## 4 Experimental Validation  
### Experimental Platform  
An overview of the experimental platform is illustrated in Figure 11. This platform was designed and manufactured exactly according to the simulation model at a scale of 1:10. There were six diesel engine models in the experimental platform. In order to appropriately simulate the thermal behavior of the engines, the surface geometries and materials were exactly the same as the real diesel engines in the marine cabin. Controllable heating sources (see Figure 12a) were installed on the engine models to heat the engines. Figure 12b shows an engine thermal pack. Two axial flow ventilators (Model HF-100/125, as shown in Figure 12b) were used as the ventilation sources. A digital vortex flowmeter (Model DY110, see Figure 13a) was adopted to measure the air flow, and a thermal Infrared Imager (see Figure 13c) was used to collect the engine temperature. Figure 14 shows the distribution of temperature sensors, where 46 temperature sensors (Model Pt100) were installed. A temperature reader (see Figure 15a) was used to display the sensor measurements.  
\begin{table}
\begin{tabular}{c c c} \hline
**No.** & **Temperature Volumes (\(\geq\)50 \({}^{\circ}\)C)** & **Temperature Volumes (\(\geq\)55 \({}^{\circ}\)C)** \\ \hline (a) 30\% RH & 996.1 m\({}^{3}\) & 220.3 m\({}^{3}\) \\ (b) 50\% RH & 976.5 m\({}^{3}\) & 124.2 m\({}^{3}\) \\ (c) 70\% RH & 947.1 m\({}^{3}\) & 152.9 m\({}^{3}\) \\ (d) 90\% RH & 930.8 m\({}^{3}\) & 158.8 m\({}^{3}\) \\
**Without spray cooling** & **1214.8 m\({}^{3}\)** & **434.1 m\({}^{3}\)** \\ \hline \end{tabular}
\end{table}
Table 6: Isothermal areas of the high-temperature regions.  
Figure 11: Diagram and image of the experimental platform.  
Figure 14: Illustration of (**a**) distribution of temperature sensors, (**b**) sensor locations, and (**c**) a PT100 temperature sensor.  
Figure 12: Images of (**a**) heating sources and engine models, (**b**) engine thermal pack, and (**c**) axial flow ventilator.  
Figure 13: Images of (**a**) digital vortex flowmeter, (**b**) connection of vortex flowmeter and ventilator, and (**c**) thermal Infrared Imager.  
Figure 15b shows the voltage-controlled power source (Model TDGC\({}_{2}\)-10 KVA), which was used to control the heating sources in the experimental platform. A digital wattmeter (see Figure 15c) was used to calculate the heating power, and an intelligent pressure anemometer (Model JX-1000-1F, as shown in Figure 15d) was used to collect the pressure, air speed, and flow at the output vent.  
The reason for choosing a DY-100 digital vortex flowmeter is to address the uncertainty of the measurements, in particular the measurement of the flow rate of the flowing air. Thanks to low wind resistance, the DY-100 flowmeter is capable of measuring the flow rate with very high precision, in the range of [0 3000 m\({}^{3}\)/h]. In addition, a specially designed structure was fabricated to reduce the effect of measurement uncertainty, as shown in Figures 13b and 16. The tapered tubes were employed at the two ends of the flowmeter to make sure of stable air flow. The length of the flow tube connected to the flowmeter was five times that of the tube diameter, which can decrease the uncertainty of the sensor measurements.  
Figure 16: Installation of the DY-100 digital vortex flowmeter.  
Figure 15: Images of (**a**) temperature display, (**b**) voltage-controlled power source, (**c**) digital wattmeter and (**d**) intelligent pressure anemoscope.