Thesis (M. Env. St.)--University of Adelaide, Centre of Environmental Studies, 1985. / Includes bibliographical references.

The principal objective of the present thesis has been to develop a methodology for the simulation and optimization of electric power generation by solar ponds. / A mathematical model for the analysis of the economic performance of a solar pond electric power system using a heat engine is developed. A salient feature of this model is a simple method for the analysis of a Rankine cycle. Other features include a mathematical model of the solar pond, of the energy exchange properties of the heat exchangers, as well as of the power required by the circulating pumps. The net electric power is expressed in terms of the thermodynamic properties of the organic working fluid, the temperatures of various thermodynamic states, the flow rates, the temperature and geometry of the solar pond, and the local climatic conditions. The system sizing and operating conditions which minimize the cost per kilowatt hour of electric energy is then determined through an optimization routine. / The optimal storage depth and heat extraction scheduling are obtained by a semi-analytical method as well as a discrete optimal control technique. The possibility of an ice storage to act as a cooling source for an SPPP has also been investigated, which showed considerable improvement in the system's efficiency and reduction of electric energy cost. / The possibility of making the NCZ of a solar pond float over a layer of fresh water has been investigated. The economical feasibility study of the concept for electric power generation was achieved using the model developed earlier. / The thesis finally examines the means of enhancing the thermal storage under a solar pond by circulating LCZ brine through a network of buried horizontal pipes in the warmer part of the year. This heat stored can be used for the operation of a heat engine during the winter time if the LCZ brine is then used as a heat sink rather than a heat source. / The present thesis has shown that the commonly held belief that SPPP can only function at acceptable efficiencies under semi-tropical conditions of SPPP in northern climates resulted in electric energy costs of 8.5 (CENTS)/KWh which is comparable with that of estimated by Israelis for an SPPP in semi-tropical conditions.

This research presents the development of a transmittance- absorptance parameter for a solar pond. Such a parameter represents, directly, the fraction of the incident solar radiation which is absorbed at the bottom of the solar pond. It can be used to represent pond performance through an equation analogous to the Hottel-Whillier-Bliss Equation for a flat-plate solar collector. The above parameter is called the transmittance - absorptance product and is an energy-weighted quantity. Monthly values of the proposed parameter are developed from an hour-by-hour simulation. The simulation utilizes hourly values of spectral solar radiation reaching the earth's surface which are computed from a state-of-the-art algorithm that has been slightly modified to better estimate diffuse spectral radiation at large solar zenith angles; the modification is also presented. Thermal conductive losses through the water layers and the surrounding earth together with evaporative and convective losses are usually the only loss mechanisms considered for a solar pond. Under clear skies and to a lesser extent under cloudy skies, a longwave radiation heat loss also occurs from the pond surface. The estimation of radiative loss from any terrestrial surface requires detailed computations and atmospheric data. The procedure has been greatly simplified through a correlation which yields spectral atmospheric emissivity from the amounts of absorbing gases present in the atmosphere. It is recommended for further study that the performance of a solar pond be estimated using the proposed transmittance-absorptance product to compute the solar energy absorbed in the pond, and that the longwave radiative loss from the pond be included in the analysis. A comparison with data obtained from an existing solar pond is recommended to validate the results obtained in this study. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

No description available.

Thesis (Ph.D.)--University of Western Australia, 2006.

Bibliography: leaves 150-175. / xv, 175, [114] leaves, [10] leaves of plates : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The information collected from physico-chemical, biological and experimental investigation is used to make appropriate recommendations about solar salt pond management. Proper management of biological systems in essential for production of high quality salt. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1998?

