ANNEX IIITEST PROCEDURE
Appendix 2ETC TEST CYCLE
3.EMISSIONS TEST RUN
At the manufacturers request, a dummy test may be run for conditioning of the engine and exhaust system before the measurement cycle.
NG and LPG fuelled engines shall be run-in using the ETC test. The engine shall be run over a minimum of two ETC cycles and until the CO emission measured over one ETC cycle does not exceed by more than 10 % the CO emission measured over the previous ETC cycle.
3.1.Preparation of the sampling filters (diesel engines only)
At least one hour before the test, each filter (pair) shall be placed in a closed, but unsealed Petri dish and placed in a weighing chamber for stabilisation. At the end of the stabilisation period, each filter (pair) shall be weighed and the tare weight shall be recorded. The filter (pair) shall then be stored in a closed Petri dish or sealed filter holder until needed for testing. If the filter (pair) is not used within eight hours of its removal from the weighing chamber, it must be conditioned and reweighed before use.
3.2.Installation of the measuring equipment
The instrumentation and sample probes shall be installed as required. The tailpipe shall be connected to the full flow dilution system.
3.3.Starting the dilution system and the engine
The dilution system and the engine shall be started and warmed up until all temperatures and pressures have stabilised at maximum power according to the recommendation of the manufacturer and good engineering practice.
3.4.Starting the particulate sampling system (diesel engines only)
The particulate sampling system shall be started and running on by-pass. The particulate background level of the dilution air may be determined by passing dilution air through the particulate filters. If filtered dilution air is used, one measurement may be done prior to or after the test. If the dilution air is not filtered, measurements at the beginning and at the end of the cycle, may be done, and the values averaged.
3.5.Adjustment of the full flow dilution system
The total diluted exhaust gas flow shall be set to eliminate water condensation in the system, and to obtain a maximum filter face temperature of 325 K (52 °C) or less (see Annex V, Section 2.3.1, DT).
3.6.Checking the analysers
The emission analysers shall be set at zero and spanned. If sample bags are used, they shall be evacuated.
3.7.Engine starting procedure
The stabilised engine shall be started according to the manufacturer's recommended starting procedure in the owner's manual, using either a production starter motor or the dynamometer. Optionally, the test may start directly from the engine preconditioning phase without shutting the engine off, when the engine has reached the idle speed.
3.8.Test cycle
3.8.1.Test sequence
The test sequence shall be started, if the engine has reached idle speed. The test shall be performed according to the reference cycle as set out in Section 2 of this Appendix. Engine speed and torque command set points shall be issued at 5 Hz (10 Hz recommended) or greater. Feedback engine speed and torque shall be recorded at least once every second during the test cycle, and the signals may be electronically filtered.
3.8.2.Analyser response
At the start of the engine or test sequence, if the cycle is started directly from the preconditioning, the measuring equipment shall be started, simultaneously:
start collecting or analysing dilution air;
start collecting or analysing diluted exhaust gas;
start measuring the amount of diluted exhaust gas (CVS) and the required temperatures and pressures;
start recording the feedback data of speed and torque of the dynamometer.
HC and NOx shall be measured continuously in the dilution tunnel with a frequency of 2 Hz. The average concentrations shall be determined by integrating the analyser signals over the test cycle. The system response time shall be no greater than 20 s, and shall be coordinated with CVS flow fluctuations and sampling time/test cycle offsets, if necessary. CO, CO2, NMHC and CH4 shall be determined by integration or by analysing the concentrations in the sample bag, collected over the cycle. The concentrations of the gaseous pollutants in the dilution air shall be determined by integration or by collecting into the background bag. All other values shall be recorded with a minimum of one measurement per second (1 Hz).
3.8.3.Particulate sampling (diesel engines only)
At the start of the engine or test sequence, if the cycle is started directly from the preconditioning, the particulate sampling system shall be switched from by-pass to collecting particulates.
If no flow compensation is used, the sample pump(s) shall be adjusted so that the flow rate through the particulate sample probe or transfer tube is maintained at a value within ± 5 % of the set flow rate. If flow compensation (i.e. proportional control of sample flow) is used, it must be demonstrated that the ratio of main tunnel flow to particulate sample flow does not change by more than ± 5 % of its set value (except for the first 10 seconds of sampling).
Note: For double dilution operation, sample flow is the net difference between the flow rate through the sample filters and the secondary dilution air flow rate.
The average temperature and pressure at the gas meter(s) or flow instrumentation inlet shall be recorded. If the set flow rate cannot be maintained over the complete cycle (within ± 5 %) because of high particulate loading on the filter, the test shall be voided. The test shall be rerun using a lower flow rate and/or a larger diameter filter.
