Experimental Investigation of Heat Transfer Enhancement of CuO–Water and ZnO–Water Nanofluids Flowing Over a Heated Plate

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Dale A. McCants ◽  
Andrew M. Hayes ◽  
Titan C. Paul ◽  
Jamil A. Khan ◽  
Aly H. Shaaban
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Constant Heat Flux ◽  
Copper Plate ◽  
Heated Plate ◽  
Transfer Coefficients ◽  
Constant Heat ◽  
Heat Transfer Coefficients ◽  
Transmission Electron ◽  
Zno Nanofluids

In this paper, experimental investigation has been performed to characterize the heat transfer behavior of CuO–water and ZnO–water nanofluids. Nanofluids containing different volume percent (vol %) of nanoparticle concentrations flowed over a flat copper plate under a constant heat load. The constant heat flux was maintained using evenly placed cartridge heaters. The heat transfer coefficients of nanofluids were measured and compared with the results obtained from identical experiments performed with de-ionized (DI) water. In order to thoroughly characterize the nanofluids, nanoparticle size was investigated to inspect for possible agglomeration. The particle size was measured by using both a transmission electron microscope (TEM) and a dynamic light scattering system (DLS). Enhancement of convective heat transfer of nanofluids was 2.5–16% depending on the nanoparticle concentrations and Reynolds number. The plausible mechanisms of the enhanced thermal performance of CuO and ZnO nanofluids will be discussed in the following paper.

Evaluating the Thermal Characteristics of Copper-II and Zinc-Oxide Nanofluids Flowing Over a Heated Flat Plate

2008 ◽  
Author(s):  
Dale A. McCants ◽  
Jamil A. Khan ◽  
Andrew M. Hayes ◽  
Aly Shaaban
Keyword(s):  
Heat Transfer ◽  
Zinc Oxide ◽  
Flat Plate ◽  
Thermal Characteristics ◽  
Constant Heat Flux ◽  
Heated Plate ◽  
Transfer Coefficients ◽  
Cross Sectional ◽  
Heat Transfer Coefficients ◽  
Transmission Electron

Thermal characteristics of CopperII and Zinc-Oxide nanofluids have been investigated for flow over a heated flat plate. Fluid containing different volume-percents nanoparticles flow over a heated flat plate at specified laminar flow velocities. The heated plate experienced a constant heat flux from cartridge heaters spaced evenly along the length of the plate. The flow channel’s cross-sectional area was a square of dimensions 5cm × 5cm. Investigation of the heat transfer occurring in a plane along the centerline of the plate in the direction of the flow was performed. The heat transfer coefficients were calculated and plotted verses the Reynolds number and compared with the results obtained from distilled de-ionized water. Nanoparticle size from the fluids was investigated to inspect for possible agglomeration using both a transmission electron microscope (TEM) and a dynamic light scattering system (DLS).

Forced Convective Boiling of Refrigerant HCFC123 in a Mini-Tube

2010 ◽  
Author(s):  
Koichi Araga ◽  
Keisuke Okamoto ◽  
Keiji Murata
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Pool Boiling ◽  
Constant Heat Flux ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Convective Boiling ◽  
Frictional Pressure Drop ◽  
Heat Transfer Coefficients

This paper presents an experimental investigation of the forced convective boiling of refrigerant HCFC123 in a mini-tube. The inner diameters of the test tubes, D, were 0.51 mm and 0.30 mm. First, two-phase frictional pressure drops were measured under adiabatic conditions and compared with the correlations for conventional tubes. The frictional pressure drop data were lower than the correlation for conventional tubes. However, the data were qualitatively in accord with those for conventional tubes and were correlated in the form φL2−1/Xtt. Next, heat transfer coefficients were measured under the conditions of constant heat flux and compared with those for conventional tubes and for pool boiling. The heat transfer characteristics for mini-tubes were different from those for conventional tubes and quite complicated. The heat transfer coefficients for D = 0.51 mm increased with heat flux but were almost independent of mass flux. Although the heat transfer coefficients were higher than those for a conventional tube with D = 10.3 mm and for pool boiling in the low quality region, they decreased gradually with increasing quality. The heat transfer coefficients for D = 0.30 mm were higher than those for D = 0.51 mm and were almost independent of both mass flux and heat flux.

