Boiling heat transfer characteristics of a sulfuric-acid flow in thermochemical iodine–sulfur cycle

•We measure the boiling heat transfer coefficients of sulfuric acid solution.•The experimental results are lower than the estimated values for single component.•Stephan–Körner correlation is used to predict the experimental results.•We decided 2.00 as the empirical constant of the Stephan–Körner correlation.

The Japan Atomic Energy Agency has been conducting research and development on the thermo-chemical iodine–sulfur (IS) process, which is one of the most attractive water-splitting hydrogen production methods that uses nuclear thermal energy. The sulfuric acid decomposer is one of the key components of the IS process. The boiling heat transfer coefficients of sulfuric acid solutions are required to design the sulfuric acid decomposer. These coefficients were measured in aqueous solutions where the mole fraction of H2O ranged from 0.17 to 0.37 (heat flux range from 16.9 kW/m2 to 5.6 kW/m2) and compared with the empirical correlations formulated for binary mixtures. A combination of the Stephan–Körner correlation, using the empirical constant A0 = 2.00, and the Nishikawa–Fujita correlation was used to predict the experimental results with an accuracy of ±10%.