| 摘要 |
An exhaust pipe having an internal wall (3) surface which is provided with a catalytic layer (4) has a helical twist, the pitch of the twist being between 0.2 and 10 times the diameter (d) of the clear free flow central cross-section of the pipe. The pipe may be formed of one, two or more separate strips suitably bent and welded along their joining edges. The pipe may be of square cross-section or of clover-leaf shape and is surrounded by thermal insulation. <IMAGE> |
