scholarly journals Experimental Investigation into the Forced Convective Heat Transfer of Aqueous Fe3O4 Nanofluids under Transition Region

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jie Ma ◽  
Yinchen Xu ◽  
Wenlie Li ◽  
Jiantao Zhao ◽  
Shuping Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Transition Region ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Axial Distance ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Initial Expectation

The forced convective heat transfer (FCHT) properties of nanofluids, made of Fe3O4 nanomaterials and deionized water, are firstly measured by a self-made forced convective heat transfer apparatus. The nanofluid flows through a horizontal copper tube in the transition region with Reynolds numbers in the range of 2500–5000. Some parameters including Reynolds number, axial distance, and mass concentration are also investigated. The preliminary results are firstly presented that the heat transfer coefficients of Fe3O4 nanofluids systematically decrease with increasing concentration of nanoparticles under transition region which contradicts the initial expectation.

scholarly journals Experimental Study of Forced Convective Heat Transfer in a Coiled Flow Inverter Using TiO2–Water Nanofluids

2020 ◽  
Vol 10 (15) ◽  
pp. 5225
Author(s):  
Barbara Arevalo-Torres ◽  
Jose L. Lopez-Salinas ◽  
Alejandro J. García-Cuéllar
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Thermal ◽  
Convective Heat Transfer Coefficients

The curved geometry of a coiled flow inverter (CFI) promotes chaotic mixing through a combination of coils and bends. Besides the heat exchanger geometry, the heat transfer can be enhanced by improving the thermophysical properties of the working fluid. In this work, aqueous solutions of dispersed TiO2 nanometer-sized particles (i.e., nanofluids) were prepared and characterized, and their effects on heat transfer were experimentally investigated in a CFI heat exchanger inserted in a forced convective thermal loop. The physical and transport properties of the nanofluids were measured within the temperature and volume concentration domains. The convective heat transfer coefficients were obtained at Reynolds numbers (NRe) and TiO2 nanoparticle volume concentrations ranging from 1400 to 9500 and 0–1.5 v/v%, respectively. The Nusselt number (NNu) in the CFI containing 1.0 v/v% nanofluid was 41–52% higher than in the CFI containing pure base fluid (i.e., water), while the 1.5 v/v% nanofluid increased the NNu by 4–8% compared to water. Two new correlations to predict the NNu of TiO2–water nanofluids in the CFI at Reynolds numbers of 1400 ≤ NRe ≤ 9500 and nanoparticle volume concentrations ranges of 0.2–1.0 v/v% and 0.2–1.5 v/v% are proposed.

Study on Forced Convective Heat Transfer of FC-72 in Vertical Small Tubes

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Yantao Li ◽  
Yulong Ji ◽  
Katsuya Fukuda ◽  
Qiusheng Liu
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Bulk Liquid ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Abstract This paper presents an experimental investigation of the forced convective heat transfer of FC-72 in vertical tubes at various velocities, inlet temperatures, and tube sizes. Exponentially escalating heat inputs were supplied to the small tubes with inner diameters of 1, 1.8, and 2.8 mm and effective heated lengths between 30.1 and 50.2 mm. The exponential periods of heat input range from 6.4 to 15.5 s. The experimental data suggest that the convective heat transfer coefficients increase with an increase in flow velocity and µ/µw (refers to the viscosity evaluated at the bulk liquid temperature over the liquid viscosity estimated at the tube inner surface temperature). When tube diameter and the ratio of effective heated length to inner diameter decrease, the convective heat transfer coefficients increase as well. The experimental data were nondimensionalized to explore the effect of Reynolds number (Re) on forced convection heat transfer coefficient. It was found that the Nusselt numbers (Nu) are influenced by the Re for d = 2.8 mm in the same pattern as the conventional correlations. However, the dependences of Nu on Re for d = 1 and 1.8 mm show different trends. It means that the conventional heat transfer correlations are inadequate to predict the forced convective heat transfer in minichannels. The experimental data for tubes with diameters of 1, 1.8, and 2.8 mm were well correlated separately. And, the data agree with the proposed correlations within ±15%.

