Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Civil Engineering in the Faculty of Engineering at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2014 / The current problems of orifice, nozzle and Venturi flow meters are that they are limited to turbulent flow and the permanent pressure drop produced in the pipeline. To improve these inadequacies, converging-diverging (C-D) tubes were manufactured, consisting of symmetrical converging and diverging cones, where the throat is the annular section between the two cones, with various angles and diameter ratios to improve the permanent pressure loss and flow measurement range. The objective of this study was firstly to evaluate the permanent pressure loss, secondly to determine the discharge coefficient values for various C-D tubes and compare them with the existing differential pressure flow meter using Newtonian and non-Newtonian fluids, and finally to assess the performance of these differential pressure flow meters. The tests were conducted on the multipurpose test rig in the slurry laboratory at the Cape Peninsula University of Technology. Newtonian and non-Newtonian fluids were used to conduct experiments in five different C-D tube flow meters with diameter ratios (β) of 0.5, 0.6 and 0.7, and with angles of the wall to the axis of the tube (θ) of 15°, 30° and 45°. The results for each test are presented firstly in the form of static pressure at different flow rates. It was observed that the permanent pressure loss decreases with the flow rate and the length of the C-D tube. Secondly, the results are presented in terms of discharge coefficient versus Reynolds number. It was found that the Cd values at 15° drop earlier than at 30° and 45°; when viscous forces become predominant, the Cd increases with increasing beta ratio. The Cd was found to be independent of the Reynolds number for Re>2000 and also a function of angle and beta ratio. Preamble Performance of a symmetrical converging-diverging tube differential pressure flow meter Finally, the error analyses of discharge coefficients were assessed to determine the performance criteria. The standard variation was found to increase when the Reynolds number decreases. The average discharge coefficient values and their uncertainties were determined to select the most promising C-D tube geometry. An average Cd of 0.96, with an uncertainty of ±0.5 % for a range of Reynolds numbers greater than 2,000 was found. The comparison between C-D tubes 0.6(15-15) and classical Venturi flow meters reveals that C-D 0.6(15-15) performs well in turbulent range and shows only a slight inaccuracy in laminar. This thesis provides a simple geometrical differential pressure flow meter with a constant Cd value over a Reynolds number range of 2000 to 150 000.

Maximum asset performance is one of the major goals for electric power system managers. To reach this goal minimal life cycle cost and maintenance optimization become crucial while meeting demands from customers and regulators. One of the fundamental objectives is therefore to relate maintenance and reliability in an efficiently and effectively way, which is the aim of several maintenance methods such as the Reliability Centered Maintenance method (RCM). Furthermore, this necessitates the determination of the optimal balance between preventive and corrective maintenance to obtain the lowest total cost. This thesis proposes methods for defining the importance of individual components in a network with respect to total interruption cost. This is a first step in obtaining an optimal maintenance solution. Since the methods consider several customer nodes simultaneously, they are especially suitable for network structures that serve many purposes/customers e.g. transmission and distribution networks with more than one load point. The major results are three component reliability importance indices, which are applied in two case studies. The first case study is based on a network in the Stockholm area. The second case study is performed for one overhead line system in the rural parts of Kristinehamn. The application studies demonstrate that the indices are possible to implement for existing electrical networks and that they can be used for maintenance prioritization. Consequently these indices constitute a first step in the overall objective of a maintenance optimization method. The computations of the indices are performed both with analytical and simulation based techniques. Furthermore, the indices can be used to calculate the component contribution to the total system interruption cost. The approach developed for the importance indices can be utilized in any multi-state network that can be measured with one performance indicator. / QC 20101130