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Advances in Mechanical Engineering
Volume 2011 (2011), Article ID 103502, 10 pages
http://dx.doi.org/10.1155/2011/103502
Research Article

Effects of Delta-Shaped Obstacles on the Thermal Performance of Solar Air Heater

Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, India

Received 5 March 2011; Revised 3 August 2011; Accepted 18 August 2011

Academic Editor: Hyung Hee Cho

Copyright © 2011 Adisu Bekele et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

An experimental investigation has been carried out to study the effect of delta-shaped obstacles mounted on the absorber surface of an air heater duct with an aspect ratio 6 : 1 resembling the conditions close to solar air heaters. This study encompassed the Reynolds number (Re) ranging from 3400 to 27600, longitudinal pitch of the obstacle ( 𝑃 𝑙 / 𝑒 ) varied from 3/2 to 11/2, and relative obstacle height ( 𝑒 / 𝐻 ) varied from 0.25 to 0.75. The relative obstacle transverse pitch ( 𝑃 𝑡 / 𝑏 ) = 7 / 3 and the angle of attack of flow on obstacle = 90° are kept constant during the whole experimentation. By comparing the heat transfer data obtained from the obstacle-mounted duct with that of smooth duct under similar geometrical and flow conditions, the obstacle-mounted duct enhances the heat transfer by 3.6-times at R e = 7 2 7 6 . 8 2 , 𝑃 𝑙 / 𝑒 = 3 / 2 , and 𝑒 / 𝐻 = 0 . 7 5 .