*2.1. Engine Test Bed Installation*

The engine test bed is a MAN4L 20/27 diesel engine, which is a commonly used medium speed, direct injection marine diesel engine. The general data of the engine are listed in Table 1.


**Table 1.** The dimensions of engine used in the model.

Figure 1 illustrates the engine test bed layout, which is installed in the laboratory with a hydraulic dynamometer for applying the engine load. The pressure sensors with a water cooling system are arranged in the cylinder head of each cylinder. Due to the two in-cylinder pressure sensors using one cooling tubule, in the two red circles, there are two pressure sensors mounted in each circle. There are also inlet receiver pressure and temperature, pressure and temperature before turbine, fuel consumption measurements, etc. Together with these measurements, the engine main performance parameters can be obtained to investigate the engine combustion process.

**Figure 1.** Engine test bed: (**a**) Overview of the test bed; (**b**) the in-cylinder pressure sensor installation in the test bed (the red circle).
