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Optical properties of V-trough concentrators

Abstract

A new approach to study the optical behavior of V-trough concentrators is developed, based on the use of three characteristic angles defining the appearance, disappearance and return to the outside space of the cavity of a reflection mode. The probability of occurrence of a given number of reflections for beam radiation is determined as a function of these angles and the optical efficiency calculated. It is shown that the optical efficiency can be approximated by a function of two parameters, the angular acceptance function, T, and the mean number of reflections, n, as T * p{sup n/T}. Deviations between exact and approximate optical efficiency increase as n increases or as p decreases. For troughs with C ≤ 2.5 the maximal error for beam radiation is 3.4% for p ≥ 0.8 (8.3% for p ≥ 0.7). For diffuse radiation the maximal error is less than 2% for configurations whose optical efficiency is above 0.6. A further simplification was introduced to obtain the optical efficiency for diffuse radiation, approximating T by an analytical expression and n by an empirical linear function of the inverse of the vertex angle. Results accurate up to 5% for p = 0.8, were obtained. Increasing the concentration  More>>
Authors:
Fraidenraich, N.; [1]  Almeida, G. J.
  1. Universidade Federal de Pernambuco, Recife, PE Brasil (Brazil)
Publication Date:
Jul 01, 1991
Product Type:
Journal Article
Resource Relation:
Journal Name: Solar energy; Journal Volume: 47; Journal Issue: 3; Other Information: FAO/AGRIS record; ARN: US9143490; Country of input: International Atomic Energy Agency (IAEA)
Subject:
14 SOLAR ENERGY; CONCENTRATION RATIO; CONCENTRATORS; ELECTRICAL EQUIPMENT; ENERGY TRANSFER; OPTICAL PROPERTIES; PHOTOVOLTAIC CELLS; SOLAR ENERGY
OSTI ID:
22342452
Country of Origin:
FAO
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0038-092X; TRN: XF15A1178048773
Availability:
Available on-line: http://www.physics.arizona.edu/~cronin/Solar/References/Solar%20Concentrator%20Models/V%20Trough/Fraidenraich_1991_Solar-Energy.pdf
Submitting Site:
INIS
Size:
page(s) 147-155
Announcement Date:
Jun 19, 2015

Citation Formats

Fraidenraich, N., and Almeida, G. J. Optical properties of V-trough concentrators. FAO: N. p., 1991. Web. doi:10.1016/0038-092X(91)90073-6.
Fraidenraich, N., & Almeida, G. J. Optical properties of V-trough concentrators. FAO. doi:10.1016/0038-092X(91)90073-6.
Fraidenraich, N., and Almeida, G. J. 1991. "Optical properties of V-trough concentrators." FAO. doi:10.1016/0038-092X(91)90073-6. https://www.osti.gov/servlets/purl/10.1016/0038-092X(91)90073-6.
@misc{etde_22342452,
title = {Optical properties of V-trough concentrators}
author = {Fraidenraich, N., and Almeida, G. J.}
abstractNote = {A new approach to study the optical behavior of V-trough concentrators is developed, based on the use of three characteristic angles defining the appearance, disappearance and return to the outside space of the cavity of a reflection mode. The probability of occurrence of a given number of reflections for beam radiation is determined as a function of these angles and the optical efficiency calculated. It is shown that the optical efficiency can be approximated by a function of two parameters, the angular acceptance function, T, and the mean number of reflections, n, as T * p{sup n/T}. Deviations between exact and approximate optical efficiency increase as n increases or as p decreases. For troughs with C ≤ 2.5 the maximal error for beam radiation is 3.4% for p ≥ 0.8 (8.3% for p ≥ 0.7). For diffuse radiation the maximal error is less than 2% for configurations whose optical efficiency is above 0.6. A further simplification was introduced to obtain the optical efficiency for diffuse radiation, approximating T by an analytical expression and n by an empirical linear function of the inverse of the vertex angle. Results accurate up to 5% for p = 0.8, were obtained. Increasing the concentration ratio, C, from 1.5 to 2.5 for a vertex angle being one third of the acceptance angle, decreased the optical efficiency from 0.74 to 0.59, for p = 0.8. For a given C, the dependence of the optical efficiency on the vertex angle is rather weak, suggesting that large trough angles might be favoured by cost-benefit analysis. (author)}
doi = {10.1016/0038-092X(91)90073-6}
journal = {Solar energy}
issue = {3}
volume = {47}
journal type = {AC}
place = {FAO}
year = {1991}
month = {Jul}
}