(246f) Joule Boosted Sulphuric Acid Compact Heat Exchanger for Solar H2 Production

The construction of a solar-renewable powered hydrogen production facility has been considered, relevant to the Sulphur Thermochemical Cycles. It is of interest the material and heat transfer challenges for sulphuric acid sensible heat increasing, boiling and super-heating in a 500 kW Solar Powered Demo Plant (SOL2HY2) using sulphur thermochemical cycles. Sulphuric acid decomposition is common in many of the sulphur cycles, including the HyS cycle, formerly known as the Westinghouse cycle. In these processes, the overall H₂SO₄ decomposition reaction  H₂SO₄ into SO₂ + O₂ + H₂O is done in two steps: H₂SO₄ into SO₃ + H₂O that occurs approximately at 400°C and the highly endothermic reaction SO₃ into O₂+½ O₂, that occurs at >850°C which is the main objective of using solar power capable of high temperatures. One of the major challenges is the material compatibility and scale of boiling sulphuric acid, arguably one of the most corrosive components to handle, adding the challenge of 330°C nucleate boiling. Simulations and experimental data has been obtained using SiSiC variable porosity ceramic heat exchanger media between e=0.8 to e=0.95. Boundary conditions relevant to the demo plant have been simulated using joule heaters in different external and internal configurations using a continuous porous media treatment and computational fluid dynamics. A conceptual design has been obtained based on heat transfer calculations. Mechanical considerations for its final construction are discussed, including material-relevant aspects and overall coupling with the system.