Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen

被引:28
作者
Chang, HM [1 ]
Choi, YS
Van Sciver, SW
Dal Choi, K
机构
[1] Natl High Magnet Field Lab, Tallahassee, FL 32310 USA
[2] Korea Polytech Univ, Shihung 429793, Kyonggi Do, South Korea
关键词
nitrogen (A); heat transfer (C); cryostats (E); transformers (E);
D O I
10.1016/S0011-2275(03)00168-1
中图分类号
O414.1 [热力学];
学科分类号
摘要
Heat transfer analysis on a newly proposed cryogenic cooling system is performed for HTS transformers to be operated at 63-66 K. In the proposed system, HTS pancake windings are immersed in a liquid nitrogen bath where the liquid is cooled simply by colder copper sheets vertically extended front the coldhead of a cryocooler. Liquid nitrogen in the gap between the windings and the copper sheets develops a circulating flow by buoyancy force in subcooled state. The heat transfer coefficient for natural convection is estimated from the existing engineering correlations, and then the axial temperature distributions are calculated analytically and numerically with taking into account the distributed AC loss in the windings and the thermal radiation on the walls of liquid-vessel. The calculation results show that the warm end of the HTS windings can he maintained at only 2-3 K above the freezing temperature of nitrogen, with acceptable values for the height of HTS windings and the thickness of copper sheets. It is concluded that the cooling by natural convection of subcooled liquid nitrogen can be an excellent option for compactness, efficiency, and reliability of HTS transformers. (C) 2003 Elsevier Ltd. All rights reserved.
引用
收藏
页码:589 / 596
页数:8
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