Heat transfer resistances in the measurements of cold helium vapour temperature in a subatmospheric process line

26th International Cryogenic Engineering Conference & International Cryogenic Materials Conference 2016

材料科学;物理学

Adamczyk, A.^1 ; Pietrowicz, S.^1 ; Fydrych, J.^2

Wroclaw University of Technology, Department of Thermodynamics, Theory of Machines and Thermal Systems, Wyb. Wyspia"skiego 27, Wroclaw

50-370, Poland^1

European Spallation Source ERIC, P. O. Box 176, Lund

221 00, Sweden^2

关键词: Crucial parameters;    External surfaces;    Heat transfer resistance;    Helium temperatures;    Low thermal conductivity;    Measurement quality;    Measurement techniques;    Subatmospheric pressures;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/171/1/012139/pdf
DOI  :  10.1088/1757-899X/171/1/012139

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

The superfluid helium technology, which is essentially used in particle accelerators, requires complex cryogenic systems that include long lines transferring cold helium vapours at a subathmospheric pressure below 50 mbar. Usually in large systems the subatmospheric pressure is generated by a set of warm and cold compressors. In consequence, the heat loads to the line and especially the helium temperature in the inlet to the cold compressors are crucial parameters. In order to measure the helium temperature the temperature sensors are usually fixed to the external surface of the process lines. However, this technique can lead to unwanted measurement errors and affect the temperature measurement dynamics mainly due to low thermal conductivity of the pipe wall material, large pipe diameters and low helium density. Assembling a temperature sensor in a well (cold finger) reaching the centerline of the flowing helium is a technique that can improve the measurement quality and dynamics (response time). The paper presents the numerical simulations of heat transfers occurring in the both measurement techniques and discusses the impacts of the heat transfer resistances on the temperature measurement dynamics.