To dehumidify a humid air stream, existing air conditioning (AC) systems substantially overcool the outdoor humid air below its dew point, thereby significantly reducing energy efficiency. Directly capturing humidity, membrane-based liquid-desiccant dehumidification systems separate sensible and latent cooling (SSLC) loads and thus offer a promising pathway for a high-performance AC solution. Design of an energy-efficient SSLC-AC system, however, rests largely on detailed understating of the dehumidification process. While some studies have identified the dehumidification process mainly depends on membrane characteristics, other studies have argued that the process is limited by desiccant liquid or alternatively air thermo-hydraulic physics for typical humid climate conditions. The present study examines performance and physics of the membrane-based liquid-desiccant dehumidification process over a wide range of climate conditions through a novel 3D, two-phase, multi-species CFD model. Decoupling the thermodynamic and hydraulic effects, the study reveals that the dehumidification rate is a linear function of the water vapor pressure potential (J=α ΔP) summarizing the system's thermodynamic state. The slope of the curve (i.e., α) depends on hydraulic transport characteristics of the membrane pores, air stream, and desiccant solution. More importantly, it was found that the air dehumidification process is mainly limited by the air-side transport physics for thin liquid-desiccant films and commonly used porous superhydrophobic membranes. Additionally, results show that, depending on ambient/desiccant conditions and physical dehumidifier characteristics, energy effectiveness and dehumidification rate vary from 13 to 34% and from 0.13 to 1.4 g m⁻² s⁻¹, respectively. Therefore, the present study allows to efficiently design future SSLC-based AC systems exhibiting high performance energy metrics.

为了对潮湿的空气流进行除湿，现有的空调 (AC) 系统将室外潮湿空气的温度大大降低到其露点以下，从而显着降低了能源效率。直接捕获湿度，基于膜的液体干燥剂除湿系统将显冷和潜冷 (SSLC) 负载分开，从而为高性能 AC 解决方案提供了一条有前途的途径。然而，节能 SSLC-AC 系统的设计很大程度上取决于对除湿过程的详细低估。虽然一些研究已经确定除湿过程主要取决于膜特性，但其他研究认为该过程受到干燥剂液体或典型潮湿气候条件下的空气热工水力物理学的限制。本研究通过一种新颖的 3D、两相、多物种 CFD 模型，检查了基于膜的液体干燥剂除湿过程在各种气候条件下的性能和物理特性。将热力学和水力效应解耦，研究表明除湿率是水蒸气压势的线性函数（J=α ΔP ) 概括了系统的热力学状态。曲线的斜率（即α）取决于膜孔、空气流和干燥剂溶液的水力传输特性。更重要的是，发现空气除湿过程主要受到薄液体干燥剂薄膜和常用多孔超疏水膜的空气侧传输物理的限制。此外，结果表明，根据环境/干燥剂条件和物理除湿机特性，能源效率和除湿率在 13% 至 34% 和 0.13 至 1.4 gm ^-2 s ^{-1 之间变化}， 分别。因此，本研究允许有效地设计未来基于 SSLC 的交流系统，展示高性能能源指标。