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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Temperature inhomogeneity in high capacity pulse tube cryocoolers

Abstract: High power pulse tube cryocoolers are expected to be a very promising candidate for high temperature superconductors (HTS) cooling. Unfortunately there are still some problems significantly deteriorating the performance of these cryocoolers, one of which is temperature inhomogeneity. Several different theories have been proposed to explain the mechanism and many factors have been indicated as contributors to the generation and development of temperature inhomogeneity. However, some relations between these factors are seldom noticed, nor classified. The underlying mechanisms are not yet clear. The paper classifies, as internal and external, factors leading to temperature inhomogeneity based on their location. We examine some apparently unreasonable assumptions that have been made and difficulties in simulation and measurement. Theoretical and experimental research on the driving mechanism and suppression of temperature inhomogeneity is reviewed, and potential analysis and measurement methods which could be used in future are identified.

Key words: Temperature inhomogeneity, Internal streaming, High capacity, Pulse tube cryocooler

Chinese Summary  <31> 大功率脉管制冷机的温度非均匀性

目的:大功率脉管制冷机中存在的温度非均匀性问题导致回热器效率低下,严重阻碍制冷机性能的提高。本文回顾回热器非均匀性问题的理论与试验研究,对当前理论与实验的研究结果进行细致的分类与探讨,并展望将来非均匀性研究可能的发展方向。
方法:1. 当前回热器非均匀性理论与实验研究主要包括形成机理、发展机制和抑制方法三个方面。其中对其形成机理和发展机制的研究以理论为主,抑制方法的研究以实验为主。2. 回热器温度非均匀性的形成机理,按照其诱发因素的来源可划分为内源性与外源性因素,其中内源性因素包括与回热器相关和变径流道等,外源性因素包括自然对流效应及外界温度扰动。3. 发展机制主要认为是气体粘度与温度之间的正向关系导致的回热器内温度与流阻的正反馈效应。4. 抑制方法主要是增加回热器内径向热导率,阻断其发展机制,或增加回热器长径比,抑制其影响范围。
结论:1. 温度非均匀性形成机制复杂,为多因素耦合作用;2. 气体粘度与温度之间的正向关系导致的回热器内温度与流阻的正反馈效应是导致非均匀性发展的主要因素;3. 增加回热器径向热导率和回热器长径比可有效抑制非均匀性。

关键词组:温度非均匀性;内部流;大功率;脉管制冷机


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DOI:

10.1631/jzus.A1400296

CLC number:

TB651

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On-line Access:

2015-11-04

Received:

2014-09-24

Revision Accepted:

2015-03-01

Crosschecked:

2015-10-12

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