3.8.4.Engine stalling
If the engine stalls anywhere during the test cycle, the engine shall be preconditioned and restarted, and the test repeated. If a malfunction occurs in any of the required test equipment during the test cycle, the test shall be voided.
3.8.5.Operations after test
At the completion of the test, the measurement of the diluted exhaust gas volume, the gas flow into the collecting bags and the particulate sample pump shall be stopped. For an integrating analyser system, sampling shall continue until system response times have elapsed.
The concentrations of the collecting bags, if used, shall be analysed as soon as possible and in any case not later than 20 minutes after the end of the test cycle.
After the emission test, a zero gas and the same span gas shall be used for re-checking the analysers. The test will be considered acceptable if the difference between the pre-test and post-test results is less than 2 % of the span gas value.
For diesel engines only, the particulate filters shall be returned to the weighing chamber no later than one hour after completion of the test and shall be conditioned in a closed, but unsealed Petri dish for at least one hour, but not more than 80 hours before weighing.
3.9.Verification of the test run
3.9.1.Data shift
To minimise the biasing effect of the time lag between the feedback and reference cycle values, the entire engine speed and torque feedback signal sequence may be advanced or delayed in time with respect to the reference speed and torque sequence. If the feedback signals are shifted, both speed and torque must be shifted the same amount in the same direction.
3.9.2.Calculation of the cycle work
The actual cycle work Wact (kWh) shall be calculated using each pair of engine feedback speed and torque values recorded. This shall be done after any feedback data shift has occurred, if this option is selected. The actual cycle work Wact is used for comparison to the reference cycle work Wref and for calculating the brake specific emissions (see Sections 4.4 and 5.2). The same methodology shall be used for integrating both reference and actual engine power. If values are to be determined between adjacent reference or adjacent measured values, linear interpolation shall be used.
In integrating the reference and actual cycle work, all negative torque values shall be set equal to zero and included. If integration is performed at a frequency of less than 5 Hertz, and if, during a given time segment, the torque value changes from positive to negative or negative to positive, the negative portion shall be computed and set equal to zero. The positive portion shall be included in the integrated value.
Wact shall be between - 15 % and + 5 % of Wref
3.9.3.Validation statistics of the test cycle
Linear regressions of the feedback values on the reference values shall be performed for speed, torque and power. This shall be done after any feedback data shift has occurred, if this option is selected. The method of least squares shall be used, with the best fit equation having the form:
where:
=
feedback (actual) value of speed (min-1), torque (Nm), or power (kW)
=
slope of the regression line
=
reference value of speed (min-1), torque (Nm), or power (kW)
=
y intercept of the regression line
The standard error of estimate (SE) of y on x and the coefficient of determination (r2) shall be calculated for each regression line.
It is recommended that this analysis be performed at 1 Hertz. All negative reference torque values and the associated feedback values shall be deleted from the calculation of cycle torque and power validation statistics. For a test to be considered valid, the criteria of Table 6 must be met.
Table 6
Regression line tolerances
| a Until 1 October 2005, the figures shown in brackets may be used for the type-approval testing of gas engines. The Commission shall report on the development of gas engine technology to confirm or modify the regression line tolerances applicable to gas engines given in this table. | |||
| Speed | Torque | Power | |
|---|---|---|---|
| Standard error of estimate (SE) of Y on X | Max 100 min–1 | Max 13 % (15 %)a of power map maximum engine torque | Max 8 % (15 %)a of power map maximum engine power |
| Slope of the regression line, m | 0,95 to 1,03 | 0,83–1,03 | 0,89–1,03 (0,83–1,03)a |
| Coefficient of determination, r2 | min 0,9700 (min 0,9500)a | min 0,8800 (min 0,7500)a | min 0,9100 (min 0,7500)a |
| Y intercept of the regression line, b | ± 50 min-1 | ± 20 Nm or ± 2 % (± 20 Nm or ± 3 %)a of max torque whichever is greater | ± 4 kW or ± 2 % (± 4 kW or ± 3 %)a of max power whichever is greater |
Point deletions from the regression analyses are permitted where noted in Table 7.
Table 7
Permitted point deletions from regression analysis
| Conditions | Points to be deleted |
|---|---|
| Full load and torque feedback < torque reference | Torque and/or power |
| No load, not an idle point, and torque feedback > torque reference | Torque and/or power |
| No load/closed throttle, idle point and speed > reference idle speed | Speed and/or power |