Module Manufacture

Manufacture of gas-separation membrane modules is largely a machine-assisted, labor-intensive operation. Polymer dopes are typically prepared batchwise with sufficient hold time to insure uniformity. The membrane performance is largely controlled by the polymer precipitation step and very dependent upon phase behavior and precipitation kinetics. Thus, it is essential that processing conditions be maintained as uniformly and as constant as possible if product quality and uniformity is to be preserved. For this reason, membrane-fihn formation and hollow-fiber spinning processes are usually operated continuously or for extended run times. Since the intermediate film or fiber must eventually be converted into discrete items, the continuous process is typically interrupted by collection of the membrane formed on spools or fiber skeins where it may be inventoried briefly before batch processing into the final assembly resumes. 

Gas-separation-module assembly is typically an operator-machine interactive process, because the scale of operation cannot justify the type of automation necessary for the high-volume dialysis and filter-module assembly lines. This also has some advantages in enabling products to be sized and tailored to the application. 

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Some confusion can occur over the rejection coefficients quoted by membrane module manufacturers. The intrinsic rejection of good quality membranes measured in a laboratory test system might be in the range 99.5 to 99.7 %, whereas... 

Photovoltaic Module Manufacturing Biomedical Products Technologies Electric Utility Solar Power Generation Optoelectronics... 

This chapter will focus on three types of membrane extracorporeal devices, hemodialyzers, plasma filters for fractionating blood components, and artificial liver systems. These applications share the same physical principles of mass transfer by diffusion and convection across a microfiltration or ultrafiltration membrane (Figure 18.1). A considerable amount of research and development has been undertaken by membrane and modules manufacturers for producing more biocompatible and permeable membranes, while improving modules performance by optimizing their internal fluid mechanics and their geometry. 

A major degradation mechanism of modules is the decrease in fill factor. This is caused by an increase in the diode quality factor of the cells making up the module and by an increase in series resistance. The former is related more to the absorber and heterojunction properties and less to the ZnO properties. The series resistance increases because the conductivity of the ZnO drops and because the interconnects are deteriorating. Wennerberg et al. have assessed the individual contributions to increased series resistance [50]. Klaer et al. [52,53] have described a transmission-line test structure that allows to separate the contributions of contact and sheet resistance, respectively. The test structure is prepared by the same scribing techniques as those used in module manufacturing. 

Although it has been reported that an external DC electric field can induce an electrophoretic back transport that can significantly enhance flux in crossflow membrane filtration, its commercial implementation appears to be restricted by several factors. These include lack of suitably inexpensive corrosion-resistant electrode materials, concerns about energy consumption, and the complexity of module manufacture. 

Due to the large economical and technological potential of silicon ribbons, their application in solar wafer production will be a major milestone in PV cost reduction. Thus, it is very likely that silicon wafer based PV module manufacturing will maintain the cost advantage over other upcoming technologies and, therefore, the role as the major PV technology. 

Hie three major membrane configurations, flat sheet, spiral wound, and hollow fiber, each having advantages and limitations, will he reviewed briefly prior to considering the detailed analysis of these devices. Some of these issues include relative magnitudes of active membrane area per unit separator volume, mtninrizakm of pressure buildup in the permeant stream, membrane integrity, and the ease of module manufacture and membrane replacement. 

DuPont s patents are especially noteworthy in that they provide an unusually thorough description of module manufacture and insightful discussion of how design variables may affect performance. In particular, the patents... 

The detailed descriptions of module manufacture, process control, and the effects of non-idealities such as plugged fibers, fiber size variation, and broken fibers provided in the DuPont patents make them a great introduction to hollow fiber membrane technology. The manufacturers of the next generation of membrane products will benefit from this insight. 

Compatible sealing materials - Are sealing and tubesheet materials available that are compatible with the gases and process streams involved in the intended appHcation and with the module manufacturing process ... 

Module manufacture - Can a reliable membrane module be manufactured in a cost-effective manner ... 

Table 6.14 Classification of commercial UF/MF membranes and dead-end modules Manufacturer Membrane... 

FIGURE 6.16 A photograph of a Mach-Zehnder modulator manufactured by Lumera is shown. 

Membranes in the form of hollow fibre modules are used commonly for gas dehydration. In comparison to spiral wound modules made from flat sheet membranes, hollow fibre membrane modules contain more membrane surface area per unit volume thereby reducing the size of the module. Additionally, hollow fibre module manufacturing costs are lower [1] and hollow fibre designs easily permit permeate sweep. 

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