Oscillating flow heat transfer: a comprehensive review

The oscillating flow heat transfer (OFHT) has been an area of interest to researchers for the last four decades due to the substantial improvement in the performance of such devices. The present paper reviews oscillatory flow heat transfer in detail by considering the type of interaction medium, design, and applications as essential criteria. This paper also overviews the role of oscillating flow heat transfer in the various heat exchanger types such as packed beds, parallel plate channels, finned tubes, ribbed tubes, and the application. Oscillating flow heat exchanger performance mainly depends on oscillation frequency, tidal displacement, axial temperature gradient, tube dimension, and fluid properties. The results of these investigations over a period of five decade are presented in terms of performance indicators viz. enhancement of effective thermal diffusivity by 17,900 folds, Heat flux from 60 to 10⁴ W/m², axial temperature gradient of 200 K/m, and Nusselt number of 65.93 to 139.8. The significant enhancement in the performance of OFHT is due to combined effect of increase in periodic lateral heat conduction and longitudinal convection due to flow oscillation in presence of axial temperature gradient. The design of the compact system is possible because of significant enhancement in these performance indicators. The significance of this mode of heat transfer is widely known in applications such as Stirling machines, cryogenic refrigerators, or pulsed-tube cryocoolers. Furthermore, heat transfer improvement through oscillatory and pulsating flows is essential in many fields of chemical and mechanical applications where a compact and efficient system is required. This study will benefit new researchers in the understanding of the oscillating flow heat transfer mechanism and the variety of applications for such heat exchangers.