# Heat Load Forecasting of Marine Diesel Engine Based on Long Short-Term Memory Network
## 3 Case Study
### Principle Analysis and Data Processing
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Number** & **Variable** & **Description** & **Unit** \\ \hline
1 & \(T\) & Exhaust temperature & \({}^{\circ}\)C \\
2 & \(T_{a1}\) & Cylinder scavenge box temperature & \({}^{\circ}\)C \\
3 & \(T_{e1}\) & Diesel engine inlet oil temperature & \({}^{\circ}\)C \\
4 & \(T_{e2}\) & lubricating oil outlet temperature & \({}^{\circ}\)C \\
5 & \(P_{o1}\) & Diesel inlet oil pressure & Mpa \\
6 & \(T_{o3}\) & Main engine inlet oil temperature & Mpa \\
7 & \(T_{w1}\) & High temperature cooling fresh water outlet temperature & \({}^{\circ}\)C \\
8 & \(P_{w1}\) & High temperature cooling fresh water inlet pressure & Mpa \\
9 & \(T_{w2}\) & Cylinder liner cooling water outlet temperature & \({}^{\circ}\)C \\
10 & \(T_{e2}\) & Pressurized air temperature after cooler & \({}^{\circ}\)C \\
11 & \(T_{e3}\) & Exhaust temperature before supercharger & \({}^{\circ}\)C \\
12 & \(T_{f1}\) & Fuel oil temperature at unit inlet & \({}^{\circ}\)C \\
13 & \(T_{e4}\) & Outlet temperature of cylinder piston cooling oil & \({}^{\circ}\)C \\
14 & \(P_{f1}\) & Fuel pressure after fuel filter & Mpa \\
15 & \(P_{f2}\) & Fuel inlet pressure of main engine & Mpa \\
16 & \(P_{w2}\) & Inlet pressure of cylinder liner cooling water & Mpa \\
17 & \(P_{c2}\) & Pressurizer inlet oil pressure & Mpa \\
18 & \(T_{a4}\) & Exhaust temperature after supercharger & \({}^{\circ}\)C \\
19 & \(N_{T}\) & Turbocharger speed & rpm \\
20 & \(P_{a1}\) & Exhaust valve air pressure & Mpa \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Initial Variables. Figure 4: Heat map of the correlation matrix. the combustion chamber is determined by the outlet temperature of the cylinder liner cooling water, thereby indicating its sensitivity to changes in the exhaust temperature. The cylinder liner cooling water inlet pressure and the sweep box temperature are important factors affecting the exhaust temperature. Six variables with correlations higher than 0.5 are derived. The significance of their \(p\)-values is below 0.001. If the temperature of the pressurized air after the cooler is excessively high, then the exhaust temperature rises because the fresh gas entering the diesel engine is cooled by the cooler after being pressurized by the turbocharger into the combustion chamber. With the increase in supercharger speed, the increase in exhaust energy is affected by the increase in exhaust temperature. The reason is that the high-temperature exhaust gas from the combustion chamber flows through the supercharger. Another factor to be considered is the fuel pressure after the diesel filter. This refers to whether the faulty filter is reflected by the fuel pressure. Fuel quality and exhaust temperature can be affected by damaged filters. The three variables \(T_{a2}\), \(N_{T}\), and \(P_{f1}\) mentioned above are all important with a significance of less than 0.001, and the predictive variables will be affected, although their correlations are below 0.5, 0.1117, 0.1863, and 0.3574, respectively. Therefore, these factors are considered when deriving the final set of variables for the input model as follows. \[X_{t}^{*}=\left\{T_{a1},T_{02},T_{o3},T_{w2},T_{a2},T_{a4},P_{f1},P_{w2},N_{T}\right\}\]