CDL Thd-VKM: Integration of Vehicle and Engine Cycle Simulation

The simulation of the thermal behavior of internal combustion engines represents an important contribution to the engine development process. In particular the projection of the warm-up behavior constantly gains significance. In this work the lumped thermal capacitance method is applied for simulating the thermal behavior. The structure of the engine is represented as thermal network. Compared with the finite element method the number of elements (knots) is substantially reduced. The heat flows between the individual knots are computed from suitable heat transfer relations. The oil and coolant circuits as well as the heat transfer between solid and fluid are likewise considered. The transient thermal behaviour of the engine is described by applying the first law of thermodynamics to each node of the system. Links to a vehicle and an engine cycle simulation program allow the use of accurate boundary conditions for the simulation. Thermal networks were developed in different discretization levels, which differ by the number of lumped masses. The simulation results are compared to other calculation and experimental data for evaluating the quality of the models. Both stationary and transient engine conditions were simulated regarding temperature and fuel consumption. Finally several sample applications of the developed model are presented. Thereby, the effect of different measures on the warm-up behavior and the fuel consumption is examined.