance.The helium adsorption capacity of the activated carbon was first evaluated.The heat capacity and flow resistance of the activated carbon with adsorbed helium were measured and compared with the commonly-used regenerator materials such as stainless steel wire mesh,lead,and magnetic Er3 Ni and HoCu2.Results show that the specific heat capacity of the activated carbon with adsorbed helium are higher than those of the other materials investigated at 3.0 MPa and 16-25 K,and its flow resistance is close to that of Er3Ni,a little bit higher than that of HoCu2,and much less than that of the stainless steel wire mesh.These results confirm that it is feasible to use activated carbon with adsorbed helium as a regenerator material.%在30 K以下温区,低温制冷机工质气体氦气的比热已高于目前常用的蓄冷材料,导致回热器蓄冷能力严重不足,限制了制冷机性能的提高.本文使用活性炭吸附部分工质气体氦气直接作为回热器填料的研究,是对制冷机蓄冷材料研究的一个全新探索.实验测试了15～30 K温度范围内活性炭对氦气的吸附量,并将其比热与不锈钢丝网、铅球、磁性材料Er3Ni/HoCu2等常规蓄冷材料进行了比较.另外,搭建了阻力测试装置,对活性炭吸附氦气式蓄冷单元以及磁性材料Er3Ni、HoCu2和不锈钢丝网的流动阻抗进行了实验测试.研究结果表明,活性炭吸附氦气式蓄冷单元比热在25K以下已经接近甚至高于目前已知的常规蓄冷材料,同时,其流动阻抗与磁性材料Er3Ni的数值接近,略高于HoCu2,但低于635目不锈钢丝网.基于比热与流阻的角度,初步验证了其作为极低温区制冷机蓄冷器的可行性.