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Exergy analysis and performance improvement of liquid-desiccant deep-dehumidification system: An engineering case study

Guan, Bowen, Zhang, Tao, Jun, Liu, Liu, Xiaohua
Energy 2020 v.196 pp. 117122
air, air flow, case studies, cost effectiveness, energy conservation, engineering, exergy, factories, heat, heat pumps, humidity, mass transfer, temperature
Engineering case studies are important for providing valuable experience and reference for energy conservation in actual industrial factories with deep-dehumidification requirements. In this study, on-site measurements were conducted to reveal the performance of a liquid-desiccant deep-dehumidification system applied in a photographic film factory. The results reveal the current system has a limited exergy efficiency of 17.7%, because the high heat source temperature (120 °C) required for regeneration induces large parameter differences in heat and mass transfer processes, which dominates the exergy loss of the system. To improve the system performance, the limiting value of the required heat source temperature is investigated. It was revealed that the humidity ratio of the exhaust air determines the required heat source temperature and an increase in regeneration air flow rate helps decrease it. Next, a refined system combined with a heat pump cycle is developed with a near-optimal regeneration air flow rate. In the refined system, a low heat source temperature of 45.6 °C is achieved, which helps to significantly improve the exergy efficiency of the system from 17.7% to 28.6%. Operating the refined system, 33.7% of the system’s running cost can be saved to ensure a cost-effective operation compared with the original system.