Numerical Investigation of Heat Transfer Enhancement in Ribbed Elliptical Passage

Mohammed W. Al-Jibory , Farhan Lafta Rashid and Shahid Mahdy Talib

Abstract

This study presents a numerical investigation for heat transfer enhancement and fluid flow in elliptical and circular passages equipped with circular ribs having triangular cross section. Boundary conditions are inlet

coolant air temperature is 300 K with Reynolds numbers (Re = 7901). The surrounding constant hot air temperatures was (673 K). The numerical simulations were done by using Software FLUENT Version 15 in this part, it was presented the effect of using circular ribs in circular and elliptical passage channel on the fluid flow and heat transfer characteristics. Ribs used with pitch-rib height of 10, circular passage of 36 mm internal diameter and elliptical passage of 46×26 mm, 1.5 mm passage thickness and 0.5 m long. The temperature, velocity distribution contours, cooling air temperature distribution at the passage centerline, the inner wall surface temperature of the duct and thermal performance factor, the turbulent Eddy dissipation and turbulent kinetic energy are presented in this study. Passage with ribs was the better case which leads to increase the coolant air temperature by 9.1% for circular passage and 5% for elliptical passage, the temperature at the exit of centerline passage is greater than the elliptical passage by 3.96%. The turbulent Eddy dissipation for ribbed circular passage be higher than for ribbed elliptical passage by 100%. The values of turbulent kinetic energy for ribbed circular passage be larger than that for elliptical passage by 300% at the exist. The enhancement performance factor for ribbed circular passage be higher than that for elliptical one 120%. The higher friction factor ratio was found for elliptical cross section passage with ribs. Circular cross section with ribs is the best result (lower pressure drop and higher heat transfer enhancement).