i Declaration I, Johann Richard Bredell, the undersigned, hereby declare that this thesis is my own original work. It is being submitted for the Degree of Master of Engineering (Mechanical) at the University of Stellenbosch. It has not been submitted, in its entirety or in part, for any degree or examination at any other University. …………………………… Signature of candidateThis ………. day of ………………….ii Abstract Forced draft air-cooled steam condensers (ACSCs) consisting of multiple fan units are used in direct cooled power plants to condense steam in a closed steam cycle. Axial flow fans located below an A-frame configuration of finned tube heat exchanger bundles, force ambient air through the system. In so doing, heat from the condensing steam is rejected to the environment via the finned tubes. The performance of an air-cooled system is proportional to the air mass flow rate and the temperature difference between the finned tubes and the ambient air. A variation in either will directly affect the efficiency of the steam turbines.Air flow distortions at the fan inlet caused by structures, wind and other fans may result in a significant reduction in flow rate as well as fan blade vibration. This phenomenon has an adverse affect on the cooling capacity of an ACSC, and consequently turbine performance, due to a decrease in air mass flow rate. In this study the effect of inlet flow distortions on fan performance (i.e. flow rate and fan shaft power) in an ACSC is numerically investigated by modelling a section (or sector) of such a system using the commercial computational fluid

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Background. Injuries inflicted by gunshot wounds (GSWs) are an immense burden on the South African (SA) healthcare system. In 2005, Allard and Burch estimated SA state hospitals treated approximately 127 000 firearm victims annually and concluded that the cost of treating an abdominal GSW was approximately USD1 467 per patient. While the annual number of GSW injuries has decreased over the past decade, an estimated 54 870 firearm-related injuries occurred in SA in 2012. No study has estimated the burden of these GSWs from an orthopaedic perspective. Objective. To estimate the burden and average cost of treating GSW victims requiring orthopaedic interventions in an SA tertiary level hospital. Methods. This retrospective study surveyed more than 1 500 orthopaedic admissions over a 12-month period (2012) at Groote Schuur Hospital, Cape Town, SA. Chart review subsequently yielded data that allowed analysis of cost, theatre time, number and type of implants, duration of admission, diagnostic imaging studies performed, blood products used, laboratory studies ordered and medications administered. Results. A total of 111 patients with an average age of 28 years (range 13 -74) were identified. Each patient was hit by an average of 1.69 bullets (range 1 -7). These patients sustained a total of 147 fractures, the majority in the lower extremities. Ninety-five patients received surgical treatment for a total of 135 procedures, with a cumulative surgical theatre time of >306 hours. Theatre costs, excluding implants, were in excess of USD94 490. Eighty of the patients received a total of 99 implants during surgery, which raised theatre costs an additional USD53 381 cumulatively, or USD667 per patient. Patients remained hospitalised for an average of 9.75 days, and total ward costs exceeded USD130 400. Individual patient costs averaged about USD2 940 (ZAR24 945) per patient. Conclusion. This study assessed the burden of orthopaedic firearm injuries in SA. It was estimated that on average, treating an orthopaedic GSW patient cost USD2 940, used just over 3 hours of theatre time per operation, and necessitated a hospital bed for an average period of 9.75 days. Improved understanding of the high incidence of orthopaedic GSWs treated in an SA tertiary care trauma centre and the costs incurred will help the state healthcare system better prioritise orthopaedic trauma funding and training opportunities, while also supporting cost-saving measures, including redirection of financial resources to primary prevention initiatives.

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