Efficiency of Surface Heat Transfer Intensifiers for Laminar and Turbulent Flows in Heat Exchanger Channels

Abstract

The present work presents the comparison of efficiency of surface-type intensifiers in a wide range of geometric parameters and in the range of Reynolds numbers corresponding to rated laminar and turbulent flow regimes in a channel on the basis of a single general criterion. It is also aimed to clarify objective thermal and hydraulic properties of intensifiers, to present a table of intensifier optimal parameters for the further theory and practice development, to formulate practical recommendations for selecting intensifier types and parameters in the design of promising energy-saving heat transfer equipment. The comparison of intensifiers efficiency was carried out under identical conditions for constricted and unobstructed channels containing intensifiers of various shapes. It is shown that intensifiers in the form of transverse annular ridges and systems of spherical holes show high thermal and hydraulic efficiency at specific flow operating parameters and design parameters of both, a channel and intensifier. The acquired results and recommendations on optimal parameters of surface-type intensifiers make it possible to calculate and design heat exchangers with intensifier optimal configurations and sizes. To confirm the obtained fundamental knowledge in the field of surface heat transfer augmentation based on a system of spherical holes/ridges several heat exchanger prototypes were developed.