Design and fabrication of treble flow membrane based dehumidifier
Zee, Jonathan Zheng Jie
Date of Issue2016
School of Mechanical and Aerospace Engineering
This report details the comparison between the existing industrial membrane system and the newly developed hollow fibre membrane based tubular flow heat and mass exchanger used for dehumidification. A large amount of funding has been put into the development of liquid desiccant air conditioning (LDAC) systems in the recent years. This is because LDAC systems can be powered mainly by waste heat. The LDAC system dehumidifies the air by absorbing moisture from the surrounding environment with the use of desiccants. This allows for the conservation of up to 50% of energy in both the domestic and industrial arenas. To discover the most effective and suitable desiccant for the dehumidification process, various types of liquid desiccants in the market are compared. Despite of its corrosive properties, the most frequently used desiccant in the LDAC system is lithium chloride. Being able to resist crystallisation, desiccant solution mixtures with reactivation temperatures that are similar are becoming increasingly popular. In addition, they are relatively low in cost. Nonetheless, in order to overcome the common issue of corrosion presented by desiccant salts, plastic heat exchanges are used in LDAC systems. Three individual input scenarios are used to analyse the distribution pattern of the newly developed membrane’s overall flow. The operational parameters of this membrane are dependent on the consistency shown through the distribution flow patterns. The overall performance of the dehumidification of the membrane is also analysed through experiments to arrive at a conclusion. Inputs of various air flow rates were used and the density of the lithium chloride measured to check for any concentration changes. The results were gathered and demonstrated in a psychometric chart. As a comparison, a commercialised membrane by memsys was used throughout both experiments. The experiments showed results which suggest that the newly developed membrane functions best within the parameter of low air flow rate. While the newly developed membrane may not possess the desired dehumidification standards when compared to existing membranes of industrial quality, it does provide the basis required for the next stage of research.
Final Year Project (FYP)
Nanyang Technological University