Abstract

Liquid desiccant air-conditioning is an energy-efficient alternative to conventional vapor compression systems due to its ability to handle sensible and latent heat loads independently. Membrane-based processes are prevalent in desalination research due to their superior abilities to separate fluids. The membrane-assisted separation process is also suitable for use in liquid desiccant air-conditioning systems as it can minimize the problems of corrosion, which has so far prevented the widespread use of liquid desiccant systems. In this study, we have utilized the flat-sheet polytetrafluoroethylene membranes for liquid–vapor separation and combined multieffect design with vacuum conditions, for enhanced liquid–vapor separation across the membrane. Preliminary experiments and literature surveys indicate that the conventional vacuum multieffect membrane distillation system exhibits poor performance when the feed concentration is above 26%. Therefore, efforts are made to enhance its performance when operating at higher concentrations (30% and 34%) by employing flat-plate-type heat exchangers to preheat the liquid desiccant and by maintaining high air-side vacuum. The regeneration process can be optimized based on increase in concentration (ΔC) and performance ratio (PR), by controlling the operating conditions. The evaluations of the regenerator performance for different operating parameters including heat source temperature, circulation cross-flow rate are presented along with analysis. Preheating the LiCl solution before regeneration resulted in improved performance; PR of 0.58 and ΔC of 2.4% are achieved for 34% LiCl concentration.

Graphic abstract

Schematic representation of the membrane-assisted LDAC test bed

中文翻译：

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液体干燥剂再生系统的实验研究：高进料浓度的性能分析

摘要

液体干燥剂空调由于能够独立处理显热和潜热负荷，因此是传统蒸汽压缩系统的节能替代方案。在脱盐研究中，基于膜的工艺因其卓越的分离能力而广为流行。膜辅助分离工艺也适用于液体干燥剂空调系统，因为它可以最大程度地减少腐蚀问题，迄今为止，腐蚀问题阻止了液体干燥剂系统的广泛使用。在这项研究中，我们将平板聚四氟乙烯膜用于液-汽分离，并将多效设计与真空条件结合使用，以增强整个膜的液-汽分离。初步实验和文献调查表明，当进料浓度高于26％时，常规真空多效膜蒸馏系统的性能较差。因此，通过采用平板型热交换器来预热液体干燥剂并保持高的空气侧真空度，努力提高其在较高浓度（30％和34％）下的性能。再生过程可以基于浓度增加（ΔC）和性能比（PR），通过控制工作条件。在分析的同时，提出了对包括热源温度，循环错流率在内的不同运行参数对蓄热室性能的评估。再生前将LiCl溶液预热可提高性能；的0.58 PR和Δ Ç的2.4％的34％的LiCl的浓度来实现。

图形摘要

膜辅助LDAC测试台的示意图