Effect of Operating and Geometrical Parameters on Ammonia Decomposition in a Tubular Reactor Driven by Concentrating Solar Power

Abstract

Following the massive consumption of traditional fossil fuels, the technology of concentrating solar power embedded with energy storage is becoming more and more attractive. Within this new trend, ammonia-based thermochemical energy storage is prospectively promising. The aim of this study is to simulate the ammonia decomposition reaction in a tubular reactor fully packed with homogeneously isotropic catalyst particles. Ignoring the radial heat conduction and pressure drop, a one-dimensional thermodynamic mathematical model is established to simulate ammonia conversion accounting for operating pressure and temperature, solar flux distribution, and geometric structure. It is concluded from the simulation results that the effect of the operating temperature on ammonia conversion is more predominant than the effect of the operating pressure. Furthermore, for the four styles of solar flux distribution, the distribution with the lowest effective deviation is the most suitable style for ammonia decomposition, and the efficiency is improved about 15% compared with σ=0.5. Regarding the geometric structure, the conversion rate progressively increases with diameter and length of the tubular reactor, and an optimization formula is subsequently proposed for geometric design. Ultimately, the design and optimization criterion for the tubular reactor are presented.