Award Date

December 2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Committee Member

Robert F. Boehm

Second Committee Member

Yi-Tung Chen

Third Committee Member

Woosoon Yim

Fourth Committee Member

Yahia Baghzouz

Fifth Committee Member

Rama Venkat

Number of Pages

82

Abstract

Most places on our planet receive an annual average radiation between 800-1000 W/m2. In the man-made world, this radiation is largely incident on stationary structures such as buildings, roads, monuments, bridges etc. Moreover, in the natural world also, there are large tracts of barren land which can be put to good use given their solar energy potential. The vision of the current research is to concentrate all this available solar energy to a more readily usable form. Therefore, stationary nonimaging solar concentrator technologies are sought after. This dissertation work is an exhaustive research on the nonimaging concentrating mechanisms with stationary applications in mind. Novel nonimaging concentrator designs have been proposed and verified through raytracing computer simulations. A possible coupling of the proposed nonimaging concentrators with passive solar tracking mechanism has also been discussed.

The effect of Fresnel reflection and total internal reflection (TIR) losses on the performance parameters and thereby, energy collection of refractive-type nonimaging solar concentrators has also been researched. A raytracing analysis has been carried out to illustrate the effects of Fresnel reflection and TIR losses on different types of stationary dielectric-filled nonimaging concentrators. The refractive index of a dielectric fill material determines the effective acceptance angle of a solid stationary nonimaging collector. Larger refractive indices yield larger acceptance angles and, thereby, larger energy collection. However, they also increase the Fresnel reflection losses. The relative benefit of increasing refractive index from an energy collection standpoint has also been assessed. This work is significant because it presents a realistic idea of the diurnal energy collection when a stationary concentrator is subjected to reflection losses. The work should be of interest to readers in the area of nonimaging optics especially when applied to stationary solar energy applications.

The application of novel design ideas to mitigate the energy losses and improve the collection efficiency has been discussed in detail. The use of anti-reflective coatings and the concept of stacked CPCs are the areas that have been explored in detail. Some truncated designs of solid nonimaging concentrators for stationary applications have also been investigated as a part of this research work. In short, this work will be found resourceful in stationary solar energy collection applications and the uses are endless, viz. building integration, stationary solar collector fields etc. Future work in the topic should investigate to solve the material constraints imposed to further improve the effectiveness of the proposed stationary solar collector designs.

Keywords

dielectric concentrators; diurnal energy collection; nonimaging optics; photonics for energy; refractive index; stacked CPC design

Disciplines

Mechanical Engineering | Oil, Gas, and Energy | Sustainability

Language

English


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