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The Scientific World Journal
Volume 2013, Article ID 714180, 14 pages
http://dx.doi.org/10.1155/2013/714180
Research Article

Experimental Research of Dynamic Instabilities in the Presence of Coiled Wire Inserts on Two-Phase Flow

1Department of Mechanical Engineering, Faculty of Engineering, Bayburt University, 69000 Bayburt, Turkey
2Department of Mechanical Engineering, Faculty of Engineering, Atatürk University, 25240 Erzurum, Turkey
3Department of Mechanical Engineering, Faculty of Engineering and Architecture, Technical University of Erzurum, Erzurum, Turkey

Received 21 October 2012; Accepted 10 December 2012

Academic Editors: T.-C. Jen and R.-H. Yeh

Copyright © 2013 Gokhan Omeroglu 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

The aim of this study is to experimentally investigate the effect of the coiled wire insertions on dynamic instabilities and to compare the results with the smooth tube for forced convection boiling. The experiments were conducted in a circular tube, and water was used as the working fluid. Two different pitch ratios ( and 5.55) of coiled wire with circular cross-sections were utilised. The constant heat flux boundary condition was applied to the outer side of the test tube, and the constant exit restriction was used at the tube outlet. The mass flow rate changed from 110 to 20 g/s in order to obtain a detailed idea about the density wave and pressure drop oscillations, and the range of the inlet temperature was 15–35°C. The changes in pressure drop, inlet temperature, amplitude, and the period with mass flow rate are presented. For each configuration, it is seen that density wave and pressure drop oscillations occur at all inlet temperatures. Analyses show that the decrease in the mass flow rate and inlet temperature causes the amplitude and the period of the density wave and the pressure drop oscillations to decrease separately.