Contribution à l'optimisation de la puissance thermique disponible en régime transitoire pour le confort dans une automobile

High efficiency automotive engines have been developed to cope with the fuel price rising and air pollution standards evolution. High efficiency combustion leads to reduced engine capacity and fuel consumption for the same performance, but also contributes decreasing the available thermal power for the car cabin heating system. Car parts manufacturers so propose additional heating systems to compensate for the thermal deficit and ensure passengers’ confort during thermal transient periods (cold start, urban driving). The goal of this work is to develop a new additional heating system using heat recovery on admission and exhaust lines. A zero-dimensional combustion model is developed for engine performance and emissions prediction. A thermal simulation software using nodal method to describe heat transfer between the engine components (water loop, oil loop, engine block. . . ) is coupled with the combustion model. The global model is therefore able to predict the car cabin blown air temperature, depending on vehicle characteristics, heating strategies and driving cycles. The software is validated by comparison of numerical results with experimental measurements realised on a car placed in a climatic wind tunnel. Simulations of different new heating systems are finally used to identify the best solution, compared to existing technologies, taking into account environmental and economical objectives. This highlights the significant potential of heat recovery on the engine admission line. An increase of 28°C of the blown air temperature and a decrease of 18% of the fuel consumption are obtained compared to conventional electric heaters.