Publication: Experimental study on electro-thermal energy generated from bundle of inline powered tubes
Date
2018
Authors
Mohammed K.G.
Salman Y.K.
Ahmed T.M.
Journal Title
Journal ISSN
Volume Title
Publisher
International Journals of Engineering and Sciences Publisher
Abstract
Energy generated by laminar natural convection from an inclined bundle of cylinders subjected to a constant heat flux was studied experimentally. The test rig was designed to investigate bundle of five cylinders arranged in a form that the bundle has three cylinders in a column and three cylinders in a row and has constant both longitudinal (flow direction) and traversing cylinders spacing distances equal 5 D. The experiments cover RaL, D range varies from 5.06 x 104 to 1.08 x 105 and five angles of inclination 0 � (horizontal), 30 o, 45 o, 60 � and 90�. The variation of local surface temperature Tx, local heat transfer coefficient hx and average heat transfer coefficient hL with cylinder length are depicted for all cylinder orientations and empirical formulas for the variation average Nusselt number NuL, D with the Rayleigh number RaL,D are also presented for all bundle inclination angles and for each individual cylinder in the bundle. Results show that, for all inclination angles with the exception of the vertical and for present cylinders configuration and arrangement as mentioned above, an improvement in the heat transfer rate for second and third cylinders in a bundle column in comparison with first cylinder in the column and other two cylinders in row on the left and right sides of the second cylinder in the column (Three cylinders in the bundle behave as single cylinder showing no interference effect in the bundle). This improvement having a significant ultimate value in horizontal bundle, decreasing in a moderate rate between horizontal to 60o range and a sharp reduction in heat transfer between 60 � to 90 � (vertical orientation lowest heat transfer rate). Generally, the heat transfer process improving as the bundle moves from vertical to horizontal even when consider a situation for single cylinder. For a single horizontal cylinder, heat transfer results show a good agreement with previous work and a contradictory agreement for single vertical cylinder. Heat transfer results also show a good agreement with the available experimental and analytical works for a horizontal inline bundle. � IJENS.