Vehicle thermal management: A model-based approach

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Vehicle thermal management: A model-based approach

Cipollone, Roberto / Villante, Carlo

Cooling system design has a crucial role in defining engine performance, operational limits and thermal comfort. Many further improvements with respect to the actual situation can be obtained through a more accurate control of an-board thermal needs. To this new interest the definition of new technical specifications must follow. The technical literature, however, seems not fully satisfying this need, not focusing on the influence of these technical specifications on system design, reliability and costs. In this paper the authors present a contribution in this direction, showing the capabilities of an active intelligent management of the engine cooling system. This can be obtained through different control strategies, strongly diversified for their cost-performance ratio. The potentiality of a model-based controller has been also investigated and compared with the correspondent closed-loop controller. The conclusions are: -maximum temperature of the engine metal parts must be limited to preserve materials and to avoid knocking phenomena; -temperature gradients must also be limited inside metal parts not to determine distortions during engine exercise; temperature oscillations during time must be limited to increase engine resistance to thermal fatigue; -metal parts warm-up time must be limited to reduce engine emissions and to enhance engine thermal efficiency lowering fuel consumption; -maximum lubricant temperature must be limited, as well as its temperature fluctuations stabilize lubricant properties; lubricant warm-up time must be shortened to limit the extension of insufficiently lubricated conditions; -temperature oscillations inside the cabin must be lowered to assure passenger comfort; -cabin warm-up (in winter) or cool-down (during summer) period must be also limited; -cabin air humidity has also to be controlled.