Development of a smart powering system with ammonia fuel cells and internal combustion engine for submarines

The current limitations of hydrogen storage technology in submarines have prompted the need for alternative solutions. One promising option is the use of ammonia, a readily stored fuel. This paper presents an innovative, integrated system that runs on ammonia and does not rely on atmospheric air. The system combines Direct Ammonia Fuel Cell (DAFC) stack and an Internal Combustion Engine (ICE) technology to generate power, freshwater, and cooling. The system also recovers waste heat and utilizes it efficiently to produce these useful outputs. The study further aims to assess the system's performance using energy and exergy analysis methods and to conduct a parametric analysis to examine the impact of parameters and operating conditions on system efficiency. In the developed integrated system, the quantities of net power produced, cooling provided, and freshwater flow rate produced under specified conditions are 4069 kW, 589.5 kW, and 1.269 kg/s, respectively. Its energy and exergy efficiency were found to be 38.58% and 44.77%, respectively. The analysis study also obtains that increasing the ammonia flow rate supplied to the ICE and the steam flow rate provided to the turbine, as well as the reference temperature, could potentially improve both energetic and exergetic efficiencies.