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Thesis (MEng)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: In the present study, research was conducted to determine the feasibility of water energy storage through which the output of heated air by an upward facing solar air heater could be prolonged. Following a systematic approach, a number of experimental test swere initially performed on an upward facing solar air heater in order to obtain a benchmark that could be used to evaluate the influence of water storage during the day-time performance of a solar air heater. As expected, an increase in the air mass flow rate not only led to an increase in the collector efficiency but also to a decrease in the temperature gain across the collector. In addition, a number of day- and night-time experiments were executed on a plastic covered water tank in order to evaluate it's ability to store and discharge thermal energy. Results clearly indicated that the plastic covered water tank was both an ideal collector and storage medium of solar energy. Experimental results also revealed that the plastic covered water tank was an ideal source of thermal energy for a solar air heater during night-time operation. Subsequently, both day- and night-time experiments were performed on an upward facing solar air heater in which plastic covered water tanks were installed. Day-time experimental results revealed that the modified solar air heater still had the same collector efficiency tendency, as observed in the initial solar air heater experiments, but that the water energy storage led to a dramatic decrease in the absorber plate temperature and in the corresponding temperature gain experienced across the collector. In contrast, the night-time operation results clearly indicated that the water energy storage was not only able to prolong the output of heated air by the solar air heater, but was further able to increase the air temperature by between 7.5 and 1.5 °e, depending on the air mass flow rate. It was furthermore shown in the study that available theory is able to accurately predict the performance of an upward facing solar air heater, either with or without water energy storage, as long as the equations are employed within their range of validity / AFRIKAANSE OPSOMMING:In die hierdie studie is daar ondersoek ingestel na die lewensvatbaarhied van son-energiestoring in water ten einde die tydperk van lugverhitting deur 'n son-Iugverwarmer te verleng. 'n Sistematiese prasedure is gevolg waardeur daar aanvanklik 'n aantal eksperimente op 'n son-Iugverwarmer uitgevoer is am sodoende die eienskappe van so 'n lugverhiUingstelsel, sander energie storing, te vekry. Die resultate het getoon dat 'n toename in die massavloei tempo van die lug lei tot 'n toename in die kollektor effektiwiteit van die stelsel, maar terselfdetyd lei tot 'n afname in die temperatuur styging in die kollektor. Met die eienskappe van die lugverwarmingstelsel bekend, is daar voorts 'n aantal dag- en nag-eksperimente uitgevoer op 'n plastiek bedekte watertenk am die storing en vryselling van termiese energie deur die watertenk te kwantifiseer. Die resultate het daarap gedui dat die plastiek bedekte watertenk nie net beide 'n goeie kollektor en stoor medium vir son-energie is nie, maar oak dat dit 'n ideale bran van termiese energie vir 'n lugverwarmingstelsel tydens die nag is. Met inagname van die vorige resultate, is daar dan 'n aantal plastiek bedekte watertenks in die apparaat geinstalleer, en 'n aantal dag- en nag-eksperimente is uitgevoer. Die dageksperimente het getoon dat die die nuwe lugverwarmer met water energie storing dieselfde eienskappe toon ten opsigte van die kollektor effektiwiteit as die oorspronkilke son-Iugverwarmer. Tog, as gevolg van die laer absoberende plaat temperature was die temperatuur toename in die kollektor heelwat laer. In kontras hiermee dui die nagresultate aan dat die plastiek bedekte watertenks nie net die vermoe het am die tydperk van lugverwarming te verleng nie, maar oak dat die lug tempertuur, afhangende van die massavloei tempo van die lug, met tussen 1.5 en 7.5 °C verhoog kan word. Die studie het laastens oak getoon dat dit moontlik is am met behulp van beskikbare teorie die temperatuur toename in die kollektor van 'n son-Iugverwarmer met of sander water energie storing, akkuraat te voorspel, mits die vergelykings binne hul geldige gebiede gebruik word.

No description available.

Double diffusive phenomena occur in many natural systems and in a variety of engineering applications, such as solar ponds. In a solar pond, the erosion of gradient zone due to convection and diffusion is the main cause of inefficiency and hence, requires lot of maintenance. In this thesis, control of erosion of the gradient zone in a solar pond situation has been studied through experiments and transient numerical simulations. A laboratory solar pond was setup in a tank of size 19cm X 19cm X 19cm, and was heated from below. A polymer additive, Carboxy Methyl Cellulose (CMC) was used to increase the viscosity of the working fluid. With 0.01% CMC, viscosity enhancement of the working fluid by 25 to 30 times was achieved, without changing any other properties. The transient momentum, energy and species conservation equations along with continuity equation were solved numerically, using the SIMPLER algorithm with 2 mm grid spacing. The experiments conducted with the addition of CMC, showed delays in the onset of convection and reduced erosion of the gradient zone. The erosion rates obtained from the numerical simulations agreed with the experimental observation. The impact of viscosity on the onset of convection, kinetic energy, convection pattern, frequency of bursts and erosion rate of the gradient zone, were simulated. Numerical simulations revealed that, there is a nonlinear relationship between the viscosity and erosion rate of the gradient zone. Increase in viscosity by a factor of 15 reduced the erosion of gradient zone completely, indicating the dominant role played by Turbulent entrainment. The present work indicates that the control of erosion of gradient zone in solar pond using the polymer additive shows lot of promise. The use of the polymer additive as a method to increase viscosity will lower the maintenance costs and, increase the reliability and efficiency of solar ponds, with less than 5% increase in the initial cost.