Dynamic Simulations of the Humidification Tower for an Advanced Humid Air Turbine System

The gas turbine system known as AHAT (Advanced Humid Air Turbine) has been drawing attention. This system employs a humidification tower to increase the air mass flow at the compressor outlet. To estimate the humidifying transients, a dynamic model of the humidification tower was developed. This paper describes the humidification tower dynamics based on simultaneous differential equations considering heat and mass equilibrium of humid air, feed water, vessel materials, and packing materials. Values calculated using the model were compared to the experimental values obtained from laboratory-scale experiments. The calculation error margin was 3.8 degrees for air outlet temperature and 10.9% for air outlet absolute humidity. The developed model was then applied to a demonstration-scale conditions. The maximum change rate of absolute humidity at the humidification tower exit for startup and shutdown operations was 8.6%/s for 30 seconds. The maximum change rate of absolute humidity was influenced by the minimum area flow rate which corresponded to performance of packing materials.