Investigation on Intertube Falling-Film Heat Transfer and Mode Transitions of Aqueous-Alumina Nanofluids

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Binglu Ruan ◽  
Anthony M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Horizontal Tube ◽  
Sodium Dodecylbenzene Sulfonate ◽  
Falling Film ◽  
Dodecylbenzene Sulfonate ◽  
Reynolds Number Increase ◽  
New Type ◽  
Aqueous Aluminum ◽  
Mode Transitions ◽  
Film Heat Transfer

Horizontal-tube falling-film heat transfer characteristics of aqueous aluminum oxide nanofluids at concentrations of 0 vol %, 0.05 vol %(0.20 wt %), 0.5 vol %(1.96 wt %), 1 vol %(3.86 wt %) (with and without sodium dodecylbenzene sulfonate), and 2 vol %(7.51 wt %) are investigated and compared with predictions developed for conventional fluids. The thermophysical properties of the nanofluids, including thermal conductivity, kinematic viscosity, and surface tension, are reported, as is the mode transition behavior of the nanofluids. The experimental results for heat transfer are in good agreement with predictions for falling-film flow and no unusual Nu enhancement was observed in the present studies. Additionally, a 20% mode transitional Reynolds number increase was recorded for transitions between sheets and jets and jet-droplet mode to droplet mode. Although the findings with water-alumina nanofluids are not encouraging with respect to heat transfer, the results extend nanofluid data to a new type of flow and may help improve our understanding of nanofluid behavior. Moreover, this work provides a basis for further work on falling-film nanofluids.

The Intertube Falling Film: Part 1—Flow Characteristics, Mode Transitions, and Hysteresis

1996 ◽  
Vol 118 (3) ◽  
pp. 616-625 ◽  
Author(s):  
X. Hu ◽  
A. M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Horizontal Tube ◽  
Falling Film ◽  
Flow And Heat Transfer ◽  
Transition Criteria ◽  
Continuous Sheet ◽  
Mode Transitions ◽  
Regime Map ◽  
Flow Regime Map

When a liquid film falls from one horizontal tube to another below it, the flow may take the form of discrete droplets, jets, or a continuous sheet; the mode plays an important role in the wetting and heat transfer characteristics of the film. Experiments are reported that explore viscous, surface tension, inertial, and gravitational effects on the falling-film mode transitions. New flow classifications, a novel flow regime map, and unambiguous transition criteria for each of the mode transitions are provided. This research is part of an overall study of horizontal-tube, falling-film flow and heat transfer, and the results may have important implications on the design and operation of falling-film heat exchangers.

Falling film heat transfer analysis on a bank of horizontal tube evaporator

AIChE Journal ◽  
1988 ◽  
Vol 34 (9) ◽  
pp. 1539-1549 ◽  
Author(s):  
G. Kocamustafaogullari ◽  
I. Y. Chen
Keyword(s):  
Heat Transfer ◽  
Horizontal Tube ◽  
Heat Transfer Analysis ◽  
Falling Film ◽  
Film Heat Transfer

Heat Transfer of Falling Film Flowing Around a Horizontal Tube With Nanofluids

2009 ◽  
Author(s):  
Binglu Ruan ◽  
Anthony M. Jacobi ◽  
Liansheng Li
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Horizontal Tube ◽  
High Heat ◽  
Working Fluid ◽  
Sodium Dodecylbenzene Sulfonate ◽  
Falling Film ◽  
High Heat Transfer ◽  
High Heat Transfer Coefficient ◽  
The Impact

Due to its high heat transfer coefficient and low working fluid inventory, the horizontal-tube, falling-film heat exchanger finds wide application as an absorber, condenser and evaporator. Recent advances in nanotechnology suggest the use of nanofluids in heat exchangers. Some researchers find an enhanced heat transfer with nanofluids, while others report no enhancement or a deleterious effect on heat transfer when applying nanoparticles in the working fluids. In the current work, the thermal conductivity and kinematic viscosity of aqueous alumina nanofluids are measured at concentrations of 0 vol%, 0.05 vol%, 0.5 vol%, 1 vol% (with and without sodium dodecylbenzene sulfonate, SDBS), and 2 vol%. For these nanofluids, the impact of nanoparticles on thermal conductivity and viscosity is small (less than 5% for thermal conductivity and 13% for viscosity). The heat transfer characteristics of these nanofluids are measured and compared to predictions from the literature for conventional fluids. The falling-film heat transfer for these nanofluids is in good agreement with predictions, and no unusual heat transfer enhancement is observed in the present studies. Although the findings with water-alumina nanofluids are not encouraging with respect to heat transfer, the results extend nanofluid data to a new type of flow and may help improve our understanding of nanofluid behavior. Moreover, this work provides a basis for further work on falling-film nanofluids.

Numerical Simulation of the Liquid Flowing and Heat-Transfer outside the Tube of the Horizontal-Tube Falling Film Evaporator

2012 ◽  
Vol 614-615 ◽  
pp. 296-300 ◽  
Author(s):  
Wei Kang Hu ◽  
Li Yang ◽  
Lei Hong Guo
Keyword(s):  
Heat Transfer ◽  
Horizontal Tube ◽  
Water Desalination ◽  
Falling Film ◽  
Transfer Enhancement ◽  
Film Evaporation ◽  
Film Evaporator ◽  
Spray Density ◽  
Performance Of Heat Transfer ◽  
Falling Film Evaporation

This paper mainly studies the falling film evaporator in the field of water desalination. Using the method of fluent simulates the process of the liquid flowing and heat-transfer on the horizontal-tube falling film evaporation. The author analyses the distribution of the liquid film, and obtain the rule that spray density, evaporation temperature, temperature difference and pipe diameter affect the performance of heat-transfer in a certain range. So the paper plays a guiding role in heat transfer enhancement in the falling film evaporator.

Heat-transfer film coefficients of falling film horizontal tube evaporators

Desalination ◽  
2004 ◽  
Vol 166 ◽  
pp. 223-230 ◽  
Author(s):  
Li Xu ◽  
Murong Ge ◽  
Shichang Wang ◽  
Yuxin Wang
Keyword(s):  
Heat Transfer ◽  
Horizontal Tube ◽  
Transfer Film ◽  
Falling Film
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