Thermal analysis of a coaxial helium panel of a cryogenic vacuum pump for advanced divertor of DIII-D tokamak
It is planned to install a 50,000 1/s cryogenic pump for particle removal in the D3-D tokamak. A critical component of this cryogenic pump will be a helium panel which has to be maintained at a liquid helium temperature. The outer surface area of the helium panel has an area of 1 m{sup 2} and consists of a 2.5 cm diameter, 10 m long tube. From design considerations, a coaxial geometry is preferable since it requires a minimum number of welds. However, the coaxial geometry also results in a counter flow heat exchanger arrangement, where the outgoing warm fluid will exchange heat with incoming cold fluid. This is of concern since the helium panel must be cooled from liquid nitrogen temperature to liquid helium temperature in less than 5 minutes for successful operation of the cryogenic pump. In order to analyze the thermal performance of the coaxial helium panel, a finite difference computer model of the geometry was prepared. The governing equations took into account axial as well as radial conduction through the tube walls. The variation of thermal properties was modeled. The results of the analysis showed that although the coaxial geometry behaves like a counter flow heat exchanger, within the operating range of the cryogenic pump a rapid cooldown of the helium panel from liquid nitrogen temperature to the operating temperature is feasible. A prototypical experiment was also performed at General Atomics (GA) which verified the concept and the analysis. 4 refs., 8 figs.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114
- OSTI ID:
- 5370416
- Report Number(s):
- GA-A-20519; CONF-910635-12; ON: DE91017814
- Resource Relation:
- Conference: Cryogenic engineering conference and international cryogenic materials conference, Huntsville, AL (United States), 11-14 Jun 1991
- Country of Publication:
- United States
- Language:
- English
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Design of the advanced divertor pump cryogenic system for DIII-D
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Related Subjects
CRYOPUMPS
THERMAL ANALYSIS
DIVERTORS
DOUBLET REACTORS
FINITE DIFFERENCE METHOD
HEAT EXCHANGERS
HELIUM II
TEMPERATURE DISTRIBUTION
EQUIPMENT
EVEN-EVEN NUCLEI
FLUIDS
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
ITERATIVE METHODS
LABORATORY EQUIPMENT
LIGHT NUCLEI
NUCLEI
NUMERICAL SOLUTION
PUMPS
QUANTUM FLUIDS
STABLE ISOTOPES
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
VACUUM PUMPS
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