| abstract |
The disclosure relates to a modular form of solar energy collector apparatus in which several double-wall glass tube collectors, each with vacuum jacket, depend from opposite sides of an elongated manifold. The manifold includes split halves of foamed polymer insulation and rigid fiberglass reinforced skin thereon, assembled about closed-looped, serpentine liquid carrying tubes preferably of metal or glass in U-tube configurations depending from the manifold halves and extending into the larger double-walled glass tubes, the serpentine tube being connected, respectively, into inlet and outlet header pipes. The interior chamber of the collector tubes is closed by the manifold, thereby enclosing a part of each U-tube branch of the serpentine in a non-turbulent air space. Solar energy collected on the absorber surface of the inner glass tube wall is transmitted to the U-tube and liquid therein. The U-tube within the collectors is blackened and non-reflecting. Principal heat transfer from absorber to U-tube is by radiation with some conduction and convection transfer. The heat transfer liquid is entirely within a closed circuit, which avoids leaks, reduces weight, and cycle time of the liquid is reduced to a fraction of other liquid systems. |