Design of distributed JT (Joule-Thomson) effect heat exchanger for superfluid 2 K cooling device
Design of distributed JT (Joule-Thomson) effect heat exchanger for superfluid 2 K cooling device
复制标题
超流2K冷却装置分布式JT（焦耳-汤姆逊）效应换热器设计
DOI：
10.1088/1742-6596/969/1/012084
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
K. Kim
中科院分区：
文献类型：
--
作者：
S. Jeong;C. Park;K. Kim
通过降低液氦的蒸气压，可以很容易地从4.2 K的液氦中获得2k或更低的超流体。而为了获得更好的冷却性能，本文专门设计的调温器可以有效地利用2k腔室汽化氦的冷能，实现所谓的分布式焦耳-汤姆逊（JT）膨胀效应。本文介绍了用于2k JT冷却装置的分布式JT效应换热器的设计方法。新开发的热交换器通过使用毛细管，可以在回热式热交换器的高压部分连续显着压降。与传统的回热式换热器不同，高效JT效应HX在考虑换热特性的同时，还必须考虑压降效应。采用外径0.64 mm、内径0.4 mm的毛细管，积极利用换热器热流处的连续压力损失实现分布式JT效应。通过将换热器划分为换热部件和JT阀等多个子单元进行分析。为了更准确地估计螺旋缠绕毛细管的压降，对高雷诺数下的摩擦因数进行了初步的实验研究。利用建立的压降关系式和传热关系式，确定了2k JT制冷机的分布式JT效应换热器的规格。
Superfluid at 2 K or below is readily obtained from liquid helium at 4.2 K by reducing its vapour pressure. For better cooling performance, however, the cold energy of vaporized helium at 2 K chamber can be effectively utilized in a recuperator which is specially designed in this paper for accomplishing so-called the distributed Joule-Thomson (JT) expansion effect. This paper describes the design methodology of distributed JT effect heat exchanger for 2 K JT cooling device. The newly developed heat exchanger allows continuous significant pressure drop at high-pressure part of the recuperative heat exchanger by using a capillary tube. Being different from conventional recuperative heat exchangers, the efficient JT effect HX must consider the pressure drop effect as well as the heat transfer characteristic. The heat exchanger for the distributed JT effect actively utilizes continuous pressure loss at the hot stream of the heat exchanger by using an OD of 0.64 mm and an ID of 0.4 mm capillary tube. The analysis is performed by dividing the heat exchanger into the multiple sub-units of the heat exchange part and JT valve. For more accurate estimation of the pressure drop of spirally wound capillary tube, preliminary experiments are carried out to investigate the friction factor at high Reynolds number. By using the developed pressure drop correlation and the heat transfer correlation, the specification of the heat exchanger with distributed JT effect for 2 K JT refrigerator is determined.