4.4.5Guidelines for the Selection of an Engine Group
4.4.5.1 the engine group may be defined by basic characteristics and specifications in addition to the parameters defined in 4.3.8 for an engine family.
4.4.5.2 The following parameters and specifications must be common to engine within an engine group:
.1 bore and stroke dimensions
.2 method and design features of pressure charging and exhaust gas system.
- constant pressure
- pulsating system
.3 method of charge air cooling system,
- with/without charge air cooler
.4 design features of the combustion chamber that effect NOx emission.
.5 design feature of the fuel injection system, plunger and injection cam which may profile basic characteristics that effect NOx emission, and
.6 maximum rated power per cylinder at maximum rated speed. The permitted range of derating within the engine group shall be declared by the manufacturer and approved by the Administration.
4.4.5.3 Generally, if the parameters required by 4.4.5.2 are nor common so all engines within a prospective engine group, then those engines may not be considered as an engine group. However, an engine group may be accepted if only one of those parameters or specifications is not common for all of the engines within a prospective engine group provided the engine manufacturer or the ship owner ran, within the Technical File, prove to the Administration that sorts a transgression of that one parameter or specification would still result in all engines within the engine group complying with the NOx emission limits.
4.4.6Guidelines for Allowable Adjustment or Modification within an Engine Group
4.4.6.1 Minor adjustments and modifications in accordance with the engine group concept are allowed after pee-certification or final test bed measurement within an engine group upon agreement of the panics concerned and approval of the Administration, if:
.1 as inspection emission-relevant engine parameters and/or provisions of a ready means for verification as the engine and/or data provided by the engine manufacturer confirm that the adjusted or modified engine complies with the applicable NOx emission limits, The engine test bed results sin NOx emissions should be accepted as an option for verifying on-board adjustments or modifications to as engine within an engine group, or
.2 on-board measurement confirms that the adjusted sir modified engine complies with the applicable NOx emission limits.
MEPC 39/6/1
ANNEX
Page 19
4.4.6.2 Examples of adjustments and modification within an engine group that may be permitted, but are not limited to those described below:
.1 For on-board conditions, adjustment of;
- injection rinsing for compensation of fuel property differences,
- injection rinsing fur optimization of maximum cylinder pressure,
- fuel delivery differences between cylinders.
.2 For performance optimization, modification of:
- turbochanger,
- injection pump components,
- plunger specification
- delivery valve specification
- injection nozzles,
- cam profiles,
- intake and/or exhaust valve
- injection cam
- combustion chamber.
4.4.6.3 The abuse examples of modifications after a test-bed trial concern essential improvements of components or engine performance during the life of an engine. This is one of the main reasons for the existence of the engine group concept. The Administration, upon application. may accept the results from a demonstration test carried out on one engine, possibly a test engine, indicating the effects of the modifications on the NOx level which may be accepted for all engines within that engine group without requiring certification measurements on each engine of the group.
4.4.7 Guidelines for the Selection of the Parent Engine of an Engine Group
It is not always possible to select a parent engine from small volume production engines in the same way as the mass produced engines (engine family). The first engine ordered may be registered as the parent engine. The method used to select the parent engine to represent the engine group shall be agreed to and approved by the Administration (see 4.3.9).
Chapter 5 - PROCEDURES FOR NOx EMISSION MEASUREMENTS ON A TEST BED
5.1 GENERAL
5.8.1 This procedure shall be applied to every first certification sensing of a marine engine regardless of the location of that testing.
5.1.2 This chapter specifies the measurements and calculation methods for gaseous exhaust emissions from reciprocating internal combustion engines (RIC engines) under steady-state conditions, necessary for determining the average weighted value for the NOx exhaust gas emission.
5.1.3 Many of the procedures described below are detailed accounts of laboratory methods, since determining an emissions value requires performing a complex net of individual measurements, rather than obtaining a single measured value. Thus, the results obtained depend as much on the process of performing the measurements as they depend on the engine and test method.
