Plenum-To-Plenum Natural Circulation Heat Transfer in a Prismatic Very High-Temperature Reactor for Different Coolants
Multiphase Reactors Engineering and Applications Laboratory (mReal) at Missouri University of Science and Technology (S&T) has developed a natural convection heat transfer test facility with one riser and one downcomer between two plena to investigate loss of flow accident scenario (LOFA) for a prismatic very high temperature reactor (VHTR). Using advanced heat transfer coefficient probe and T-thermocouples (1.6 mm), this paper reports the effect of the outer surface temperatures of the upper plenum and downcomer channel (278.15, 288.15, 298.15, and 308.15 K) on the intensity of natural circulation during LOFA with helium at 413.685 kPa. The results showed that there is a reduction in the centerline temperature of ∼10.14% and inner wall surface temperatures of ∼7.4% along the riser channel with decreasing upper plenum and downcomer temperatures from 308.15 K to 278.15 K. A reversal in the direction of heat transfer is observed close to the exit of the riser channel (Z/L = 0.773) for outer surface temperature 288.15, 298.15, and 308.15 K due to the end effect. It is worth mention that, the negative signals of heat fluxes are observed along the downcomer channel for all operating conditions, which confirms heat removal from helium and a downward flow along the downcomer channel, hence establishment of natural circulation. The results also showed a gain in the values of heat transfer coefficients along the riser channel with decreasing the outer surface temperature which is consistent with the literature. In comparison to the literature with air as coolant, the current results showed the role of helium on the thermal performance of natural circulation loop in terms of co-circulation of plumes and end effects.
S. M. Alshehri et al., "Plenum-To-Plenum Natural Circulation Heat Transfer in a Prismatic Very High-Temperature Reactor for Different Coolants," Proceedings of the International Topical Meeting on Advances in Thermal Hydraulics (2018, Orlando, FL), pp. 670-681, American Nuclear Society (ANS), Nov 2018.
International Topical Meeting on Advances in Thermal Hydraulics, ATH 2018 (2018: Nov. 11-15, Orlando, FL)
Chemical and Biochemical Engineering
Keywords and Phrases
Argon; Atmospheric temperature; Carbon dioxide; Coolants; Fluids; Heat transfer coefficients; Helium; Hydraulics; Natural convection; Nitrogen; Surface properties; Conduction cooldown; High operating pressure; Local heat transfer coefficient; Modular reactors; Natural circulation; Nonuniform heating; Oregon State University; Transfer technique; High temperature reactors; Heat transfer technique; Prismatic modular reactor
International Standard Book Number (ISBN)
Article - Conference proceedings
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01 Nov 2018