A comparative thermodynamic analysis of helium distribution systems with central and distributed precooling heat exchangers

27th International Cryogenics Engineering Conference and International Cryogenic Materials Conference 2018

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

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

22 100, Sweden^1

Wroclaw University of Science and Technology, Department of Thermodynamics, Theory of Machines and Thermal Systems, Wyb. Wyspianskiego 27, Wroclaw

50-370, Poland^2

关键词: Distribution systems;    Financial aspects;    Preliminary design;    Second law efficiencies;    Subatmospheric pressures;    Temperature and pressures;    Thermo dynamic analysis;    Throttling valves;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/502/1/012173/pdf
DOI  :  10.1088/1757-899X/502/1/012173

来源: IOP

【 摘 要 】

All the cryogenic systems of large scientific facilities using He II technologies apply the Joule-Thomson expansion for final production of superfluid helium. Their cryogenic plants supply subcooled liquid helium at 4.5 K which is precooled to 2.2 K before throttling to a sub-Atmospheric pressure in Joule-Thomson valves. The precooling of the 4.5 K helium can be done in one central heat exchanger or in a number of small heat exchangers located just at the throttling valves. Since there are cons and pros for the both architectures, it is important to take into account all thermodynamics and financial aspects in choosing the best layout in the preliminary design of any new large He II system. The paper presents a comparative thermodynamic analysis of the both cooling schemes in respect to the size of cryogenic distribution systems and heat loads subjected to their components. The analysis is based on calculations of the second-law efficiencies which are preceded by a numerical modelling of temperature and pressure distributions along the process lines.