| 摘要 |
PROBLEM TO BE SOLVED: To exactly obtain NOx removal efficiency of a NOx removal device in an engine system including a cylinder bypass line even if a NOx concentration in exhaust gas diluted more by air than that at an outlet side of the NOx removal device is measured.SOLUTION: A part of intake air from an exhaust gas turbocharger to an engine is bypassed to a merging part that is placed downstream from a catalyst type NOx removal device in an exhaust gas passage. Both Nox concentration and O2 concentration at a side downstream from the merging part in the exhaust gas passage are detected, a converted NOx concentration at an outlet of the NOx removal device when an oxygen concentration in the exhaust gas is set to a certain standard oxygen concentration, is obtained and then, the converted NOx concentration at the outlet side of the NOx removal device is represented as NOx*o and the converted NOx concentration at the inlet side of the NOx removal device is represented as NOx*i and NOx removal efficiency is obtained by the following equation(i) NOx removal efficiency (%)={(NOx*i-NOx*o)/NOx*i}×100(i) |
