Membrane fouling is a major challenge of membrane distillation when employed as a regenerator in liquid desiccant air-conditioning systems. The present work investigated the impacts of feed temperature and flow velocity on the occurrence of membrane fouling using a bench-scale direct contact membrane distillation (DCMD) system to regenerate a 27.5 wt% of lithium chloride (LiCl) solution. The membranes used at different operating conditions were characterized and compared by scanning electron microscopy and water contact angle measurement. The results showed that increasing feed inlet temperature significantly improved the DCMD regeneration capacity but reduced the membrane hydrophobicity. The DCMD operated at a higher cross flow velocity exhibited a higher propensity of membrane fouling. Membrane fouling tended to accumulate from loose LiCl crystals to a dense scaling layer with an increase in both feed inlet temperature and cross flow velocity. Membrane cleaning with deionized water w
Liquid desiccant cooling (LDC) systems are being widely considered as a promising alternative for energy savings and the regeneration is one of the most significant processes of the LDC systems. This paper presents a direct contact membrane distillation (DCMD) regenerator for liquid desiccants regeneration of LDC systems and fresh water production simultaneously. The novelty of this study is to use the response surface method to establish models to predict the DCMD regeneration performance with highly concentrated lithium chloride solutions based on the experimental investigation. The interactive effects of the operating parameters, i.e. initial feed concentration, feed inlet temperature, distillate inlet temperature, and feed and distillate flow rates were studied and the optimal conditions of the DCMD regenerator to maximize the feed concentration increase and transmembrane water flux were identified. The experimental results showed that stable regeneration performance and water prod
anodic oxidation. As a result, one can obtain amorphous barrier-type oxides, crystalline barrier-type oxides or amorphous nanoporous oxides. Currently, highly-ordered nanoporous anodic aluminum oxides (AAO) are obtained with various electrolytes to form nanostructures with a range of geometrical features. This material can serve as a template for nanofabrication of variety of nanowires, nanotubes and nanodots. In this way, porous alumina can be fabricated electrochemically through anodic oxidation of aluminum, yielding highly ordered arrays of nano-holes several hundreds down to several tens of nanometers in size.
Sol-gel chemistry offers a flexible approach to obtain a diverse range of materials. It allows differing chemistries to be achieved as well as the ability to produce a wide range of nano-/micro-structures.