Analysis and Optimization of Waste Heat Recovery from Ammonia Containers and an Ammonia Decomposition-Based Hydrogen Production and Liquefaction System

Abstract

To address the utilization of flue gas waste heat from ammonia vessel combustion, cold energy and a small amount of ammonia, a combined cooling, heating and power (CCHP) supply and a small-scale ammonia-to-hydrogen system with a mass flow rate of 44.78 kg/h were designed. The system was simulated using Aspen HYSYS software. An equilibrium hydrogen model for the conversion process from orthohydrogen to parahydrogen is demonstrated to prove the feasibility of a hydrogen liquefaction system. The thermodynamic performance and economic sensitivity performance analysis of the system was performed by changing the parameters. The MATLAB software was used to perform multi-objective optimization of the system, which was combined with the energy analysis to determine the distribution of energy use in the system. The results show that the highest net output power of the system is 1391.83 kW, at which time the thermal efficiency is 42.37% and the specific energy consumption is 6.33 kW/kg. The optimized exergy efficiency, Heat exchange area per net unit power (APR) and Levelized cost of hydrogen (LCOH) were 63.297%, 4.926 $/kg-LH₂ and 0.506 m²/kW, respectively. This system is of greater significance for environmental protection and energy transition.