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Pool Boiling and Thin Film Evaporation
Published in Ralph L. Webb, Nae-Hyun Kim, Principles of Enhanced Heat Transfer, 2004
The test apparatus is similar to that used by Webb and Pais [1992] and is described in detail by Chien and Webb [1998a, 1998b]. Boiling occurred in a 178-mm-long cylindrical glass vessel with brass end flanges. The wall temperature was measured by 0.25-mm-diameter iron-constantan-sheathed thermocouples located below the tube wall at 180° opposite positions. The design allowed the test section to be rotated and wall temperature measured as a function of circumferential angle. The test tubes were 140 mm long, 9.53 mm ID, and 18 to 19.5 mm OD. Heat input was provided by a 9.52-mm-diameter, 129-mm-long, 500-W electric cartridge heater in the copper tube. Data were taken for 26.7°C saturation temperature using procedures described by Chien and Webb [1998a].
Nonnuclear Experimental Capabilities to Support Design, Development, and Demonstration of Microreactors
Published in Nuclear Technology, 2023
P. Sabharwall, J. L. Hartvigsen, T. J. Morton, J. Yoo, S. Qin, M. Song, D. P. Guillen, T. Unruh, J. E. Hansel, J. Jackson, J. Gehin, H. Trellue, D. Mascarenas, R. S. Reid, C. M. Petrie
Quarter symmetry is assumed, and one quarter of the hex block is modeled for the coupled temperature structural analysis. The bottom of the model is set to be fixed (constrained not to move axially) while the plane symmetry is applied to the two side surfaces for the quarter hex block model shown in Fig. 11. The inner surface of the heat pipe is fixed at a constant temperature of 650°C while the whole model is assumed to have an initial temperature of 20°C. As for the heating process, the total applied heat load was parametrically varied up to a maximum of 1902 W (317 W per cartridge heater). The cartridge heaters were modeled as monolithic 304 stainless steel with uniform volumetric heating, and the hex block and the heat pipe sheath were also modeled using 304 stainless steel. The cartridge-heater-to-hex-block gaps and the hex-block-to-heat-pipe gap were assumed to be filled by BN paste to ensure a perfect thermal contact during the whole experiment period. The BN paste is not included in the structural analyses currently, but this expansion phenomenon of BN will be investigated in a future study. The structural simulations included only elastic deformation with no consideration of creep or plasticity in the model. Radial heat losses to the quartz tube and axial heat losses besides heat transferred to the heat pipe were not included. More detailed material properties and the model setup can be found in Yoo et al.,10 Petrie and Ezell,16 and Qin et al.17