Thermal Dispersion and Convection Heat Transfer during Laminar Transient Flow in Porous Media
Pathak, M. G.
Ghiaasiaan, S. M. (Seyed M.)
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Solid-fluid thermal interactions during unsteady flow in porous media play an important role in the regenerators of pulse tube cryocoolers. Pore-level thermal processes in porous media under unsteady flow conditions are poorly understood. The objective of this investigation was to study the pore-level thermal phenomena during pulsating and unidirectional sinusoidal flow through a generic, two-dimensional porous medium by numerical analysis. Furthermore, an examination of the effects of flow pulsations on the thermal dispersion and heat transfer coefficient that are encountered in the standard, volume-average energy equations for porous media were carried out. Pulsating and unidirectional sinusoidal inlet flow rates were chosen as an intermediate step towards the more difficult problem of periodic flow. The investigated porous media are periodic arrays of square cylinders. Detailed numerical data for the porosities of 0.75 and 0.84, with flow pulsation frequencies of 0 - 80 Hz, were obtained at Reynolds numbers of 560 and 980. Based on these numerical data, the instantaneous as well as cycle-average thermal dispersion and heat transfer coefficients, to be used in the standard unsteady volume-average energy conservation equations for flow in porous media, were derived.