**Appendix B**

### *Calibration of NOx and HC Emissions Models*

The coefficients *aem* ~ *eem* (*aNOx* ~ *eNOx* and *aHC* ~ *eHC*) in the NOx and HC emissions models in Equation (5) are constants which can be determined by engine test data using the least square fitting method. The test data provided in the technical file of the engine EIAPP (Engine International Air Pollution Prevention) certificate has been used for modelling the NOx and HC emissions as well as the fuel consumption. When calibrating the engine fuel consumption model and emissions model, the engine test data come from the same operating points (i.e., 25%, 50%, 75%, 100% of rated engine load), which are selected along both the generator curve (E2 cycle) and the propeller curve (E3 cycle). However, the engine installed on the benchmark chemical tanker has been tested only for E2 cycle rather than E3 cycle due to the installed controllable pitch propeller. So, the test data for E3 cycle is obtained based on the mean value of the E3 cycle test data of the other four engines from the same engine family. "The mean value of data of different engines is taken in the following way, firstly, the mean value of data of different engines at nominal points are taken as the new nominal value of the engine; secondly, the mean values of part load percentages, i.e., the ratios of part load value to nominal value, along generator curve (E2 cycle) and propeller curve (E3 cycle) of different engines are taken as the part load percentages of the engine along generator curve and propeller curve, respectively [41]." Note that the specific HC emission data at the point of 75% nominal power of the E2 cycle is believed too high (0.42g/kWh) to be reasonable compared to the data of the other points and there is no physical explanation for the measurement that lies so far outside the line that connects the other data points. Therefore, it is corrected (as a rule of thumb) to a lower value (0.30g/kWh) as shown in Figure A2b to make the trend smoother and the fitting results more acceptable in spite of the fact that we only have E2 cycle data of one two-stroke diesel engine. The modelling result of the NOx and HC emissions of the main engine are shown in Tables A1 and A2, Figures A1 and A2.

<sup>Φ</sup>*HC,nom* **(g**/**s)** **Nominal Parameters**

> *Meng,nom* **(kNm)**


**Table A1.** Coefficients of NOx emission model of main engine.

**Table A2.** Coefficients of HC emission model of main engine.

*aHC*

*neng,nom* **(rpm)**  **Coe**ffi**cients**

> *cHC*

*dHC*

*eHC*

*bHC*

**FigureA2.**HC

The calibrated coefficients of the engine torque model, NOx and HC emissions model of the auxiliary engine, are shown in Tables A3–A5. The modelling results of the fuel consumption and emissions of both the main engine and auxiliary engines are shown in Figures A3 and A4.

(**a**) HC emission flow (**b**) Specific HC emission flow

 emission.


**Table A3.** Coefficients of engine torque model of auxiliary engine.

**Table A4.** Coefficients of NOx emission model of auxiliary engine.


**Table A5.** Coefficients of HC emission model of auxiliary engine.


**Figure A4.** Specific NOx and HC emissions of main engine and auxiliary engines.
