Heat transfer from a flat plate at one end of a rectangular duct containing pressurized He II. 4. Numerical analysis for transient heat transfer

A numerical analysis of transient heat transfer produced by step heat inputs to a flat plate located at one end of a rectangular duct containing pressurized He II was performed. The computer code, SUPER-2D, that is the two-dimensional heat transfer code for He II developed by Tatsumoto et al. based on the two fluid model was used for the calculation. The time lag from the application of the step heat input to the occurrence of λ transition, which is called a lifetime, was obtained for various values of step heat flux for bulk liquid temperatures ranging from 1.8 to 2.0 K. The calculations were made for three rectangular ducts with different cross sectional area. The ratios of the cross sectional area of the duct to heated surface area, Ad/Ah, were 1.0, 1.6 and 2.0. Effect of the Ad/Ah on the lifetime was clarified. The solutions were compared with the experimental data by Shiotsu et al. for the ducts with the same structure and the corresponding conditions. They agreed with the experimental data. It was confirmed that the computer code, SUPER-2D, can describe transient heat transport in He II as well as steady-state one. (author)