Low-Order Analysis of Conjugate Heat Transfer in Pulsating Flow with Fluctuating Temperature

Abstract

Realizing enhanced heat transfer in any kind of thermodynamic process directly improves its efficiency or reduces its size. Therefore it is of fundamental interest that in periodic flows enhanced heat transfer has been reported repeatedly. Because of the huge number of different parameters in turbulent pulsating flows, e.g. perturbation amplitudes, flow regimes, it is difficult to identify relevant effects. To develop a more global insight into the dynamics of conjugate heat transfer in pulsating flows, a transient lumped model is formulated and analyzed in this study. It is derived from a one dimensional analysis of the conjugate heat transfer from the bulk of a pulsating flow through a wall of finite thickness. All hydrodynamic mechanisms of the pulsating flow are modeled through an harmonically oscillating heat transfer coefficient. Additionally an harmonically oscillating bulk temperature is considered. Two wall configurations of increasing complexity are analyzed: Firstly a lumped capacity model to scrutinize the effect of a dynamic behavior of the wall temperature. Finally, the most general case of a one dimensional finite volume discretization of the wall is presented and the dynamic of the wall temperature itself is examined. The results show that enhanced time averaged heat transfer is possible.