http://hdl.handle.net/10628/27 Mon, 20 May 2013 21:49:53 GMT 2013-05-20T21:49:53Z http://hdl.handle.net/10628/314 Title: A review of the "tea cup effect" and removal of suspended solids from water. Authors: Mashauri, Damas A. Abstract: Suspended solids problem in water is an issue as old as water treatment itself. Suspended solids can be causative to eroding through abrasion of impellers, pump casings, pipes and other water works related appurtenances. It is therefore appropriate that suspended solids must be removed as early as possible in the water works treatment facilities. It is usually done at the river/lake intakes to reduce the coarse particulate matter that would otherwise adversely affect the water works thereafter. The fine particles that will escape the entrapment at the intake works would therefore require further and more effective system that would remove this fraction. By and large this removal process is achieved by chemically aided process such as coagulation/flocculation unit operation. This process is expensive and demands high level trained personnel to man them. In the same vein then a simple and effective system is proposed. This is a swirl or grit removal system that does not need any chemicals, moving parts or even highly trained personnel to operate them. This paper is looking at the theory of the “Tea Cup Effect” and how it has been used in practice to remove or reduce suspended solids from water. The paper gives some examples where such devices have been used and how effective they have been. Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/10628/314 2011-01-01T00:00:00Z http://hdl.handle.net/10628/312 Title: An investigation on the effects of feeder outages and non-linear loads on 11kV ring distribution network efficiency. Authors: Kapali, David; Gope, Gideon Abstract: This study investigates the impact of power quality problems on the efficiency of a ring distribution network. The paper focuses on the effects of outage and harmonics on the distribution network efficiency and the practical implications on power system economics and reliability. An 11 kV ring distribution network was modeled and simulated in DigSilent PowerFactory (Demo version) 14.0.512 software package. Five case studies were conducted on the network for normal operation conditions and abnormal conditions (outage and harmonics). A methodology to estimate the technical losses (economic losses) in the distribution system was developed and used as a basis for determining the network efficiency. A load flow based analysis was carried out on the distribution system to determine the voltage and current profiles under normal and abnormal conditions. It emerged that the loss of feeder cables or lines in the network has an adverse impact on the efficiency of the network. This raises the question on the existence and the need of an optimum supply configuration. It also puts an increased focus on the need of improved reliability engineering in distribution systems as the costs of failures could be high. The authors conclude that the efficiency of a ring distribution network is affected adversely during contingency (outage and harmonics). The degree to which the efficiency is affected depends on the initial optimal design configuration and the nature of the disturbance or contingency condition. Preventative steps that can be taken to “harden” equipment and systems to PQ problems are also suggested. Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/10628/312 2011-01-01T00:00:00Z http://hdl.handle.net/10628/275 Title: Development of a sun tracking system for a small solar concentrator. Authors: Mutaleni, C.; Bishi, Isabel; Zulu, Andrew; Rajaram, Swaminathan Abstract: An automatic sun tracking system was extended to a parabolic dish solar concentrator which can be used to cook or heat water. Parabolic dish solar concentrator has been in use couple of decades ago but has been tracking the sun manually. The automatic sun tracking system was incorporated on the parabolic dish with success and it works satisfactory. Every time the dish was left in the sun, it was found facing the sun as expected. These systems has been researched and developed before and applied on large scale applications like solar power generation plants and small electricity generation projects for remote areas which are not connected to national power grids. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10628/275 2010-01-01T00:00:00Z http://hdl.handle.net/10628/259 Title: Design and development of solar concentrator for thermal applications. Authors: Bishi, Isabel; Zulu, Andrew; Rajaram, Swaminathan Abstract: Parabolic mirror surfaces are found wherever energy needs to be focused effectively and accurately. They are found built into car headlights, spotlights as well as astronomical telescopes. This research concerns the study of transformation of solar energy into thermal energy and focusing this energy at a point to heat water. In this document the parabola was explored to design a simple, cheap and effective solar water heater. Local communities in Namibia can produce similar water heaters using available materials and the fuel; sunlight is abundant throughout the year in most areas. The main part of the heater, the collector can have any shiny material as long as it refracts the sun’s rays. In this project a parabolic solar concentrator was designed and constructed to heat water at the focal point, which is then stored in a tank for use. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10628/259 2010-01-01T00:00:00Z