Study On Gas-liquid Two-phase Heat And Mass Transfer Performance And Enhancement In Humidifier Of HAT Cycle

The Humid Air Turbine(HAT)cycle has attracted wide attention due to its high specific power,high efficiency,and low pollution.Humidifier is one of the key components of the HAT cycle,and its performance is critical to the overall performance of the system.The gas-liquid two-phase flow inside the humidifier is very complicated.Most of the current researches on the humidifier are based on using the inlet and outlet parameters to study the overall performance of the humidifier,and the internal flow process is not researched deeply enough.Studying the internal humidification process of the humidifier and grasping the heat and mass transfer laws between the gas and liquid phases will further improve the performance of the humidifier and accumulate a solid data foundation for the humidifier design and performance evaluation system.This paper established a one-dimensional calculation model of the thermodynamic process inside the humidifier,studied the gas-liquid two-phase flow characteristics inside the humidifier,and proposes two measures to strengthen the gas-liquid heat and mass transfer process according to its internal flow state.In terms of theoretical calculations,a one-dimensional mathematical model of the interior of the humidifier was established based on the mass conservation equation,energy conservation equation,and heat and mass transfer equations.Based on the humidifier inlet and outlet parameters and internal gas-liquid measurement experimental data,the accuracy of the model calculation was verified.The calculation and analysis of the gas-liquid two-phase heat and mass transfer process in the humidifier under different water-gas ratios and inlet water temperatures.The study found that the water-to-air ratio has a greater impact on the performance of the humidifier.Increasing the water-to-air ratio and the inlet water temperature,the water and air temperature at the same height inside the humidifier all increase,and the overall humidification capacity increases.When the inlet water temperature increases,the wet air at the bottom reaches saturation state faster.The heat transfer and exergy efficiency distribution in the humidifier were further analyzed.The driving force of heat and mass transfer between water and air along the height of the humidifier changed greatly.The exergy loss was mainly concentrated at the bottom in the experiment,and reasonably arrange the air intake conditions can improve the overall performance of the humidifier.In terms of performance enhancement: In order to enhance the gas-liquid two-phase driving force in the humidifier and strengthen the heat and mass transfer process in the humidifier,two measures are adopted:1)The residual heat of the heat exchanger is added to the different position of the gas and water sides respectively.2)Use the waste heat from the outlet of the economizer to heat the make-up water and perform layered spraying.The performance of gas-liquid heat and mass transfer in the humidifier and the influence on the overall performance of the HAT cycle after the two strengthening measures are analyzed.Both measures can increase the temperature and moisture content at the outlet of the humidifier,while recycling the low-grade waste heat of the system,and improving the specific work and efficiency of the HAT system.