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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-431-1

ISBN Online: 978-1-56700-430-4

First Thermal and Fluids Engineering Summer Conference
August, 9-12, 2015 , New York City, USA

EXPERIMENTAL STUDY OF FORCED CONVECTION HEAT TRANSFER DURING UPWARD AND DOWNWARD FLOW OF HELIUM AT HIGH PRESSURE AND HIGH TEMPERATURE

Get access (open in a dialog) pages 981-984
DOI: 10.1615/TFESC1.fnd.012797

Аннотация

Fundamental high pressure/high temperature forced convection experiments have been conducted in support of the development of a Very High Temperature Reactor (VHTR) with a prismatic core. The experiments utilize a high temperature/high pressure flow test facility constructed for forced convection and natural circulation experiments. The test section has a single 16.8 mm ID flow channel in a 2.7 m long, 108 mm OD graphite column with four 2.3kW electric heater rods placed symmetrically around the flow channel. This experimental study presents the role of buoyancy forces in enhancing or reducing convection heat transfer for helium at high pressures up to 70 bar and high temperatures up to 873 °K. Wall temperatures have been compared among 10 cases covering the inlet Re numbers ranging from 500 to 3,000. Downward flows display higher and lower wall temperatures in the upstream and downstream regions, respectively, than the upward flow cases due to the influence of buoyancy forces. In the entrance region, convection heat transfer is reduced due to buoyancy leading to higher wall temperatures, while in the downstream region, buoyancy-induced mixing causes higher convection heat transfer and lower wall temperatures. However, their influences are reduced as the Reynolds number increases. This experimental study is of specific interest to VHTR design and validation of safety analysis codes.