Marine Engine/ Ship Propulsion System Simulation

Transcription

1 Marine Engine/ Ship Propulsion System Simulation Gerasimos Theotokatos Department of Naval Architecture, Ocean & Marine Engineering University of Strathclyde November 2015

2 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

3 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

4 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, 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 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).

5 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

6 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

7 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

8 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

9 Simulation examples

10 MVEM modelling- Validation MAN Diesel & Turbo 12K98ME-C engine

11 2-s marine engine slow steaming operation Blower activation vs. T/C cut-out MAN Diesel & Turbo 12K98ME-C engine

12 SIMULATION RESULTS MAN Diesel & Turbo 9K90MC engine engine torque (knm) rack position (-) reference model 1 model time (s) reference model 1 model time (s) scav. receiver pressure (bar) 3 2 reference model 1 model time (s) T/C speed (rpm) engine speed (rpm) exh. receiver temperature (K) reference model 1 model time (s) reference model 1 model time (s) reference model 1 model time (s) 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

13 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) model 1 model 2 T/C speed (rpm) model 1 model 2 scav. receiver pressure (bar) time (s) 4 model model time (s) exh. receiver temperature (K) time (s) 800 model model time (s)

14 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

15 0-D ENGINE SIMULATION in MATLAB/Simulink

16 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) kw Engine speed (MCR) 94 rpm bmep (MCR) 18 bar bsfc (L1) 173 g/kwh Turbocharger units 3 ABB 714

17 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 CYLINDERS INLET PORTS 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 MCR : 94 rpm Brake MCR : kw (56000 BHP) MCR : 18 bar Boost MCR : 3.6 bar

18 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) Measured Predicted Time (sec)

19 0-D ENGINE SIMULATION - Results MAN Diesel & Turbo 7K98MC engine

20 0-D ENGINE SIMULATION - Results 7K98MC engine

21 CFD models Design studies Geometry assembly Mesh generation Analysis Post-processing Results analysis and engineering review is always critical

22 Diesel CFD Combustion Simulation

23 Diesel CFD Combustion Simulation Measured vs Predicted NOx Measured Vectis NOx [ppm] Start of Injection [CAdeg]

24 LNG fuel Zero SOx emissions 85% reduced NOx emissions 25-30% reduced CO2 emissions Particulate matter emissions eliminated

25 Dual Fuel marine engines Diesel mode Dual fuel mode with pilot fuel Engine characteristics MCR 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

26 Results for diesel mode and dual fuel mode operation

27 Results for diesel mode and dual fuel mode operation

28 Questions?