This paper is devoted to the experimental study of He I natural circulation loop under nucleate boiling conditions, which simulates the cooling system of the 4 Tesla superconducting solenoid CMS under construction at CERN for the LHC. The test section consists of an electrically heated copper tube of 0.10-m ID and 0.95-m long. Uniform heat fluxes in the range of 0-2000 W/m2 were employed. All data were generated near atmospheric pressure. Reported are results of the boiling curves and the effect of heat flux on the heat transfer coefficient under boiling. An attempt is carried out to predict the boiling incipience and to correlate the heat transfer coefficient based on the combining effect of forced convection and nucleate boiling by a power-type asymptotic model. |
