Performance study of integrated aftercool-humidifier based on surface foaming hydrophilic modification

Abstract

Humid Air Turbine (HAT) cycle is high efficiency, flexibility and low NOx emissions, making it particularly well-suited for distributed energy resources (DERs) systems. In order to meet the regulation requirements of DERs, it is necessary to effectively reduce the volumetric inertia and thermal inertia of HAT cycle, thereby enhancing its flexibility. An innovative integrated aftercool-humidifier based on surface modification technology, utilizing hydrophilic porous medium on the internal surface of the humidifier, was optimally designed in this study. An integrated aftercool-humidifier experimental system is designed with a horizontal coaxial-tube structure, and the humidification process is achieved through three-stage spraying. The experimental system can control the water and air flow rates and can measure the water and air temperatures as well as the pressure loss. A comprehensive thermodynamic analysis of the effectiveness of the parameters such as water–air ratio and inlet water temperature had been carried out with the help of a one-dimensional simulation model, which is optimized by the experimental results. Compared to traditional packing humidifier, the aftercool-humidifier can reduce the equipment volume by 42.4% while achieving similar humidification performance. Limitation of the flooding velocity has been overcome. Under the condition of ensuring humidification performance, the maximum flow rate of the working fluid is increased by 24.7%. By analyzing the saturation line and the operating line in the temperature-enthalpy diagram, it is found that the aftercool-humidifier provides stronger mass transfer driving forces than the traditional one. Research on the effectives of inlet parameters showed that the water temperature has a greater impact on the outlet humidity of the aftercool-humidifier than the water–air ratio. Higher inlet water temperature significantly promotes the humidification performance, similar to the mechanism of traditional humidifiers. By analyzing the exergy loss of the aftercool-humidification process, it is found that conditions with higher inlet water temperatures result in lower exergy losses and higher exergy efficiency. Under the same water--air ratio conditions, the aftercool-humidifier achieves an exergy efficiency of 73%, compared to 58.7% for traditional packing humidifiers.