Experimental Study on Helium Natural Convection Heat Transfer for Two Coolant Flow Channels within Prismatic Very High Temperature Reactor

Abstract

Laboratory experiments for helium natural convection heat transfer in a separate-effects dual-channel facility have been performed at Multiphase Reactors Engineering Applications Laboratory (mReal). Natural convection is considered as an important aspect of passive safety features of the prismatic block nuclear reactor during accident scenarios. The current facility consists of two channels (riser and downcomer) for coolant flow between upper and lower plena. Heat transfer characteristic across the riser and downcomer channels are investigated at different levels of heat fluxes ranging from 860 W/m 2 to 2293 W/m 2 at 413.7 kPa using sophisticated non-invasive heat flux foil sensors. The heat transfer data in terms of the local wall surface and helium temperatures are collected at different axial and radial locations. Also, the local Nusselt numbers are estimated along the riser channel. The experimental evidence shows a reversal in the direction of heat transfer close to the outlet of the riser channel (Z/L = 0.956) as well as a reduction in the wall surface temperature due to co-circulation. The radial temperature distributions along the riser channel showed a unique peaking in the center close to the exit (Z/L = 0.956), which is consistent with the reversal of heat flow direction observed at the Z/L = 0.956.

Department(s)

Nuclear Engineering and Radiation Science

Second Department

Chemical and Biochemical Engineering

Keywords and Phrases

Co-circulation; Dual-channel facility; Natural convection; Nusselt numbers

International Standard Serial Number (ISSN)

0003-018X

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Nuclear Society, All rights reserved.

Publication Date

01 Jan 2017

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