Complete engine thermal model

Thermal management has become a crucial issue in the design of modern vehicles. On one side, with high specific power outputs, the amount of excess heat to be disposed of is a serious challenge for vehicle reliability. On the other hand, at ordinary use, the excess heat available is limited and often insufficient to provide adequate heating to the cabin and to the catalytic converter controlling the vehicle harmful emissions. This is particularly true during the vehicle warm-up process in cold climates, significantly influencing real-world fuel consumption. Furthermore, the advent of hybrid vehicles drastically increases the complexity of the task at hand since electric motors do not provide a significant source of the needed heat.

Modeling the thermal behaviour of a complete engine poses a peculiar challenge since it requires implementing in a single numerical platform a number of physical phenomena significantly different in nature. Nevertheless, this is found necessary since the magnitude and the relative effect of these phenomena change significantly within the wide spectrum of engine running conditions.

In practice the model needs to relate all the engine heat sources to the heat sinks. The three relevant heat sources are the heat rejection from the combustion chamber, the heat rejection from the exhaust system and engine internal friction. The heat rejection is the energy lost by the thermodynamic cycle via convection with the engine internal surfaces. The heat sinks are: the engine coolant circuit, the oil system and the external environment.

The conjugate heat transfer model focus of this work offers a framework to collect, connect and relate all available information related to engine heat fluxes and temperatures. This regardless of the information origin (i.e. experimental or numerical). Models of this kind will be likely to be the tools of choice for the study and development of future engine and vehicle thermal management.

Session Time Slot(s): 
07/03/2017 - 10:45am-07/03/2017 - 11:10am
Room III
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