Experimental study of hypervapotron channel with square fin structure for divertor cooling by one-side, electric joule heating system

Abstract

The lack of cooling capacity to maintain the thermal steady state of the divertor is becoming a severe engineering problem in preparation for DEMO fusion reactor. But, there is not much literature comparing with the existing sub-cooled flow boilng heat transfer correlation and analyzing the Hypervapotron boiling curve. To simulate the fusion thermal condition, experimental loop that can withstand high temperature (150℃) and high pressure (20 bar) was constructed. And one-side electric joule heating system that can apply heat flux of up to 10.4 MW/m2 was developed. In addition, it was verified that stable operation is possible by confirming that the flow rate and the channel inlet temperature fluctuation rate are 1% or less, respectively. This experiment was carried out to evaluate the boiling heat transfer of Hypervapotron cooling channel at 10 bar, 40 ∼ 80 subcooling, 0.108 ∼ 0.284 kg /s and maximum effective heat flux of 6.87 MW/m2. Among the sub-cooled flow boiling heat transfer correlations, Thom correlation (1965), Jens & Lottes correlation (1951), and Aaladiev correlation (1957) differed significantly from the experimental data. But Shah 1977 (error rate: 4.75 %) and Kandlikar 1998 (error rate: 16.57 %) correlations were well predicted.