The Effect of Varying Tube Diameters on Enhancement Heat Transfer by Forced Convection through a Horizontal Tube

Abstract

Forced convection (FC) is one of the important topics in engineering applications. Therefore, the process of improving the convection heat transfer coefficient (CHC) and determining the factors causing it has become a subject of interest to researchers. One enhancement approach is the varying dimension of the flow conduit. The present work involved the experimental study of forced convection inside copper cylinder fixed horizontally with varying heat flux and diameter (D = 0.02, 0.035, and 0.045) m, to investigate CHC, in this study assuming the flow is hydrodynamically fully developed. The work covers all the values of the imposed heat flux (HF) under investigation of (7.33≤q≤ 107.424 W/m2) that yields Reynolds numbers range (1252≤ Re ≤ 3032) was investigated. Experimental results showedthat the effect of varying the diameter wasexamined and results indicated that the Nusselt number (Nu) increased as the diameter increased which lead to higher surface temperature (SF) distribution along the smallest diameter tube. Results also show that the values of the local Nu (LNu) are always decreased and reached itslowest value at the tube exit section of the imposed HF. For all tubes, the result shows that an increase in the tube diameter results increasing in Nuav.