Experimental Investigation of Corona Wind Heat Transfer Enhancement With a Heated Horizontal Flat Plate

1995 ◽  
Vol 117 (2) ◽  
pp. 309-315 ◽  
Author(s):  
B. L. Owsenek ◽  
J. Seyed-Yagoobi ◽  
R. H. Page
Keyword(s):  
Heat Transfer ◽  
Infrared Camera ◽  
Local Heat Transfer ◽  
Threshold Value ◽  
Local Heat ◽  
Heated Plate ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Heat Transfer Efficiency ◽  
Corona Wind

Corona wind enhancement of free convection was investigated with the needle-plate geometry in air. High voltage was applied to a needle suspended above a heated plate, and heat transfer coefficients were computed by measuring the plate surface temperature distribution with an infrared camera. Local heat transfer coefficients greater than 65 W/m2 K were measured, an enhancement of more than 25:1 over natural convection. The enhancement extended over a significant area, often reaching beyond the 30 cm measurement radius. At high power levels, Joule heating significantly reduced the effective impingement point heat transfer coefficient. The corona wind was found to be more efficient with positive potential than with negative. The heat transfer efficiency was optimized with respect to electrode height and applied voltage. The needle-plate heat transfer effectiveness improved rapidly with increasing height, and became relatively insensitive to height above a threshold value of about 5 cm.

scholarly journals Study of natural and forced heat transfer coefficients on a vertical heated plate

2015 ◽  
Vol 7 (4) ◽  
pp. 195-202
Author(s):  
SIMIONESCU Stefan-Mugur ◽  
◽  
BALAN Corneliu ◽  
Keyword(s):  
Heat Transfer ◽  
Heated Plate ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The Use of Thin Films for Increasing Evaporation and Condensation Rates in Process Equipment

1959 ◽  
Vol 81 (4) ◽  
pp. 297-306 ◽  
Author(s):  
E. L. Lustenader ◽  
R. Richter ◽  
F. J. Neugebauer
Keyword(s):  
Heat Transfer ◽  
Thin Films ◽  
Surface Tension ◽  
Experimental Investigation ◽  
Process Equipment ◽  
Test Apparatus ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Evaporation And Condensation

This paper describes an experimental investigation of an evaporating and condensing test apparatus in which over-all heat-transfer coefficients as high as 8000 Btu/(hr) (sq ft) (deg F) were obtained with water by utilizing thin films both in evaporation and condensation. The films were obtained by wiping on the evaporating surface and utilizing surface tension effects on the condensing surface. The phenomena on both the evaporating and the condensing surfaces are amenable to theory.

scholarly journals Numerical Analysis of Water Forced Convection in Channels with Differently Shaped Transverse Ribs

2011 ◽  
Vol 2011 ◽  
pp. 1-25 ◽  
Author(s):  
Oronzio Manca ◽  
Sergio Nardini ◽  
Daniele Ricci
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
High Heat ◽  
Constant Heat Flux ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
High Heat Transfer ◽  
Friction Factors ◽  
Turbulent Water

Heat transfer enhancement technology has the aim of developing more efficient systems as demanded in many applications. An available passive method is represented by the employ of rough surfaces. Transversal turbulators enhance the heat transfer rate by reducing the thermal resistance near surfaces, because of the improved local turbulence; on the other hand, higher losses are expected. In this paper, a numerical investigation is carried out on turbulent water forced convection in a ribbed channel. Its external walls are heated by a constant heat flux. Several arrangements of ribs in terms of height, width, and shape are analyzed. The aim is to find the optimal configuration in terms of high heat transfer coefficients and low losses. The maximum average Nusselt numbers are evaluated for dimensionless pitches of 6, 8, and 10 according to the shape while the maximum friction factors are in the range of pitches from 8 to 10.

scholarly journals An Experimental Investigation of Heat Transfer Coefficients in a Spanwise Rotating Channel With Two Opposite Rib-Roughened Walls

1989 ◽  
Author(s):  
M. E. Taslim ◽  
A. Rahman ◽  
S. D. Spring
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Reynolds Numbers ◽  
Blockage Ratio ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
The Heat Transfer Coefficient ◽  
Rotating Channel

Liquid crystals are used in this experimental investigation to measure the heat transfer coefficient in a spanwise rotating channel with two opposite rib-roughened walls. The ribs (also called turbulence promoters or turbulators) are configured in a staggered arrangement with an angle of attack to the mainstream flow, α, of 90° for all cases. Results are presented for three values of turbulator blockage ratio, e/Dh (0.1333, 0.25, 0.333) and for a range of Reynolds numbers from 15,000 to 50,000 while the test section is rotated at different speeds to give Rotational Reynolds numbers between 450 and 1800. The Rossby number range is 10 to 100 (Rotation number of 0.1 to 0.01). The effect of turbulator blockage ratios on heat transfer enhancement is also investigated. Comparisons are made between the results of geometrically identical stationary and rotating passages of otherwise similar operating conditions. The results indicate that a significant enhancement in heat transfer is achieved in both the stationary and rotating cases, when the surfaces are roughened with turbulators. For the rotating case, a maximum increase over that of the stationary case of about 45% in the heat transfer coefficient is seen for a blockage ratio of 0.133 on the trailing surface in the direction of rotation and the minimum is a decrease of about 6% for a blockage ratio of 0.333 on the leading surface, for the range of rotation numbers tested. The technique of using liquid crystals to determine heat transfer coefficients in this investigation proved to be an effective and accurate method especially for nonstationary test sections.

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