Design of the Cooling System for the Cit Central Solenoid
The large expected temperature rises in the Compact Ignition Tokamak (CIT) central solenoids motivate this general study on how to minimize the cooling time of large electromagnets to maintain an acceptable operating frequency. Liquid nitrogen (LN2) was chosen as a cooling fluid because of the benefits from the high heat-transfer rates characteristic of boiling. A computer program was developed to model the flow and heat transfer of two-phase nitrogen in complex flow circuits. In the model, heat-transfer and flow pressure drop calculations were based on existing empirical correlations. A radial cooling passage geometry was adopted in which liquid nitrogen flows up through the inlet annulus and runs radially outward through cooling passages situated between pancakes to the PF coil exit annulus (Figure 1). The radial arrangement was found to be effective, based on its short cooldown time and generation of small thermal stresses.
KeywordsPressure Drop Flow Passage Boil Heat Transfer Poloidal Field Cooling Passage
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