Effects of pH and surfactant on the forced convection of Al2O3/water and TiO2/water nanofluids

2020 ◽  
pp. 1-18
Author(s):  
Deepak Khurana ◽  
Sudhakar Subudhi
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Particle Concentration ◽  
Sodium Dodecyl ◽  
Suspension Stability ◽  
Heat Transfer Characteristics ◽  
Maximum Enhancement ◽  
Effects Of Ph ◽  
Set Up ◽  
The Stability

Abstract The present paper deals with the forced convection of Al2O3/water and TiO2/water nanofluids with the variation of pH and addition of surfactant in nanofluids. The aim of this study is to investigate the effect of suspension stability on the heat transfer and pressure drop characteristics of nanofluids. The present experimental set up is same as used by our earlier paper [1]. The suspension stability of nanofluids is improved by varying pH of nanofluids. The pH in this study is varied from 3.5±0.2 to 12.5±0.2. Addition of surfactants is employed to improve the suspension stability of nanofluids. The SDS (sodium dodecyl sulfate) surfactant of 0.05 wt % is used to increase the stability of nanofluids in the present study. It is observed that by increasing the suspension stability with the variation of pH and addition of surfactant, the heat transfer characteristics have improved appreciably. The maximum enhancement in heat transfer is obtained with TiO2/water nanofluids at a particle concentration of 0.1 vol % and a pH of 3.5±0.2.

Experimental Study on Flow Boiling Heat Transfer in an Extremely Small Tube

2006 ◽  
Author(s):  
Haruhiko Ohta ◽  
Koichi Inoue ◽  
Yuichiro Shimada
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Boiling ◽  
Vapor Quality ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Flow Boiling Heat Transfer ◽  
Small Tube

Flow boiling heat transfer in a single small tube is investigated by using FC72 as a working fluid. The heat transfer coefficients are measured in the ranges of heat flux 2–24kW/m2 and mass velocity 100–400kg/m2s under the condition of near atmospheric pressure. Test tube, made of stainless steel, has an inner diameter of 0.51mm and a heated length of 200mm. The tube is located horizontally in a vacuum chamber to reduce the heat loss and to minimize the time to obtain data regarded as that of steady state. In the single-phase region, heat transfer coefficients due to forced convection are in good agreement with the values from the conventional theories. In the saturated region, measured heat transfer characteristics are quite different depending on whether the test liquid is deaerated or not deaerated before the experiments. By using deaerated liquid, three different heat transfer regimes are observed: In the first regime, the heat transfer is dominated by nucleate boiling in low vapor quality, and the heat transfer is deteriorated or enhanced depending on the channel confinement and heat flux. In the second regime, the heat transfer is dominated by two-phase forced convection in moderate quality as is well known for the tubes of normal size. In the third regime, the heat transfer is dominated again by two-phase forced convection, but is deteriorated in high quality. One or two regimes can disappear or become unclear depending on the conditions of flow and heating. The effects of vapor quality and mass velocity on the heat transfer characteristics due to two-phase forced convection in the moderate vapor quality are clarified in the experimental ranges tested. And a reason for the gradual heat transfer deterioration observed in high quality is discussed based on the liquid-vapor behaviors inherent in small diameter tubes.

Packing Characteristics and Its Effect on Heat Transfer Characteristics in Melting of Granular Packed Bed Subject to Horizonal Forced Convection

2002 ◽  
Author(s):  
Y. L. Hao ◽  
Y.-X. Tao
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Melting Process ◽  
Packed Bed ◽  
Time Interval ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Ice Particles ◽  
Different Types ◽  
Series Of Experiments

A series of experiments are conducted to investigate the characteristics and its effect on the melting and heat of a packed bed consisting of melting ice particles to horizontal forced convection. The volumes and situations of the melting ganular packed beds are by the visualization observations and measurements digital camcorders within the range of Re = 71 ~ 2291, Gr/Re2 = 1.48×10−5 ~ 17.32, and Ste = 0.0444 ~ 0.385, respectively. The mass of ice particles is measured at the time interval during the melting process. Two types of pattern can be found under the different conditions. The different types of heat transfer characteristics emerge in type of packing pattern. The correlations for each type of pattern are obtained based on the experimental results.

Concentrated-Leakage Detection by Emulation of Temperature Field

2012 ◽  
Vol 224 ◽  
pp. 93-96 ◽  
Author(s):  
Xin Jian Wang ◽  
Ri Yun Li ◽  
Jian Sheng Chen
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Numerical Optimization ◽  
Underground Water ◽  
Lapse Rate ◽  
Leakage Detection ◽  
Heat Transfer Characteristics ◽  
Coupled Equations ◽  
Set Up ◽  
Flow States

In order to detect the concentrated leakage passages(CLP) more effectively and precisely, the temperature field emulation method of irregularity dam including seepage and leakage is established based on numerical optimization of concentrated leakage passage detection with kinds of boundary conditions. In this model, the effect of lapse rate, radiation from sun and wind speed on temperature field is included. The flow states of underground water determined, the heat transfer characteristics presented and the coupled relation between seepage and temperature distribution constructed, the coupled equations between seepage and heat transfer are set up.

New Bio-Inspired, Multiphase Forced Convection Cooling by ABS Plastic or Encapsulated Paraffin Beads

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Fatemeh Hassanipour ◽  
José L. Lage
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Particle Concentration ◽  
Acrylonitrile Butadiene Styrene ◽  
Parallel Plates ◽  
Mixing Effect ◽  
Particle Mixing ◽  
Channel Temperature ◽  
Convection Cooling ◽  
Change Material

Preliminary experimental results of forced convection by octadecane paraffin (encapsulating phase-change material (EPCM)) particles, acrylonitrile butadiene styrene plastic particles, or by clear (of particulates) water flowing through a heated parallel-plates channel are reported. The objective is to investigate the mixing effect of the particles vis-à-vis the latent heat effect. The particle concentration is kept at 3% in volume. The results, in terms of surface-averaged channel temperature and heat transfer coefficient for different fluid speed and heat-flux, indicate the mixing effect to account from 19% to 68% of the heat transfer enhancement produced by using EPCM particles. Hence particle mixing, even at a very low particle concentration, is an effective convection mechanism.

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