Thermohydraulic performance of rectangular ducts with different multiple V-rib roughness shapes: A comprehensive review and comparative study

The use of rib roughness in numerous forms, shapes and sizes is the utmost common and effective way to increase the thermohydraulic performance of a rectangular duct. Investigators reported various rib roughness shapes in the literature for studying fluid flow and heat transfer in rectangular duct. A number of experimental and CFD studies carried out on rib roughened rectangular duct for their performance analysis were reported in the literature. This comprehensive review of literature reveals that a lot of work has been described on design of rectangular duct by experimental approach. This review also reveals that rare studies have been done on CFD analysis of rectangular duct. Based on the comprehensive literature review, it is found that single V-rib with combined staggered rib is better thermo hydraulic as compared other single V-rib and discrete multiple V-rib is better as compared arc shaped multiple rib and continuous multiple V-rib rectangular duct. This work also presents, a CFD based study on the heat transfer and fluid flow characteristics of a rectangular duct with different types of multiple V-rib. Three-dimensional and turbulent flow analyses were conducted using a commercial CFD ANSYS package. The grid dependency was studied, followed by validation of the various CFD models against the experimental data. The RNG k-epsilon model was selected as the most suitable one. It is apparent that the turbulence produced by various multiple V-rib configurations results in a greater increase in the convective heat transfer coefficient for a rectangular duct. The thermohydraulic performance is discussed in order to examine the overall effects of the various multiple V-rib roughness shapes and working parameters. The results show that discrete multiple V-rib with staggered rib roughness shapes provide better thermo hydraulic performance than other similar rib roughness shapes. (C) 2015 Elsevier Ltd. All rights reserved.