Enhancing the dehumidification performance of LiCl solution with surfactant PVP-K30

Adding additives into liquid desiccant cooling system (LDCS) can enhance its mass transfer performance. However, the additives proposed by previous researchers are volatile and odorous which is a great threat to the indoor air quality. Therefore, this study introduced a new kind of non-volatile, odorless and nontoxic additive, i.e. polyvinyl pyrrolidone (PVP-K30), into LDCS for better dehumidification performance. Comparative studies were carried out to investigate the dehumidification performance of LiCl solution with and without the additive PVP-K30. The mass fraction PVP-K30 was chosen to be 0.4%. The results show that the dehumidification rate and dehumidification effectiveness have an average relative increment of 22.7% and 19.9% respectively with the addition of surfactant. The enhancement is attributed to the reduction of surface tension of liquid desiccant which is demonstrated by the decrement of contact angle from 58.5 to 28.0. Correspondingly, the wetting ratio of desiccant falling film on plate has a relative increment of 16.9% from 82.7% to 96.7%, and the film thickness of falling film decreases from 0.681 mm to 0.583mm. To sum up, the adding of additive PVP-K30 into LDCS provides an effective and practical way to enhance the vapor absorption performance in an absorber and so does the system efficiency. (C) 2018 Elsevier B.V. All rights reserved.