Marine Engine/ Ship Propulsion System Simulation Gerasimos Theotokatos Department of Naval Architecture, Ocean & Marine Engineering University of Strathclyde November 2015
SIMULATION OF MARINE DIESEL ENGINE Understanding of the physical processes Investigating the interaction between the subsystems Initial testing of alternative design options Examining circumstances with high risk in installation integrity
SIMULATION TOOLS Transfer function models development of control schemes Mean value models fast transient response estimation engine control system design process Zero or One-Dimensional Models more detailed modelling of engine components performance prediction, transient response studies 3-D models (FEM, CFD) investigation, optimization of components design
Recommended reading 1. Internal Combustion Engine Fundamentals, John B Heywood. 2. G.P. Merker, Ch. Schwarz, G. Stiesch, F. Otto, Simulating Combustion - Simulation of combustion and pollutant formation for engine-development, 2006 3. Theotokatos G., (2010), On the Cycle Mean Value Modelling of Large Two- Stroke Marine Diesel Engine, Proceedings of the Institution of Mechanical Engineers, Part M, Journal of Engineering for the Maritime Environment, Vol. 224, No M3, pp. 193-205. 4. Theotokatos G., Tzelepis V. A computational study on the performance and emission parameters mapping of a ship propulsion system, Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, (2013).
MEAN VALUE MODELS Advantages: Engine modelling with acceptable accuracy Limited amount of input data Reasonable time of execution Drawbacks: Require data (experimental/simulation) for calibration Categories: Quasi-steady models (no mass accumulation is considered between the engine components) Modelling of engine receivers as open thermodynamic systems
MEAN VALUE ENGINE MODELLING (MVEM) Modelled engine components engine ambient to ambient via engine exhaust piping system compressor N TC turbine air cooler scavenging receiver exhaust receiver engine cylinders N E engine crankshaft
MVEM APROACH Angular momentum conservation dne 30( shqe QP ) dt ( I I I ) E sh P dntc 30( QT QC ) dt I TC Engine scavenging and exhaust receivers are modelled as open thermodynamic systems dm dt m m / in out ht in in out out v dt / dt Q m h m h udm / dt / mc p mrt / V 6 non-linear first order differential equations
MVEM IMPLEMENTED in MATLAB/SIMULINK Modular construction using Elements Flow controllers (compressor, turbine, engine cylinders) Flow receivers (engine receivers) Mechanical elements (engine crankshaft, T/C shaft) Fixed fluid (ambient), Propeller, Engine governor, Nord schedule engpar To Workspace PID governor FR Nord Neng pscav Nord schedule time fixed flluid ambient OUT_FF compressor INP_u OUT_u Ntc Qcomp INP_d OUT_d Sum_in OUT Sum_out Open Thermodynamic Systemscavenging receiver engine cylinders INP_u OUT_u FR OUT_shaft Neng INP_d OUT_d OUT_u Sum_in OUT_d Sum_out Open Thermodynamic turbine Systemexhaust receiver INP_u OUT_u Ntc Qturb INP_d OUT_d OUT_FF fixed fluid exhaust ambient T1 Q_comp N_tc Q_turb T/C shaft Engine crankshaft INP_eng Neng INP_load Neng OUT propeller T2
Simulation examples
MVEM modelling- Validation MAN Diesel & Turbo 12K98ME-C engine
2-s marine engine slow steaming operation Blower activation vs. T/C cut-out MAN Diesel & Turbo 12K98ME-C engine
