| 摘要 |
An EGR cooler has tubes (3) and a shell (1) for enclosing the tubes (3). Cooling water (9) is supplied into and discharged from the shell (1) and exhaust gas (10) from a diesel engine is guided into each of the tubes (3) so as to conduct heat exchange of the exhaust gas (10) with the cooling water (9). An inner periphery of each of the tubes (3) is formed with spiral protrusions (12, 13) each having an inclination angle (&thetas;) in a range of 26 DEG -50 DEG to a plane perpendicular to an axis (x) of the tube (3). <IMAGE> |
