Heat-transfer from single horizontal tubes in fluidized beds: Influence of tube diameter, moisture and diameter-definition by Geldart C fines content

2013 ◽  
Vol 235 ◽  
pp. 1038-1046 ◽  
Author(s):  
Matthias Merzsch ◽  
Stefan Lechner ◽  
Hans Joachim Krautz
Keyword(s):  
Heat Transfer ◽  
Fluidized Beds ◽  
Tube Diameter ◽  
Fines Content ◽  
Horizontal Tubes

Local Heat Transfer Coefficients around Horizontal Tubes in Fluidized Beds

1980 ◽  
Vol 102 (1) ◽  
pp. 152-157 ◽  
Author(s):  
R. Chandran ◽  
J. C. Chen ◽  
F. W. Staub
Keyword(s):  
Heat Transfer ◽  
Particle Size ◽  
Fluidized Beds ◽  
Local Heat Transfer ◽  
Local Heat ◽  
General Tendency ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Horizontal Tubes ◽  
System Pressure

The local characteristics of heat transfer from horizontal tubes immersed in fluidized beds were investigated experimentally. Steady-state heat transfer measurements were obtained in air-fluidized beds of glass beads, both for a single tube and a ten-row bare tube bundle. The test results indicated that local heat transfer coefficients are strongly influenced by angular position and gas flow rate, as well as by particle size and system pressure. The heat transfer coefficients, averaged around the circumference of the tube, exhibited a general tendency to increase with decreasing particle size and increasing system pressure. The heat transfer coefficients for a tube in an inner-row position within the bundle were found to be slightly higher than those for a tube in the bottom-row. Comparison of the average heat transfer coefficient data obtained in this study with some of the existing correlations for heat transfer from horizontal tubes showed that the correlations are unsatisfactory.

Effects of Heat Exchanger Tube Parameters on Nucleate Pool Boiling Heat Transfer

1998 ◽  
Vol 120 (2) ◽  
pp. 468-476 ◽  
Author(s):  
Moon-Hyun Chun ◽  
Myeong-Gie Kang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Roughness ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Tube Diameter ◽  
Nucleate Pool Boiling ◽  
Pool Boiling Heat Transfer ◽  
Horizontal Tubes ◽  
Vertical Tubes

In an effort to determine the combined effects of major parameters of heat exchanger tubes on the nucleate pool boiling heat transfer in the scaled in-containment refueling water storage tank (IRWST) of advanced light water reactors (ALWRs), a total of 1966 data points for q″ versus ΔT have been obtained using various combinations of tube diameters, surface roughness, and tube orientations. The experimental results show that: (1) increased surface roughness increases the heat transfer coefficient for both horizontal and vertical tubes, and the effect of surface roughness is more pronounced for the vertical tubes compared to the horizontal tubes, (2) the two heat transfer mechanisms, i.e., increased heat transfer due to liquid agitation by bubbles generated and reduced heat transfer by the formation of large vapor slugs and bubble coalescence, are different in two regions of low heat flux (q″ ≤ 50 kW/m2) and high heat flux (q″ > 50 kW/m2) depending on the orientation of tubes and the degree of surface roughness, and (3) the heat transfer rate decreases as the tube diameter is increased for both horizontal and vertical tubes, but the effect of tube diameter on the nucleate pool boiling heat transfer for vertical tubes is greater than that for horizontal tubes. Two empirical heat transfer correlations for q″, one for horizontal tubes and the other for vertical tubes, are obtained in terms of surface roughness (ε) and tube diameter (D). In addition, a simple empirical correlation for nucleate pool boiling heat transfer coefficient (hb) is obtained as a function of heat flux (q″) only.

Numerical calculation of wall-to-bed heat transfer coefficients in Geldart B bubbling fluidized beds with immersed horizontal tubes

2018 ◽  
Vol 333 ◽  
pp. 193-208 ◽  
Author(s):  
Peter Ostermeier ◽  
Fabian Dawo ◽  
Annelies Vandersickel ◽  
Stephan Gleis ◽  
Hartmut Spliethoff
Keyword(s):  
Heat Transfer ◽  
Numerical Calculation ◽  
Fluidized Beds ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Horizontal Tubes
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