An Experimental Investigation of Natural Convection Heat Transfer through Horizontal Open Ended Four Sided Tubes with Different Aspect Ratios.

Document Type : Research Studies

Authors

1 Mechanical Department., Faculty of Industrial Education., Suez University., Suez., Egypt.

2 Teacher., Industrial Technical School., Zagazig., Egypt.

Abstract

Experimental investigation of free convection heat transfer from the inside surface of horizontal four sided tubes of different aspect ratio with a uniformly heated surface is presented. The aspect ratios is changed from 1 to 0.25. The experiments covered a range of Rayleigh number, Ra from 2.02x105 to 4.6×106. The local and average heat transfer coefficients and Nusselt numbers are estimated for different aspect ratios at different Rayleigh numbers. The experimental results showed that the aspect ratio has a significant effect on the local and average heat transfer coefficients. It is noticed that temperature distributions increase with the increase of axial distance from both ends of the tube upto a maximum value at the middle of the tube. Also, the local Nu increases with the increase of aspect ratio at the same axial distance. The results obtained were correlated with the available data for the horizontal four sided tubes.

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