SIMULATION RESULTS MAN Diesel & Turbo 9K90MC engine 1.2 100 engine torque (knm) rack position (-) 1 0.8 0.6 reference model 1 model 2 0.4 0 10 20 30 40 50 60 70 80 90 100 time (s) 5000 4000 3000 reference model 1 model 2 2000 0 10 20 30 40 50 60 time (s) 70 80 90 100 4 scav. receiver pressure (bar) 3 2 reference model 1 model 2 1 0 10 20 30 40 50 60 70 80 90 100 time (s) T/C speed (rpm) engine speed (rpm) exh. receiver temperature (K) 90 80 70 reference model 1 model 2 60 0 10 20 30 40 50 60 70 80 90 100 time (s) 12000 10000 8000 reference model 1 model 2 6000 0 10 20 30 40 50 60 70 80 90 100 1000 time (s) reference 800 600 model 1 model 2 400 0 10 20 30 40 50 60 time (s) 70 80 90 100 Comparison of the two modelling approaches results for a fast engine transient run of 100 s - ordered speed changes 94 rpm 69 rpm 94 rpm
SIMULATION RESULTS Comparison of two modelling approaches results for a slow engine transient of 500 s ordered speed changes: 94 rpm 69 rpm 94 rpm engine speed (rpm) 100 95 90 85 80 75 model 1 model 2 T/C speed (rpm) 11500 11000 10500 10000 9500 9000 8500 model 1 model 2 scav. receiver pressure (bar) 70 0 50 100 150 200 250 300 350 400 450 500 time (s) 4 model 1 3.5 3 2.5 2 model 2 1.5 0 50 100 150 200 250 300 350 400 450 500 time (s) exh. receiver temperature (K) 8000 0 50 100 150 200 250 300 350 400 450 500 time (s) 800 model 1 750 model 2 700 650 600 550 500 0 50 100 150 200 250 300 350 400 450 500 time (s)
0-D ENGINE SIMULATION Thermodynamic / Control Volume Type Basic Engineering Elements Flow Receivers ( cylinders, plenums ) Flow Controllers (valves, heat exchangers, compressors, turbines ) Mechanical Elements (crankshaft, shafts, loads) Turbocharger Intercooler Gas Exchange Governor Electronic PID Propeller Torque Demand Fuel Injection Friction Scavenging Combustion Heat Transfer Engine/propeller Dynamics
0-D ENGINE SIMULATION in MATLAB/Simulink
0-D SIMULATION OF A LARGE TWO- STROKE DIESEL ENGINE Engine Parameters Bore 900 mm Stroke 2550 mm Number of cylinders 9 Brake Power (MCR) 41130 kw Engine speed (MCR) 94 rpm bmep (MCR) 18 bar bsfc (L1) 173 g/kwh Turbocharger units 3 ABB 714
TURBOSHAFT 3 TURBOSHAFT 2 TURBOSHAFT 1 MAN B&W 9K90MC ENGINE SIMULATION EXHAUST RECEIVER TURB. 1 EX.GAS TURB. 2 EX.GAS TURB. 3 EX.GAS EXHAUST VALVES 1 2 3 4 5 6 7 8 9 CYLINDERS 1 2 3 4 5 6 7 8 9 INLET PORTS 1 2 3 4 5 6 7 8 9 AIR AIR AIR SCAVENGING RECEIVER AIR COOLER 1 COMP. 1 AIR COOLER 2 COMP. 2 AIR COOLER 3 COMP. 3 Cylinders No. : 9 Bore : 900 mm Stroke : 2550 mm Compr. Ratio : 16.8 Turbochargers : 3 ABB VTR-714 Speed @ MCR : 94 rpm Brake Power @ MCR : 41200 kw (56000 BHP) BMEP @ MCR : 18 bar Boost pressure @ MCR : 3.6 bar
SIMULATION RESULTS vs. MEASURED DATA Engine: MAN B&W 9K90MC Ship: Containership / Length 280 m / 4600 TEU Operation: at MCR speed Rack Position (%) Boost Pres. (bar) Shaft Torque (knm) Eng. Speed (rpm) 90 88 86 84 82 80 3.15 3.10 3.05 3.00 2.95 2.90 3500 3400 3300 3200 3100 96.5 96.0 95.5 95.0 94.5 94.0 93.5 Measured Predicted 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Time (sec)
0-D ENGINE SIMULATION - Results MAN Diesel & Turbo 7K98MC engine
0-D ENGINE SIMULATION - Results 7K98MC engine
CFD models Design studies Geometry assembly Mesh generation Analysis Post-processing Results analysis and engineering review is always critical
Diesel CFD Combustion Simulation
Diesel CFD Combustion Simulation Measured vs Predicted NOx 3000 2500 Measured Vectis NOx [ppm] 2000 1500 1000 500 0-18 -16-14 -12-10 -8-6 -4-2 Start of Injection [CAdeg]
LNG fuel Zero SOx emissions 85% reduced NOx emissions 25-30% reduced CO2 emissions Particulate matter emissions eliminated
Dual Fuel marine engines Diesel mode Dual fuel mode with pilot fuel Engine characteristics MCR 8775 kw @ 514 rpm BMEP 20 bar Gas mode Diesel mode BSEC 7258 kj/kwh BSFC Pilot fuel 1.0 g/kwh 190 g/kwh Number of valves Cylinder configuration Turbocharger 2 inlet and 2 exhaust valves per cyl. 9 in-line 1 unit
Results for diesel mode and dual fuel mode operation
Results for diesel mode and dual fuel mode operation
Questions?