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Experimental Study and Analysis About Flow and Heat Transfer in Micro-tubes(PDF)

南京师范大学学报（工程技术版）[ISSN:1006-6977/CN:61-1281/TN]

Issue:
2007年01期
Page:
27-31
Research Field:
Publishing date:

Info

Title:
Experimental Study and Analysis About Flow and Heat Transfer in Micro-tubes
Author(s):
Zhao Xiaobao1; Liu Zhigang2; Li Bei1
1.School of Power Engineering,Nanjing Normal University,Nanjing 210042,China;2.Energy Research Institute of Shandong Academy of Sciences,Jinan 250014,China
Keywords:
m icro- tube;  friction facto r;  Nusse lt number
PACS:
TK124
DOI:
-
Abstract:
The steam w ith different pressures w ere used as hea ting sources to hea t the m icro-tubes and the d istilled w ate r, used as the w ork ing flu id, flow ed through m icro- tubes w ith inner d iam eters of 215μm, 322 μm, 530 μm and 765 μm, respective ly. A t the sam e tim e, pressure drops and flow rates in m icro- tubesw ere experim enta lly m easured. A s the Reyno lds num ber v aried in the range from 100 up to 7 000 in the expe rim en ts and the friction fac to r and the Nusselt number were obta ined correspond ing ly. The exper imenta l resu lts w ere com pared w ith the classical flow theories and the c lassica l convective hea t transfe r co rre lations in lam inar, transitiona l and turbu lent reg im es for conventional tubes. The compared resu lts indicated that the va lues o f the friction facto rs in m icro-tubes we re in rough agreem en tw ith those of the Po iseu ille equations and theNusselt num berw ere slightly less than those of the c lassica l lam -i nar hea t transfer correlations at a low Reynolds number. As Reyno lds numberw as la rger than 1 800~ 2 000, the va-l ues o f the fr iction facto r departs from those o f the Po iseu ille equations and theNusselt num be r reached the va lues o f the transitiona l heat transfer co rre lations. The va lues of the fr iction factors w ere approx im ate ly equa l to or near tho se of the B lassius equation and the Nusse lt numbers w ere larger than those of the c lassical turbu lent corre lations w hen Reyno lds num be r reached 3 000~ 7 000.

References:

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Last Update: 2013-04-29