## 1 Introduction
However, given the effectiveness of the application of exhaust gas treatment systems such as SCR (Selective Catalytic Reduction) and Scrubber, the main energy source in marine industry is still Heavy Fuel Oil (HFO). In reality, this choice is also a consequence of the fact that shipowners must guarantee an adequate return on investment, and the major contributors in the life cycle cost of a ship are precisely maintenance and fuel. Therefore, HFO is preferred because besides having the lowest cost among fuels, it is very available on the market, has a low sulfur content variant, and has a consolidated and branched distribution network. However, it should also be noted that the standards currently achieved by the main marine diesel engine manufacturers ensure that the conventional marine turbocharged diesel engines (TDEs) have the potential to further reduce their fuel consumption and their emissions, improving their energy efficiency. Therefore, monitoring and setting the performance of TDEs is vital: indeed, the efficiency of any onboard machinery is directly related to its performance in order to get an efficient combustion. Shipowners know very well that ensuring an efficient combustion reduces not only pollutant emissions but also fuel and maintenance costs. Conventionally, there are several ways to monitor the performance of a TDE: measuring the peak pressure by mechanical peak pressure gauge; indicator card measurement; digital pressure monitoring; intelligent combustion monitoring; monitoring of engine control parameters; engine parameters; log book monitoring; and engine emission evaluation. All these techniques, which are actually very effective, currently have the limit of providing for the offline processing of the data obtained in the monitoring and subsequent adjustment of the engine. However, numerous studies [8; 9; 10; 11; 12] have demonstrated the possibility of simulating engine operation with remarkable precision. The adoption of the Industry 4.0 paradigm by engine manufacturers has led the development of a new generation of products equipped with advanced automation systems [13]. These automation systems are made up of a dense network of sensors that allows the detection of performance data of the TDEs and a series of actuators that are able to adjust the functional parameters of most of the auxiliary devices, in order to make the TDE always work at a maximum of its possibilities. Unfortunately, the common current practice foresees that, especially when new TDEs are installed, the manufacturer controls the monitoring functions, and the data collected are exploited only for diagnostic and maintenance purposes. In this paper, a software tool that is capable of processing the in-live performance of TDEs is described. In particular, with reference to the main international standards, the tool instantly processes the data collected by the network of sensors installed on board, obtaining the engine performance data in-live and allowing the dynamic optimization of TDE operation. Particular attention was paid to writing the routine for the evaluation of air polluting emissions, because the latter can be significantly reduced in the first instance by acting on the combustion parameters and subsequently on the actuators that regulate the operation of both the SCR and Scrubber. Given the importance of determining the emissions, the tool calculates them by using two methods, the Air Nozzle and the Carbon Balance methods, both widely described below.