Items in cart [1] Questions? Call 888-624-8373

PAPERBACK list:$19.00 Web:$17.10 add to cart PDF BOOK your price: $15.00 add to cart Rights & Permissions Free Resources PDF EXECUTIVE SUMMARY Display this book on your site! Related Titles The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs Potential Applications of Concentrated Solar Energy: Proceedings of a Workshop Other Related Titles Potential Applications of Concentrated Solar Photons (1991) Commission on Engineering and Technical Systems (CETS) Web Search Builder Use this book's key terms to search within this book, across our collection, or across the Web. Skim This Chapter Skim this chapter and use this chapter's key terms to search within this book. Reference Finder Paste in your own text to find books that relate to your topic. Page 64   E-mail  Facebook  Digg  Stumble  Twitter More The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. APPENDIX D Intensity Influence The photocatalytic process at a TiO2 particle can be schematically represented in a simplified reaction scheme as: The actual reaction mechanism is more complicated and can involve a number of intermediates, such as hydroxyl radicals species adsorbed on the TiO2 surface, radicals, and radical ions. A summary of literature and Solar Energy Research Institute data [1] for the effect of intensity [irradiance (photons/area-time)] on the photocatalyzed rate of oxidation indicates that at or above I sun near-ultraviolet equivalence, the reaction rate varies as the square root of intensity. This square root dependence can be rationalized by the increased importance of processes like e-h+ recombination [Eq. (4)] and the reaction of photogenerated e- and h+ with intermediates. A collector also brings a reflectance loss. The impact of these two phenomena on the achievable rate is now estimated (see Figure D-1). A. Photon Rate Arriving at Catalyst i. Plate: (direct + diffuse)(area) = (Id + 0.25Id)(1.0) = 1.25 Id (photons/time) ii. Concentrator: (direct)(collector x-section) + (diffuse)(tube x-section) (0.8 Id)(1.0) + (0.25Id)(0.1) (reflectance = 0.8) = 0.825Id Page 64 Front Matter (R1-R10) Executive Summary (1-4) 1 Introduction (5-10) 2 Review and Evaluation of Various Application Areas (11-47) 3 Organization, Technology Transfer, Program Direction, and Institutional Issues (48-50) 4 Conclusions and Recommendations (51-54) Appendix A: Statement of Task (55-56) Appendix B: Committee Meetings and Activities (57-61) Appendix C: List of European Visits (62-63) Appendix D: Intensity Influence (64-66) Appendix E: Pressure Dependence of Photochemical Reactions (67-68) Appendix F: Knowledge Base and Status of Technology of Solar Fuels (69-79)

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 64
Potential Applications of Concentrated Solar Photons APPENDIX D Intensity Influence The photocatalytic process at a TiO2 particle can be schematically represented in a simplified reaction scheme as: The actual reaction mechanism is more complicated and can involve a number of intermediates, such as hydroxyl radicals species adsorbed on the TiO2 surface, radicals, and radical ions. A summary of literature and Solar Energy Research Institute data [1] for the effect of intensity [irradiance (photons/area-time)] on the photocatalyzed rate of oxidation indicates that at or above I sun near-ultraviolet equivalence, the reaction rate varies as the square root of intensity. This square root dependence can be rationalized by the increased importance of processes like e-h+ recombination [Eq. (4)] and the reaction of photogenerated e- and h+ with intermediates. A collector also brings a reflectance loss. The impact of these two phenomena on the achievable rate is now estimated (see Figure D-1). A. Photon Rate Arriving at Catalyst i. Plate: (direct + diffuse)(area) = (Id + 0.25Id)(1.0) = 1.25 Id (photons/time) ii. Concentrator: (direct)(collector x-section) + (diffuse)(tube x-section) (0.8 Id)(1.0) + (0.25Id)(0.1) (reflectance = 0.8) = 0.825Id

OCR for page 65
Potential Applications of Concentrated Solar Photons FIGURE D-1 Illustration of calculation for configurations and concentrator. B. Rate Loss Let PR = photon rate RA = reactor area Since intensity I = PR/RA and rate per unit area varies as the square root of I, Rate = (rate per area)(area)

OCR for page 66
Potential Applications of Concentrated Solar Photons REFERENCE 1. Turchi, C., and Ollis, D.F. J. Catal. 119, 483 (1989).

Representative terms from entire chapter:

intensity potential