Patent ID: 7395820

Claim:
A tubular jacket ( 3 ) for a parabolic trough collector, said parabolic trough collector comprising a parabolic mirror ( 1 ) having a focal point (F) and a normal axis (N) and a receiver tube ( 2 ) arranged at said focal point to receive solar radiation reflected from the parabolic mirror ( 1 ), said parabolic mirror ( 1 ) being arranged outside of said receiver tube ( 2 ) and said receiver tube ( 2 ) comprising the tubular jacket ( 3 ) and an absorber tube ( 4 ), said absorber tube being arranged inside the tubular jacket, wherein said tubular jacket ( 3 ) comprises a glass tube and structural elements ( 9 a , 9 b , 9 c , 9 d ), said structural elements ( 9 a , 9 b , 9 c , 9 d ) extend around said tubular jacket at least over respective angular ranges of 20° to 65° on opposite sides of said normal axis (N); whereby said structural elements focus sunlight that falls directly on the receiver tube ( 2 ) from the sun but which would otherwise be deflected away from the absorber tube without the presence of said structural elements as well as sunlight that is reflected from the parabolic mirror but which would otherwise not reach said absorber tube without the presence of said structural elements on said absorber tube ( 4 ).