Ching-Jung Chuang

CFD analysis on fluid flow through multifilament woven filter cloths

The effects of woven structures on fluid flow through the basic weaves of multifilament woven filter cloths were studied numerically by using the fluid-flow software fluent™. From results of the numerical solution, the flow pattern and the resistance to flow in the interstices were obtained. Results of this work show that the construction of the fabric pores has a significant influence on the flow pattern in the interstices and the downstream. It is also shown that the plain weave gives the highest fluid-flow resistance while the satin weave gives the lowest under the same thread count. Furthermore, in the case of tightly woven filter cloths, the flow is predominantly through the yarns of the cloth; while the flow will generally be directed around the yarns of a loosely woven cloth, especially if the yarns are twisted tightly. A comparison of fluid flow through multifilament woven filter cloth with that of monofilament woven filter cloth is also discussed.

Performance evaluation of ePTFE and PVDF flat-sheet module direct contact membrane distillation

This paper reports experiments using a flat-sheet module with 0.18 approximately 0.45 microm ePTFE (expanded polytetrafluoroethylene) and PVDF (polyvinylidene fluoride) membranes to show the effects of membrane properties, salt concentration and fluid hydrodynamics on the permeate flux and salt rejection of DCMD (direct contact membrane distillation). A theoretical prediction of the permeate flux was carried out, and was in close agreement with the experimental results. In addition, the energy integration of the process was also analyzed in order to evaluate module design to increase energy efficiency. According to the simulated results of the energy integration design, a combination of simultaneous cooling of the permeate stream and an additional heat exchanger to lower the temperature of the permeate stream not only enhances the MD flux, but also reduces energy consumption.

Hydraulic Radius of Three Dimensional Woven Fabric Structures

A theoretical model has been developed to evaluate the effect of geometrical parameters of three-dimensional fabrics on hydraulic radius of different fabric structures. Results show that the hydraulic radius increases logarithmically with the increase of weave spacing between yarns and is independent on the yarn diameter. As any fabric is composed of a certain percentage of one to four different pore types, its hydraulic radius can be evaluated by taking the composition of pore types and hydraulic radius of pore types into account. The analytical result of the model can be used to design and select woven fabrics in accordance with the filtration requirement, encouraging textile industry to develop new fabrics to meet the requirement of specific industrial applications.