# Two Stroke Engine

 Symbol: Identifier: ShipEnergySystems.Engines.TwoStrokeEngine Version: 3.6 File: ShipEnergySystems.Engines.TwoStrokeEngine.mo Connectors: Signal Input stopEngine Fuel Connector fuelOil Exhaust Gas Connector exhaustGas Exhaust Gas Connector exhaustGasBypass Water Connector coolingWaterIn Water Connector coolingWaterOut Water Connector HTcoolingWaterIn Water Connector HTcoolingWaterOut Mechanical Connector shaft
 Simulation der Motoreneffizienz basierend auf Verlustkennlinien Verwendung der angeforderten Motorleistung zur Berechnung des Kraftstoffverbrauchs, der Kühlleistung, Konvektionsverluste und der Abgaswärme Berechnung des abgeführten Wärmestroms in den HT-und NT-Kühlwasserkreislauf Konvektionsverluste werden im Motorenraum als Wärmequelle berücksichtigt berücksichtigung des ausströmenden Abgases für weitere Berechnungen
 Simulation of engine efficiency based on characteristic curves The requested engine power is used as input for the calculation of fuel consumption, cooling demand, convection losses and exhaust gas properties Calculation of the resulting heat flow into the HT- and LT-cooling water Convection losses are considered as heat sources in the assigned engine room Consideration of outflowing exhaust gas flow for further calculations

## Description

The Two-Stroke Engine is a refinement of the simple engine and simulates engine performance based on characteristic curves. The requested engine power is used as an input for calculation of the required amount of fuel oil and the resulting heat flows into cooling water and the exhaust gas flow. The consumption is corrected according to the lower heating value of the fuel oil.

The fuel consumption is calculated based on the engine power and the characteristic curve of the specific fuel consumption under reference conditions and standard fuel at the test rig, with the correction of the energy content of the used fuel (lower heating value) compared to the fuel at the test rig:

The cooling heat flow QdotCooling is calculated with an energy balance over the whole component.

Figure 1: Sankey Diagram of the Two-Stroke Engine

The engine has two cooling flows:

• a high temperature flow (HT)
• a low temperature flow (LT)
• The cooling flow rate of each variable is defined as a percentage of QdotCooling. The percentage of QdotCooling is set with the curve PercentageCoolingCurve.

The outlet temperature of the high temperature cooling water is calculated with the cooling flow QdotCooling.JacketCooler. The cooling flow of the JacketCooler is defined with the curve PercentageCoolingCurve.

The outlet temperature of the low temperature cooling water is calculated with the cooling flow QdotCooling.ScavengeAirCooler and QdotCooling.OilCooler. The percentage heat going to the scavenge air cooler is defined in PercentageCoolingCurve, whereas the heat going to the oil cooler is defined as the remaining portion of QdotCooling not going to the jacket cooler or scavenge air cooler.

Figure 2: QdotCooling of the Two-Stroke Engine

The ports for the cooling water cycle can be turned on using useCoolantPorts. The cooling water flow resistance inside the engine is not considered. In the case that it is needed in the simulation, a flow resistance has to be added externally.

The type of fuel the engine uses can be selected using the parameter Fuel. The fuel flow connector can be enabled with useFuelPort if the engine receives fuel at a different state than parameterized in the fuel tank. Otherwise, the engine reads the fuel pressure and temperature from the fuel tank. In either case, the fuel consumption data is available as a result. The fuel consumption is automatically withdrawn from the fuel tank.

When the parameter useEngineRoom is true, the required combustion air is drawn from an engine room component. The engine is assigned to an engine room with its engineRoomID. The heat transfer from engine to engine room is implemented as fixed percentage of the MCR whenever the engine is running. When an engine room is not used, a parameter TEngineRoom is available to define the temperature of the incoming air.

If it is desired to use the exhaust gas for further calculations, a port for the outflowing exhaust gas can be turned on using the parameter useExhaustGasPort.