Membrane-based liquid desiccant dehumidification (MLDD), as a promising technology for temperature and humidity control, suffers from a degradation of effectiveness when handling large air flows in industrial sectors. Existing methods such as multi-stage dehumidifying and internally cooling provide a solution to solve this issue, but their implementation in the large-scale systems is somehow challenging due to the difficulty in sealing ducts, and their mechanisms for enhancing effectiveness have not yet been clarified in depth. This paper aims to apply a tractable multi-stage internally-cooled structure for improving the MLDD effectiveness at an acceptable cost and to uncover the underlying mechanisms from the perspective of the driving forces for heat and mass transfer. A dimensionless finite-difference model is first developed to capture the physical fields of the multi-stage internally-cooled membrane-based liquid desiccant dehumidifier (MI-MLDD). The MI-MLDD is then compared with the single-stage adiabatic one (SA-MLDD) in terms of the effectiveness, maldistribution and thermodynamic limits of driving forces. Four structural improvement methods including increasing stages and layers in the unlimited-size and fixed-size schemes are proposed to further improve the MI-MLDD effectiveness. Their enhancing mechanism is explained by introducing six dimensionless parameters that denote the intensity, distribution and maximum driving forces of heat and mass transfer respectively. Besides, the specific cooling capacity is defined to evaluate the energy efficiency variation of dehumidifiers caused by different effectiveness improvement methods. Compared to the SA-MLDD, the MI-MLDD increases the sensible and latent effectiveness by up to $64\%$ and $18\%$ due to the mitigated maldistribution and the increased minimum local driving forces, even as the air-to-solution flow ratio exceeds 2.4. The unlimited-size scheme improves the MI-MLDD effectiveness more significantly than the fixed-size one due to a linear increase in the number of heat and mass transfer units. The specific cooling capacity could reach the maximum value at the condition where the MI-MLDD operates without unfunctional contact areas. These findings highlight the potential of MI-MLDD for handling the large flow air with the improved performance.

基于膜的液体干燥剂除湿（MLDD）作为一种有前途的温度和湿度控制技术，在处理工业领域的大量气流时会降低效率。现有的方法（例如多级除湿和内部冷却）提供了解决此问题的解决方案，但是由于难以密封管道，因此在大型系统中的实施在某种程度上具有挑战性，并且尚未阐明提高效率的机制。深入。本文旨在应用易于处理的多级内部冷却结构，以可接受的成本提高MLDD的有效性，并从传热和传质的驱动力角度揭示潜在的机理。首先建立无因次有限差分模型，以捕获多级内部冷却膜基液体干燥剂除湿机（MI-MLDD）的物理场。然后将MI-MLDD与单级绝热模型（SA-MLDD）在驱动力的有效性，分布不均和热力学极限方面进行了比较。提出了四种结构改进方法，包括无限大小和固定大小方案中增加阶段和层数，以进一步提高MI-MLDD的有效性。通过引入六个无量纲参数来解释它们的增强机制，这些参数分别表示传热和传质的强度，分布和最大驱动力。除了，定义特定的制冷量以评估除湿器的能效变化是由不同的效率改进方法引起的。与SA-MLDD相比，MI-MLDD将显着和潜在的效力提高了多达$64％$ 和 $18％$由于缓和的分布不均和最小的局部驱动力增加，即使空气与溶液的流量比超过2.4。由于传热和传质单元数量的线性增加，无限制方案比固定尺寸方案更有效地提高了MI-MLDD的效率。在MI-MLDD运行而没有不起作用的接触区域的条件下，比制冷量可能会达到最大值。这些发现凸显了MI-MLDD在处理大流量空气中具有改进性能的潜力。