The invention discloses a groove type solar direct
stream heat collecting
pipe which is used for a solar thermal
power generation system. The heat collecting
pipe can directly receive solar focusing
radiation to heat working medium water in the
pipe so as to generate steam and comprises an absorption pipe, a glass casing pipe and connection devices at the two ends of the heat collecting pipe. A heat absorption pipe is composed of a stainless steel pipe, a selective absorption
coating on the surface of the outer wall of the heat absorption pipe and a filling structure in the heat absorption pipe. The filling structure is an annular
metal foam layer with an axial spiral groove, and the thickness of the layer gradually reduces in the flowing direction of a work medium. A vacuum layer is arranged between the absorption pipe and the glass casing pipe. The connection devices at the two ends of the heat collecting pipe are made of flanges and corrugate pipes. A glass-
metal sealing connecting opening is processed in a crumpling mode. According to the groove type solar direct
stream heat collecting pipe, on one hand, radial gas-liquid two-phase flow type reconstruction with gas inside and liquid outside in the absorption pipe is achieved, the fact that circumferential
heat stress distribution of the absorption pipe is uneven is changed, and the problem of induction invalidation of
heat stress is solved; on the other hand, local
residual stress in the heat sealed technology can be reduced, and the problem of invalidation of end portion sealing connecting of the glass casing pipe is solved. The groove type solar direct
stream heat collecting pipe can obviously improve the reliability and stability of the solar direct stream heat collecting pipe.