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The need to improve the engine performance and fuel consumption subject to ever more stringent emission standard spar the interest in the aspects of understanding and quantifying the thermal behavior of engine components and systems. Considering these points during the design of the vehicle thermal management system based on test would consume far too many resources. Fortunately, the simulation tools have become more prominent in the pre-prototype phase of the vehicle development process and they had reached a mature stage; where they can contribute successfully to a significant extend to meet the vehicle development targets. In this work, a methodology to model the Vehicle Thermal Management System (VTMS) in order to understand and quantify its behavior has been developed. The partial systems under consideration are: the gas circuit, the cooling circuit, the lubrication circuit and the thermal capacitance of the engine structure under the vehicle driving conditions.

The stricter fuel consumption and emission regulations put the worldwide carmakers and suppliers under pressure to develop more efficient thermal management systems. High engine efficiency, increased comfort requirements, and stringent emission regulations are examples of the political and public conflicting requirements. The coolant system of current vehicles is already limited on performance due to package and styling constraints. Therefore, any future incremental demands on the coolant system will need to be managed effectively so as to remain within these constraints. Simulation-based design and virtual prototyping can insure greater product performance and quality of both the time and cost required by traditional build-and-test approach for the development of the vehicle thermal management process and the development process in general.

In order to improve the accuracy of vehicle simulation under transient cycle conditions and thus predict performance and fuel consumption, consideration of the complete system engine/drivetrain/vehicle is necessary. The coupling of otherwise independent simulation programs is therefore necessary for the vehicle and engine. The description of thermally transient processes enables the calculation of the heat balance of the engine, which in turn enables the simulation of warming up operation. Through consideration of the engine warming up process, the quality of the prediction of fuel consumption and emissions is improved. The combination of the simulation programs CRUISE and BOOST to determine the engine heat balance has proven to be successful for the analysis of transient drive cycles.