Convective Heat Transfer of Alumina Nanofluids in a Microchannel

2010 ◽  
Author(s):  
Saeid Vafaei ◽  
Dongsheng Wen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Axial Distance ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

This work reports an experimental study of convective heat transfer of aqueous alumina nanofluids in a horizontal microchannel under laminar flow condition. The variation of local heat transfer coefficients, in both entrance and developed flow regime, is obtained as a function of axial distance. The heat transfer coefficient of nanofluids is found to be dependent upon not only nanoparticle concentration but also mass flow rate. Different to the behavior in conventional-sized channels, the major heat transfer coefficient enhancement is observed in fully developed region in microchannels. Discussions of the results suggest that the heterogeneous nature of nanoparticle flow should be considered.

Time-Dependent Transpiration Heat Transfer in Porous Cylinders

1974 ◽  
Vol 96 (2) ◽  
pp. 218-224 ◽  
Author(s):  
D. M. Burch ◽  
B. A. Peavy ◽  
R. W. Allen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Chemical Reactor ◽  
Analytic Solutions ◽  
Transient Temperature ◽  
Transfer Coefficients ◽  
Forced Convective Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Transient Temperature Distribution

This paper investigates the transient temperature distribution within transpiration-heated and -cooled porous tubes that occur after a step increase in the rate of convective heat transfer at one of the tube surfaces. Analytic solutions are presented for transpiration cooling, catalytic chemical reactor, and tubular regenerator applications. These solutions include the effect of forced convective heat transfer at both tube surfaces where conventional heat-transfer coefficients are used to define the boundary conditions.

scholarly journals Numerical Investigation On The Impingement Of A Circular Jet Of Nanofluids On A Circular Flat Plate

2021 ◽  
Author(s):  
Dhimitri Kucuqi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Experimental Model ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

A numerical study was conducted to investigate and validate experimental convective heat transfer coefficient data associated with an Al2O3-H2O nanofluid through the use of an impingement jet on a flat, circular disk. It was observed that, in conjunction with experimental data, nanofluids provided increased local convective heat transfer coefficients in comparison to the base fluid. Nanofluid concentrations outlined in the experimental model, from 0.0198 to 0.0757 wt%, were investigated in a numerical model and resulting convective heat transfer coefficients were compared. In contrast to the experimental model, the maximum heat transfer enhancement occurred at the nanofluid concentration of 0.0757 wt%. In addition, several other models were tested with various Reynolds numbers and jet height-to-jet diameter ratios for further investigation along with discussion of sources of error. Overall, in comparison to experimental data, the lowest percentage errors achieved for the Reynolds numbers of 4245.7 and 8282 were 17.9% and 34.9%, respectively.

scholarly journals Numerical Investigation On The Impingement Of A Circular Jet Of Nanofluids On A Circular Flat Plate

2021 ◽  
Author(s):  
Dhimitri Kucuqi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Convective Heat Transfer ◽  
Experimental Model ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

A numerical study was conducted to investigate and validate experimental convective heat transfer coefficient data associated with an Al2O3-H2O nanofluid through the use of an impingement jet on a flat, circular disk. It was observed that, in conjunction with experimental data, nanofluids provided increased local convective heat transfer coefficients in comparison to the base fluid. Nanofluid concentrations outlined in the experimental model, from 0.0198 to 0.0757 wt%, were investigated in a numerical model and resulting convective heat transfer coefficients were compared. In contrast to the experimental model, the maximum heat transfer enhancement occurred at the nanofluid concentration of 0.0757 wt%. In addition, several other models were tested with various Reynolds numbers and jet height-to-jet diameter ratios for further investigation along with discussion of sources of error. Overall, in comparison to experimental data, the lowest percentage errors achieved for the Reynolds numbers of 4245.7 and 8282 were 17.9% and 34.9%, respectively.

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