Thesis (Master)--İzmir Institute of Technology, İzmir, 2005 / Keywords: Solar energy plant, solar collectors, fresnel lens, spherical geometry, solar tracking system. Includes bibliographical references (leaves 113-114).

Thesis (Ph.D.)--University of Stellenbosch, 2002. / Bibliography. Also available via the Internet.

Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 69-70). Also available via Humboldt Digital Scholar.

This thesis investigates the use of heat pipes for removing heat from flat plate solar collectors and transferring the energy to air in a space heating system. Heat pipes are passive devices which are very efficient at transporting heat energy. They operate using a closed evaporation-condensation cycle. This thesis presents the fundamentals of flat plate collectors, heat pipes, and a set of parameters for evaluating a heat pipe flat collector. Also included are the results of this project and the recommendations for improvements.

The concept of achieving low cost (≈ $20/m²) and ultra low weight (5 kg/m²) for heliostats is explored theoretically and experimentally. The objective of this work is to significantly improve the cost and performance of the structure under concern, without sacrificing strength and efficiency. The focus is on an innovative design of stretched-membrane heliostats. A reflective membrane of thin film is supported by a taut fishnet structural membrane consisting of graphite fiber-polymer matrix composite. The reflective and structural membranes are attached to a ring frame made of wood. The nonlinear problem of stress-strain analysis is formulated and solved using the finite-element code NASTRAN. The analysis is done for loads which include the initial stretching of the film and structural membrane and the pressure load due to wind. The scope of the present work is limited to analyzing the structural deformation behavior of flat-plate heliostats and partial extension to parabolic and semi-hemispherical dish reflectors.

Based on constitutive equations of piezoelectricity and two-port modeling method, the models of piezoelectric materials are investigated. The equivalent circuit models of the piezoelectric element in the energy harvesting system are explored. It is found that there exists an optimal external impedance that gives the maximum output power. Experiments are conducted to verify the optimal impedance theory. / The energy storage devices in the piezoelectric energy harvesting system are analyzed. The charge/discharge efficiencies of the energy storage devices are mainly considered. Based on the analysis of the electric characteristics of the energy storage devices, we find the leakage resistances of the energy storage devices are the dominant factor that influences the charge/discharge efficiency in the piezoelectric energy harvesting system. A quick test method is proposed to experimentally study the charge/discharge efficiencies of the energy storage devices. The experimental results verify our findings. Adaptability, lifetime, and protection circuit of the energy storage devices are also discussed. It can be concluded that the supercapacitors are suitable and more attractive than the rechargeable batteries to store the energy in the piezoelectric energy harvesting system. / Two schemes of piezoelectric energy harvesting circuits are analyzed: one-stage and two-stage energy harvesting schemes. The efficiency of the two-stage harvesting scheme is found to be related to several factors including the energy storage device voltage. Analysis and experiments using one-stage energy harvesting circuit to harvest a varying excitation source are explored. The results show that one-stage energy harvesting scheme can achieve higher efficiency than the two-stage scheme towards a range of energy storage voltages. / Using piezoelectric elements to harvest energy from ambient vibration has been of great interest recently. Because the power harvested from the piezoelectric elements is relatively low, energy storage devices are needed to accumulate the energy for intermittent use and energy harvesting circuits are applied to transfer the electrical energy from the sources to the storage devices. Therefore, a piezoelectric energy harvesting system can be basically divided into three parts: the energy source, the energy harvesting circuit, and the energy storage device. These three parts are explored in this thesis. / Guan Mingjie. / "September 2006." / Adviser: Wei-Hsin Liao. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1822. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 123-128). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

The design of a point focus, distributed receiver solar power system is presented. It is shown that a two axis concentrator, with a two axis solar tracker and drive, has significant advantages over other possible optical systems. It is further shown that each concentrator should have its own optical receiver attached. A new dish and mount design is presented. This design provides a much stronger, lower cost dish. It further provides an easy way to attach a cheap drive system. The new mount is a gimbal, or cradle, in which the dish is mounted. The cradle provides a polar axis mount for the dish. The dish and cradle are very strong and will survive high winds in any orientation. Several other significant improvements to other parts of the solar energy collection system are presented. These include an improvement to the receiver cavity design, a thermal shield and secondary reflector to be added to the receiver, an improved steam output system for the receiver, a plumbing system that eliminates the need for flexible couplings in the water lines, and a water distribution system that eliminates nearly half of the thermal insulation needed on the pipes going through the collector array. Two economic optimizations are presented. The first analyses the return on investment for various dish spacings. The second analyses the cost per unit area of the concentrator dish and mount. It is found that the optimum dish diameter is ten meters and the optimum packing density in a conventional array is about 13%. / Graduation date: 1995

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1983. / Vita. Abstract. Includes bibliographical references (leaves 80-82). Also available via the Internet.

Unglazed transpired solar collectors (UTSCs) preheat makeup ventilation air for buildings, thereby reducing energy used for heating. The performance of the UTSC is dependent on the heat loss from the absorber plate, which is strongly affected by the wind speed. To date, correlations to determine UTSC heat loss are limited to flat or sinusoidal plate corrugations. In reality, trapezoidal corrugations have been added to UTSCs to provide them with structural stiffness. These corrugations prevent the attachment of the flow to the absorber plate and cause flow separation which increases the heat loss. In this study, a numerical simulation of a UTSC with trapezoidal shape corrugation has been performed to investigate the heat loss in the developing region due to wind on the UTSCs. It has been found that heat loss from new configuration is up to three times greater than the heat loss from a perforated flat absorber plate. A correlation of heat loss due to the wind speed and suction velocity was developed. This study also includes an evaluation of the effectiveness in the asymptotic region. In this case, wind speed had no effect. A correlation was derived in terms of suction velocity.

No description available.