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This paper introduces a novel design of an internal combustion engine heat transfer model within a comprehensive simulation environment. The modelling is based on a lumped mass parameters approach. The paper discusses an approach for a heat transfer model, implemented in MATLAB/SIMULINK, the coupling process and the physical interface. The methodology of implementing this model in a comprehensive simulation environment is presented. The calculation of the combustion process and the inner circuits for the water and oil loops, considered as boundary conditions for the Heat Transfer Model are performed using the 1D engine cycle simulation program BOOST i.e. the 1D cooling simulation program KULI. This results in a scalable and modular structure of the model, which in turn permits a flexible design of different engine types. In order to carry out a comprehensive thermal calculation, a coupled simulation with these three different models is performed.

The thermal management of cars and commercial vehicles has become increasingly complex in the last years. Sophisticated simulation tools assist the engineer in finding a suitable solution to the problem of making a good thermal management. But the possibilities of the available software are still limited, in particular it is often not possible to search for the best solution. In this paper we present new approaches that extend the possibilities of such programs, where special emphasis is put on the optimization of parameters. These approaches, embedded in an easy-to-use graphical user interface, mark a big step towards finding an optimal solution.

A comprehensive simulation method is presented for the optimization of vehicle warm-up. Sophisticated one dimensional simulation methods based on network theory are used for flow simulation to limit computation time and guarantee high simulation quality. Partial integration of three dimensional flow simulation methods help to improve accuracy. Simulation sub-models for the engine, the HVAC system, and the passenger cabin are combined to simulate the warm-up process of the vehicle. This functionality is implemented in a modern software tool named KULI to support the development engineer as good as possible. Steady state and transient simulation are used to optimize the warm-up behavior.

An efficient air-conditioning system is an important factor for the commercial success of an automotive product, because of the thermal comfort for the passengers being an important incentive for the purchaser. A simulation tool is presented that makes it possible to design and optimize A/C refrigerant circuits together with the engine cooling system in a very early stage of the design process. This tool is based on networks including the enhanced heat exchange theory which also takes into consideration refrigerant phase changes. A graphical user interface and predefined simulation models which are based on the respective geometry of the system components make it easy to create a virtual vehicle for mathematical analysis of the various heat and mass flows. High flexibility and short calculation time together with high accuracy enable the engineer to make efficient investigations.

Heat management must allow the adjustment of optimal operating temperatures of all components of a vehicle. A comprehensive simulation model (KULI) will contain all components relevant for heat management. This includes heat sources, heat exchangers, fans, etc. Main aspects of the simulation are flow and heat transfer analysis. Not only the engine cooling system can be covered with this simulation tool, also the air-conditioning circuit including phase changing models is a part of it (KULI AC). To fulfill the needs of integrating various software tools to an overall simulation cluster an interface to a fluid flow 1-dimensional software (FLOWMASTER) was developed. The use of 1- dimensional methods and mesh flow theory for modeling the underhood air flow of vehicles is very efficient method. For complex flow patterns however it is desirable to use CFD analysis.

This paper shows one example of cooling system, optimized by utilizing computer simulation in the early development stage. First, a numerical simulation is conducted to obtain the air flow rate through engine compartment room by the software “STREAM”. Second, ΔTw are calculated by the software “KULI”, developed by Steyr-Daimler-Puch AG, to evaluate the original cooling system. Third, the optimization of this system is conducted by the design of experiment for cost saving and weight reduction. The test value was well matched with the calculated one and CAE was confirmed to be very helpful for saving the proto-build cost and time period.