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Proceedings Paper

Upgrade of the CFHT closed-cycle cooling heat-rejection process
Author(s): Ivan Look; Chas Cavedoni; Grant Matsushige; Tom Vermeulen; Casey Elizares; Steve Bauman
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Paper Abstract

CFHT currently removes heat from the Closed-Cycle Cold Heads of the telescope prime focus instruments, MegaPrime (Wide-Field Optical Imager) and WIRCam (Wide-Field Infrared Camera) by using water-cooled Helium Compressors which provide gas transfer characteristics allowing the dewars to achieve Cryogenic Temperatures. In addition, CFHT uses air-cooled Compressor Units to provide Closed-Cycle cooling for their telescope Cassegrain instrument, SITELLE (Optical imaging Fourier transform spectrometer). With the addition of a new instrument at the end of 2017, SPIRou (near-infrared spectropolarimeter); an upgrade to the Closed-Cycle cooling system was required to remove the extra 10 kW of heat. Therefore the decision to design and develop a more efficient and less complicated cooling system was pursued. The initial concepts were incorporated from Chas Cavedoni of the GEMINI Observatory, the master mind behind their ambient air cooling system. The cool ambient temperatures experienced year round on Mauna Kea (+4° C to +21° C), coupled with the relatively warm (+10° C to +32° C) cooling water required by the Helium Compressor Units; lends itself to a much simpler and less expensive Fluid-Cooling system which essentially utilizes a glorified Radiator (Heat Exchanger). This paper shall describe the Design Considerations, System Design, and System Performance of this new cooling method and share the lessons learned from this innovative concept. This new design will not only provide cooling for the additional 10 kW introduced by SPIRou, but also handle the existing 10 kW (MegaPrime and WIRCam) currently being removed by stand-alone Refrigeration Chillers. An additional 10kW capacity has been incorporated into the new system to provide cooling for future expansion, which ultimately results in a Fluid Cooling System capable of removing a 30 kW heat load.

Paper Details

Date Published: 6 July 2018
PDF: 8 pages
Proc. SPIE 10700, Ground-based and Airborne Telescopes VII, 107002U (6 July 2018); doi: 10.1117/12.2311409
Show Author Affiliations
Ivan Look, Canada-France-Hawaii Telescope (United States)
Chas Cavedoni, Gemini Observatory North (United States)
Grant Matsushige, Canada-France-Hawaii Telescope (United States)
Tom Vermeulen, Canada-France-Hawaii Telescope (United States)
Casey Elizares, Canada-France-Hawaii Telescope (United States)
Steve Bauman, Canada-France-Hawaii Telescope (United States)

Published in SPIE Proceedings Vol. 10700:
Ground-based and Airborne Telescopes VII
Heather K. Marshall; Jason Spyromilio, Editor(s)

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