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Heat Transfer Research
Импакт фактор: 1.199 5-летний Импакт фактор: 1.155 SJR: 0.267 SNIP: 0.503 CiteScore™: 1.4

ISSN Печать: 1064-2285
ISSN Онлайн: 2162-6561

Выпуски:
Том 51, 2020 Том 50, 2019 Том 49, 2018 Том 48, 2017 Том 47, 2016 Том 46, 2015 Том 45, 2014 Том 44, 2013 Том 43, 2012 Том 42, 2011 Том 41, 2010 Том 40, 2009 Том 39, 2008 Том 38, 2007 Том 37, 2006 Том 36, 2005 Том 35, 2004 Том 34, 2003 Том 33, 2002 Том 32, 2001 Том 31, 2000 Том 30, 1999 Том 29, 1998 Том 28, 1997

Heat Transfer Research

DOI: 10.1615/HeatTransRes.2018016318
pages 235-253

EXPERIMENTAL INVESTIGATION OF AXIAL HEAT TRANSFER AND ENTRANCE EFFECT IN RANDOMLY PACKED BEDS BY A NAPHTHALENE SUBLIMATION TECHNIQUE

Jingyu Wang
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
Yan Liu
Key Laboratory of Thermal-Fluid Science and Engineering, Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P.R. China
Jian Yang
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
Yi-Tung Chen
Nevada Center for Advanced Computational Methods, Department of Mechanical Engineering , University of Nevada-Las Vegas, University of Reno, Las Vegas, NV, 89118, USA
Qiu-Wang Wang
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China

Краткое описание

Local average heat transfer characteristics along the axial direction in randomly packed beds are investigated experimentally by using a naphthalene sublimation technique and the heat-to-mass transfer analogy. Packed beds of three particle diameters of 12 mm, 10 mm, and 8 mm are investigated, respectively. The relationship between the Nusselt number along the axial direction and the axial porosity distribution is analyzed, and the influence of the entrance effect on the overall heat transfer is explored. In the present paper, the axial porosity distribution is obtained by numerical analysis of a randomly packed bed generated by a discrete element method (DEM). The results of pressure drop show that most experimental points lie within ± 20% deviations of the Ergun equation and that the pressure distribution along the axial direction decreases almost linearly. Furthermore, it is found that in the axial direction, the Nusselt number increases in the first three layers and stays almost constant after that, where the heat transfer is fully developed. The development of Nusselt number along the axial direction can be attributed to the change of axial porosity distribution and to the alterative turbulence. Besides, the Nusselt number in the first layer is about 60–80% of the average Nusselt number in the bulk of the packed bed in the present Reynolds number range (373–2867). Finally, the entrance effect can have an influence on the overall Nusselt number when the packed bed is shorter than 8–16 particle diameters.


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