用于飞机新型环境控制系统的高压膜法除湿特性和实验研究

The advanced environmental control system(ECS) of current aircraft is mainly high pressure de-water air cycle system, in which water vapor is removed by lowering humid air temperature below dew point by the cold airflow from an expansion turbine. The de-water process consumes a lot of cooling capacity and the system is complex and less reliable. In this project we propose an original high pressure de-vapor ECS based on membrane dehumidification, in which a selective membrane dehumidifier(MD) is used to remove high partial pressure water vapor without condensing and air-water separating process. Thus the system is a humidity and heat independent control system. The cooling capacity is significantly increased, and the new system has no condenser so there is no condenser frozen problem. High pressure membrane dehumidifier (HPMD) is the key component of this novel system. There are differences of water vapor partial pressure, temperature and humid air total pressure between the two humid airflows on two sides of the membrane wall. These differences have significant influences on relative humidity and flow resistance. Taking these influences into consideration, a detailed mathematical and simulation model of heat and mass transfer in the HPMD will be set up. For the HPMD, the simulation results and will be corrected and verified by the experimental results, therefore the characteristic of heat and mass transfer across the membrane and pressure drop along the membrane under high pressure and temperature difference will be clarified. Comprehensive studies will be carried out with cooling capacity, coefficient of performance, entropy generation rate and other comprehensive performance parameters. In addition, comparison studies will be carried out to figure out the fundamental thermodynamic reasons for the performance difference between this new ECS and the traditional high pressure de-water ECS. The research work of this project will provide a new method and lay a solid foundation to greatly improve the performance of the ECS of aircraft.

飞机目前主流环境控制系统（ECS）是高压“除水”空气循环制冷系统：采用露点冷凝法对高压空气减湿，冷量消耗大、系统复杂且可靠性较差。本项目提出并研究膜法高压“除湿”式飞机新型环境控制系统：利用膜对水蒸气的选择透过性、无相变去除高压空气中的水蒸气，系统以湿、热独立处理方式运行，消除传统系统易冻堵缺陷且整体性能显著提高。针对核心的高压空气膜除湿组件，根据膜两侧湿空气中水蒸气分压差、温差及湿空气总压对其相对湿度和流动阻力的显著影响，建立水蒸气跨膜微介观传热传质模型，通过数值模拟和性能实验，厘清高压湿空气大温差、大压差下跨膜传热传湿和沿程流动特性；通过对此种新型环控系统的理论分析、建模计算，与传统高压“除水”式环控系统进行制冷量、性能系数和熵产率等综合性能参数对比研究，从而揭示新型高压“除湿”式和传统“除水”式环控系统性能差异的热力学本质原因。本项目将为飞机先进环控系统研究奠定扎实的理论和实验基础。

飞机目前主流环境控制系统（ECS）是高压“除水”空气循环制冷系统：采用露点冷凝法对高压空气减湿，冷量消耗大、系统复杂且可靠性较差。本项目提出并研究膜法高压“除湿”式飞机新型环境控制系统：利用膜对水蒸气的选择透过性、无相变去除高压空气中的水蒸气，系统以湿、热独立处理方式运行，消除传统系统易冻堵缺陷且整体性能显著提高。针对核心的高压空气膜除湿组件，根据膜两侧湿空气中水蒸气分压差、温差及湿空气总压对其相对湿度和流动阻力的显著影响，建立水蒸气跨膜微介观传热传质模型，通过数值模拟和性能实验，厘清高压湿空气大温差、大压差下跨膜传热传湿和沿程流动特性；通过对此种新型环控系统的理论分析、建模计算，与传统高压“除水”式环控系统进行制冷量、性能系数和熵产率等综合性能参数对比研究，从而揭示新型高压“除湿”式和传统“除水”式环控系统性能差异的热力学本质原因。本项目将为飞机先进环控系统研究奠定扎实的理论和实验基础。本项目按计划完成以下工作：.(1).按计划完成了温度、湿度、压力耦合条件下的高压湿空气跨膜传热传质和流动特性理论和模拟研究。.(2).按计划完成了高压膜除湿组件的实验研究，并验证了理论模型。.(3).按计划完成了高压膜除湿和高压除水两种飞机环控系统的性能模拟对比研究，从热力学第二定律揭示了高压膜除湿性能更优的本质原因。.在相同的引气条件下，本项目提出的膜法高压除湿式环控系统，相比传统高压除水式环控系统，制冷量提升60%以上。