变湿吸附法以水为杠杆来高效驱动直接空气碳捕集，目前其循环理论及能效研究相对匮乏。本文从热力学循环的角度对变湿吸附工艺进行分析，在温度–湿度–吸附量三维坐标系中构建出六步变湿吸附循环。比较了基础恒温变湿吸附循环以及六步变湿吸附循环的理想比能耗、热力学效率及吸附剂效率等循环评价指标，并分析了温湿度对各评价指标的影响规律。在25°C、30% RH 的吸附条件下，引入变温过程可至多降低28% 的捕集能耗，并将热力学效率上限提高119%。

Moisture swing adsorption (MSA) method uses water as a lever to efficiently drive direct air carbon capture. At present, its cycle theory and energy efficiency research are relatively scarce. In this paper, MSA process is analyzed from the perspective of thermodynamic cycle, and a 6-step MSA cycle is constructed in the three-dimensional coordinate system of temperature, humidity, and adsorption capacity. Ideal specific energy consumption, thermodynamic efficiency and adsorbent efficiency of basic isothermal MSA cycle and the 6-step MSA cycle are compared, and the effects of temperature and humidity on each indicator are analyzed. Under the adsorption condition of 25°C and 30% RH, the introduction of temperature swing process can reduce capture energy consumption by 28% at most, and increase the limit of thermodynamic efficiency by 119%.