Modeling load effect of marine diesel engines on cooling system operation

Abstract

The article provides analysis of the load effect of the marine internal combustion engines (ICE) on the tem-perature parameters of the water cooling system of ICEs equipped with L32-40 Vis diesel engines. In ICE cooling systems the drive motors of the pumps supplying the cooling water operate at a constant speed and provide a constant water supply. The thermal state of a marine diesel ICE is regulated by valves according to deviation of the actual temperature values of cooling water from the preset values. By closing or opening the water lines the valves change the proportion of cooling water flows of the external and internal circuits fed to the heat exchangers. There is implemented the principle of regulating the deviation of the main coordinate - the temperature of the cooling water. The influence of other factors on the operation of the system is taken into account with a delay. Modeling the operation of the high-temperature circuit of the cooling system of the main ship engine of the ferry was carried out using the simulator of the engine room TRANSAS TechSim 5000. There have been obtained graphical results of changing the cooling circuit water temperature with increased and decreased loads on diesel engines by changing the set speed with different initial and final values at a constant water temperature in the external cooling circuit. The graphs helped obtain numerical and qualitative indicators of transient processes (duration, oscillation, overshoot, final temperature values, etc.) for the different initial conditions - ranges of diesel load changes. The resulting graphical dependences are analyzed, conclusions about the modes of working out the disturbing influences by the cooling system, the parameters of transient processes and the features of the operation of the standard control system and the cooling system circuit of the main marine diesel engine in terms of ensuring optimal performance of the system are drawn. It has been inferred that the standard control system under some initial conditions does not provide the optimal parameters of transient processes.