Modeling and numerical investigation on the effects of filling ratio in a large separate heat pipe loop

Abstract

Large separate heat pipe is a potential selection to establish the passive cooling system to remove decay heat from the Spent Fuel Pool. In this system, heat pipes are expected to work properly and effectively for a long time without human intervention. Due to the physical dimensions and structures, flow patterns, and fluid distribution in large-scale heat pipes differ from those in conventional ones. Based on the condensation flow patterns, a flow condensation model is presented. Then, a separate heat pipe model considering filling ratio effects is developed. Using the new model, the mean absolute errors of simulation are 5.5% (water), 5.1% (ammonia), and 4.3% (R134a). While in the conventional condensation model, these errors are 29.4%, 9.7%, and 10%. It is found

Research Progress on Thermal Hydraulic Characteristics of Spent Fuel Pools: A Review

“…Compared with water and R134a heat pipes, ammonia heat pipes have the best heat transfer performance, providing an additional 40% heat transfer capacity [48]. Moreover, Kuang et al [49] pointed out that the optimal filling rate of a water-heat pipe is about 17%, and the optimal filling rate of an R134a or ammonia heat pipe is between 20% and 70%. An excessive or low filling rate will result in a reduced heat transfer capacity.…”

“…At the condensation end of a passive cooling system, fully stratified flow is the main flow mode. Kuang et al [49] pointed out that there are two heat transfer mechanisms for the condensation of saturated steam on the inner wall of the tube and the gas-liquid interface: membrane condensation on the tube wall and conduction condensation in the tube. They therefore proposed a condensation model in the tube, which greatly reduces the calculation error.…”