Static and dynamic compact thermal modeling of internal convection

Objects undergoing heat transfer by convection internally, i.e. not at their boundaries, need a special care in their modeling. The first objective of this work is to extend the general formulation made earlier for compact thermal models in order to cover this case. The single resistor model based on the heat transfer coefficient h is replaced with a compact model linking all relevant nodes using h as well as fluid thermal capacitance and inertia, such as to satisfy thermodynamic constraints derived earlier for conduction compact models. The second objective of this work is a fundamental analysis of transient convection in order to offer an alternative to the quasi-static assumption usually made due to the lack of a more adequate model. A generalization is suggested of the static heat transfer coefficient h into a dynamic representation that is suitable for fast transients.