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This thesis concerns incompressible, planar, two-dimensional flow past impervious and porous bluff membranes as well as impervious streamlined membranes or planar sails. Each membrane was held by two supports which were thin relative to the distance between them. The angle between the flow direction and the line joining the supports was set at right angles for the bluff membranes and at small angles for the streamlined membranes. Experiments were made for various membrane lengths as a proportion of the distance between the supports. Materials of different density and porosity were used for the bluff membranes. A theory, based on Bearman-Fackrell's numerical solution of Parkinson-Jandali's wake-source model for bluff bodies, was developed for the impervious and porous bluff membranes and found to give good prediction of the drag coefficient. Previous theoretical solutions for the planar sail showed serious disagreement with the experimental results mainly because of flow separation.

The proton exchange membrane is one key component of direct methanol fuel cells, which has double functions of conducting protons, separating fuels and oxidant. At present, the performance and price of sulfonic acid proton exchange membrane used in direct methanol fuel cells are deeply concerned. In order to reduce membrane 's cost and improve performance of Nafion membrane, three different kinds of membranes have been studied in this thesis. These membranes are SPEEK membranes, SPEEK/ZP composite membranes and Nafion/ZP composite membranes.

A fuel cell is an energy device that converts chemical energy to electrical energy. Low temperature fuel cells, namely the hydrogen fuel cell and the direct methanol fuel cell are preferred amongst other fuel cell types for stationary and vehicular applications, due to their small size and their low operating temperature. The direct methanol fuel cell has several advantages over the hydrogen fuel cell including ease of transport and storage since methanol is a liquid. Since methanol is used directly in the cell there is no need for a reforming process, which results in a less complicated system. However, direct methanol fuel cell are in their infancy and many problems need to be overcome before reaching commercialization. The direct methanol fuel cell has several disadvantages, namely, the sluggish methanol oxidation reaction, the high cost of state-of-the-art proton exchange membranes, the high methanol permeability from anode to cathode and the dependence on the conductivity on membrane water content, which limits their use to temperatures below the boiling point of water, while the need is to work at high temperatures. Attempts to overcome the disadvantages of the state-of-the-art membrane were made in this study, including the development on novel proton exchange membranes and also the modification of existing state-of-the-art membranes.

<p>For a direct methanol fuel cell (DMFC), the proton exchange membrane must conduct protons and be a good methanol barrier. In addition to the high methanol permeability achieved by these membranes, they are very expensive and contribute greatly to theoverall cost of fuel cell set up. The high cost of the DMFC components is one of the main issues preventing its commercialization. The main objective of this study was thus to produce highly proton conductive membranes that are cheap to manufacture and have low methanol permeability.</p>

Thesis (MScIng)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis (Ph.D.)--University of Texas at Dallas, 2007. / Includes vita. Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2002. / Adviser: James Dickson. Includes bibliographical references. Also available via World Wide Web.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: James M. Dickson. Includes bibliographical references (leaves 393-400). Also available online.