Experimental investigation of the unusual behavior of local heat transfer coefficient in the transition region of a circular tube with a bell-mouth entrance

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	Experimental investigation of the unusual behavior of local heat transfer coefficient in the transition region of a circular tube with a bell-mouth entrance
	Tam L.-M.; Ghajar A.J.
	1996-12-01
Source Publication	American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD
ISSN	02725673
Volume	330 Pages:115-123
Abstract	The local heat transfer characteristics for ethylene glycol water mixtures flowing in a horizontal circular straight tube with a bell-mouth inlet have been determined experimentally over a flow Reynolds number range of 1500 to 27,000. A wall-boundary heating condition of uniform heat flux was imposed. The variation of local heat transfer coefficient with length in the transition and turbulent flow regimes is very unusual. For the bell-mouth inlet, the boundary layer along the tube wall is at first laminar and then changes through a transition region to the turbulent condition causing a dip in the Nu-x/D curve. The length of the dip in the transition region is much longer than that in the turbulent region. For our experiments the length of the dip in the transition region varied from x/D = 100 to 175 in comparison to an x/D < 25 for the turbulent region. The presence of the dip in the transition region causes a significant influence on both the local and the average heat transfer coefficients. This is particularly important for heat transfer calculations in short tubes with a bell-mouth inlet.
URL	View the original
Language	英語English
Fulltext Access	View Full-Text via Scopus
Document Type	Journal article
Collection	University of Macau
Affiliation	Oklahoma State University - Stillwater
Recommended Citation GB/T 7714	Tam L.-M.,Ghajar A.J.. Experimental investigation of the unusual behavior of local heat transfer coefficient in the transition region of a circular tube with a bell-mouth entrance[J]. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 1996, 330, 115-123.
APA	Tam L.-M.., & Ghajar A.J. (1996). Experimental investigation of the unusual behavior of local heat transfer coefficient in the transition region of a circular tube with a bell-mouth entrance. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 330, 115-123.
MLA	Tam L.-M.,et al."Experimental investigation of the unusual behavior of local heat transfer coefficient in the transition region of a circular tube with a bell-mouth entrance".American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD 330(1996):115-123.

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