Compact linear Fresnel reflector solar thermal powerplants

This paper evaluates Compact Linear Fresnel Reflector (CLFR) concepts suita ble for large scale solar thermal electricity generation plants. in the CLF R, it is assumed that there will be many parallel linear receivers elevated on tower structures that are close enough for individual mirror rows to ha ve the option of directing reflected solar radiation to two alternative lin ear receivers on separate towers. This additional variable in reflector ori entation provides the means for much more densely packed arrays. Patterns o f alternating mirror inclination can be set up such that shading and blocki ng are almost eliminated while ground coverage is maximised. Preferred desi gns would also use secondary optics which will reduce tower height requirem ents. The avoidance of large mirror row spacings and receiver heights is an important cost issue in determining the cost of ground preparation, array substructure cost, tower structure cost, steam line thermal losses, and ste am line cost. The improved ability to use the Fresnel approach delivers the traditional benefits of such a system, namely small reflector size, low st ructural cast, fixed receiver position without moving joints, and noncylind rical receiver geometry. The modelled array also uses low emittance all-gla ss evacuated Dewar tubes as the receiver elements. Alternative versions of the basic CLFR concept that are evaluated include absorber orientation, abs orber structure, the use of secondary reflectors adjacent to the absorbers, reflector field configurations, mirror packing densities, and receiver hei ghts. A necessary requirement in this activity was the development of speci fic raytrace and thermal models to simulate the new concepts. (C) 2000 Else vier Science Ltd. All rights reserved.