(480b) Heat Transfer within a Ceramic Heat Exchanger Used for Sulfuric Acid Decomposition

A critical area of the Sulfur-Iodine(SI) thermochemical cycle is the point of interaction between the high temperature heat source and the sulfuric acid decomposition section. A design of heat exchanger is required which optimizes thermal efficiency and is capable of withstanding the corrosive environment of boiling/superheated sulfuric acid. Earlier acid decomposition experiments were performed using metal components, but the next phase of testing will focus on ceramic heat exchangers. Key advantages to using a ceramic heat exchanger in the decomposition of sulfuric acid are: 1) minimal corrosion attack when compared to metals, 2) potential to manufacture complex shapes from sintering methods, and 3) potential of ceramic foams to aid heat transfer.

Reported within this paper is an experimental and computational analysis of a ceramic heat exchanger used for the decomposition of sulfuric acid. Initial experiments using water yielded average heat transfer coefficients and Nusselt numbers for a range of operating conditions with a temperature limit of 850°C. Heat transfer coefficients and Nusselt numbers are then applied to a finite element model where the transient response of the system is computed. Included within the analysis are temperature, specific heat transfer coefficients, axial conduction, thermal radiation, and temperature dependent enthalpy to account for decomposition of sulfuric acid. Results and conclusions are presented in mind of future advancements and applications of ceramic heat exchangers for thermochemical hydrogen production technology.

Conclusions of this paper are not only applicable to a SI cycle, they are also applicable to the broader sulfuric acid production industry and the solar-thermal applications of sulfuric acid decomposition.