Design Of 3-Stream(He-He-He) Plate-Fin Heat Exchanger For Helium Plant

Abstract

Plasma Research belongs to a new generation of tokamaks with the major objective being steady state operation of advanced configuration plasma. Liquid helium plant is required for superconducting magnets. The effectiveness of the heat exchangers which is used in the helium plant should be close to 100%. For some cases, heat exchangers with effectiveness less than 90% can be a reason for failure of helium plant to produce liquid helium. To achieve such high effectiveness, it is necessary to use plate fin heat exchangers, which provides very high heat transfer surface area for heat exchange per unit volume (ratio greater than 700 m2/m3) of heat exchanger. Such heat exchangers also have benefit of low pressure drop of fluid flowing through it. The helium refrigerator and liquefier (HRL), planned for development at Institute for plasma research (IPR), will have eight main heat exchangers, 3 turbo expanders with Joule- Thomson expansion valves for achieving liquid helium production. The fourth exchanger, whose nominal operating temperature range is ~30 K to ~10 K, is the 3-stream type (He/He/He) plate fin heat exchanger. This 3-stream (He/He/He) heat exchanger will be installed inside a vacuum chamber having vacuum of about ¡¼10¡½^(-5) mbar. High effectiveness, compact volume and low pressure drop are main optimizing parameters for the design of this heat exchanger. This design work is a step towards the development of the indigenous liquid helium plant.