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Thesis (Ph.D.)--University of Tulsa, 1990. / Bibliography: leaves 103-106.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The continuous growth in the world’s population together with the increasing scarcity of water resources, especially drinkable water, has cultivated an environmentally-conscious society. As consumers are looking for eco-friendly alternatives or methods, manufacturers are including environmentally-friendly (EF) products in their product mix to address this topic. However, there seems to be a disconnect between manufacturers of EF product solutions and consumers. Consumers are either not aware of EF products or they are still hesitant in adopting environmentally-friendly products as the perception is that they are either too expensive or there is something amiss with the product’s functionality. It is up to suppliers and marketers of EF goods to do a better job of educating consumers about their products. This research study was conducted to understand the domestic consumer’s ecological behaviour and key influencing factors when purchasing water-efficient fittings. The literature review in this study gives us background on the status quo in terms of climate change, the green consumer, and water supply issues. A survey was conducted amongst domestic consumers in the plumbing retail environment to test their willingness to purchase water-efficient fittings based on their profile, habits and key influencing factors. The profile of the respondent showed a consumer who is more affluent. The water-efficient consumer’s primary concern is to save costs by reducing their water bill. Cost saving is the key influencing driver in terms of consumer’s willingness to purchase water-efficient fittings.

Solving for energy losses in pipe junctions has been a focus of study for many years. Although pipe junctions and fittings are at times considered "minor losses" in relation to other energy losses in a pipe network, there are cases where disregarding such losses in flow calculations will lead to errors. To facilitate these calculations, energy loss coefficients (K-factors) are commonly used to obtain energy losses for elbows, tees, crosses, valves, and other pipe fittings. When accurate K-factors are used, the flow rate and corresponding energy at any location in a pipe network can be calculated. K-factors are well defined for most pipe junctions and fittings; however, the literature documents no complete listings of K-factors for crosses. This study was commissioned to determine the K-factors for a wide range of flow combinations in a single pipe cross and the results provide information previously unavailable to compute energy losses associated with crosses. To obtain the loss coefficients, experimental data were collected in which the flow distribution in each of the four cross legs was varied to quantify the influence of velocity and flow distribution on head loss. For each data point the appropriate K-factors were calculated, resulting in over one thousand experimental K-factors that can be used in the design and analysis of piping systems containing crosses.

The overall reliability of a power transformer depends to a great extent on the sound operation of the bushings thereof. In view of its overwhelming advantages, resin impregnated paper (RIP) is acquiring prominence over conventional oil impregnated paper (OIP) in transformer bushings. The main advantages of RIP bushings are low dielectric loss and capability of positioning them at any desired angle over the transformer. The RIP structure, being an all-solid system, is completely free from oil phase. The temperature rise in RIP bushings under normal operating conditions is seen to be a difficult parameter to control in view of the limited options for effective cooling. The degradation of dry-type insulation such as RIP is often due to thermal and electrical stresses. The long time performance thereof, depends strongly, on the maximum operating temperature. In order to be able to predict the regional temperature, it is necessary to consider the thermal and electrical parameters of insulation in question; and to identify and solve the governing equations under the relevant boundary conditions. Electrical failure of insulation is known to be an extremal random process wherein nominally identical specimens of equipment insulation, at constant stress fails at inordinately different times. In order to be able to estimate the life of power equipment like transformer bushing, it is necessary to run long duration ageing experiments under accelerated stresses, to acquire and analyze insulation specific failure data. The present work is an attempt to provide reliability and life estimation of High Voltage RIP bushing insulation. The literature survey carried out in this view indicate that investigation on thermal and electric field distribution and the models for failure under combined stress and analysis of the data so as to be able to estimate the possible life of RIP bushing is scanty. Having these aspects in focus, the scope of the present work is defined as: (i) Mapping of the temperature and electric field distribution in the body of 400kV RIP bushing (ii) Deduction of parameters of the probabilistic models for the failure under electrical and thermal ageing (iii) Estimation of life based on diagnostic testing using PD With this in view, the temperature distribution in the body of a 400kV RIP bushing is studied considering the heat generation both in central conductor and that in the insulation. Presence of multiple materials with non-confirming interfaces makes analytical solution rather difficult and hence numerical approach is adopted. In the present work, vertex-centered Finite Volume Method (FVM) is employed for both thermal and electrical analysis. The electric stress distribution is accurately evaluated considering both the non-zero conductivity of the RIP material and the presence of capacitive grading foils. These analysis has clearly shown that Stress grading foils uniforms the stress across the major portion of the bushing insulation Enhancement of the electric conductivity by the temperature is not found to be affective in changing the electric field distribution The temperature distribution is shown to have a maxima near the flange due to the influence of top oil temperature of the transformer Heat generated in the dielectric due to the prevailing electric stress is shown to be insignificant. This ruled out the possibility of thermal runaway and hence the dielectric temperature is within the safe working limits for the bushing considered. The deduction of physical models governing insulation failure depends on the nature of stress. In this work, the insulation failure at constant accelerated stress has been considered and the estimation of life is computed based on inverse power law coupled with Arrhenius law. A high degree of scatter is generic to the experimental data forming the ingredients to develop the models. In view of this, the concept of a random process is invoked. Probabilistic models for the failure of RIP bushing under synergy are adopted and an attempt is made to estimate the life. The well known Weibull distribution and probability plotting of life data is used in this endeavor. The maximum likelihood estimation is used to determine the scale and shape parameters of the Weibull distribution. In the diagnosis of the extent of degradation of insulation due to PD, under long duration electric stress, a non-conventional voltage application method called the classical stepped stress method is adopted. In this technique, the voltage is applied in pre-determined steps over predetermined duration of time. The magnitude of voltage steps is carefully computed based on Miners law and the end-of-life is computed using inverse power law. In summary, this thesis work has contributed to the thermal and electrical degradation of resin impregnated paper insulation for high voltage transformer bushing. The thermal and electrical field distributions computed in the body of bushing clearly shown that these stresses are well within the limit, thereby ruling out the possibility of a thermal runaway. Comparing the estimates of the most probable life of RIP, based on several methods appears to show that any of the method can be adopted. However, as matter of caution and safety, the lowest among them can be taken as a reasonable estimate.