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J. YANG, F. B. CHEUNG,J. L. REMPE,S. B. KIM,서균렬 한국원자력학회 2006 Nuclear Engineering and Technology Vol.38 No.2
An experimental study was performed to evaluate the effects of surface coating and an enhanced insulation structure onthe downward facing boiling process and the critical heat flux on the outer surface of a hemispherical vessel. Steady-stateboiling tests were conducted in the Subscale Boundary Layer Boiling (SBLB) facility using an enhanced vessel/insulationdesign for the cases with and without vessel coatings. Based on the boiling data, CHF correlations were obtained for bothplain and coated vessels. It was found that the nucleate boiling rates and the local CHF limits for the case with micro-porouslayer coating were consistently higher than those values for a plain vessel at the same angular location. The enhancement inthe local CHF limits and nucleate boiling rates was mainly due to the micro-porous layer coating that increased the localliquid supply rate toward the vaporization sites on the vessel surface. For the case with thermal insulation, the local CHFlimit tended to increase from the bottom center at first, then decrease toward the minimum gap location, and finally increasetoward the equator. This non-monotonic behavior, which differed significantly from the case without thermal insulation, wasevidently due to the local variation of the two-phase motions in the annular channel between the test vessel and the insulationstructure.
CHF enhancement by vessel coating for external reactor vessel cooling
Yang, J.,Dizon, M.B.,Cheung, F.B.,Rempe, J.L.,Suh, K.Y.,Kim, S.B. Elsevier 2006 Nuclear engineering and design Vol.236 No.10
<P><B>Abstract</B></P><P>In-vessel retention (IVR) is a key severe accident management (SAM) strategy that has been adopted by some operating nuclear power plants and proposed for some advanced light water reactors (ALWRs). One viable means for IVR is the method of external reactor vessel cooling (ERVC) by flooding the reactor cavity during a severe accident. As part of a joint Korean–United States International Nuclear Energy Research Initiative (K-INERI), an experimental study has been conducted to investigate the viability of using an appropriate vessel coating to enhance the critical heat flux (CHF) limits during ERVC. Toward this end, transient quenching and steady-state boiling experiments were performed in the subscale boundary layer boiling (SBLB) facility at the Pennsylvania State University using test vessels with micro-porous aluminum coatings. Local boiling curves and CHF limits were obtained in these experiments. When compared to the corresponding data without coatings, substantial enhancement in the local CHF limits for the case with surface coatings was observed. Results of the steady-state boiling experiments showed that micro-porous aluminum coatings were very durable. Even after many cycles of steady-state boiling, the vessel coatings remained rather intact, with no apparent changes in color or structure. Moreover, the heat transfer performance of the coatings was found to be highly desirable with an appreciable CHF enhancement in all locations on the vessel outer surface but with very little effect of aging.</P>
Yang, J.,Cheung, F.B.,Rempe, J.L.,Suh, K.Y.,Kim, S.B. Korean Nuclear Society 2006 Nuclear Engineering and Technology Vol.38 No.2
An experimental study was performed to evaluate the effects of surface coating and an enhanced insulation structure on the downward facing boiling process and the critical heat flux on the outer surface of a hemispherical vessel. Steady-state boiling tests were conducted in the Subscale Boundary Layer Boiling (SBLB) facility using an enhanced vessel/insulation design for the cases with and without vessel coatings. Based on the boiling data, CHF correlations were obtained for both plain and coated vessels. It was found that the nucleate boiling rates and the local CHF limits for the case with micro-porous layer coating were consistently higher than those values for a plain vessel at the same angular location. The enhancement in the local CHF limits and nucleate boiling rates was mainly due to the micro-porous layer coating that increased the local liquid supply rate toward the vaporization sites on the vessel surface. For the case with thermal insulation, the local CHF limit tended to increase from the bottom center at first, then decrease toward the minimum gap location, and finally increase toward the equator. This non-monotonic behavior, which differed significantly from the case without thermal insulation, was evidently due to the local variation of the two-phase motions in the annular channel between the test vessel and the insulation structure.