Static-flow-instability in Subcooled Flow Boiling in Wide Rectangular Parallel Channels
Author | : |
Publisher | : |
Total Pages | : 8 |
Release | : 1995 |
ISBN-10 | : OCLC:68210781 |
ISBN-13 | : |
Rating | : 4/5 (81 Downloads) |
Book excerpt: The Advanced Neutron Source (ANS) is a state-of-the-art research reactor facility that will be built at the Oak Ridge National Laboratory (ORNL) and is designed to become the world's most advanced thermal neutron flux source for scientific experiments. Therefore, the core of the ANS reactor (ANSR) must be designed to accommodate very high power densities using very high coolant mass fluxes and subcooling levels, The nominal average and peak heat fluxes in the ANSR are approximately 6 and 12 MW/M2, respectively, with a nominal total thermal power of 303 MW. Highly subcooled heavy-water coolant (1.7 MPa and 85°C at the core exit) flows vertically upward at a very high mass flux of almost 27 Mg/M2-s. The cooling channels in each fuel assembly are all parallel and share common inlet and outlet plenums, effectively imposing a common pressure drop across all the channels. This core configuration is subject to flow excursion (FE) and/or flow instability that may occur once boiling is initiated in any one of the channels. The FE phenomenon constitutes a different thermal limit than a true critical heat flux (CHF) or departure from nucleate boiling (DNB). In such a system, initiation of boiling in one of the channels (i.e., the hot channel) can result in flow redistribution to the other cooler channels. This report details testing to document this phenomenon.