Zero carbon emission and cold energy recovery: Thermodynamic evaluation of a combined ammonia gas turbine and transcritical CO2 cycle

This research proposes a combined cycle system that integrates an ammonia gas turbine with a self-condensing transcritical CO2 (tCO2) power cycle. For the first time, the cold energy of liquid ammonia is utilized to condense the gaseous CO2 at the vortex tube outlet in the tCO2 cycle. This approach resolves the issue of incomplete CO2 condensation in the vortex tube and reduces the number and variety of compression components, ensuring efficient use of the cold energy of liquid ammonia. Additionally, by splitting the CO2 after the pump, the pinch point issue in the low-temperature recuperator (LTR) is addressed. This paper establishes a simulation model of the combined cycle, analyzes the feasibility of the cycle from a thermodynamic perspective, and investigates the impact of the split ratio, vortex tube inlet temperature and pressure, vortex tube outlet pressure, turbine inlet temperature and pressure and sCO2 turbine inlet temperature and pressure on the performance of cycle. This research offers a new method for the efficient use of both high-temperature waste heat from the ammonia gas turbine and the cold energy of liquid ammonia, as well as a novel solution to the CO2 condensation challenges in the tCO2 cycle.