Abstract: A thermally devitrifiable sealing composition exhibiting a sealing temperature below about 420.degree. C. and compatibility with a glass having a linear coefficient of thermal expansion (0.degree.-300.degree. C.) of about 83.times.10.sup.-7 /.degree. C. consisting of about 4-10 parts by weight of particulate cordierite for each 100 parts by weight of a devitrifiable glass consisting essentially, expressed in parts by weight on the oxide basis as calculated from the batch, of about______________________________________ PbO 77.4 .+-. 2.0 ZnO 10.2 .+-. 1.0 B.sub.2 O.sub.3 8.9 .+-. 1.0 SiO.sub.2 2.6 .+-. 0.25 MgO 0.17 .+-. 0.10 BaO 0.22 .+-. 0.10 F 0.35 .+-. 0.

Abstract: A solar energy collector structure has been provided which comprises a plurality of at least partially evacuated tubular members arranged in a group lying in parallel axial alignment. Each tubular member is joined to a next adjacent tubular member of the group to form a self supporting structure having at least one enclosed flow channel defined by intersticies of tubular members so joined. An absorber surface, disposed in communication with the flow channel, intercepts and absorbs solar energy, which is carried by a working fluid in the heat exchange relation with the absorber surface.

Abstract: A solar energy collector structure has been provided which comprises a plurality of at least partially evacuated tubular members arranged in a group and closely packed in parallel axial alignment. The tubular members are joined together to form a tube sheet. A unitary insulating support structure having a recess therein is adapted to receive the tube sheet in tandem therewith, the tube sheet being sealed within the recess of the support structure along respective opposite lateral margins thereof to form a flow channel therebetween. The support structure has headers integrally formed therewith and includes means for providing flow communication with the flow channel. An absorber, disposed behind the tube sheet, in communication with the flow channel, intercepts and absorbs solar energy, which by heat transfer is carried off by a working fluid in heat exchange relation with the absorber.