Heavy Duty Vehicle Engines

European Test Procedure

The steady state cycle (ESC) is used to prevent abnormally high emissions if an engine is made to operate at extreme conditions where emission controls may not be very effective. On the other hand, the transient cycle (ETC) represents the actual operating conditions and is better suited for the engines operating on alternative fuels or employing aftertreatment devices. For certification to Euro 3 standards, the conventional diesel engines are tested by the ESC only. However, the diesel engines with advanced emission control systems   such as    after-treatment devices and    the SI engines such as natural gas engines are tested by both the procedures. From the Euro 4 standards implemented in year 2005, all heavy-duty engines are tested by both the ESC and ETC test procedures.

ESC and ELR Tests

The ESC and ELR test procedures are shown in Figs 4.4 and 4.5. Weighting factors for the ESC test for each mode are also shown on Fig. 4.4.
The test is carried out at three engine speeds and idle. The test speeds are determined as shown on Fig 4.4. At each of the three speeds, emissions are measured at 25%, 50%, 75% and 100 % loads. To ensure that there are no abnormal operating conditions which could result in abnormally high emissions, testing agency is authorized to select three more modes as indicated.  The dynamic load response (ELR) test is carried out for smoke emissions. The engine is accelerated from 10% load to full load at maximum possible acceleration. In this way engine runs through the entire fuel/air ratios defined by the engine fuel management system.  Thus, smoke emission from the diesel engines is measured for the entire range of fuel delivery i.e. fuel-air ratios. Peak smokes emissions are compared with the permissible limits as specified in the standards.