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Improvement of solar thermal plant efficiency by the use of secondary concentrators
Date Issued
01-01-2018
Author(s)
Sundararajan, T.
Indian Institute of Technology, Madras
Balaji, Shanmugapriya
Chaitanya Prasad, G. S.
Abstract
A solar collector field based on linear Fresnel reflectors has been set up with support from the Department of Science and Technology, Government of India. Fresnel mirrors coupled with secondary concentrator are employed to focus solar radiation on a coated stainless steel receiver tube of 70 mm diameter. The collector system directly generates superheated steam at about 45 bar and 400oC. The receiver tube is covered with borosilicate glass, with the annular space evacuated to reduce heat losses. Theoretical studies have been carried out to optimize the secondary concentrator profile and to assess the heat losses from the solar collector. Compound-parabolic, trapezoidal and segmented- parabolic configurations are considered for the secondary concentrator. It is shown that the segmented parabolic configuration can provide high optical efficiency as well as nearly uniform flux distribution on the receiver tube. Evacuation of the annular space between the absorber tube and the glass cover, significantly reduces heat losses and improves the temperature distribution within the absorber.
Volume
2018-August