Performance of an array of compound parabolic concentrations with plain tubular receivers

Operational aspects for an array of four 1.27X-CPC troughs, connected in series, were evaluated using solar radiation to establish the characteristic performance curve. To produce the limbs of each concentrator, a carefully prepared master mold was fabricated from which castings of polyester resin/fiber glass were produced and made reflective with a film of aluminized acrylic laminate. Four different cases investigated included the array with and without an acrylic cover plate and provided with copper receiver tubes which were either oxidized or made black using a special treatment which increased the optical efficiency 7–10%. The experimental results obtained were used to generate efficiency vs Δt/G relationships. For each case, these relationships could be represented linearly with intercepts to yield optical efficiencies that ranged from 0.545 up to 0.695. The introduction of the cover plate, although decreasing the optical efficiency by 15%, served to suppress heat losses by a factor greater than two. This type of solar collector is suited for applications such as hot water generation, space conditioning, and moderate temperature process heat. Even though CPC collectors have been studied for more than 10 years, many new potential applications remain.