Thesis (Ocean E)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1979. / Supervised by Loren R. Haury, Douglas E. Kenyon and Henri O. Berteaux. Includes bibliographical references (leaves 134-137).

This thesis studies the optimal design for a photovoltaic-powered medium-head (30 meters) water pumping system, with the emphasis on improving the efficiency and reducing the maintenance requirements of the electrical subsystem. The reduction of maintenance requirements is realized by replacing the conventional brush-type permanent magnet dc motor with a brushless dc (BLDC) motor. Different BLDC motor control techniques such as position-sensorless operation, sinusoidal and trapezoidal excitations are investigated. The improvement in efficiency is achieved by maximizing the output power from the photovoltaic array and by minimizing the losses in various parts of the electrical sub-system. A microprocessor-based double-loop maximum power tracking scheme is developed for maximization of the photovoltaic array output power. Over 99% utilization factor is achieved for a typical clear day regardless of the season of the year. The system losses are minimized mainly by performing loss analysis and selecting most suitable switching topologies and switching components. Experimental results show that the combined converter-motor efficiency is comparable to those of high-efficiency brush-type dc motor systems. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

M.Ing. (Engineering Management) / The purpose of this dissertation was to compare the local manufacturing of liquid pumps in South Africa against the importation of pumps manufactured on the international markets as well as also investigate the capacity limitations of the local pump manufacturers; the technologies available on overseas markets (in terms of electric, solar and wind-powered liquid pumps) and comparing the technologies to those available in South Africa. Five of the leading pump manufacturers were researched in this dissertation namely: KSB; Grundfos; Howden Pumps; Sulzer Pumps Africa and Warman Pumps. South African pump manufacturers are importing most of their pumps from international markets with the primary reason being to meet demands. By comparison, South African pump manufacturers are finding it difficult to produce pumps with equivalent or lower costs than the pumps which are produced on the international markets. Pump manufacturers on international markets offer greater cost savings for South African pump manufacturers which ultimately results in financial savings and a higher yield in profits. Many international pump manufacturers use advanced technology which makes the production costs of pump components as much as twenty percent (20%) less as compared to the South African pump industry. The importation of pumps is a method used to increase the local supply of pumps as the cost of the pump, including import costs, are not as costly as actually manufacturing the pumps in South Africa. While South African pump manufacturers manufacture pumps of relatively high energy consumption and monetary costs; they also produce standard conventional pumps which are required to supply the local demand. Local pump manufacturers were approached to find out exactly how they cope with these stringent requirements by the South African markets, yet still achieve the profits in the industry to remain afloat. Various pump forms were researched specifically relating to the pumps used on the South African markets with regards to their production costs, advantages and disadvantages (wind and solar pump technologies). Standard conventional pumps are preferred on local markets by as much as fifteen percent (15%) with newer technologies (solar and wind powered pumps) being preferred on the international markets. South Africa continues to demand standard conventional pumps (electric-driven pump) although demands for newer technology is on the increase. The international market’s production lines are mature and well established which results in a lower cost of production which leads to these pumps being of more demand as compared to newer pumps which are currently the preference. Local pump manufacturers can satisfy the demand and benefit from the lower importation cost of standard conventional pumps. The preliminary results suggest that the importing of pumps from international markets aid local manufacturers in keeping up with the demand and accquiring sufficient profits. Modern technologies such as solar and wind power is a growing maket in South Africa and is becoming increasingly common. The research approach used in this study involved targeting five of the local pump manufacturers in South Africa. Each manufacturer was asked a series of questions relating to the research questions in order to draw up conclusions regarding the problem statement and hypothesis. Findings from the conducted surveys were compared to the literature which is currently published. Findings show that local pump manufacturers are dependent on imports in order to satisfy the demand for standard conventional pumps rather than manufacturing their own and the use of newer technologies are increasing in the local pump industry.

The objective of this research project is to develop new software tools capable of operational optimisation of existing, large-scale water distribution networks. Since pumping operations represent the main operating cost of any water supply scheme, the optimisation problem is equivalent to providing a new sequence for pumping operations that makes better use of the different electricity tariff structures available to the operators of distribution systems. The minimisation of pumping costs can be achieved by using an optimal schedule that will allow best use of gravitational flows, and restriction of pumping to low-cost power periods as far as possible. A secondary objective of the operational optimisation is to maintain the desired level of disinfectant chlorine at the point of delivery to consumers. There is a steady loss of chlorine with residence time in the system. If the level drops too low there is a risk of bacterial activity. Re-dosage points are sometimes provided in the network. Conversely, too high a level produces an unacceptable odour. The combinatation of dynamic elements (reservoir volumes and chlorine concentration responses) and discrete elements (pump stati and valve positions) makes this a challenging Model Predictive Control (MPC) and constrained optimisation problem, which was solved using MINLP (Mixed Integer Non-linear Programming). The MINLP algorithm was selected for its ability to handle a large number of integer choices (valves open or shut / pumps on or off in this particular case). A model is defined on the basis of a standard element, viz. a vessel containing a variable volume, capable of receiving multiple inputs and delivering just two outputs. The physical properties of an element can be defined in such a way as to allow representation of any item in the actual network: pipes (including junctions and splits), reservoirs, and of course, valves or pumps. The overall network is defined by the inter-linking of a number of standard elements. Once the network has been created within the model, the model predictive control algorithm minimises a penalty function on each time-step, over a defined time horizon from the present, with all variables also obeying defined constraints in this horizon. This constrained non-linear optimization requires an estimate of expected consumer demand profile, which is obtained from historical data stored by the SCADA system monitoring the network. Electricity cost patterns, valve positions, pump characteristics, and reservoir properties (volumes, emergency levels, setpoints) are some of the parameters required for the operational optimisation of the system. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2004.

A computer-based analog model to determine market potential for electric power-driven water pumps in developing countries. The purpose of this study is to develop a computer-based model that predicts the market potential for electric water pumps in developing nations.The logic employed in such an analysis first seeks out countries which at some point in their recent history have exhibited unusually high growth rates in aggregate pump demand during a period of several years. Next, the researcher evaluates the significance of specific social and economic "indicator" variables when matched with raw trade statistics for that country via stepwise regression--a computer assisted procedure. Finally, by isolating the economic and/or social factors that most closely parallel a country's pump demand, one can identify and rank the developing countries offering the greatest potential sales. The systematically chosen highpotential markets are then worthy of individual consideration and additional resource contribution in a given firm's strategic marketing plan.Since reach of the data were locally unavailable, a trip to the Department of Com©erce in Washington, D.C. and the United Nations in New York City was required. Funding to proceed with Part III of this report was solicited from, and granted by, a major domestic producer of electric water pump motors.The results of the research identified eight indicator variables directly correlated to the demand for imported pumps in developing nations. The regression equation composed of these eight variables, then, will be accepted as the best available model for predicting a country's pumpdemand. The regression equation also shows that each of the eight indicator variables contributes to changes in pump demand in different magnitudes.The research has identified forty-four developing nations with significant growth-rates in one or more of the eight indicator variables. Market projections are finally derived by comparing an individual country's indicator variable growth-rate to its historical pump demand growth-rate.

Thesis (PhD) -- University of South Australia, 1998

Mémoire (M.Eng.)--Université du Québec à Chicoutimi, 1995. / Document électronique également accessible en format PDF. CaQCU

Thesis--Copenhagen. / Summary in Danish. Includes bibliographical references and index.

Thesis--Copenhagen. / Summary in Danish. Includes bibliographical references and index.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.