Liquid desiccant air conditioning systems (LDAS) are an energy-efficient and eco-friendly alternative to conventional air conditioning systems. The performance of a LDAS significantly depends on its simultaneous heat and mass transfer components, namely dehumidifier and regenerator. These components are referred to as liquid desiccant energy exchangers (LDEEs) since the working fluids (air and desiccant) exchange both heat and moisture. There has been a lot of research on LDEEs over the last two decades to improve their performance, thereby enhancing the efficiency of the LDAS. The main objective of this comprehensive review paper is to summarize the developments of LDEEs. The desiccant material, and design, operating, and performance parameters of LDEEs are explained in detail. Even though a lot of research has been done on LDEEs, they are not much utilized in the practical heating, ventilation, and air conditioning (HVAC) systems. To address this issue, future research should prioritize its focus on (i) practical problems of LDEEs such as cross contamination, and leakage and blockage of the membrane, (ii) long term performance study in the practical systems, (iii) noncorrosive and inexpensive solution, (iv) compatible material for efficient heat and mass transfer, and (v) generalized design and performance control methodology. The discussions presented in this communication will be useful to ascertain the crucial research gaps that need to be addressed by future research studies.

液体干燥剂空调系统（LDAS）是传统空调系统的节能，环保的替代方案。LDAS的性能在很大程度上取决于其同时进行的传热和传质组件，即除湿机和再生器。这些成分被称为液体干燥剂能量交换器（LDEE），因为工作流体（空气和干燥剂）会同时交换热量和水分。在过去的二十年中，针对LDEE进行了大量研究，以提高其性能，从而提高LDAS的效率。这份全面的综述论文的主要目的是总结LDEEs的发展。详细说明了LDEE的干燥剂材料，设计，操作和性能参数。即使对LDEE进行了大量研究，在实际的采暖，通风和空调（HVAC）系统中，它们的利用率不高。为解决此问题，未来的研究应优先关注（i）LDEE的实际问题，例如交叉污染，膜的泄漏和阻塞；（ii）实际系统中的长期性能研究；（iii）无腐蚀且价格便宜解决方案；（iv）用于高效传热和传质的兼容材料；（v）通用设计和性能控制方法。本交流中的讨论将有助于确定未来研究需要解决的关键研究空白。未来的研究应将重点放在（i）LDEE的实际问题上，例如交叉污染，膜的泄漏和阻塞；（ii）在实际系统中进行长期性能研究；（iii）无腐蚀且价格低廉的解决方案；（iv）用于高效传热和传质的兼容材料，以及（v）通用的设计和性能控制方法。本交流中的讨论将有助于确定未来研究需要解决的关键研究空白。未来的研究应将重点放在（i）LDEE的实际问题上，例如交叉污染，膜的泄漏和阻塞；（ii）在实际系统中进行长期性能研究；（iii）无腐蚀且价格低廉的解决方案；（iv）用于高效传热和传质的兼容材料，以及（v）通用的设计和性能控制方法。本交流中的讨论将有助于确定未来研究需要解决的关键研究空白。