TY - JOUR
T1 - Analysis of self-cooled binary current leads containing high temperature superconductors
AU - Hull, J. R.
AU - Unal, A.
AU - Chyu, M. C.
N1 - Funding Information:
*Present address: Department of Mechanical Engineering, Texas Tech University, Lubbock, T.X 79409-1021, USA Work at Argonne National Laboratory was supported by the US Department of Energy, Conservation and Renewable Energy, as part of a programme to develop electric power technology, under Contract W-31-109-Eng-,38. The submitted manuscript has been authored by a contractor of the US Government under contract No. W-31-109-ENG-38. Accordngly, the US Government retains a nonexclusive, royalty- free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes,
Funding Information:
This work has been sponsored by the US Department of Energy Superconductivity Pilot Center, Conservation and Renewable Energy, under Contract W-31-109-Eng-38. The authors are indebted to Y.S. Cha, R.C. Niemann and J. Wu for many useful discussions and for
PY - 1992
Y1 - 1992
N2 - The steady-state thermal performance of a cryostat current lead composed of a normal conductor upper part and a superconductor lower part is analysed. The upper end of the lead is at ambient temperature, the lower end is immersed in liquid helium, and the cooling for the lead is totally provided by the vapour generated by the heat flux from the lead into the helium. In the limit of high heat transfer rate between the lead and the helium vapour, there is a universal relationship between mass flow rate and superconductor transition temperature that is indpendent of the thermophysical properties or geometric details of either the superconductor or the normal conductor. This relationship shows that the reduction in heat flux to the helium with self-cooled binary leads, compared to that of the best copper leads, is limited to about 20% with critical temperatures (< 130 K) of existing high temperature superconductors. In general, helium boiloff with binary leads increases with decreasing heat transfer coefficient between lead and vapour. However, for some designs, based around a nominal heat-transfer rate, an increase in heat transfer results in higher temperatures along most of the lead.
AB - The steady-state thermal performance of a cryostat current lead composed of a normal conductor upper part and a superconductor lower part is analysed. The upper end of the lead is at ambient temperature, the lower end is immersed in liquid helium, and the cooling for the lead is totally provided by the vapour generated by the heat flux from the lead into the helium. In the limit of high heat transfer rate between the lead and the helium vapour, there is a universal relationship between mass flow rate and superconductor transition temperature that is indpendent of the thermophysical properties or geometric details of either the superconductor or the normal conductor. This relationship shows that the reduction in heat flux to the helium with self-cooled binary leads, compared to that of the best copper leads, is limited to about 20% with critical temperatures (< 130 K) of existing high temperature superconductors. In general, helium boiloff with binary leads increases with decreasing heat transfer coefficient between lead and vapour. However, for some designs, based around a nominal heat-transfer rate, an increase in heat transfer results in higher temperatures along most of the lead.
KW - cryostats
KW - current leads
KW - high T superconductivity
UR - http://www.scopus.com/inward/record.url?scp=0042775813&partnerID=8YFLogxK
U2 - 10.1016/0011-2275(92)90316-3
DO - 10.1016/0011-2275(92)90316-3
M3 - Article
AN - SCOPUS:0042775813
SN - 0011-2275
VL - 32
SP - 822
EP - 828
JO - Cryogenics
JF - Cryogenics
IS - 9
ER -