H_2O对空间站5A分子筛CO_2去除性能影响

H_2O impact on CO_2 removal performance of 5A molecular sieve in space station

为进一步研究分子筛CO2去除系统应用于空间站的工作可靠性和鲁棒性,针对空间站4床分子筛(4-BMS)系统中可能出现的湿度失效保护问题展开了实验研究.测试了两种载人航天分子筛材料TC-5A与PSA-5A,研究了不同相对湿度对CO2吸附性能的影响;比较了相同湿度条件下,进口气体CO2浓度、粒径及吸附温度的变化对分子筛吸附CO2性能的影响,采用不同实验方法探究了H2O和CO2在两种分子筛材料中的竞争吸附关系.结果表明:PSA-5A吸附CO2性能优于TC-5A,但对H2O的吸附率略低于TC-5A.H2O的存在对分子筛吸附CO2影响非常大,空气中相对湿度达到60%时,分子筛基本失去了吸附CO2的能力.此外,温度升高会造成CO2的吸附量显著下降,但对H2O的吸附量影响相对较小,尤其是当相对湿度较高时.这对中国未来长期运行的空间站分子筛CO2去除系统工作有效性与工作鲁棒性的评价具有指导意义.

For the further research on reliability and robustness of molecular sieve CO2 removal system applied to the space station, the problem of the humidity failure protection of 4-bed molecular sieves （4-BMS） system in the space station was proposed and studied. The experiment was set up to test the impact of the CO2 absorbing capacity under different relative humidity of gas in two kinds of molecular sieves （TC-5A and PSA- 5A） for crewed space mission. Meanwhile, it compared the effect of CO2 adsorption when CO2 concentration of inlet gas, particles and temperature changed under the definite humidity, and explored the competitive adsorption between CO2 and H2O in TC-5A and PSA-SA using different measures. Results show that the PSA-5A has a better performance on CO2 adsorption, but slightly less than TC-5A on H2O adsorption capacity. And presence of H2O in the air had a great influence on molecular sieve adsorption of CO2 , when the relative humidity reached the 60% , the molecular sieve has basically lose the CO2 adsorption capacity. Besides, the TC-5A and the PSA-5A CO2 adsorption capacity drop significantly when the temperature rises, but has a relatively less impact on H2O adsorption, especially when RH is high. The experimental study can play a guiding role in evaluation of system reliability and robustness for the long-term orbiting space station study.